Abstract: This paper proposes an approach to the creation of design tools that address the real information needs of designers in the early stages of design of non-residential buildings. Traditional simplified design tools are typically too limited to be of much use, even in conceptual design. The proposal is to provide access to the power of detailed simulation tools, at a stage in design when little is known about the final building, but at a stage also when the freedom to explore options is greatest.

The proposed approach to tool design has been derived from consultation with design analysis teams as part of the COMFEN tool development. The paper explores how tools like COMFEN have been shaped by this consultation and how requests from these teams for real-world relevance might shape such tools in the future, drawing into the simulation process the lessons from Post Occupancy Evaluation (POE) of buildings.

Abstract: The building energy simulation program, Energy Plus (E ), cannot use standard window performance indices (U, SHGC, VT) to model window energy impacts. Rather, E uses more accurate methods which require a physical description of the window. E needs to be able to accept U and SHGC indices as window descriptors because, often, these are all that is known about a window and because building codes, standards, and voluntary programs are developed using these terms.

This paper outlines a procedure, developed for E , which will allow it to use standard window performance indices to model window energy impacts. In this ?Block? model, a given U, SHGC, VT are mapped to the properties of a fictitious ?layer? in E . For thermal conductance calculations, the ?Block? functions as a single solid layer. For solar optical calculations, the model begins by defining a solar transmittance (Ts) at normal incidence based on the SHGC. For properties at non-normal incidence angles, the ?Block? takes on the angular properties of multiple glazing layers; the number and type of layers defined by the U and SHGC.

While this procedure is specific to E , parts of it may have applicability to other window/building simulation programs.

Abstract: Three layer insulating glass units with two low-e coatings and an effective gas fill are known to be highly insulating, with center-of-glass U-factors as low as 0.57 W/m2-K (0.10 Btu/h-ft2-F). Such units have historically been built with center layers of glass or plastic which extend all the way through the spacer system.

This paper shows that triple glazing systems with non-structural center layers which do not create a hermetic seal at the edge have the potential to be as thermally efficient as standard designs, while potentially removing some of the production and product integration issues that have discouraged the use of triples.

Abstract: WINDOW 6 and THERM 6 Research Versions are software programs developed at Lawrence Berkeley National Laboratory (LBNL) for use by manufacturers, engineers, educators, students, architects, and others to determine the thermal and solar optical properties of glazing and window systems. WINDOW 6 and THERM 6 are significant updates to LBNL's WINDOW 5 and THERM 5 computer program because of the added capability to model complex glazing systems, such as windows with shading systems, in particular venetian blinds. Besides a specific model for venetian blinds and diffusing layers, WINDOW 6 also includes the generic ability to model any complex layer if the Transmittance and Reflectance are known as a function of incoming and outgoing angles. WINDOW 6 Research Version includes all of the WINDOW 5 capabilities with the addition of shading algorithms from ISO15099 which are incorporated into the program, as well as an extension of those algorithms with the matrix calculation method. THERM 6 Research Version includes all of the THERM 5 capabilities with the addition of being able to import and model WINDOW 6 glazing systems with shading devices. Those THERM 6 files with shading devices can them be imported into the WINDOW 6 Frame Library and whole windows with shading devices can then be modeled in WINDOW 6.

Abstract: Shade-screens are widely used in commercial buildings as a way to limit the amount of direct sunlight that can disturb people in the building. The shade screens also reduce the solar heat-gain through glazing the system. Modern energy and daylighting analysis software such as EnergyPlus and Radiance require complete scattering properties of the scattering materials in the system.

In this paper a shade screen used in the LBNL daylighting testbed is characterized using a photogoniometer and a normal angle of incidence integrating sphere. The data is used to create a complete bi-directional scattering distribution function (BDSF) that used in simulation programs. The resulting BDSF is compared to a model's BDSF, both directly and by calculating the solar heat-gain coefficient for a dual-pane system using Window 6.

Abstract: While window frames typically represent 20-30% of the overall window area, their impact on the total window heat transfer rates may be much larger. This effect is even greater in low-conductance (highly insulating) windows which incorporate very low conductance glazings. Developing low-conductance window frames requires accurate simulation tools for product research and development. Based on a literature review and an evaluation of current methods of modeling heat transfer through window frames, we conclude that current procedures specified in ISO standards are not sufficiently adequate for accurately evaluating heat transfer through the low-conductance frames. We conclude that the near-term priorities for improving the modeling of heat transfer through low-conductance frames are:

1. Add 2-D view-factor radiation to standard modeling and examine the current practice of averaging surface emissivity based on area weighting and the process of making an equivalent rectangular frame cavity.

2. Assess 3-D radiation effects in frame cavities and develop recommendation for inclusion into the design fenestration tools.

3. Assess existing correlations for convection in vertical cavities using CFD.

4. Study 2-D and 3-D natural convection heat transfer in frame cavities for cavities that are proven to be deficient from item 3 above. Recommend improved correlations or full CFD modeling into ISO standards and design fenestration tools, if appropriate.

5. Study 3 D hardware short-circuits and propose methods to ensure that these effects are incorporated into ratings.

6. Study the heat transfer effects of ventilated frame cavities and propose updated correlations.

Abstract: This paper demonstrates a method to determine the bidirectional transfer distribution function (BTDF) using an integrating sphere. Information about the sample?s angle dependent scattering is obtained by making transmittance measurements with the sample at different distances from the integrating sphere. Knowledge about the illuminated area of the sample and the geometry of the sphere port in combination with the measured data combines to an system of equations that includes the angle dependent transmittance. The resulting system of equations is an ill-posed problem which rarely gives a physical solution. A solvable system is obtained by using Tikhonov regularization on the ill-posed problem. The solution to this system can then be used to obtain the BTDF. Four bulk-scattering samples were characterised using both two goniophotometers and the described method to verify the validity of the new method. The agreement shown is great for the more diffuse samples. The solution to the low-scattering samples contains unphysical oscillations, but still gives the correct shape of the solution. The origin of the oscillations and why they are more prominent in low-scattering samples are discussed.

Abstract: As part of the NFRC rating process, optical data on glazing materials is combined with other information to calculate various properties of a window product. The administrative procedure for gathering such optical data is governed by NFRC 3021, which in turn refers to NFRC 3002 and NFRC 3013 for the technical procedures by which the optical properties are determined in the solar and infrared ranges, respectively. In practice, the data is compiled by the Lawrence Berkeley National Laboratory (LBNL) and becomes part of the International Glazing Database (IGDB).

NFRC 302 specifies that submitters of optical data or their representatives must participate in a ?round robin? or ILC. Often, manufacturers of glazing materials have the optical equipment necessary to perform their own measurements. NFRC 302 allows manufacturers to submit their own measured data subject to a set of checks including peer review to ensure the accuracy of such data. In some cases the glazing manufacturer does not have the required equipment and so may choose to send the samples to a test laboratory. In other cases the manufacturer of the final product such as a laminate may ask a component supplier, often a glass manufacturer, to perform the measurements for them. In such cases the ?representative? must have qualified by participating in the ILC. An ILC is only required every four years and it would be unfair to expect new product submitters to wait so long. Therefore, two interpretations are made on occasion: (1) a new data submitter does not have to wait for the next ILC if they submit a set of samples with their first dataset for comparison at LBNL (a mini ILC), or (2) if they have participated in an ILC conducted by some other reputable independent organization.

Abstract: This document reports the findings of a market and research review related to state-of-the-art highly insulating window frames. The market review focuses on window frames that satisfy the Passivhaus requirements (window U-value less or equal to 0.8 W/m2K), while other examples are also given in order to show the variety of materials and solutions that may be used for constructing window frames with a low thermal transmittance (U-value). The market search shows that several combinations of materials are used in order to obtain window frames with a low U-value. The most common insulating material seems to be Polyurethane (PUR), which is used together with most of the common structural materials such as wood, aluminum, and PVC.

The frame research review also shows examples of window frames developed in order to increase the energy efficiency of the frames and the glazings which the frames are to be used together with. The authors find that two main tracks are used in searching for better solutions. The first one is to minimize the heat losses through the frame itself. The result is that conductive materials are replaced by highly thermal insulating materials and air cavities. The other option is to reduce the window frame area to a minimum, which is done by focusing on the net energy gain by the entire window (frame, spacer and glazing). Literature shows that a window with a higher U-value may give a net energy gain to a building that is higher than a window with a smaller U-value. The net energy gain is calculated by subtracting the transmission losses through the window from the solar energy passing through the windows. The net energy gain depends on frame versus glazing area, solar factor, solar irradiance, calculation period and U-value.

The frame research review also discusses heat transfer modeling issues related to window frames. Thermal performance increasing measures, surface modeling, and frame cavity modeling are among the topics discussed. The review shows that the current knowledge gives the basis for improving the calculation procedures in the calculation standards. At the same time it is room for improvement within some areas, e.g. to fully understand the natural convection effects inside irregular vertical frame cavities (jambs) and ventilated frame cavities.

Abstract: This paper assesses the accuracy of the simplified frame cavity conduction/convection and radiation models presented in ISO 15099 and used in software for rating and labeling window products. Temperatures and U-factors for typical horizontal window frames with internal cavities are compared; results from Computational Fluid Dynamics (CFD) simulations with detailed radiation modeling are used as a reference.

Four different frames were studied. Two were made of polyvinyl chloride (PVC) and two of aluminum. For each frame, six different simulations were performed, two with a CFD code and four with a building-component thermal-simulation tool using the Finite Element Method (FEM). This FEM tool addresses convection using correlations from ISO 15099; it addressed radiation with either correlations from ISO 15099 or with a detailed, view-factor-based radiation model. Calculations were performed using the CFD code with and without fluid flow in the window frame cavities; the calculations without fluid flow were performed to verify that the CFD code and the building-component thermal-simulation tool produced consistent results. With the FEM-code, the practice of subdividing small frame cavities was examined, in some cases not subdividing, in some cases subdividing cavities with interconnections smaller than five millimeters (mm) (ISO 15099) and in some cases subdividing cavities with interconnections smaller than seven mm (a breakpoint that has been suggested in other studies). For the various frames, the calculated U-factors were found to be quite comparable (the maximum difference between the reference CFD simulation and the other simulations was found to be 13.2 percent). A maximum difference of 8.5 percent was found between the CFD simulation and the FEM simulation using ISO 15099 procedures. The ISO 15099 correlation works best for frames with high U-factors. For more efficient frames, the relative differences among various simulations are larger. Temperature was also compared, at selected locations on the frames. Small differences was found in the results from model to model.

Finally, the effectiveness of the ISO cavity radiation algorithms was examined by comparing results from these algorithms to detailed radiation calculations (from both programs). Our results suggest that improvements in cavity heat transfer calculations can be obtained by using detailed radiation modeling (i.e. view-factor or ray-tracing models), and that incorporation of these strategies may be more important for improving the accuracy of results than the use of CFD modeling for horizontal cavities.

Abstract: A field evaluation comparing the performance of low emittance (low-e) storm windows with both standard clear storm windows and no storm windows was performed in a cold climate. Six homes with single pane windows were monitored over the period of one heating season. The homes were monitored with no storm windows and with new storm windows. The storm windows installed on four of the six homes included a hard coat, pyrolitic, low-e coating while the storm windows for the other two homes had traditional clear glass. Overall heating load reduction due to the storm windows was 13% with the clear glass and 21% with the low-e windows. Simple paybacks for the addition of the storm windows were 10 years for the clear glass and 4.5 years for the low-e storm windows.

Abstract: A nine-month monitored field study of the performance of automated roller shades and daylighting controls was conducted in a 401 m2 unoccupied, furnished daylighting mockup. The mockup mimicked the southwest corner of a new 110 km2 commercial building in New York, New York, where The New York Times will be the major tenant. This paper focuses on evaluating the performance of two daylighting control systems installed in separate areas of an open plan office with 1.2-m high workstation partitions: 1) Area A had 0-10 V dimmable ballasts with an open-loop proportional control system and an automated shade controlled to reduce window glare and increase daylight, and 2) Area B had digital addressable lighting interface (DALI) ballasts with a closed-loop integral reset control system and an automated shade controlled to block direct sun. Daylighting control system performance and lighting energy use were monitored. The daylighting control systems demonstrated very reliable performance after they were commissioned properly. Work plane illuminance levels were maintained above 90% of the maximum fluorescent illuminance level for 99.9 /-0.5% and 97.9 /-6.1% of the day on average over the monitored period, respectively, in Areas A and B. Daily lighting energy use savings were significant in both Areas over the equinox-to-equinox period compared to a non-daylit reference case. At 3.35 m from the window, 30% average savings were achieved with a sidelit west-facing condition in Area A while 50-60% were achieved with a bilateral daylit south-facing condition in Area B. At 4.57-9.14 m from the window, 5-10% and 25-40% savings were achieved in Areas A and B, respectively. Average savings for the 7-m deep dimming zone were 20-23% and 52-59% for Areas A and B, respectively, depending on the lighting schedule. The large savings and good reliability can be attributed to the automatic management of the interior shades. The DALI-based system exhibited faulty behavior that remains unexplained, but operational errors are expected to be resolved as DALI products reach full maturity. The building owner received very competitive bids ($30-75 US/DALI ballast) and was able to justify use of the daylighting control system based on operational cost savings and increased amenity. Additional energy savings due to reduced solar and lighting heat gains were not quantified but will add to the total operational cost savings.

Abstract: We present a simple spreadsheet-based tool for estimating window-related energy consumption in the United States. Using available data on the properties of the installed US window stock, we estimate that windows are responsible for 2.15 quadrillion Btu (Quads) of heating energy consumption and 1.48 Quads of cooling energy consumption annually. We develop estimates of average U-factor and SHGC for current window sales. We estimate that a complete replacement of the installed window stock with these products would result in energy savings of approximately 1.2 quads. We demonstrate that future window technologies offer energy savings potentials of up to 3.9 Quads.

Abstract: Windows in the U.S. consume 30 percent of building heating and cooling energy, representing an annual impact of 4.1 quadrillion BTU (quads) of primary energy. Windows have an even larger impact on peak energy demand and on occupant comfort. An additional 1 quad of lighting energy could be saved if buildings employed effective daylighting strategies.

The ENERGY STAR(r) program has made standard windows significantly more efficient. However, even if all windows in the stock were replaced with today"s efficient products, window energy consumption would still be approximately 2 quads. However, windows can be net energy gainers or zero-energy products. Highly insulating products in heating applications can admit more useful solar gain than the conductive energy lost through them. Dynamic glazings can modulate solar gains to minimize cooling energy needs and, in commercial buildings, allow daylighting to offset lighting requirements. The needed solutions vary with building type and climate. Developing this next generation of zero-energy windows will provide products for both existing buildings undergoing window replacements and products which are expected to be contributors to zero-energy buildings.

This paper defines the requirements for zero-energy windows. The technical potentials in terms of national energy savings and the research and development (R&D) status of the following technologies are presented:

- Highly insulating systems with U-factors of 0.1 Btu/hr-ft_-?F

- Dynamic windows: glazings that modulate transmittance (i.e., change from clear to tinted and/or reflective) in response to climate conditions

- Integrated facades for commercial buildings to control/ redirect daylight

Market transformation policies to promote these technologies as they emerge into the marketplace are then described.

Abstract: The nucleation and coalescence of silver islands on coated glass was investigated by in-situ measurements of the sheet resistance. Sub-monolayer amounts of transition metals (Nb, Ti, Ni, Cr, Zr, Ta, and Mo) were deposited prior to the deposition of silver. It was found that some, but not all, of the transition metals lead to coalescence of silver at nominally thinner films with smoother topology. The smoothing effect of the transition metal at sub-monolayer thickness can be explained by a thermodynamic model of surface energies.

Abstract: It is well known that the structure and properties of diamond-like carbon, and in particular the sp3/sp2 ratio, can be controlled by the energy of the condensing carbon ions or atoms. In many practical cases, the energy of ions arriving at the surface of the growing film is determined by the bias applied to the substrate. The bias causes a sheath to form between substrate and plasma in which the potential difference between plasma potential and surface potential drops. In this contribution, we demonstrate that the same results can be obtained with grounded substrates by shifting the plasma potential. This plasma biasing (as opposed to substrate biasing) is shown to work well with pulsed cathodic carbon arcs, resulting in tetrahedral amorphous carbon (ta-C) films that are comparable to the films obtained with the conventional substrate bias. To verify the plasma bias approach, ta-C films were deposited by both conventional and plasma bias and characterized by transmission electron microscopy (TEM) and electron energy loss spectrometry (EELS). Detailed data for comparison of these films are provided.

Abstract: Computer modeling to determine fenestration product energy properties (U-factor, SHGC, VT) has emerged as the most cost-effective and accurate means to quantify them. Fenestration product simulation tools have been effective in increasing the use of low-e coatings and gas fills in insulating glass and in the widespread use of insulating frame designs and materials. However, for more efficient fenestration products (low heat loss products, dynamic products, products with non-specular optical characteristics, light redirecting products) to achieve widespread use, fenestration modeling software needs to be improved.

This paper addresses the following questions:

1) Are the current properties (U, SHGC, VT) calculated sufficient to compare and distinguish between windows suitable for Zero Energy Buildings and conventional window products? If not, what data on the thermal and optical performance, on comfort, and on peak demand of windows is needed.

2) Are the algorithms in the tools sufficient to model the thermal and optical processes? Are specific heat transfer and optical effects not accounted for? Is the existing level of accuracy enough to distinguish between products designed for Zero Energy Buildings? Is the current input data adequate?

Abstract: A review is provided covering metal plasma production, the energetic condensation of metal plasmas, and the formation of nanostructures using such plasmas. Plasma production techniques include pulsed laser ablation, filtered cathodic arcs, and various forms of ionized physical vapor deposition, namely magnetron sputtering with ionization of sputtered atoms in radio frequency discharges, self-sputtering, and high power impulse magnetron sputtering. The discussion of energetic condensation focuses on the control of kinetic energy by biasing and also includes considerations of the potential energy and the processes occurring at subplantation and implantation. In the final section on nanostructures, two different approaches are discussed. In the top-down approach, the primary nanostructures are lithographically produced and metal plasma is used to coat or fill trenches and vias. Additionally, multilayers with nanosize periods (nanolaminates) can be produced. In the bottom-up approach, thermodynamic forces are used to fabricate nanocomposites and nanoporous materials by decomposition and dealloying.

Abstract: This paper shows that the energy requirements for today's typical efficient window products (i.e. ENERGY STAR products) are significant when compared to the needs of Zero Energy Homes (ZEHs). Through the use of whole house energy modeling, typical efficient products are evaluated in five US climates and compared against the requirements for ZEHs. Products which meet these needs are defined as a function of climate. In heating dominated climates, windows with U-factors of 0.10 Btu/hr-ft2-F (0.57 W/m2-K) will become energy neutral. In mixed heating/cooling climates a low U-factor is not as significant as the ability to modulate from high SHGCs (heating season) to low SHGCs (cooling season).

Abstract: Switchable variable-tint electrochromic windows preserve the view out while modulating transmitted light, glare, and solar heat gains and can reduce energy use and peak demand. To provide designers objective information on the risks and benefits of this technology, this study offers data from simulations, laboratory tests, and a 2.5-year field test of prototype large-area electrochromic windows evaluated under outdoor sun and sky conditions. The study characterized the prototypes in terms of transmittance range, coloring uniformity, switching speed, and control accuracy. It also integrated the windows with a daylighting control system and then used sensors and algorithms to balance energy efficiency and visual comfort, demonstrating the importance of intelligent design and control strategies to provide the best performance. Compared to an efficient low-e window with the same daylighting control system, the electrochromic window showed annual peak cooling load reductions from control of solar heat gains of 19-26% and lighting energy use savings of 48-67% when controlled for visual comfort. Subjects strongly preferred the electrochromic window over the reference window, with preferences related to perceived reductions in glare, reflections on the computer monitor, and window luminance. The EC windows provide provided the benefit of greater access to view year-round. Though not definitive, findings can be of great value to building professionals.

Abstract: This guide provides consumer-oriented information about switchable electrochromic (EC) windows. Electrochromic windows change tint with a small applied voltage, providing building owners and occupants with the option to have clear or tinted windows at any time, irrespective of whether it's sunny or cloudy. EC windows can be manually or automatically controlled based on daylight, solar heat gain, glare, view, energy-efficiency, peak electricity demand response, or other criteria. Window controls can be integrated with other building systems, such as lighting and heating/cooling mechanical systems, to optimize interior environmental conditions, occupant comfort, and energy-efficiency.

Abstract: In this study, various facade designs with overhangs combined with electrochromic (EC) window control strategies were modeled for a typical commercial office building in a hot and cold climate using the DOE 2.1E building energy simulation program. EC windows were combined with overhangs since opaque overhangs provide protection from direct sun which EC windows are unable to do alone. The window wall was divided into an upper and lower aperture so that various combinations of overhang position and control strategies could be considered. The overhang was positioned either at the top of the upper window aperture or between the upper and lower apertures. Overhang depth was varied. EC control strategies were fully bleached at all times, modulated based on incident vertical solar radiation limits, or modulated to meet the design work plane illuminance with daylight. Annual total energy use (ATE), peak electric demand (PED), average daylight illuminance (DI), and daylight glare index (DGI) for south-facing private offices were computed and compared to determine which combinations of fa?ade design and control strategies yielded the greatest energy efficiency, daylight amenity, and visual comfort.

Abstract: After pioneering work in the 1980s, plasma-based ion implantation (PBII) and plasma-based ion implantation and deposition (PBIID) can now be considered mature technologies for surface modification and thin film deposition. This review starts by looking at the historical development and recalling the basic ideas of PBII. Advantages and disadvantages are compared to conventional ion beam implantation and physical vapor deposition for PBII and PBIID, respectively, followed by a summary of the physics of sheath dynamics, plasma and pulse specifications, plasma diagnostics, and process modelling. The review moves on to technology considerations for plasma sources and process reactors. PBII surface modification and PBIID coatings are applied in a wide range of situations. They include the by-now traditional tribological applications of reducing wear and corrosion through the formation of hard, tough, smooth, low-friction and chemically inert phases and coatings, e.g. for engine components. PBII has become viable for the formation of shallow junctions and other applications in microelectronics. More recently, the rapidly growing field of biomaterial synthesis makes used of PBII&D to produce surgical implants, bio- and blood-compatible surfaces and coatings, etc. With limitations, also non-conducting materials such as plastic sheets can be treated. The major interest in PBII processing originates from its flexibility in ion energy (from a few eV up to about 100 keV), and the capability to efficiently treat, or deposit on, large areas, and (within limits) to process non-flat, three-dimensional workpieces, including forming and modifying metastable phases and nanostructures. We use the acronym PBII&D when referring to both implantation and deposition, while PBIID implies that deposition is part of the process.

Abstract: Arcing on sputter targets and negatively biased substrates is known as one of the most challenging issues in physical vapor deposition of thin films and coatings. This is particularly true when high-rate deposition with reactive gases, large area deposition, and high power pulsed sputtering are considered. Much progress has been made in the development of power supplies that can handle arcing events with minimal damage to target and substrate. However, relatively little is known about the processes leading to arcs and the physics of the arcing events themselves. In this contribution, the issue of arcing is approached from the point of view of arc physics. Current knowledge of arcing and arc suppression is reviewed.

(Note: PDF contains both LBNL-54220 & LBNL-54220 Journal.)

Abstract: In this study, various facade designs with overhangs combined with electrochromic window control strategies were modeled with a prototypical commercial office building in a hot and cold climate using the DOE 2.1E building energy simulation program. Annual total energy use (ATE), peak electric demand (PED), average daylight illuminance (DI), and daylight glare index (DGI) were computed and compared to determine which combinations of fa?ade design and control strategies yielded the greatest energy efficiency, daylight amenity, and visual comfort.

Abstract: Forty-three subjects worked in a private office with switchable electrochromic windows, manually-operated Venetian blinds, and dimmable fluorescent lights. The electrochromic window had a visible transmittance range of approximately 3-60%. Analysis of subject responses and physical data collected during the work sessions showed that the electrochromic windows reduced the incidence of glare compared to working under a fixed transmittance (60%) condition. Subjects used the Venetian blinds less often and preferred the variable transmittance condition, but used slightly more electric lighting with it than they did when window transmittance was fixed.

Abstract: Efficient deposition of high-quality coatings often requires controlled application of excited or ionized particles. These particles are either condensing (film-forming) or assisting by providing energy and momentum to the film growth process, resulting in densification, sputtering/etching, modification of stress, roughness, texture, etc. In this review, the technical means are surveyed enabling large area application of ions and plasmas, with ion energies ranging from a few eV to a few keV. Both semiconductor-type large area (single wafer or batch processing with ~ 1000 cm2) and in-line web and glass-coating-type large area (> 107 m2 annually) are considered. Characteristics and differences between plasma and ion sources are explained. The latter include gridded and gridless sources. Many examples are given, including sources based on DC, RF, and microwave discharges, some with special geometries like hollow cathodes and E x B configurations.

Abstract: DElight is a simulation engine for daylight and electric lighting system analysis in buildings. DElight calculates interior illuminance levels from daylight, and the subsequent contribution required from electric lighting to meet a desired interior illuminance. DElight has been specifically designed to integrate with building thermal simulation tools. This paper updates the DElight capability set, the status of integration into the simulation tool EnergyPlus, and describes a sample analysis of a simple model from the user perspective.

Abstract: DOE-2 building energy simulations were conducted to determine if there were practical architectural and control strategy solutions that would enable electrochromic (EC) windows to significantly improve visual comfort without eroding energy-efficiency benefits. EC windows were combined with overhangs since opaque overhangs provide protection from direct sun which EC windows are unable to do alone. The window wall was divided into an upper and lower aperture so that various combinations of overhang position and control strategies could be considered. The overhang was positioned either at the top of the upper window aperture or between the upper and lower apertures. Overhang depth was varied. EC control strategies were fully bleached at all times, modulated based on incident vertical solar radiation limits, or modulated to meet the design work plane illuminance with daylight. The EC performance was compared to a state-of-the-art spectrally selective low-e window with the same divided window wall, window size, and overhang as the EC configuration. The reference window was also combined with an interior shade which was manually deployed to control glare and direct sun. Both systems had the same daylighting control system to dim the electric lighting. Results were given for south-facing private offices in a typical commercial building.

In hot and cold climates such as Houston and Chicago, EC windows with overhangs can significantly reduce the average annual daylight glare index (DGI) and deliver significant annual energy use savings if the window area is large. Total primary annual energy use was increased by 2-5% for moderate-area windows in either climate but decreased by 10% in Chicago and 5% in Houston for large-area windows. Peak electric demand can be reduced by 7-8% for moderate-area windows and by 14-16% for large-area windows in either climate. Energy and peak demand reductions can be significantly greater if the reference case does not have exterior shading or state-of-the-art glass.

Abstract: A 20-month field study was conducted to measure the energy performance of south-facing large-area tungsten-oxide absorptive electrochromic (EC) windows with a broad switching range in a private office setting. The EC windows were controlled by a variety of means to bring in daylight while minimizing window glare. For some cases, a Venetian blind was coupled with the EC window to block direct sun. Some tests also involved dividing the EC window wall into zones where the upper EC zone was controlled to admit daylight while the lower zone was controlled to prevent glare yet permit view. If visual comfort requirements are addressed by EC control and Venetian blinds, a 2-zone EC window configuration provided average daily lighting energy savings of 10?15% compared to the reference case with fully lowered Venetian blinds. Cooling load reductions were 0?3%. If the reference case assumes no daylighting controls, lighting energy savings would be 44?11%. Peak demand reductions due to window cooling load, given a critical demand-response mode, were 19-26% maximum on clear sunny days. Peak demand reductions in lighting energy use were 0% or 72-100% compared to a reference case with and without daylighting controls, respectively. Lighting energy use was found to be very sensitive to how glare and sun is controlled. Additional research should be conducted to fine-tune EC control for visual comfort based on solar conditions so as to increase lighting energy savings.

Abstract: Control system development and lighting energy monitoring of ceramic thin-film electrochromic (EC) windows were initiated at the new full-scale Window Systems testbed facility at the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, California. The new facility consists of three identically configured side-by-side private offices with large-area windows that face due south. In one room, an array of EC windows with a center-of-glass visible transmittance (Tv) range of 0.05-0.60 was installed. In the two other rooms, unshaded windows with a Tv=0.50 or 0.15 were used as reference. The same dimmable fluorescent lighting system was used in all three rooms. This study explains the design and commissioning of an integrated EC window-lighting control system and then illustrates its performance in the testbed under clear, partly cloudy, and overcast sky conditions during the equinox period. The performance of an early prototype EC window controller is also analyzed. Lighting energy savings data are presented. Daily lighting energy savings were 44-59% compared to the reference window of Tv=0.15 and 8-23% compared to the reference window of Tv=0.50. The integrated window-lighting control system maintained interior illuminance levels to within ?10% of the setpoint range of 510-700 lux for 89-99% of the day. Further work is planned to refine the control algorithms and monitor cooling load, visual comfort, and human factor impacts of this emerging technology.

Abstract: Accurately analyzing heat transfer in window frames and glazings is important for developing and characterizing the performance of highly insulating window products. This paper uses computational fluid dynamics (CFD) modeling to assess the accuracy of the simplified frame cavity conduction/convection models presented in ISO 15099 and used in software for rating and labeling window products. Three representative complex cavity cross-section profiles with varying dimensions and aspect ratios are examined. The results presented support the ISO 15099 rule that complex cavities with small throats should be subdivided; however, our data suggest that cavities with throats smaller than 7 mm should be subdivided, in contrast to the ISO 15099 rule, which places the break point at 5 mm. The agreement between CFD modeling results and the results of the simplified models is moderate for the heat transfer rates through the cavities. The differences may be a result of the underlying ISO 15099 Nusselt number correlations being based on studies where cavity height/length aspect ratios were smaller than 0.5 and greater than 5 (with linear interpolation assumed in between). The results presented here are for horizontal frame members because convection in vertical jambs involves very different aspect ratios that require three-dimensional CFD simulations.

Abstract: A computer tool such as RESFEN can help consumers and builders pick the most energy-efficient and cost-effective window for a given application, whether it is a new home, an addition, or a window replacement. It calculates heating and cooling energy use and associated costs as well as peak heating and cooling demand for specific window products. Users define a specific "scenario" by specifying house type (single-story or two-story), geographic location, orientation, electricity and gas cost, and building configuration details (such as wall, floor, and HVAC system type). Users also specify size, shading, and thermal properties of the window they wish to investigate. The thermal properties that RESFEN requires are: U-factor, Solar Heat Gain Coefficient, and air leakage rate. RESFEN calculates the energy and cost implications of the window compared to an insulated wall. The relative energy and cost impacts of two different windows can be compared.

RESFEN 3.0 was a major improvement over previous versions because it performs hourly calculations using a version of the DOE 2.1E (LBL 1980, Winkelmann et al. 1993) energy analysis simulation program. RESFEN 3.1 incorporates additional improvements including input assumptions for the base case buildings taken from the National Fenestration Rating Council (NFRC) Annual Energy Subcommittee's efforts

Abstract: A low-cost building communications network is needed that would allow individual window and lighting loads to be controlled fromsan existing enterprise LAN network. This building communications network concept, which we term Integrated Building EnvironmentalsCommunications System (IBECSTM), would enable both occupant-based and building-wide control of individual window, lighting, andssensor devices. IBECS can reduce the cost of systemic control because it allows a drastic cost reduction in per point networking costs.sThis kind of effort is needed to encourage the control industry to make the commitment to build this technology and to demonstratesto prospective customers that this breakthrough approach to more comprehensive systemic control will provide them with high-quality,sconvenient control while saving them money.

The development and demonstration of network interfaces to DC- and AC-motorized shades and to an electrochromic window aresdescribed. The network interfaces enable one to control and monitor the condition of these fenestration appliances from a variety of sources,sincluding a user?s personal computer. By creating a functional specification for an IBECS network interface and testing a prototype, thesability to construct such an interface was demonstrated and the cost-effective price per point better understood. The network interfacesswere demonstrated to be reliable in a full-scale test of three DC-motorized Venetian blinds in an open-plan office over 2 years and in limitedsbench-scale tests of an electrochromic window.

Abstract: The effect of ion mass and charge state on plasma transport through a 90 deg.-curved magnetic filter is experimentally investigated using a pulsed cathodic arc source. Graphite, copper, and tungsten were selected as test materials. The filter was a bent copper coil biased via the voltage drop across a low-ohm, selfbias resistor. Ion transport is accomplished via a guiding electric field, whose potential forms a trough shaped by the magnetic guiding field of the filter coil. Evaluation was done by measuring the filtered ion current and determination of the particle system coefficient, which can be defined as the ratio of filtered ion current, divided by the mean ion charge state, to the arc current. It was found that the ion current and particle system coefficient decreased as the mass-to-charge ratio of ions increased. This result can be qualitatively interpreted by a very simple model of ion transport that is based on compensation of the centrifugal force by the electric force associated with the guiding potential trough.

Abstract: Most commercial buildings utilize windows and other glazed envelope components for a variety of reasons. Glass is a key element in the architectural expression of the building and typically provides occupants with a visual connection with the outdoors and daylight to enhance the quality of the indoor environment. But the building skin must serve a crucial function in its role to help maintain proper interior working environments under extremes of external environmental conditions. Exterior temperature conditions vary slowly over a wide range and solar and daylight fluxes can vary very rapidly over a very wide range. The technical problem of controlling heat loss and gain is largely solved with highly insulating glazing technologies on the market today. The challenge of controlling solar gain and managing daylight, view and glare is at a much earlier stage. In most cases a static, fixed control solution will not suffice. Some degree of active, rapid response to changing outdoor conditions and to changing interior task requirements is needed. This can be provided with technology within the glass or glazing assembly itself, or the functionality can be added to the facade either on the interior or exterior of the glazing. In all cases sensors, actuators, and a control logic must be applied for proper functionality. Traditional manually operated mechanical shading systems such as blinds or shades can be motorized and then controlled by occupant action or by sensors and building controls. Emerging smart glass technology can dynamically change optical properties, and can be activated manually or by automated control systems. In all of these cases electric lighting should be controlled to meet occupant needs, while maximizing energy efficiency and minimizing electric demand. As with the fenestration controls, lighting control requires sensors (photocells or the human eye), actuation (switching or dimming) and a control logic that determines what action should be taken under each set of conditions. Some variation on the combination of all of these elements comprises the typical equipment and systems found in most commercial buildings today. The new challenge is to provide a fully functional and integrated facade and lighting system that operates appropriately for all environmental conditions and meets a range of occupant subjective desires and International Symposium on objective performance requirements. And finally these rigorous performance goals must be achieved with solutions that are cost effective and operate over long periods with minimal maintenance.

Abstract: Switchable electrochromic (EC) windows have been projected to significantly reduce the energy use of buildings nationwide. This study quantifies the potential impact of electrochromic windows on US primary energy use in the commercial building sector and also provides a broader database of energy use and peak demand savings for perimeter zones than that given in previous LBNL simulation studies. The DOE-2.1E building simulation program was used to predict the annual energy use of a three-story prototypical commercial office building located in five US climates and 16 California climate zones. The energy performance of an electrochromic window controlled to maintain daylight illuminance at a prescribed setpoint level is compared to conventional and the best available commercial windows as well as windows defined by the ASHRAE 90.1-1999 and California Title 24-2005 Prescriptive Standards. Perimeter zone energy use and peak demand savings data by orientation, window size, and climate are given for windows with interior shading, attached shading, and horizon obstructions (to simulate an urban environment).

Perimeter zone primary energy use is reduced by 10-20% in east, south, and west zones in most climates if the commercial building has a large window-to-wall area ratio of 0.60 compared to a spectrally selective low-e window with daylighting controls and no interior or exterior shading. Peak demand for the same condition is reduced by 20-30%. The emerging electrochromic window with daylighting controls is projected to save approximately 91.5-97.3 1012 Btu in the year 2030 compared to a spectrally selective low-E window with manually-controlled interior shades and no daylighting controls if it reaches a 40% market penetration level in that year.

Abstract: Automated shading and daylighting control systems have been commercially available for decades. The new challenge is to provide a fully functional and integrated facade and lighting system that operates appropriately for all environmental conditions and meets a range of occupant subjective desires and objective performance requirements. These rigorous performance goals must be achieved with solutions that are cost effective and can operate over long periods with minimal maintenance. It will take time and effort to change the marketplace for these technologies and practices, particularly in building a series of documented success stories, and driving costs and risks to much lower levels at which their use becomes the norm. In recent years, the architectural trend toward highly-transparent all-glass buildings presents a unique challenge and opportunity to advance the market for emerging, smart, dynamic window and dimmable daylighting control technologies.

We believe it is possible to accelerate product market transformation by developing projects where technical advances and the interests of motivated manufacturers and innovative owners converge. In this paper we present a case study example that explains a building owner"s decision-making process to use dynamic window and dimmable daylighting controls. The case study project undertaken by a major building owner in partnership with a buildings R&D group was designed explicitly to use field test data in conjunction with the market influence of a major landmark building project in New York City to stimulate change in manufacturers" product offerings. Preliminary observations on the performance of these systems are made. A cost model that was developed with the building owner is explained.

Abstract: The authors explore the feasibility of adding a performance option to DOE"s EnergyStar Windows program whereby windows of differing U-factors and SHGCs can qualify so long as they have equivalent annual energy performance. An iterative simulation procedure is used to calculate trade-off equations giving the change in SHGC needed to compensate for a change in U-factor. Of the four EnergyStar Window climate zones, trade-off equations are possible only in the Northern and Southern zones. In the North/Central and South/Central zones, equations are not possible either because of large intrazone climate variations or the current SHGC requirements are already near optimum.

Abstract: The condensation of energetic metal ions on a surface may cause self-sputtering even in the absence of substrate bias. Charge-state-averaged self-sputtering yields were determined for both zirconium and gold ions generated by a cathodic vacuum arc. Films were deposited on differently biased substrates exposed to streaming Zr and Au vacuum arc plasma. The self-sputtering yields for both metals were estimated to be about 0.05 in the absence of bias, and exceeding 0.5 when bias reached - 50 V. These surprisingly high values can be reconciled with binary collision theory and molecular dynamics calculations taking high the kinetic and potential energy of vacuum arc ions into account.

Abstract: We present the concept for a smart highly efficient dynamic window that maximizes solar heat gain during the heating season and minimizes solar heat gain during the cooling season in residential buildings. We describe a prototype dynamic window that relies on an internal shade, which deploys automatically in response to solar radiation and temperature. This prototype was built at Lawrence Berkeley National Laboratory from commercially available off-the-shelf components. It is a stand-alone, standard-size product, so it can be easily installed in place of standard window products. Our design shows promise for near-term commercialization. Improving thermal performance of this prototype by incorporating commercially available highly efficient glazing technologies could result in the first window that could be suitable for use in zero-energy homes. The unit"s predictable deployment of shading could help capture energy savings that are not possible with manual shading. Installation of dynamically shaded windows in the field will allow researchers to better quantify the energy effects of shades, which could lead to increased efficiency in the sizing of heating, ventilation, and air conditioning equipment for residences.

Abstract: Experimentally observed charge state distributions are known to be higher at the beginning of each arc discharge. Up to know, this has been attributed to cathode surface effects in terms of changes of temperature, chemical composition and spot mode. Here it is shown that the initial decay of charge states of cathodic arc plasmas may at least in part due to charge exchange collisions of ions with neutrals that gradually fill the discharge volume. Sources of neutrals may include evaporated atoms from macroparticles and still-hot craters of previously active arc spots. More importantly, atoms are also produced by energetic condensation of the cathodic arc plasma. Self-sputtering is significant when ions impact with near-normal angle of incidence, and ions have low sticking probability when impacting at oblique angle of incidence. Estimates show that the characteristic time for filling the near-cathode discharge volume agrees well with the charge state decay time, and the likelihood of charge exchange is reasonably large to be taken into account.

Abstract: The charge-state-resolved ion energy distributions of metal ions present in a cathodic arc plasma have been measured and analyzed. Contrary to literature data, lower energies were observed for higher charged ions. The observations were explained by opposing acceleration by pressure gradient and electron-ion coupling, and deceleration by part of the discharge voltage. The distributions were well fitted by shifted Maxwellian distributions, giving additional information on plasma parameters. These results are of importance for an improved understanding of the evolution of ion energy distributions, and is hence instrumental for future progress in thin film growth modelling.

Abstract: This document, the THERM 5 / WINDOW 5 NFRC Simulation Manual, discusses how to use the THERM and WINDOW programs to model products for NFRC certified simulations and assumes that the user is already familiar with those programs. In order to learn how to use these programs, it is necessary to become familiar with the material in both the THERM User"s Manual and the WINDOW User"s Manual. In general, this manual references the User"s Manuals rather than repeating the information.

If there is a conflict between either of the User Manual and this THERM 5 / WINDOW 5 NFRC Simulation Manual, the THERM 5 / WINDOW 5 NFRC Simulation Manual takes precedence. In addition, if this manual is in conflict with any NFRC standards, the standards take precedence. For example, if samples in this manual do not follow the current taping and testing NFRC standards, the standards not the samples in this manual, take precedence.

Abstract: Ultrathin silver films that are not continuous show relatively high absorption in the visible and low reflection in the infrared. For low-emissivity application on window glass, coalescence of silver islands is crucial for obtaining the desired optical properties of the coating, namely high transparence in the visible and high reflectivity in the infrared. It is well known that the energy of ions arriving at the substrate and the type of underlayer affect nucleation and growth of silver islands. There are a number of studies on nucleation and growth, but little is known about coalescence of silver islands synthesized by more energetic condensation, e.g. filtered cathodic vacuum arc (FCVA). In this work, the effect of underlayer on nucleation and growth of silver films deposited by FCVA was investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). The results arescompared with data obtained by magnetron sputtering.

From the results, plane and titanium-oxide-coated glass requires more material to achieve the same value of resistance than for the zinc oxide coated glass. It is related with the energy of interaction between the surface and the silver atom. Silver films made by cathodic arc deposition show an earlier onset of island coalescence and formation of short links. It was found that silver islands in energetic deposition exhibit a reduced aspect ratio when compared to evaporation and sputtering. Nb underlayer affects nucleation and growth of coalescence of silver only in the case of few monolayer of Nb was introduced.

Abstract: Pulsed plasmas offer the use of much higher power (during each pulse) compared to continuously operatedsplasmas, and additional new parameters appear such as pulse duty cycle. Pulsed processing may helpsmeeting the demands of increasingly sophisticated materials processes, including thin film deposition,splasma etching, plasma cleaning of surfaces, and plasma immersion ion implantation. The high kineticsenergy of ions allows processes to occur far from thermodynamic equilibrium. Pulsed plasmas are drivensby external pulsed power sources, and one has to consider the power source and the plasma as a coupledssystem. The dynamic plasma impedance is a key quantity from an electrical engineering point of view.sFrom a plasma physics point of view, one needs to consider the dynamics of plasma species, their densitysand energy distribution, ionization and recombination reactions, and, most importantly, the development ofstransient sheaths. Dimensionless scaling parameters are a useful tool putting the variety of plasmasparameters in relation to characteristic quantities. This is illustrated by several examples of pulsedsprocesses relevant to thin film deposition. The emerging technology of pulsed sputtering is discussed insdetail including the possibility to achieve the mode of self-sustained self-sputtering during each pulse.

Abstract: A variety of coatings is commercially produced on a very large scale, including transparent conducting oxides and multi-layer silver-based low-emissivity and solar control coatings. A very brief review of materials and manufacturing process is presented and illustrated by ultrathin silver films and chevron copper films. Understanding the close relation between manufacturing processes and bulk and surface properties of materials is crucial for film growth and self-assembly processes.

Abstract: Accurately analyzing heat transfer in window frame cavities is essential for developing and characterizing the performance of highly insulating window products. Window frame thermal performance strongly influences overall product thermal performance because framing materials generally perform much more poorly than glazing materials. This paper uses Computational Fluid Dynamics (CFD) modeling to assess the accuracy of the simplified frame cavity conduction/convection models presented in ISO 15099 and used in software for rating and labeling window products. (We do not address radiation heat-transfer effects.) We examine three representative complex cavity cross-section profiles with varying dimensions and aspect ratios. Our results support the ISO 15099 rule that complex cavities with small throats should be subdivided; however, our data suggest that cavities with throats smaller than seven millimeters (mm) should be subdivided, in contrast to the ISO 15099 rule, which places the break point at five mm. The agreement between CFD modeling results and the results of the simplified models is moderate. The differences in results may be a result of the underlying ISO correlations being based on studies where cavity height/length (H/L) aspect ratios were smaller than 0.5 and greater than five (with linear interpolation assumed in between). The results presented here are for horizontal frame members because convection in vertical jambs involves very different aspect ratios that require three-dimensional CFD simulations. Ongoing work focuses on quantifying the exact effect on window thermal performance indicators of using the ISO 15099 approximations in typical real window frames.

Abstract: Antimony, antimony-copper, and antimony-silver thin films were prepared by DC magnetron sputtering on glass substrates. Their reflectance and transmittance in the visible range were measured before and after electrochemical lithiation. The mixed metal films exhibited larger changes in reflectance and small shifts in the optical absorption edge compared with pure antimony films. Electrochromic cycling speed and stability of the Sb-Li system were improved by the addition of copper and silver.

Abstract: Arc and glow discharges are defined based on their cathode processes. Arcs are characterized by collective electron emission, which can be stationary with hot cathodes (thermionic arcs), or nonstationary with cold cathodes (cathodic arcs). A brief review on cathodic arc properties serves as the starting point to better understand arcing phenomena in sputtering. Although arcing occurs in both metal and reactive sputtering, it is more of an issue in the reactive case. Arcing occurs if sufficiently high field strength leads to thermal runaway of an electron emission site. The role of insulating layers and surface potential adjustment through current leakage is highlighted. In the situation of magnetron sputtering with racetrack, the need for a model with two spatial dimensions is shown. In many cases, arcing is initiated by breakdown of dielectric layers and inclusions. It is most efficiently prevented if formation and excessive charge-up of dielectric layers and inclusions can be avoided.

(Note: PDF contains both LBNL-54220 & LBNL-54220 Journal.)

Abstract:

Abstract: Thick and multilayered glazings generally have a nonuniform distribution of absorbed solar radiation which is not taken into account by current methods for calculating the center of glass solar gain and thermal performance of glazing systems. This paper presents a more accurate method for calculating the distribution of absorbed solar radiation inside thick and multilayered glazings and demonstrates that this can result in a small but significant difference in steady-state temperature profile and Solar Heat Gain Coefficient for some types of glazing systems when compared to the results of current methods. This indicates that a more detailed approach to calculating the distribution of absorbed solar radiation inside glazings and resulting thermal performance may be justified for certain applications.

Abstract: A DOE-2.1E energy simulation analysis of a switchable electrochromic (EC) glazing with daylighting controls has been conducted for prototypical office buildings in New York (NY). The modeling included four types of office buildings: old and New vintages and large (10,405 m2, 112,000 ft2) and small (502m2, 5400 ft2) buildings. Five commercially available, base case windows with and without interior shades were modeled. Window area varied from 0 to 60% of the exterior floor-to-floor wall area. The electric lighting had either no controls or continuous daylighting controls. The prototypes were modeled in New York City or Buffalo.

Energy performance ata are given for each of the four perimeter zones. Data are presented as a function of window-to-wall ratio in order to better understand the interactions between 1) electric lighting energy use and daylight admission and 2) solar heat gains and space-conditioning energy use. Maximum and minimum reductions in energy use between the EC glazing and all other base case conditions are also presented. Projected energy use reductions relative to typical specified NY office buildings are presented as an indication of the potential impacts EC glazings might have in retrofit and new construction.

The energy and demand reductions provided by EC glazings with daylighting controls relative to what is typically specified in office buildings in NY are quite substantial. EC glazings will also dampen fluctuations in interior daylight levels and window brightness, potentially increasing visual comfort.

Abstract: There is a significant and growing interest in the use of highly-glazed facades in commercial buildings. Large portions of the facade or even the entire facade are glazed with relatively high transmittance glazing systems, and typically with some form of sun control as well. With origins in Europe the trend is expanding to other regions, including the United States. A subset of these designs employ a second layer creating a double envelope system, which can then accommodate additional venting and ventilation practices. The stated rationale for use of the these design approaches varies but often includes a connection to occupant benefits as well as sustainable design associated with daylighting and energy savings. As with many architectural trends, understanding the reality of building performance in the field as compared to design intent is often difficult to ascertain. We have been particularly interested in this emerging trend because prior simulation studies have shown that it should be technically possible to produce an all-glass facade with excellent performance although it is not a simple challenge. The published solutions are varied enough and sufficiently complex that we undertook a year-long international review of advanced facades to better understand the capabilities and limitations of existing systems and the tools and processes used to create them. This is also intended to create a framework for addressing the missing tools, technologies, processes and data bases that will be needed to turn the promise of advanced facades into realities. This summary, available as a PDF file and a web site, reports those findings.

Abstract: Mixed metal thin films containing magnesium and a first-row transition element exhibit very large changes in both reflectance and transmittance on exposure to hydrogen gas. Changes in electronic structure and coordination of the magnesium and transition metal atoms during hydrogen absorption were studied using dynamic in situ transmission mode X-ray absorption spectroscopy. Mg K-edge and Ni, Co, and Ti L-edge spectra reflect both reversible and irreversible changes in the metal environments. A significant shift in the nickel L absorption edge shows it to be an active participant in hydride formation. The effect on cobalt and titanium is much less dramatic, suggesting that these metals act primarily as catalysts for formation of magnesium hydride.

Abstract: Advanced window wall systems have the potential to provide demand response by reducing peak electric loads by 20-30% in many commercial buildings through the active control of motorized shading systems, switchable window coatings, operable windows, and ventilated doubleskin facade systems. These window strategies involve balancing daylighting and solar heat gains, heat rejection through ventilation, and night-time natural ventilation to achieve space-conditioning and lighting energy use reductions without the negative impacts on occupants associated with other demand responsive (DR) strategies.

This paper explores conceptually how advanced window systems fit into the context of active load management programs, which cause customers to directly experience the time-varying costs of their consumption decisions. Technological options are suggested. We present pragmatic criteria that building owners use to determine whether to deploy such strategies. A utility"s perspective is given. Industry also provides their perspectives on where the technology is today and what needs to happen to implement such strategies more broadly in the US.

While there is significant potential for these advanced window concepts, widespread deployment is unlikely to occur with business-as-usual practice. Technologically, integrated windowlighting-HVAC products are underdeveloped. Implementation is hindered by fragmented labor practices, non-standard communication protocols, and lack of technical expertise. Design tools and information products that quantify energy performance, occupant impacts, reliability, and other pragmatic concerns are not available. Interest within the building industry in sustainability, energy-efficiency, and increased occupant amenity, comfort, and productivity will be the driving factors for these advanced facades in the near term ? at least until the dust settles on the deregulated electricity market.

Abstract: Structural and electronic properties of co-sputtered Ni-Mg thin films with varying Ni to Mg ratio were studied by in-situ x-ray absorption spectroscopy in the Ni L-edge and Mg K-edge regions. Co-deposition of the metals led to increased disorder and decreased coordination around Ni and Mg compared to pure metal films. Exposure of the metallic films to hydrogen resulted in formation of hydrides and increased disorder. The presence of hydrogen as a near neighbor around Mg caused a drastic reduction in the intensities of multiple scattering resonances at higher energies. The optical switching behavior and changes in the x-ray spectra varied with Ni to Mg atomic ratio. Pure Mg films with Pd overlayers were converted to MgH2: the H atoms occupy regular sites as in bulk MgH2. Although optical switching was slow in the absence of Ni, the amount of H2 absorption was large. Incorporation of Ni in Mg films led to an increase in the speed of optical switching but decreased maximum transparency. Significant shifts in the Ni L3 and L2 peaks are consistent with strong interaction with hydrogen in the mixed films.

Abstract: Evaluation of solar heat gain and daylight distribution through complex window and shading systems requires the determination of the bi-directional transmission distribution function (BTDF). Measurement of BTDF can be timeconsuming, and inaccuracies are likely because of physical constraints and experimental adjustments. A general calculation methodology, based on more easily measurable component properties, would be preferable and would allow much more flexibility. In this paper, measurements and calculations are compared for the specific case of prismatic daylight-redirecting panels. Measurements were performed in a photogoniometer equipped with a digital-imaging detection system. A virtual copy of the photogoniometer was then constructed with commercial ray-tracing software. For the first time, an attempt is made to validate detailed bi-directional properties for a complex system by comparing an extensive set of experimental BTDF data with ray-tracing calculations. The results generally agree under a range of input and output angles to a degree adequate for evaluation of glazing systems. An analysis is presented to show that the simultaneously measured diffuse and direct components of light transmitted by the panel are properly represented. Calculations were also performed using a more realistic model of the source and ideal model of the detector. Deviations from the photogoniometer model were small and the results were similar in form. Despite the lack of an absolute measurement standard, the good agreement in results promotes confidence in both the photogoniometer and in the calculation method.

Abstract: Ultrathin silver films have been deposited on glass and oxide-coated glass using filtered cathodic arc deposition and, for comparison, magnetron sputtering. The energetic differences between these deposition methods lead to initially different film properties. Silver films made by cathodic arc deposition show an earlier onset of island coalescence, indicating a lower aspect ratio than islands produced by evaporation and sputtering. However, the as-deposited films are thermodynamically unstable, exhibiting changes on a timescale of minutes. While films of islands tend to increase their sheet resistance with time, the sheet resistance of contiguous films shows a decrease. Both effects can be explained by silver mobility driven to minimize film and interfacial energy.

Abstract: We have observed reversible mirror-to-transparent state switching in a variety of mixed metal thin films containing magnesium and first-row transition elements including Ni, Fe, Co, Mn, and Ti. The very large changes in both reflectance and transmittance on loading these films with hydrogen are accompanied by significant structural and electronic transformations. The valence states and coordination of metal atoms during hydrogen loading were followed using dynamic in situ transmissionmode X-ray absorption spectroscopy. Time-resolved Mg K-edge and Ni, Co, Mn, and Ti L-edge spectra reflect both reversible and irreversible changes in the metal environments. These spectra are compared to those of reference materials and to predictions from calculations.

Abstract: Variable reflectance coatings (switchable mirrors) have significant advantages over traditional absorbing devices for radiant energy control in a variety of architectural and aerospace applications due to their large dynamic ranges in both transmission and reflection in the visible and near infrared regimes. Although electrochromic and gasochromic metal hydride films have been the primary focus of recent research in this field, other systems merit consideration. Two of these, based on electrochemical conversion of copper to copper oxides and of pnicogens to lithium pnictides are discussed here. Three distinct states are available in the copper system: the highly reflecting metal, the transparent Cu(I) oxide, and the black, highly absorbing Cu(II) oxide. Metallic thin films of elemental antimony and bismuth are reversibly converted to transparent, semiconducting lithium pnictides by cathodic polarization in a non-aqueous lithium electrolyte. Like the metal hydrides, these systems provide substantial modulation of near infrared transmission and reflection, but have somewhat lower visible reflectance in their mirror states.

Abstract: The International Energy Conservation Code (IECC), published by the International Code Council, the code development orgalization of building code officials, contains new provisions that save energy and reduce air pollution emissions. Its most significant new provision is a prescriptive standard for solar heat gain control in windows in wanner climate zones. Because solar heat gain through windows is one of the largest components of residential cooling loads, this standard reduces cooling loads dramatically, which in turn reduces electricity consumption, utility bills, and powerplant pollution emissions. It can also reduce the size of cooling equipment, a capital cost saving that can offset increased costs for the higher performance windows needed to meet the standard.

This paper documents the potential energy efficiency, dollar, and pollution reduction benefits of the IECC"s solar heat gain standard. Using the RESFEN model developed at Lawrence Berkeley National Laboratory, we simulated a typical new home in ten southern states that would be affected the new IECC solar heat gain standard. Our analysis found that in these ten states, adoption of the IECC in its first year could save 400 million kWh, $38 million in electric bills, and 233 MW of peak electricity generating capacity. The cumulative savings from these homes in year 20 would rise to 80 billion kwh, $7.6 billion in electricity bills, and 4,660 Megawatts of generating capacity. In year twenty, the electric energy savings would also prevent the emission of 20,000 tons of NOx and over 1.5 million tons of carbon equivalent.

Extrapolating the calculations in this paper to include other states with significant cooling load reduction from the IECC leads us to believe peak savings from new construction will total 300MW annually. Given that the window replacement and remodeling market is slightly larger than the new construction market (and here the baseline is poorer performing single glazing), leads to the conclusion that savings which include the remodeling and replacement market should exceed 600MW annually. This would eliminate the need to build two average sized 300MW power plants every year. Additional, similar savings could also be expected from applying this technology to windows in commercial buildings, although we have not accounted for these savings in these estimates.

Abstract: Energy Star is a voluntaly partnership between the U.S. Department of Energy (DOE), the U.S. Environmental Protection Agency (EPA), and industry. Energy Star, at both DOE andsEPA, is based on legislative mandates to implement voluntary, non-regulatory programs to promote products that are substantially more efficient than required by Federal standards (the DOE Energy Star program originated with Section 127 of the Energy Policy Act of 1992 (EPACT), and the EPA Energy Star program originated with Section 103 of the CleansAir Act amendments of 1990). The base criteria under EPACT requires DOE to establish voluntary energy efficiency product programs that serve to increase the technical energy performance potential of products, are cost-effective for the consumer, save energy and thus reduce green house gas emissions. Criteria used by EPA under the Clean Air Act are similar but reflect a greater emphasis on reducing green house gas emissions.

The primary objective of the partnership is to expand the market for energy-efficient products. EPA and DOE use the Energy Star label to recognize and promlote the most energy-efficient subset of the market. The label is a simple mechanism that allows consumers to easily identify the most energy-efficient products in the marketplace. In developing specifications for the Energy Star label, EPA and DOE consider several key factors, including:

- Energy and enviromental savings based on unit sales aggregated at the national level;

- Assurance that the efficient product offers the same or better overall performance as a less efficient product;

- Assurances that the technologies or processes required for a more efficient product are commercially available and nonproprietary.

Abstract: Should I get new windows, repair my existing ones, or buy retrofit products? Which strategy will save me more money on my monthly utility bills and make my house more comfortable? What is the best solution for my house and my budget?

As a building professional, you?re asked these questions by friends, family members, and prospective clients. They may have turned to you because the only other source of window advice for most homeowners is a sales representative with just one solution: the product he or she is trying to sell. Whether it?s storm windows or insulating blinds, replacement sashes or new windows, rarely does a salesperson offer alternatives. And the projected energy savings are all too often conjured from guesses and expectations, rather than from real data or calculations.

What makes valid energy savings projections particularly complicated is the lack of energy information for existing products. Although purchasers of new windows can find National Fenestration Rating Council (NFRC) ratings for U-factor and solar heat gain coefficient (SHGC) and Energy Star labels, these testing procedures haven?t been applied to old windows or to many retrofit products, so consumers have few data to help make retrofit comparisons (see ?A Window Glossary?).

Abstract: Direct comparison measurements were made between various prime/storm window combinations and a well-weatherstripped, single-hung replacement window with a low-E selective glazing. Measurements were made using an accurate outdoor calorimetric facility with the windows facing north. The double-hung prime window was made intentionally leaky. Nevertheless, heat flows due to air infiltration were found to be small, and performance of the prime/storm combinations was approximately what would be expected from calculations that neglect air infiltration. Prime/low-E storm window combinations performed very similarly to the replacement window. Interestingly, solar heat gain was not negligible, even in north-facing orientation.

Abstract: Curved magnetic filters are often used for the removal of macroparticles from cathodic arc plasmas. This study addresses the need to further reduce losses and improving plasma throughput. The central figure of merit is the system coefficient kappa defined as a filtered ion current normalized by the plasma-producing arc current. The coefficient kappa is investigated as a function of continuous and pulsed magnetic field operation, magnetic field strength, external electric bias, and arc amplitude. It increases with positive filter bias but saturates at about 15 V for relatively low magnetic field (~10 mT), whereas stronger magnetic fields lead to higher kappa with saturation at about 25 V. Further increase of positive bias reduces kappa. These findings are true for both pulsed and continuous filters. Bias of pulsed filters has been realized using the voltage drop across a self-bias resistor, eliminating the need for a separate bias circuit. Almost 100 A of filtered copper ions have been obtained in pulsed mode, corresponding to kappa[approximate]0.04. The results are interpreted by a simplified potential trough model.

Abstract: Over the past 15 years, low-emissivity and other technological improvements have significantly improved the energy efficiency of windows sold in the United States. However, as interest increases in the concept of zero-energy homes?buildings that do not consume any nonrenewable or net energy from the utility grid?even today?s highest-performance window products will not be sufficient. This simulation study compares today?s typical residential windows, today?s most efficient residential windows, and several options for advanced window technologies, including products with improved fixed or static properties and products with dynamic solar heat gain properties. Nine representative window products are examined in eight representative U.S. climates. Annual energy and peak demand impacts are investigated. We conclude that a new generation of window products is necessary for zero-energy homes if windows are not to be an energy drain on these homes. Windows with dynamic solar heat gain properties are found to offer significant potential in reducing energy use and peak demands in northern and central climates, while windows with very low (static) solar heat gain properties offer the most potential in southern climates.

Abstract: The purpose of this report is to characterize the nonresidential fenestration market in order to better understand market barriers to, and opportunities for, energy-efficient fenestration products. In particular, the goal is to:

- Better understand how glazing products flow between industry groups.

- Identify major decision makers directing the product flow.

- Understand industry trends for certain technologies or products.

- Characterize the role of energy codes and standards in influencing industry trends.

- Assess the impact of product testing and certification programs on the industry.

The U.S. glass industry is a $27 billion enterprise with both large producers and small firms playing pivotal roles in the industry. While most sectors of the glass industry have restructured and consolidated in the past 20 years, the industry still employs 150,000 workers. Nonresidential glazing accounts for approximately 18% of overall U.S. glass production. In 1999, nonresidential glazing was supplied to approximately 2.2 billion ft2 of new construction and additions. That same year, nonresidential glazing was also supplied to approximately 1.1 billion ft2 of remodeling construction. With an industry this large and complex, it is to be expected that many market participants can influence fenestration selection. If market barriers to the selection of high performance fenestration products are better understood, then the U. S. Department of Energy (USDOE), the Northwest Energy Efficiency Alliance (NEEA), and others can develop programs and policies that promote greater energy efficiency in commercial glazing products.

Abstract: The greatest potential in the U.S. for cost-effective energy savings from currently available energy efficient residential windows and skylights exists in the southern market. Prindle and Arasteh recently reported that ten southern states could save over 400 million kwh and 233 MW of peak electricity generating capacity annually by adopting the International Energy Conservation Code (IECC) standard of 0.40 (or less) solar heat gain coefficient (SHGC) for new construction (Prindle & Arasteh 2001). In 2000, Anello et al. demonstrated savings of 14.7 percent in reduced cooling load with high-performance windows (Anello et al. 2000). In 2002, Wilcox demonstrated savings of 20 percent while simulation analysis estimates cooling energy savings in the 30 percent range (Wilcox 2002).

In the southern market, there is significant opportunity for reducing cooling energy use with low solar gain low-E windows. Yet, the southern market has been slow to embrace this new technology. Market research shows that while low-E products have achieved up to 70 percent of the market share in some colder climates (Jennings, Degens & Curtis 2002), they have gained less than 10 percent of the southern windows market (Prindle & Arasteh 2001).

This paper will explore the residential windows market by considering the following: market barriers unique to the southern market; distribution channels in the South; the roles of utilities, codes officials, and other organizations; and other indirect factors that influence this market. This paper will profile current market transformation efforts with case studies of the Florida Windows Initiative, sponsored by the Efficient Windows Collaborative at the Alliance to Save Energy, and the Texas Windows Initiative, sponsored by the American Electric Power Company. Finally, this paper will identify the next steps that will be critical to transforming the southern residential windows market to more efficient window and skylight products.

Abstract: An electrochromic mirror electrode based on reversible uptake of hydrogen in nickel magnesium alloy films is reported. Thin, magnesium-rich Ni-Mg films prepared on glass substrates by cosputtering from Ni and Mg targets are mirror-like in appearance and have low visible transmittance. Upon exposure to hydrogen gas or on cathodic polarization in alkaline electrolyte, the films take up hydrogen and become transparent. When hydrogen is removed, the mirror properties are recovered. The transition is believed to result from reversible formation of Mg2NiH4 and MgH2. A thin overlayer of palladium was found to enhance the kinetics of hydrogen insertion and extraction, and to protect the metal surface against oxidation.

Abstract: Temperature distribution data are presented for the warm-side surface of three different window specimens. The specimens were placed between warm and cold environmental chambers that were operated in steady state at two different standard design conditions for winter heating. The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) temperature conditions were 21.1 deg. C (70 deg. F) and -17.8 deg. C (0 deg. F) on the warm and cold sides, respectively. The International Standards Organization (ISO) temperature conditions were 20.0 deg. C (68.0 deg. F) and 0.0 deg. C (32.0 deg. F) on the warm and cold sides, respectively. Surface temperature maps were compiled using an infrared thermographic system with an external referencing technique, a traversing point infrared thermometer and thermocouples. The infrared techniques allow detailed, non-intrusive mapping of surface temperatures. Surface temperature data are plotted for the vertical distribution along the centerline of the window specimen. This paper is part of larger round-robin collaborative effort that studied this same set of window specimens. These studies were conducted to improve and check the accuracy of computer simulations for predicting the condensation resistance of window products. Data collected for a Calibrated Transfer Standard showed that convective effects outside the window gap are important for predicting surface temperatures.

Abstract:

Abstract: Ab initio total-energy density functional theory is used to investigate the low temperature (LT) monoclinic form of Mg2NiH4. The calculated minimum energy geometry of LT Mg2NiH4 is close to that determined from neutron diffraction data, and the NiH4 complex is close to a regular tetrahedron. The enthalpies of the phase change to high temperature (HT) pseudo-cubic Mg2NiH4 and of hydrogen absorption by Mg2Ni are calculated and compared with experimental values. LT Mg2NiH4 is found to be a semiconductor with an indirect band gap of 1.4 eV. The optical dielectric function of LT Mg2NiH4 differs somewhat from that of the HT phase. A calculated thin film transmittance spectrum is consistent with an experimental spectrum.

Abstract: Glass is a remarkable material but its functionality is significantly enhanced when it is processed or altered to provide added intrinsic capabilities. The overall performance of glass elements in a building can be further enhanced when they are designed to be part of a complete facade system. Finally the facade system delivers the greatest performance to the building owner and occupants when it becomes an essential element of a fully integrated building design. This presentation examines the growing interest in incorporating advanced glazing elements into more comprehensive facade and building systems in a manner that increases comfort, productivity and amenity for occupants, reduces operating costs for building owners, and contributes to improving the health of the planet by reducing overall energy use and environmental impacts. We explore the role of glazing systems in dynamic and responsive facades that provide the following functionality:

Enhanced sun protection and cooling load control while improving thermal comfort and providing most of the light needed with daylighting;

Enhanced air quality and reduced cooling loads using natural ventilation schemes employing the facade as an active air control element;

Reduced operating costs by minimizing lighting, cooling and heating energy use by optimizing the daylighting- thermal tradeoffs;

Net positive contributions to the energy balance of the building using integrated photovoltaic systems;

Improved indoor environments leading to enhanced occupant health, comfort and performance.

In addressing these issues facade system solutions must of course respect the constraints of latitude, location, solar orientation, acoustics, earthquake and fire safety, etc. Since climate and occupant needs are dynamic variables, in a high performance building the facade solution must have the capacity to respond and adapt to these variable exterior conditions and to changing occupant needs. This responsive performance capability can also offer solutions to building owners where reliable access to the electric grid is a challenge, in both less-developed countries and in industrialized countries where electric generating capacity has not kept pace with growth. We find that when properly designed and executed as part of a complete building solution, advanced facades can provide solutions to many of these challenges in building design today.

Abstract: As part of a round robin project, the performance of two wood windows and a Calibrated Transfer Standard was modeled using the THERM heat-transfer simulation program. The resulting interior surface temperatures can be used as input to condensation resistance rating procedures. The Radiation and Condensation Index features within THERM were used to refine the accuracy of simulation results. Differences in surface temperatures between the Basic calculations and those incorporating the Radiation and/or Condensation Index features are demonstrated and explained.

Abstract: Annual heating and cooling energy loads through fenestration products in both residential and commercial buildings are a significant fraction of national energy requirements. In the residential sector, 1.34 and 0.37 quads are required for heating and cooling respectively (DOE Core Data Book, 2000). In commercial buildings, cooling energy use to compensate for fenestration product solar heat gain is estimated at 0.39 quads; heating energy use to compensate for heat loss through fenestration products is estimated at 0.19 quads. Advanced products offer the potential to reduce these energy uses by at least 50% (Frost et. al. 1993). Potential electric lighting savings from fenestration products are estimated at 0.4 quads if daylight can be used effectively so that electric lighting in commercial building perimeter zones can be reduced.

Software has begun to make an impact on the design and deployment of efficient fenestration products by making fenestration product performance ratings widely available. These ratings, which are determined in part using software programs such as WINDOW/THERM/Optics, VISION/FRAME, and WIS, can now easily be used by architects, engineers, professional fenestration product specifiers, and consumers. Information on the properties of fenestration products has also influenced state and national codes (IECC, ASHRAE 90.1) and aided voluntary market transformation programs, such as the Efficient Windows Collaborative and the Energy Star Windows program, which promote efficient fenestration products.

Abstract: The computational methods for calculating the properties of glazing systems containing shading from the properties of their components have been developed, but the measurement standards and property data bases necessary to apply them have not. It is shown that with a drastic simplifying assumption these methods can be used to calculate system solar-optical properties and solar heat gain coefficients for arbitrary glazing systems, while requiring limited data about the shading. Detailed formulas are presented, and performance multipliers are defined for the approximate treatment of simple glazings with shading. As higher accuracy is demanded, the formulas become very complicated.

Abstract: Detailed heat flow measurements on a skylight mounted on a light well of significant depth are presented. It is shown that during the day much of the solar energy that strikes the walls of the well does not reach the space below. Instead, this energy is trapped in the stratified air of the light well and eventually either conducted through the walls of the well or back out through the skylight. The standard model for predicting fenestration heat transfer does not agree with the measurements when it is applied to the skylight/well combination as a whole (the usual practice), but does agree reasonably well when it is applied to the skylight alone, using the well air temperature near the skylight. A more detailed model gives good agreement. Design implications and future research directions are discussed.

Abstract: The unreliability of photosensor-based lighting controls continues to be a significant market barrier that prevents widespread acceptance of daylight dimming controls in commercial buildings. Energy savings from the use of daylighting in commercial buildings is best realized through the installation of reliable photoelectric lighting controls that dim electric lights when sufficient daylight is available to provide adequate background and/or task illumination. In prior work, the authors discussed the limitations of current simulation approaches and presented a robust method to simulate the performance of photosensor-based controls using an enhanced version of the radiance lighting simulation package. The method is based on the concept of multiplying two fisheye images: one generated from the angular sensitivity of the photosensor and the other from a 180 or 360 deg. fisheye image of the space as seen by the photosensor. This paper includes a description of the method, its validation and possible applications for designing, placing, calibrating and commissioning photosensor-based lighting controls.

Abstract: Thin, Pd-capped metallic films containing magnesium and first row transition metals (Mn, Fe, Co) switch reversibly from their initial reflecting state to visually transparent states when exposed to gaseous hydrogen or following reduction cathodic polarization in an alkaline electrolyte. Reversion to the reflecting state is achieved by exposure to air or by anodic polarization. The films were prepared by co-sputtering from one magnesium target and one manganese, iron, or cobalt target. Both the dynamic optical switching range and the speed of the transition depend on the magnesium-transition metal ratio. Infrared spectra of films in the transparent, hydrided (deuterided) states support the presence of the intermetallic hydride phases Mg3MnH7, Mg2FeH6, and Mg2CoH5.

Abstract: Energy savings from the use of daylighting in commercial buildings are realized through implementation of photoelectric lighting controls that dim electric lights when sufficient daylight is available to provide adequate workplane illumination. The dimming level of electric lighting is based on the signal of a photosensor. Current simulation approaches for such systems are based on the questionable assumption that the signal of the photosensor is proportional to the task illuminance. This paper presents a method that simulates the performance of photosensor controls considering the acceptance angle, angular sensitivity, placement of the photosensor within a space, and color correction filter. The method is based on the multiplication of two fisheye images: one generated from the angular sensitivity of the photosensor and the other from a 180- or 360-degree fisheye image of the space as seen by the photosensor. The paper includes a detailed description of the method and its implementation, example applications, and validation results based on comparison with measurements in an actual office space.

Abstract: Electrochromic glazings promise to be the next major advance in energy-efficient window technology, helping to transform windows and skylights from an energy liability to an energy source for the nation"s building stock. Monitored results from a full-scale demonstration of large-area electrochromic windows are given. The test consisted of two side-by-side, 3.7x4.6 m, office-like rooms. In each room, five 62x173-cm lower electrochromic windows and five 62x43-cm upper electrochromic windows formed a large window wall. The window-to-exterior wall ratio (WWR) was 0.40. The southeast-facing electrochromic windows had an overall visible transmittance (Tv) range of Tv =0.11-0.38 and were integrated with a dimmable electric lighting system to provide constant work plane illuminance and to control direct sun. Daily lighting use from the automated electrochromic window system decreased by 6 to 24% compared to energy use with static, low-transmission (Tv =0.11), unshaded windows in overcast to clear sky winter conditions in Oakland, California. Daily lighting energy use increased as much as 13% compared to lighting energy use with static windows that had Tv =0.38. Even when lighting energy savings were not obtainable, the visual environment produced by the electrochromic windows, indicated by well-controlled window and room luminance levels, was significantly improved for computer-type tasks throughout the day compared to the visual environment with unshaded 38%-glazing. Cooling loads were not measured, but previous building energy simulations indicate that additional savings could be achieved. To ensure visual and thermal comfort, electrochromics require occasional use of interior or exterior shading systems when direct sun is present. Other recommendations to improve electrochromic materials and controls are noted along with some architectural constraints.

Abstract: Projections of performance from small-area devices to large-area windows and enterprise marketing have created high expectations for electrochromic glazings. As a result, this paper seeks to precipitate an objective dialog between material scientists and building-application scientists to determine whether actual large-area electrochromic devices will result in signifi- cant performance benefits and what material improvements are needed, if any, to make electrochromics more practical for commercial building applications. Few in-situ tests have been conducted with large-area electrochromic windows applied in buildings. This study presents monitored results from a full-scale field test of large-area electrochromic windows to illustrate how this technology will perform in commercial build- ings. The visible transmittance (Tv) of the installed electrochromic ranged from 0.11 to 0.38. The data are limited to the winter period for a south-east-facing window. The effect of actual device performance on lighting energy use, direct sun control, discomfort glare, and interior illumination is discussed. No mechanical system loads were monitored. These data demon- strate the use of electrochromics in a moderate climate and focus on the most restrictive visual task: computer use in offices. Through this small demonstration, we were able to determine that electrochromic windows can indeed provide unmitigated transparent views and a level of dynamic illumination control never before seen in architectural glazing materials. Daily lighting energy use was 6-24% less compared to the 11%-glazing, with improved interior brightness levels. Daily lighting energy use was 3% less to 13% more compared to the 38%-glazing, with improved window brightness control. The electrochromic window may not be able to fulfill both energy-efficiency and vi- sual comfort objectives when low winter direct sun is present, particularly for computer tasks using cathode-ray tube (CRT) displays. However, window and architectural design as well as electrochromic control options are suggested as methods to broaden the applicability of electrochromics for commercial buildings. Without further modification, its applicability is expected to be limited during cold winter periods due to its slow switching speed.

Abstract: Transparent thin films of copper(I) oxide prepared on conductive SnO2:F glass substrates by anodic oxidation of sputtered copper films or by direct electrodeposition of Cu2O transformed reversibly to opaque metallic copper films when reduced in alkaline electrolyte. In addition, the same Cu2O films transform reversibly to black copper(II) oxide when cycled at more anodic potentials. Copper oxide-to-copper switching covered a large dynamic range, from 85% and 10% photopic transmittance, with a coloration efficiency of about 32 cm2/C. Gradual deterioration of the switching range occurred over 20 to 100 cycles. This is tentatively ascribed to coarsening of the film and contact degradation caused by the 65% volume change on conversion of Cu to Cu2O. Switching between the two copper oxides (which have similar volumes) was more stable and more efficient (CE = 60 cm2/C), but covered a smaller transmittance range (60% to 44% T). Due to their large electrochemical storage capacity and tolerance for alkaline electrolytes, these cathodically coloring films may be useful as counter electrodes for anodically coloring electrode films such as nickel oxide or metal hydrides.

Abstract: Infrared (IR) thermographic systems, or IR imagers, provide images that represent surface temperatures, or thermograms, by measuring the magnitude of infrared radiation emanating from the surface of an object. Because IR imagers see the radiation naturally emitted by objects, imaging may be performed in the absence of any additional light source. Modern IR imagers resolve surface temperature differences of 0.1??C or less. With this high sensitivity, they can evaluate subtle thermal phenomena, which are only revealed in the form of slight temperature gradients. Some applications that employ IR thermography include: inspections for predictive maintenance, non-destructive evaluation of thermal and mechanical properties, building science, military reconnaissance and weapons guidance, and medical imaging.

Infrared thermography can be used as both a qualitative and a quantitative tool. Some applications do not require obtaining exact surface temperatures. In such cases, it is sufficient to acquire thermal signatures, characteristic patterns of relative temperatures of phenomena or objects. This method of qualitative visual inspection is expedient for collecting a large number of detailed data and conveying them in a fashion that can be easily interpreted. In contrast, accurate quantitative thermography demands a more rigorous procedure to extract valid temperature maps from raw thermal images. However, the extra effort can produce large arrays of high-resolution temperature data, which are unrivaled by contact thermal measurement techniques, such as using thermocouple wires.

A skilled operator of an IR thermographic system, or thermographer, must be conscious of the possibility that reflected or transmitted, rather than emitted, IR radiation may be emanating from an object. These additional sources manifest themselves as signals that appear to be, but are not actually, based exclusively on the temperature of the spot being imaged.

To understand the challenges and possibilities of IR thermography, it is first necessary to review the principles of physics on which it relies.

Abstract: Thin films of titanium, zirconium and nickel oxides were deposited on conductive SnO2:F glass substrates by immersion in aqueous solutions. The films are transparent, conformal, of uniform thickness and appearance, and adhere strongly to the substrates. On electrochemical cycling, TiO2, mixed TiO2-ZrO2, and NiOx films exhibited stable electrochromism with high coloration efficiencies. These nickel oxide films were particularly stable compared with films prepared by other non-vacuum techniques. The method is simple, inexpensive, energy efficient, and readily scalable to larger substrates.

Abstract: One of our challenges for the 21st century will be to try to reduce adverse societal impacts on our planet. Buildings account for one of the nation"s largest energy costs and are the biggest source of greenhouse gas emissions. Within the building sector, windows were historically viewed as one of the weak links in buildings. The early response to this perspective was legislation to restrict window usage. The big conceptual leap in the last 25 years has been the recognition that better window technology and better building design can not only reduce these negative impacts, but can convert them into tangible human and economic benefits. The window industry has risen to the challenge of producing the cost-effective products that help translate researchers" predictions into market reality. A look at trends in glazing and new findings from an electrochromic window study by the Lawrence Berkeley National Laboratory (LBNL) provides some additional clues on where fenestration technology will take us in the 21st Century.

Two notable achievements have marked progress for the window industry in the last 25 years: Low-E coatings and spectrally selective cool glazings.

Abstract: The computational methods for calculating the properties of glazing systems containing shading from the properties of their components have been developed, but the measurement standards and property data bases necessary to apply them have not. It is shown that with a drastic simplifying assumption these methods can be used to calculate system solar-optical properties and solar heat gain coefficients for arbitrary glazing systems, while requiring limited data about the shading. Detailed formulas are presented, and performance multipliers are defined for the approximate treatment of simple glazings with shading. As higher accuracy is demanded, the formulas become very complicated.

Abstract: This paper studies the effectiveness of one commercial computational fluid dynamics (CFD) program for simulating combined natural convection and heat transfer in three dimen-sions for air-filled cavities similar to those found in the extruded frame sections of windows. The accuracy of the conjugate CFD simulations is evaluated by comparing results for surface temperature on the warm side of the specimens to results from experiments that use infrared (IR) thermography to map surface temperatures during steady-state thermal tests between ambient thermal chambers set at 0 deg. C and 20 deg. C. Validations using surface temperatures have been used in previous studies of two-dimensional simulations of glazing cavities with generally good results. Using the techniques presented and a noncontact infrared scanning radiometer we obtained surface temperature maps with a resolution of 0.1 deg. C and 3 mm and an estimated uncertainty of /-0.5 deg. C and /-3mm. Simulation results are compared to temperature line and contour plots for the warm side of the specimen. Six different cases were studied, includinga simple square sectioninasingle vertical cavity and two four-sided frame cavities as well as more complex H- and U-shaped sections. The conjugate CFD simulations modeled the enclosed air cavities, the frame section walls, and the foam board surround panel. Boundary conditions at the indoor and outdoor air/solid interface were modeled using constant surface heat-transfer coefficients with fixed ambient-air temperatures. In general, there was good agreement between the simulations and experiments, although the accuracy of the simulations is not explicitly quantified. We conclude that such simulations are useful for future evaluations of natural convec-tion heat transfer in frame cavities.

Abstract: This paper studies three-dimensional natural convection effects in window frames with internal cavities. Infrared (IR) thermography experiments, computational fluid dynamics (CFD) simulations, and calculations with traditional software for simulating two-dimensional heat conduction were conducted. The IR thermography experiments mapped surface temperatures during steady-state thermal tests between ambi-ent thermal chambers set at 0 deg. C and 20 deg. C. Using anon-contact infrared scanning radiometer and an external referencing technique, we were able to obtain surface temperature maps with a resolution of 0.1 deg. C and 3 mm and an estimated uncertainty of 0.5 deg. C and /-3 mm. The conjugate CFD simulations modeled the enclosed air cavities, frame section walls, and foam board surround panel. With the two-dimensional heat conduction simulation software, weusedcorrelations to model heat transfer in the air cavities. For both the CFD simulations and the conduction simulation software, boundary conditions at the external air/solid interface were modeled using constant surface heat-transfer coefficients with fixed ambient air temperatures.

Different cases were studied, including simple, four-sided frame sections (with one open internal cavity), simple vertical sections with a single internal cavity, and horizontal sections with a single internal cavity. The sections tested in the Infrared Thermography Laboratory (IR lab) were made of PVC. Both PVC and thermally broken aluminum sections were modeled. Based on the current investigations, it appears that the thermal transmittance or U-factor of a four-sided section can be found by calculating the average of the thermal transmittance of the respective single horizontal and vertical sections. In addition, we conclude that two-dimensional heat transfer simulation software agrees well with CFD simulations if the natural convection correlations used for the internal cavities are correct.

Abstract: Measurements of spectral transmittance T and reflectance R at normal incidence continue to be the most common and accurate source of energy performance data for glazing materials. Prediction of these radiometric properties from more fundamental materials data is often confounded by the complexity and uncertainty of coating structures. Angle-dependent radiometric properties of coated glazing will probably be predicted from normal-incidence data rather than being measured at many angles. The general error level demonstrated in round-robin tests is on the order 1-2%; it is often necessary to achieve better levels of performance. Based on results obtained following the round-robin tests, it is expected that accuracy of better than 0.5% can be generally achieved. A new type of absolute standard reference is described and tested with promising results.

Abstract: The search for and collection of daylighting analysis methods and algorithms led to two important observations. First, there is a wide range of needs for different types of methods tosproduce a complete analysis tool. These include:

- Geometry

- Light modeling

- Characterization of the natural illumination resource

- Materials and components properties, representations

- Usability issues (interfaces, interoperability, representation of analysis results, etc)

Second, very advantageously, there have been rapid advances in many basic methods in these areas, due to other forces. They are in part driven by:

- The commercial computer graphics community (commerce, entertainment)

- The lighting industry

- Architectural rendering and visualization for projects

- Academia: Course materials, research

This has led to a very rich set of information resources that have direct applicability to the small daylighting analysis community. Furthermore, much of this information is in fact available online.

Abstract: A computer tool such as RESFEN can help consumers and builders pick the most energy-efficient and cost-effective window for a given application, whether it is a new home, an addition, or a window replacement. It calculates heating and cooling energy use and associated costs as well as peak heating and cooling demand for specific window products. Users define a specific "scenario" by specifying house type (single-story or two-story), geographic location, orientation, electricity and gas cost, and building configuration details (such as wall, floor, and HVAC system type). Users also specify size, shading, and thermal properties of the window they wish to investigate. The thermal properties that RESFEN requires are: U-factor, Solar Heat Gain Coefficient, and air leakage rate. RESFEN calculates the energy and cost implications of the window compared to an insulated wall. The relative energy and cost impacts of two different windows can be compared.

RESFEN 3.0 was a major improvement over previous versions because it performs hourly calculations using a version of the DOE 2.1E (LBL 1980, Winkelmann et al. 1993) energy analysis simulation program. RESFEN 3.1 incorporates additional improvements including input assumptions for the base case buildings taken from the National Fenestration Rating Council (NFRC) Annual Energy Subcommittee?s efforts.

Abstract: Infrared thermal imagers are used at Lawrence Berkeley National Laboratory to study heat transfer through components of building thermal envelopes. Two thermal chambers maintain steady-state heat flow through test specimens under environmental conditions for winter heating design. Infrared thermography is used to map surface temperatures on the specimens" warm side. Features of the quantitative thermography process include use of external reference emitters, complex background corrections, and spatial location markers. Typical uncertainties in the data are /- 0.5 deg. C and 3 mm. Temperature controlled and directly measured external reference emitters are used to correct data from each thermal image. Complex background corrections use arrays of values for background thermal radiation in calculating temperatures of self-viewing surfaces. Temperature results are used to validate computer programs that predict heat flow including Finite-Element Analysis (FEA) conduction simulations and conjugate Computational Fluid Dynamics (CFD) simulations. Results are also used to study natural convection surface heat transfer. Example data show the distribution of temperatures down the center line of an insulated window.

Abstract: Glazing systems will fulfill important new roles in buildings in the 21st century. This paper provides an overview of three different functional impacts for advanced glazing systems. New technology and better integration with daylighting and climate control systems allow advanced glazings in building facades to 1) improve the comfort and performance of building occupants, 2) add value and reduce energy operating costs for building owners, and 3) assist in national and global efforts to reduce greenhouse gas emissions that contribute to global warming.

Abstract: Numerous glazing technologies are under development worldwide to improve the performance of building facades. High-performance glazings can provide substantial energy and related environmental benefits, but often at greatly increased first cost when compared to conventional design solutions. To increase market viability, we discuss strategies to reduce the actual and owner-perceived costs associated with developing and producing advanced window systems, specifically switchable electrochromic glazings, and we also suggest marketing strategies designed to appeal to early adopter and mainstream purchasers. These strategies may be applicable to a broad range of advanced glazing materials.

Abstract: Tests of skylights made from prototype electrochromic glazings were performed in a room-sized calorimetric test facility under ambient outdoor summer conditions in Reno, NV. The test methodology and the resultant measurements of skylight heat flows and temperatures with their diurnal variations are presented. Special test issues relating to the dynamic switchable nature of the glazings are discussed.

Abstract: Buildings account for about one-third of all energy used in the US and about two-thirds of all electricity, with associated environmental impacts.(EIA 1996) After more than 20 years of DOE-supported research universities and national laboratories, a great deal is known about the energy performance of buildings and especially their components and subsystems. The development and market introduction of improved energy efficient technology, such as low-E windows and electronic ballasts, have helped reduce energy use, and the resultant savings will increase, as use of the new technologies becomes more widespread. A variety of approaches to speed market penetration have been and are being pursued, including information dissemination, research to evaluate performance and development of computer tools for making energy performance simulations available to architects and engineers at the earliest design stages. Public-domain computer building energy simulation models, (BLAST_Support_Office 1992; Winkelmann, Birdsall et al. 1993) a controversial idea 20 years ago, have been extremely successful in facilitating the design of more energy-efficient buildings and providing the technical basis for improved state building codes, federal guidelines, and voluntary standards. But the full potential of savings, estimated at 50% of current consumption or $100 billion/year, (Bevington and Rosenfeld 1990; Todesco 1996; Holdren 1997; Kolderup and Syphers 1997; ORNL, LBNL et al. 1997) will require that architects and engineers take an integrated look at buildings beginning in the early design phase, with increasing use of sophisticated, complex and interrelated building systems. This puts a greater burden on the designer and engineer to make accurate engineering decisions.

Abstract: The optical switching properties of gadolinium-magnesium hydride have been demonstrated in a solid-state electrochromic device. With positive polarization of the hydride electrode, the visible reflectance approaches 35% with virtually zero transmission, while with negative polarization, the visible transmission exceeds 25% at 650 nm. The switching is reversible, with intermediate optical properties between the transparent and reflecting states.

Abstract: THERM 2.0 is a state-of-the-art software program, available without cost, that uses the finite-element method to model steady-state, two-dimensional heat-transfer problems. It includes a powerful simulation engine combined with a simple, interactive interface and graphic results. Although it was developed primarily to model thermal properties of windows, it is appropriate for other building components such as walls, doors, roofs, and foundations, and is useful for modeling thermal bridges in many other contexts, such as the design of equipment.

Abstract: This paper documents efforts by the National Fenestration Rating Council to develop a database on annual energy impacts of windows in a typical new, single family, single story residence in various U.S. and Canadian climates. The result is a database of space heating and space cooling energies for 14 typical windows in 52 North American climates. (Future efforts will address the effects of skylights.) This paper describes how this database was created, documents the assumptions used in creating this database, elaborates on assumptions, which need further research, examines the results, and describes the possible uses of the database.

Abstract: A method based on the ASHRAE two-node comfort model has been developed for predicting the effect of windows on thermal comfort. The method embodies separate analyses for long-wave (thermal infrared) radiation, induced drafts, and solar load effects. Of these three impacts, modeling results demonstrate that long-wave exchange between the body and the window is the most significant except for the case where the body is in direct sun, in which case the impact solar load can be more significant. For most residential-size windows, draft effects exist but are typically small.

Generally, windows are not the primary element affecting the comfort of a building"s occupants. However when a window is very hot or cold, the occupant is very close to the window, or other factors result in thermal conditions near the edge of the comfort zone, windows can become quite influential. Furthermore it is believed that current methods may under-predict discomfort caused by windows.

We discuss potential refinements to the method that might address this inaccuracy by accounting for asymmetries in radiant temperature. In the near term, the model could be used to create a simplified window comfort index. To accompany the index, we envision educational material that would educate designers and consumers on the comfort implications of glazing selection.

Abstract: Data from nighttime measurements of the net heat flow through several types of skylights is presented. A well-known thermal test facility was reconfigured to measure the net heat flow through the bottom of a skylight/light well combination. Use of this data to determine the U-factor of the skylight is considerably more complicated than the analogous problem of a vertical fenestration contained in a test mask. Correction of the data for heat flow through the skylight well surfaces and evidence for the nature of the heat transfer between the skylight and the bottom of the well is discussed. The resulting measured U-values are presented and compared with calculations using the WINDOW4 and THERM programs.

Abstract: The optical effect upon insertion of hydrogen into Pd-coated magnesium lanthanide switchable mirrors is investigated in terms of the changes of their complex refractive indices. A significant change in the optical constants of LnMg layers is seen between the as-deposited state and the dehydrided state after one cycle. Furthermore, the optical effect of switching the Pd cap layer to a PdH cap layer was determined. It is shown that the Pd layer mainly limits the visible transmittance of the hydrided stack to about 35%-40%. Whereas the extinction coefficient of dehydrided LnMg layers at 550 nm is between 2.2 and 3.1, it is as low 10-4 as in the transparent state. This is of great promise to applications requiring large optical contrast (e.g., optical switches).

Abstract: THERM is a state-of-the-art, Microsoft Windows?-based computer program developed at Lawrence Berkeley National Laboratory (LBNL) for use by building component manufacturers, engineers, educators, students, architects, and others interested in heat transfer. Using THERM, you can model two-dimensional heat-transfer effects in building components such as windows, walls, foundations, roofs, and doors; appliances; and other products where thermal bridges are of concern. THERM's heat-transfer analysis allows you to evaluate a product?s energy efficiency and local temperature patterns, which may relate directly to problems with condensation, moisture damage, and structural integrity.

This version of THERM includes several new technical and user interface features; the most significant is a radiation view-factor algorithm. This feature increases the accuracy of calculations in situations where you are analyzing non-planar surfaces that have different temperatures and exchange energy through radiation heat transfer. This heat-transfer mechanism is important in greenhouse windows, hollow cavities, and some aluminum frames.

Abstract: Optical transmittance and reflectance of window materials can be measured accurately at normal incidence using standard equipment. Sunlight often strikes at angles for which the transmittance and reflectance are significantly different from their values at normal incidence. A reliable procedure for extrapolating from normal properties to oblique properties is thus needed for accurate annual energy performance calculations and product comparisons. The structural models for the materials are greatly constrained by the limited amount of data that is usually available. For monolithic materials such as uncoated glass or plastic substrates it is possible to solve directly for the optical indices and then apply Fresnel"s equation to obtain the oblique properties. For coated glass, the situation is more complex, but a numerical solution is often possible. First, detailed optical models were constructed and accurate angle-dependent data were generated for a wide selection of coated glazing materials. Then, a set of very simple thin-film models were chosen that would converge given a limited amount of data. At 60 degree incidence, the monolithic model was often accurate to within 2% but frequently deviated farther up to 8%. The single-layer thin-film model fared little better. Highly constrained multilayer models often deviated less than 1% although convergence became increasingly specific to similar coating types.

Abstract: We investigate how a venetian blind, a common but optically complex fenestration system, contributes to the unreliable performance of daylighting control systems. Using a fully instrumented, full-scale testbed facility, we monitored the daylighting performance of a modified closed-loop proportional photoelectric control system in a private office over the course of a year. The ratio of workplane illuminance from daylight to photosensor signal is characterized in terms of solar condition and venetian blind angle. Variations in this ratio causes actual illuminance levels to be periodically insufficient. This type of characterization can be used by the installer to determine whether the initial control adjustments made during commissioning will lead to reliable performance under most daylight conditions. Commissioning guidelines are given with caution, based on our observations from this specific case study.

We quantified the effect of variability in this ratio on control performance. With a middle-of-the-road gain constant, monitored workplane illuminance levels did not fall below 90% of the design setpoint for 91% of the year. When discrepancies occurred, differences between the daylight correlation and measured conditions were the primary cause of insufficient illuminance at the workplane. This performance is not applicable to commercially-available closed-loop proportional systems because 1) typical systems are rarely commissioned properly upon installation, and 2) off-the-shelf systems combine the photosensor?s response to daylight and electric light into one gain parameter. Even though the prototype system was subject to the same discrepancies in the daylight correlation fit as commercially-available systems, performance was substantially improved because the prototype was able to separate the electric lighting contribution to workplane illuminance from the daylighting contribution, at no added cost. Commissioning should accommodate the effect of the fenestration system, since variations in luminance distributions produced by the window are the primary cause of unreliable performance.

Abstract: This paper analyzes prospects for developing a test device suitable for field verification of the types of low-emittance (low-e) coatings present on high-performance window products. Test devices are currently available that can simply detect the presence of low-e coatings and that can measure other important characteristics of high-performance windows, such as the thickness of glazing layers or the gap in dual glazings. However, no devices have yet been developed that can measure gas concentrations or distinguish among types of coatings. This paper presents two optical methods for verification of low-e coatings. The first method uses a portable, fiber-optic spectrometer to characterize spectral reflectances from 650 to 1,100 nm for selected surfaces within an insulated glazing unit (IGU). The second method uses an infrared-light-emitting diode and a phototransistor to evaluate the aggregate normal reflectance of an IGU at 940 nm. Both methods measure reflectance in the near (solar) infrared spectrum and are useful for distinguishing between regular and spectrally selective low-e coatings. The infrared-diode/phototransistor method appears promising for use in a low-cost, hand-held field test device.

Abstract: As we approach the end of the decade of the 1990s, daylighting is increasingly promoted as a design strategy and building solution that can save energy and improve human performance and satisfaction in indoor spaces. Similar claims were made in the 1970s in the aftermath of the oil embargo. Twenty-five years later, in a world newly concerned about carbon emissions, global warming, and sustainable design, daylighted buildings are again proposed as a solution. While it is possible to find some examples of well daylighted buildings that have been built in the last 25 years, the fact that there are so few suggests that the optimistic outlook for daylighting needs to be critically (re)examined.

Abstract: The use of daylight to replace or supplement electric lighting in commercial buildings can result in significant energy and demand savings. High performance fenestration systems are a necessary, but not sufficient, element of any successful daylighting design that reduces lighting energy use. However, these savings may be reduced if the fenestration systems impose adverse thermal loads. New fenestration technologies have been developed over the last twenty years, aiming at controlling the intensity of the incoming solar radiation, its interior distribution and its spectral composition, as well as thermal losses and gains. Some of these have proven successful for specific or general building applications, while others are still under development and testing to understand limitations and potential benefits.

In this paper we review the state of the art of several advanced fenestration systems which, are designed to maximize the energy-saving potential of daylighting while improving comfort and visual performance, at an affordable cost. We first review the key performance issues that successful fenestration systems must address, and then review several classes of fenestration systems intended to meet those performance needs. The systems are reviewed in two categories: static and dynamic. Static systems include not only glazings, such as spectrally selective and holographic glazings, but specialized designs of light-shelves and light-pipes, while dynamic systems cover automatically operated blinds and electrochromic glazings.

We include a discussion of the research directions in this area, and how these efforts might lead to static and dynamic hardware and system solutions that fulfill the multiple roles that these systems must play in terms of energy efficiency, comfort, visual performance, health, and amenity in future buildings.

Abstract: This paper presents the results of a study investigating the energy and daylight performance of anisotropic angular selective glazings. The DOE-2.1E energy simulation program was used to determine the annual cooling, lighting and total electricity use, and peak electric demand. RADIANCE, a lighting simulation program, was used to determine daylight illuminance levels and distribution. We simulated a prototypical commercial office building module located in Blythe, California. We chose three hypothetical conventional windows for comparison: a single-pane tinted window, a double-pane low-E window, and a double-pane spectrally selective window. Daylighting controls were used. No interior shades were modeled in order to isolate the energy effects of the angular selective glazing. Our results show that the energy performance of the prototype angular selective windows is about the same as conventional windows for a 9.14 m (30 ft) deep south-facing perimeter zone with a large-area window in the hot, sunny climate of Blythe. It is theoretically possible to tune the angular selectivity of the glazing to achieve annual cooling energy reductions of 18%, total electricity use reductions of 15%, and peak electric demand reductions of 11% when compared to a conventional glazing with the same solar-optical properties at normal incidence. Angular selective glazings can provide more uniformly distributed daylight, particularly in the area next to the window, which will result in a more visually comfortable work environment.

Abstract: When modeling thermal performance of building components and envelopes, researchers have traditionally relied on average surface heat-transfer coefficients that often do not accurately represent surface heat-transfer phenomena at any specific point on the component being evaluated. The authors have developed new experimental techniques that measure localized surface heat-flow phenomena resulting from convection. The data gathered using these new experimental procedures can be used to calculate local film coefficients and validate complex models of room and building envelope heat flows. These new techniques use a computer controlled traversing system to measure both temperatures and air velocities in the boundary layer near the surface of a building component, in conjunction with current methods that rely on infrared (IR) thermography to measure surface temperatures. Measured data gathered using these new experimental procedures are presented here for two specimens: (1) a Calibrated Transfer Standard (CTS) that approximates a constant-heat-flux, flat plate; and (2) a dual-glazed, low-emittance (low-e), wood-frame window. The specimens were tested under steady-state heat flow conditions in laboratory thermal chambers. Air temperature and mean velocity data are presented with high spatial resolution (0.25- to 25-mm density). Local surface heat-transfer film coefficients are derived from the experimental data by means of a method that calculates heat flux using a linear equation for air temperature in the inner region of the boundary layer. Local values for convection surface heat-transfer rate vary from 1 to 4.5 W/m2K. Data for air velocity show that convection in the warm-side thermal chamber is mixed forced/natural, but local velocity maximums occur from 4 to 8 mm from the window glazing.

Abstract: Tin oxide thin films were deposited by reactive radio-frequency magnetron sputtering onto In2O3:Sncoated and bare glass substrates. Optical constants in the 300-2500 nm wavelength range were determined by a combination of variable-angle spectroscopic ellipsometry and spectrophotometric transmittance measurements. Surface roughness was modeled from optical measurements and compared with atomic-force microscopy. The two techniques gave consistent results. The fit between experimental optical data and model results could be significantly improved when it was assumed that the refractive index of the Sn oxide varied across the film thickness. Varying the oxygen partial pressure during deposition made it possible to obtain films whose complex refractive index changed at the transition from SnO to SnO2. An addition of hydrogen gas during sputtering led to lower optical constants in the full spectral range in connection with a blueshift of the bandgap. Electrochemical intercalation of lithium ions into the Sn oxide films raised their refractive index and enhanced their refractive-index gradient.

Abstract: The quasi-linear constricted plasma source is a downstream plasma source with ten linearly aligned discharge cells. Each cell operates on the basis of a constricted glow discharge. The plasma output can easily be monitored by the plasma-emitted light. The information is not only intuitive but can also be used to operate on-line feedback control of the plasma source which is important for large-area plasma processing of materials.

Abstract: Films of Ti oxide, Zr oxide, Ce oxide, Ti-Ce oxide, and Zr-Ce oxide were made by means of reactive dc magnetron sputtering in a multitarget arrangement. The films were characterized by x-ray diffraction and electrochemical measurements, both techniques being firmly connected to stoichiometric information. The optical constants n and k were evalued from spectrophotometry and from variable-angle spectroscopic ellipsometry. The two analyses gave consistent results. It was found that n for the mixed-oxide films varied smoothly between the values for the pure oxides, whereas k in the band-gap range showed characteristic differences between Ti-Ce oxide and Zr-Ce oxide. It is speculated that this difference is associated with structural effects.

Abstract: THERM 2.0 is a state-of-the-art software program, available for free, that uses the finite-element method to model steady-state, two-dimensional heat-transfer effects. It is being used internationally in graduate and undergraduate laboratories and classes as an interactive educational tool to help students gain a better understanding of heat transfer. THERM offers students a powerful simulation engine combined with a simple, interactive interface and graphic results. Although it was developed to model thermal properties of building components such as windows, walls, doors, roofs, and foundations, it is useful for modeling thermal bridges in many other contexts, such as the design of equipment. These capabilities make THERM a useful teaching tool in classes on: heating, ventilation, and air-conditioning (HVAC); energy conservation; building design; and other subjects where heat-transfer theory and applications are important. THERM"s state-of-the-art interface and graphic presentation allow students to see heat-transfer paths and to learn how changes in materials affect heat transfer. THERM is an excellent tool for helping students understand the practical application of heat-transfer theory.

Abstract: Measuring the thermal performance of windows in typical residential buildings is an expensive proposition. Not only is laboratory testing expensive, but each window manufacturer typically offers hundreds of individual products, each of which has different thermal performance properties. With over a thousand window manufacturers nationally, a testing-based rating system would be prohibitively expensive to the industry and to consumers.

Beginning in the early 1990s, simulation software began to be used as part of a national program for rating window U-values. The rating program has since been expanded to include Solar Hear Gain Coefficients and is now being extended to annual energy performance.

This paper describes four software packages available to the public from Lawrence Berkeley National Laboratory (LBNL). These software packages are used to evaluate window thermal performance: RESFEN (for evaluating annual energy costs), WINDOW (for calculating a product"s thermal performance properties), THERM (a preprocessor for WINDOW that determines two-dimensional heat-transfer effects), and Optics (a preprocessor for WINDOW"s glass database).

Software not only offers a less expensive means than testing to evaluate window performance, it can also be used during the design process to help manufacturers produce windows that will meet target specifications. In addition, software can show small improvements in window performance that might not be detected in actual testing because of large uncertainties in test procedures.

Abstract: This report documents many of the validation studies (Table 1) of the DOE-2 building energy analysis simulation program that have taken place since 1981. Results for several versions of the program are presented with the most recent study conducted in 1996 on version DOE-2.1E and the most distant study conducted in 1981 on version DOE-1.3. This work is part of an effort related to continued development of DOE-2, particularly in its use as a simulation engine for new specialized versions of the program such as the recently released RESFEN 3.1. RESFEN 3.1 is a program specifically dealing with analyzing the energy performance of windows in residential buildings. The intent in providing the results of these validation studies is to give potential users of the program a high degree of confidence in the calculated results.

Abstract: Market adoption of recent, commercially available technological advances that improve the energy performance of windows will lead to immediate economic and energy savings benefits to the nation. This paper is a scoping study intended to inform the design of a major DOE initiative to accelerate market adoption of these windows in the residential sector. We describe the structure of the U.S. residential window market and the interests of the various market players. We then briefly review five recent market transformation initiatives. Finally, we summarize our findings in a list of considerations we believe will be important for the DOE?s initiative to transform the U.S. residential window market.

Abstract: Thin films of lithium nickel oxide were deposited by rf sputtering from a stoichiometric LiNiO2 target. The composition and structure of these films depended on the oxygen pressure during deposition (sputtering gas is Argon), and, to a certain extent, the target history. The sputtering geometry, i.e. the substrate to target distance and the sputtering angle were also critical. the films exhibit excellent reversibility in the potential range 1.1V to 3.8 V vs Li/Li and could be cycled in a liquid electrolyte half cell for more than 3000 cycles with a switching range Tvis close to 70%. The coloration efficiency in the visible was typically -30 to -40 cm2 c-1. The switching performance of a device utilizing a lithium nickel oxide film as counter electrode for a tungsten oxide electrochromic film is reported.

Abstract: Metallic magnesium lanthanide thin films upon insertion of hydrogen transform to a highly transparent hydride phase. With a Pd overlayer, the transformation can be produced either by electrochemical insertion of hydrogen or by exposing the film to hydrogen gas. Unlike amorphous oxide electrochromics, the transformation is accompanied by a large change in visible reflectance (about 50%). The optical switching effect in these materials is investigated in terms of changes in the complex refractive index as determined by variable-angle spectroscopic ellipsometric and normal-incidence radiometric measurements over the solar spectrum. Furthermore the optical effect of converting the Pd caplayer to Pd-H was determined. It is shown that the pd layer limits the visible transmittance of the hyrdrided stack to about 35-40%. Whereas the extinction coefficient of the dehydrided LnMg-layers at 550 nm is between 2.2 and 3.1, it is as low as 10-4 in the transparent state.

Abstract: Mixed vanadium and tungsten oxide films with compositions ranging from 0 to 100% vanadium (metals basis) were prepared by reactive sputtering from metallic vanadium and tungsten targets in an atmosphere of argon and oxygen. The vanadium content varied smoothly with the fraction of total power applied to the vanadium target. Films containing vanadium were more color neutral than pure tungsten oxide films, tending to gray-brown at high V fraction. The electrochromic switching performance of these films was investigated by in situ monitoring of their visible transmittance during lithium insertion/extraction cycling in a non-aqueous electrolyte (1M LiClO4 in PC). the solar transmittance and reflectance was measured ex-situ. Films with vanadium content greater than about 15%, exhibited a marked decrease in switching range. The coloration efficiencies followed a similar trend.

Abstract: GaN films grown on sapphire at different temperatures are investigated. A Volmer-Weber growth mode is observed at temperatures below 1000K that leads to thin films composed of oriented grains with finite size. Their size is temperature dependent and can actively be influenced by strain. Largest grains are observed in compressed films. It is argued that diffusing Ga ad-atoms dominate the observed effects with an activation energy of 2.3 /- 0.5 eV. Comparably large grain sizes are observed in films grown on off-axes sapphire substrates and on bulk GaN. This assures that the observed size limitation is a consequence of the 3D growth mode and not dependent on the choice of the substrate. In addition, the grain size and the surface roughness of the films depend on the nitrogen partial pressure in the molecular beam epitaxy (MBE) chamber, most likely due to collisions between the reactive species and the background gas molecules. This effect is utilized to grow improved nucleation layers on sapphire.

Abstract: GaN films were grown on sapphire substrates at temperatures below 1000 K utilizing a Hollow Anode nitrogen ion source. A Ga flux limited growth rate of ~0.5 pm/h is demonstrated. Active utilization of strain and the assistance of a nitrogen partial pressure during buffer layer growth are found to be crucial issues that can improve the film quality. The best films exhibit a full width at half maximum of the x-ray rocking curves of 80 arcsec and 1.85 meV for the excitonic photoluminescence measured at 4 K. A Volmer-Weber three dimensional growth mode and the spontaneous formation of cubic GaN inclusions in the hexagonal matrix are observed in the investigated growth temperature range. It is argued that this growth mode contributes to a limitation of the camer mobility in these films that did not exceed 120 cm2/Vs through a minimum canier concentration of ~10-15 cm-3 was achieved.

Abstract: Optical and radiative properties of glazing materials are primary inputs for determination of energy performance in buildings. This paper revisits the problem and reformulates the calculations to encompass a variety of solutions to practical problems in window optics. Properties of composite systems such as flexible films applied to rigid glazing and laminated glazing can be predicted from measurements on isolated components in air or other gases. Properties of a series of structures can be generated from those of a base structure. For example, the measured properties of a coated or uncoated substrate can be extended to a range of available substrate thicknesses without the need to measure each thickness. Similarly, a coating type could be transferred by calculation to any other substrate. A simple monolithic model for extrapolating from normal properties to oblique properties is shown to have sufficient accuracy for the purpose of annual energy performance calculations. A process is initiated to develop a reliable method for determination of effective indices suitable for more detailed spectral and directional optical calculations.

Abstract: A new technology called electrochromic glazing promises to provide the building industry with a means to dynamically control the visual appearance and solar gain of windows. Electrochromic glazing is a technology which allows an otherwise ordinary looking piece of laminated glass to change tint with the application of a small electrical charge. Prototype electrochromic devices have been produced in sizes up to one square foot, however, manufacturers are several years away from producing glazing samples large enough to fill the aperture of a typical perimeter office. Tooling up for the production of large samples is prohibitively expensive unless some assurance of the marketability of these new electrochromic products can be demonstrated.

Electrochromic glazings defy traditional performance rating mechanisms because of the temporal dimension of their thermal and visual characteristics. Every electrochromic glazing assembly has an infinite number of states at which the thermal and visual appearance could be characterized. Furthermore, the rate at which the assembly changes between states is vital for a complete understanding.

Abstract: Multicomponent oxides are of increasing interest for electrochromic electrodes. To reduce the large number of permutations in composition it would be useful to be able to predict the properties of the mixtures from the pure oxide components. WO3 mixed with V2O5 has been produced by a sol-gel technique in order to increase durability and color neutrality of conventional WO3 electrochromic coatings. Chemical composition was confirmed by Rutherford backscattering spectrometry (RBS). Surface morphology was analyzed by atomic force microscopy (AFM). Electrochromic performance of the films was tested by cyclic voltammetry with in-situ transmission control. Optical constants of vanadium tungsten oxides were determined over the whole solar spectrum. The measurements included variable angle spectroscopic ellipsometry and spectral transmittance and reflectance. An attempt is made to treat doped tungsten oxide as an effective medium consisting of a mixture of WO3 with V2O5. In the clear state, comparison of optical constants and thickness directly determined on the samples yields qualitative agreement with results from effective-medium analysis. The resulting component fraction also agrees as long as the film density does not deviate too much from the linearly interpolated value between the pure components. For the colored state, preferential trapping of electrons at one atom species hinders the application of effective medium theory.

Abstract: Field measurements of U-factor are reported for two projecting greenhouse windows, each paired with a picture window of comparable insulation level during testing. A well-known calorimetric field test facility was used to make the measurements. The time-varying U-factors obtained are related to measurements of exterior conditions. For one of the greenhouse windows, which was the subject of a published laboratory hotbox test and simulation study, the results are compared with published test and simulation data and found to be in disagreement. Data on interior and exterior film coefficients are presented, and it is shown that the greenhouse window has a significantly lower interior film coefficient than a conventional window under the same interior conditions. This is advanced as a possible explanation of the disagreement.

Abstract: Cerium titanium oxide samples derived from a solution have been compared against sputtered films over a wide range of different compositions. X-ray diffraction was used to investigate the structural properties of the compound material existing in a two-phase mixture MAO2-MBO2. The optical properties were evaluated over the whole solar spectrum by variable angle spectroscopic ellipsometry combined with spectrophutometry. The spectral complex refractive index was determined for CeOz and TiOz, as well as for their compounds. To reduce the large number of permutations in composition of multi-component oxides it would be useful to be able to predict the properties of the mixtures from the pure oxide components. Therefore these results were compared to those obtained by effective medium theory utilizing the optical constants of CeOz and TiOz. In order to investigate the performance as passive counter-electrode in Li based electrochromic devices the films were tested by cyclic voltammetry with in-situ transmission control. Chemical composition was measured by Rutherford backscattering spectrometry. Surface morphology was analyzed by atomic force microscopy.

Abstract: Curtain walls are assemblies of glazings and metal frames that commonly form the exterior glass facades of commercial buildings. Evaluating the thermal performance of the bolts that hold curtain wall glazings in place is necessary to accurately rate the overall thermal performance of curtain walls. Using laboratory tests and computer simulations, we assessed the thermal performance of several different configurations of bolts and glazings. Curtain-wall samples were tested in the infrared thermography laboratory at the Lawrence Berkeley National Laboratory (LBNL) in Berkeley, California. Experimental results were compared to two-dimensional simulations approximating the thermal effect of the bolts using the parallel path and the isothermal planes calculation methods. We conclude that stainless steel bolts minimally affect curtain-wall thermal performance (approximately 18%) when spaced at least nine inches apart, which is the industry standard. Performance is increasingly compromised when there is less than nine inches between bolts or when steel bolts are used. We also show that the isothermal planes method of approximating curtain wall thermal performance can be used with 2-D heat transfer software typical of that used in the window industry to give conservative results for the thermal bridging effect caused by bolts.

Abstract: The window well formed by the concave surface on the warm side of skylights and garden windows can cause surface heat-flow rates to be different for these projecting types of fenestration products than for normal planar windows. Current methods of simulating fenestration thermal conductance (U-value) use constant boundary condition values for overall surface heat transfer. Simulations that account for local variations in surface heat transfer rates (radiation and convection) may be more accurate for rating and labeling window products whose surfaces project outside a building envelope. This paper, which presents simulation and experimental results for one projecting geometry, is the first step in documenting the importance of these local effects.

A generic specimen, called the foam garden window, was used in simulations and experiments to investigate heat transfer of projecting surfaces. Experiments focused on a vertical cross section (measurement plane) located at the middle of the window well on the warm side of the specimen. The specimen was placed between laboratory thermal chambers that were operated at American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) winter heating design conditions. Infrared thermography was used to map surface temperatures. Air temperature and velocity were mapped throughout the measurement plane using a mechanical traversing system. Finite-element computer simulations that directly modeled element-to-element radiation were better able to match experimental data than simulations that used fixed coefficients for total surface heat transfer. Air conditions observed in the window well suggest that localized convective effects were the reason for the difference between actual and modeled surface temperatures. U-value simulation results were 5 to 10% lower when radiation was modeled directly.

Abstract: Heat transfer patterns in projecting fenestration products (greenhouse windows, skylights, etc.) are different than those with typical planar window products. The projecting surfaces often radiate to each other, thereby invalidating the commonly used assumption that fenestration product interior surfaces radiate to a uniform room air temperature. The convective portion of the surface heat transfer coefficient is also significantly different from the one used with planar geometries, and is even more dependent on geometry and location. Projecting fenestration product profiles must therefore be modeled in their entirety. This paper presents the results of complete cross section, variable film-coefficient, 2-D heat transfer modeling of two greenhouse windows using the next generation of window specific heat transfer modeling tools. The use of variable film-coefficient models is shown to increase the accuracy with which simulation tools can compute U-factors. Simulated U-factors are also determined using conventional constant film coefficient algorithms. The results from both sets of simulations are compared with measured values.

Abstract: CeO2-TiO2 finds use as passive counter-electrode in electrochromic devices. Thin films were produced by dc-sputtering in a wide range of compositions. Influence of total pressure and oxygen partial pressure on the optical constants of TiO2 was investigated. Slightly substoichiometric TiO2 films exhibit a red-shift of the bandgap. The TiO2 content in the compound essentially determines the degree of cathodical coloring upon Li intercalation. However, pure TiO2 films with comparable visible transmittance in the clear state behave differently during electrochemical cycling depending on oxygen stoichiometry. Films that are deposited at higher total pressure are more oxygen rich and require initial formatting until current voltage cycles become stable. CeO2-TiO2 films of intermediate compositions have the relatively highest charge capacity. Comparison with atomic force microscopy indicates a correlation of small grain size with high charge capacity.

Abstract: This paper presents the results of a study investigating the energy performance of evacuated glazings or glazings which maintain a vacuum between two panes of glass. Their performance is measured by comparing results to prototype highly insulated superwindows as well as a more conventional insulating glass unit with a low-E coating and argon gas fill. We used the DOE-2.1E energy analysis simulation program to analyze the annual and hourly heating energy use due to the windows of a prototypical single-story house located in Madison, Wisconsin. Cooling energy performance was also investigated. Our results show that for highly insulating windows, the solar heat gain coefficient is as important as the window"s U-factor in determining heating performance for window orientations facing west-south-east. For other orientations in which there is not much direct solar radiation, the window"s U-factor primarily governs performance. The vacuum glazings had lower heating requirements than the superwindows for most window orientations. The conventional low-E window outperformed the superwindows for southwest-south-southeast orientations. These performance differences are directly related to the solar heat gain coefficients of the various windows analyzed. The cooling performance of the windows was inversely related to the heating performance. The low solar heat gain coefficients of the superwindows resulted in the best cooling performance. However, we were able to mitigate the cooling differences of the windows by using an interior shading device that reduced the amount of solar gain.

Abstract: As part of a demonstration project to provide a comprehensive energy upgrade to a 294 m2 (3168 ft2) commercial building, an advanced skylight design was developed using optical light control materials and geometry to provide daylight to two adjoining offices. The skylight system was developed using outdoor physical model tests and simulation tools Limited on-site measurements and occupant polls were conducted. Market issues were addressed. The skylight systems were found to improve lighting quality and to control excessive daylight illuminance levels compared to a conventional diffusing bubble skylight. Daylighting principles developed in earlier work for vertical glazing systems (light shelves and light pipes) were shown to be applicable in skylight designs at full-scale.

Abstract: We present two perimeter daylighting systems that passively redirect beam sunlight further from the window wall using special optical films, an optimized geometry, and a small glazing aperture. The objectives of these systems are (1) to increase daylight illuminance levels at 4.6-9.1 m (15-30 ft) from the window aperture with minimum solar heat gains and (2) to improve the uniformity of the daylighting luminance gradient across the room under variable solar conditions throughout the year. The designs were developed through a series of computer-assisted ray-tracing studies, laser visualization techniques, and photometric measurements and observations using physical scale models. Bi-directional illuminance measurements in combination with analytical routines were then used to simulate daylight performance for any solar position, and were incorporated into the DOE-2.1E building energy analysis computer program to evaluate energy savings. Results show increased daylight levels and an improved luminance gradient throughout the year compared to conventional daylighting systems.

Abstract: This paper presents the results of a study investigating the energy performance of electrochromic windows in heating-dominated geographic locations under a variety of state-switching control strategies. We used the DOE-2.1E energy simulation program to analyze the annual heating, cooling and lighting energy use and performance as a function of glazing type, size, and electrochromic control strategy. We simulated a prototypical commercial office building module located in Madison, Wisconsin. Control strategies analyzed were based on daylight illuminance, incident total solar radiation, and space cooling load. Our results show that overall energy performance is best if the electrochromic is left in its clear or bleached state during the heating season, but controlled during the cooling season using daylight illuminance as a control strategy. Even in such heating dominated locations as Madison, there is still a well-defined cooling season when electrochromic switching will be beneficial. However, having the electrochromic remain in its bleached state during the winter season may result in glare and visual comfort problems for occupants much in the same way as conventional glazings.

Abstract: SnO2:F is a widely used transparent conductor and commercially available in a multilayer structure as Tech glass. Current applications include photovoltaics, electrochromics and displays. Optical design of these and other applications requires knowledge of the optical constants, in some cases, over the whole solar spectrum. Various optical property measurements were performed including variable angle spectroscopic ellipsometry, and spectral transmittance and reflectance measurements. This material is deposited in several steps and has a fairly complex structure. The measured data were fit to models based on this structure to obtain the optical indices. Atomic force microscopy confirmed the optically modeled surface roughness.

Abstract: Infrared (IR) imaging radiometers, which measure relative levels of thermal radiation energy, can be used for noninvasive surface temperature measurements of building thermal envelope components undergoing steady-state heat flow in laboratory thermal chambers. One advantage of IR measurement is that it provides large contiguous sets of surface temperature data which are useful for validating the accuracy of complex computer models that predict heat flow through thermally insulated systems. Because they give such detailed information about surface temperature, IR measurements complement hot-box measurements of heat flow. This paper recommends general procedures for reliable quantitative thermographic measurements in chambers operated for winter heating conditions. Actual surface temperature depends on heat flow, surface emittance, and environmental conditions such as air temperature, air flow field, and background thermal radiation. The infrared temperature measurements are affected by many of the same factors including surface emittance, air temperature, background thermal radiation, and air humidity. Equipment specifications for the absolute accuracy of infrared temperature measurements are typically /-1 deg. C to /-2 deg. C. Measurements that use a temperature-controlled reference emitter to remove error appear to show accuracies of /-0.5 deg. C for flat specimens with low temperature gradients.

Abstract: Photoluminescence (PL), Raman spectroscopy, and x-ray diffraction are employed to demonstrate the co-existence of a biaxial and a hydrostatic strain that can be present in GaN thin films. The biaxial strain originates from growth on lattice-mismatched substrates and from post-growth cooling. An additional hydrostatic strain is shown to be introduced by the presence of point defects. A consistent description of the experimental results is derived within the limits of the linear and isotropic elastic theory using a Poisson ratio nu =0.23 /-0.06 and a bulk modulus B=200 /-20 GPa. These isotropic elastic constants help to judge the validity of published anisotropic elastic constants that vary greatly. Calibration constants for strain-induced shifts of the near-band-edge PL lines with respect to the E2 Raman mode are given for strain-free, biaxially strained, and hydrostatically contracted or expanded thin films. They allow us to extract differences between hydrostatic and biaxial stress components if present. In particular, we determine that a biaxial stress of one GPa would shift the near-band-edge PL lines by 27 /-2 meV and the E2 Raman mode by 4.2 /-0.3 cm-1 by use of the listed isotropic elastic constants. It is expected from the analyses that stoichiometric variations in the GaN thin films together with the design of specific buffer layers can be utilized to strain engineer the material to an extent that greatly exceeds the possibilities known from other semiconductor systems because of the largely different covalent radii of the Ga and the N atom.

Abstract: Measured bidirectional transmittances and reflectances of a buff-colored venetian blind together with a layer calculation scheme developed in previous publications are utilized to produce directional-hemispherical properties for the venetian blind layer and solar heat gain coefficients for the blind in combination with clear double glazing. Results are presented for three blind slat tilt angles and for the blind mounted either interior to the double glazing or between the glass panes. Implications of the results for solar heat gain calculations are discussed in the context of sun positions for St. Louis, MO.

Abstract: Optical indices have been determined for thin films of several electrochromic oxide materials. One of the most important materials in electrochromic devices, WO3, was thoroughly characterized for a range of electrochromic states by sequential injection of Li ions. Another promising material, Li0.5Ni0.5O, was also studied in detail. Less detailed results are presented for three other common lithium-intercalating electrochromic electrode materials: V2O5, LiCoO2, and CeO2-TiO2. The films were grown by sputtering, pulsed laser deposition (PLD) and sol-gel techniques. Measurements were made using a combination of variable-angle spectroscopic ellipsometry and spectroradiometry. The optical constants were then extracted using physical and spectral models appropriate to each material. Optical indices of the underlying transparent conductors, determined in separate studies, were fixed in the models of this work. The optical models frequently agree well with independent physical measurements of film structure, particularly surface roughness by atomic force microscopy. Inhomogeneity due to surface roughness, gradient composition, and phase separation are common in both the transparent conductors and electrochromics, resulting sometimes in particularly complex models for these materials. Complete sets of data are presented over the entire solar spectrum for a range of colored states. This data is suitable for prediction of additional optical properties such as oblique transmittance and design of complete electrochromic devices.

Abstract: Thin films of lithium nickel oxide were deposited by sputtering and pulsed laser deposition (PLD) from targets of pressed LiNiO2 powder. The composition and structure of these films were analyzed using a variety of techniques, such as nuclear-reaction analysis, Rutherford backscattering spectrometry (RBS), x-ray diffraction, infrared spectroscopy, and atomic force microscopy. Crystalline structure, surface morphology and chemical composition of LixNi1-xO thin films depend strongly on deposition oxygen pressure, temperature as well as substrate-target distance. The films produced at temperatures lower than 600 deg. C spontaneously absorb CO2 and H2O at their surface once they are exposed to the air. The films deposited at 600 deg. C proved to be stable in air over a long period. Even at room temperature the PLD films are denser and more stable than sputtered films. RBS determined the composition of the best films to be Li0.5Ni0.5O deposited by PLD at 60 mTorr O2 pressure. Electrochemical tests show that the films exhibit excellent reversibility in the range 1.0 V to 3.4 V versus lithium. Electrochemical formatting which is used to develop electrochromism in other films is not needed for the stoichiometric films. The optical transmission range is almost 70% at 550 nm for 150-nm thick films. Devices made from these films were analyzed using novel reference electrodes and by disassembly after cycling.

Abstract: Variable transmission, switchable electrochromic glazings are compared to conventional static glazings using computer simulations to assess the daylighting quality of a commercial office environment where paper and computer tasks are performed. RADIANCE simulations were made for a west-facing commercial office space under clear and overcast sky conditions. This visualization tool was used to model different glazing types, to com-pute luminance and illuminance levels, and to generate a parametric set of photorealistic im-ages of typical interior views at various times of the day and year. Privacy and visual dis-play terminal (VDT) visibility is explored. Electrochromic glazings result in a more consis-tent glare-free daylit environment compared to their static counterparts. However, if the glazing is controlled to minimize glare or to maintain low interior daylight levels for critical visual tasks (e.g., VDT), occupants may object to the diminished quality of the outdoor view due to its low transmission (Tv=0.08) during those hours. RADIANCE proved to be a very powerful tool to better understand some of the design tradeoffs of this emerging glazing technology. Our ability to draw specific conclusions about the relative value of dif-ferent technologies or control strategies is limited by the lack of agreed upon criteria or standards for lighting quality and visibility.

Abstract: Thin films of lithium nickel oxide were deposited by pulsed laser deposition (PLD) from targets of pressed LiNiO2 powder with layered structure. The composition, structure and surface air sensitivity of these films were analyzed using a variety of techniques, such as nuclear reaction analysis, Rutherford backscattering spectrometry (RBS), x-ray diffraction, infrared spectroscopy, and atomic force microscopy. Optical properties were measured using a combination of variable angle spectroscopic ellipsometry and spectroradiometry. Crystalline structure, surface morphology and chemical composition of LixNi1-xO thin films depend strongly on deposition oxygen pressure, temperature as well as substrate target distance. The films produced at temperatures lower than 600 deg. C spontaneously absorb CO2 and H2O at their surface once they are exposed to the air. The films deposited at 600 deg. C proved to be stable in air over a long period. Even when deposited at room temperature the PLD films are denser and more stable than sputtered films. RBS determined that the best electrochromic films had the stoichiometric composition Li0.5Ni0.5O when deposited at 60 mTorr O2 pressure. Electrochemical tests show that the films exhibit excellent reversibility in the range 1.0 V to 3.4 V versus lithium and long cyclic life stability in a liquid electrolyte half cell. Electrochemical formatting which is used to develop electrochromism in other films and nickel oxide films is not needed for these stoichiometric films. The optical transmission range is almost 70% at 550 nm for 120 nm thick films.

Abstract: Optical indices have been determined for thin films of all materials needed to model a typical electrochromic device. Two electrochromic materials, tungsten oxide and lithium nickel oxide, are widely used in electrochromic devices. The optical indices of the underlying transparent conductors as well as a polymer electrolyte were also analyzed. The optical data was obtained using a combination of variable-angle spectroscopic ellipsometry and spectroradiometry. The data was then fit to appropriate models of structure and dispersion in order to extract the optical indices of the materials. First, the optical indices of the transparent conductive substrates were obtained and fixed in the model. The best models correspond well to independent physical measurements of film structure, such as atomic-force microscopy and surface profiling. Surface roughness, gradient composition and other types of inhomogeneity are common in both the transparent conductors and electrochromic, resulting in particularly complex models. The polymer has a homogeneous structure, but obtaining optically smooth surfaces was a problem. Complete sets of data were produced over the entire solar spectrum for a range of colored states of the films. Using the data for each layer, a realistic electrochromic device was simulated.

Abstract: Thin films of lithium nickel oxide were deposited by sputtering and laser ablation from targets of pressed nickel oxide and lithium oxide powders. These films were assembled into electrochromic test devices with tungsten oxide as the opposite electrode and a polymer electrolyte. Analysis of the failure modes was carried out at several levels: The composition and structure of the films were examined before and after cycling using a variety of techniques, such as infrared spectroscopy, nuclear-reaction analysis, Rutherford backscattering spectrometry, x-ray diffraction and atomic force microscopy. Absorption of water vapor was found to be a major factor determining the cyclic stability of the films. A new technique is described for incorporating reference electrodes made from an electronically isolated corner into devices. This structure enabled identification of potential problems associated with a particular interface. Finally, some of the devices were disassembled and the components examined. For example, a small quantity of the polymer was extracted and studied by gas chromatography and mass spectroscopy. Small organic fragments were discovered which correspond to expected weak points in the polymer structures.

Abstract: Tungsten trioxide (WO3) is the most widely used material for the active layer of electrochromic devices. Knowledge of the complex refractive index over the range of coloration states is required for device design. Optical constants of WO3 over the whole solar spectrum were determined as a function of injected charge. Films of WO3 were prepared by electron-beam evaporation, then colored in several steps by reduction with lithium (Li) up to 68 mC cm-2 mm-1 injected charge. Measurements included variable-angle spectroscopic ellipsometry and spectroscopic transmittance and reflectance at normal incidence. Analysis was complicated by the fact that a transparent-conducting layer of indium tin oxide (ITO) was required to perform lithiation. Optical indices of the glass substrate and ITO transparent conductor were determined separately and then fixed in the model. The indices of WO3 could then be extracted from measurements on the complete structure. A parametric dispersion model corresponding to Gaussian broadening of the oscillators was used to represent the dielectric response of WO3.

Abstract: This paper describes an end-use analysis of the national energy requirements of U.S. residential window technologies. We estimate that the current U.S. stock of 19 billion square feet of residential windows is responsible for 1.7 quadrillion BTUs (or quads) per year of energy use - 1.3 quads of heating and 0.4 quads of cooling energy - which represents about 2% of total U.S. energy consumption. We show that national energy use due to windows could be reduced by 25% by the year 2010 through accelerated adoption of currently available, advanced window technologies such as low-e and solar control low-e coatings, vinyl and wood frames, and superwindows. We evaluate the economics of the technologies regionally, considering both climatic and energy price variations, and find that the technologies would be cost effective for most consumers.

Abstract: Electrochrornic windows offer the ability to dynamically change the transmittance of a glazing. With the appropriate sensor and controls, this smart window can be used for energy regulation and glare control for a variety of glazing applications. The most promising are building and automotive applications. This work covers the use of sol-gel deposition processes to make active films for these windows. The sol-gel process offers a low-capital investment for the deposition of these active films. Sol-gel serves as an alternative to more expensive vacuum deposition processes. The sol-gel process utilizes solution coating followed by a hydrolysis and condensation. In this investigation we report on tungsten oxide and nickel oxide films made by the sol-gel process for electrochromic windows. The properties of the sol-gel films compare favorably to those of films made by other techniques. A typical laminated electrochromic window consists of two glass sheets coated with transparent conductors, which are coated with the active films. The two sheets are laminated together with an ionically conductive polymer. The range of visible transmission modulation of the tungsten oxide was 60% and for the nickel oxide was 20%. We used the device configuration of glass/SnO2:F/WO3/polymer/LizNiOXHy/SnO2:F to test the films. The nickel oxide layer had a low level of lithiation and possibly contained a small amount of water. Lithiated oxymethylene-linked poly(ethylene oxide) was used as the laminating polymer. Commercially available Sn02:F/glass (LOF-Tec glass) was used as the transparent conducting glass. We found reasonable device switching characteristics which could be used for devices.

Abstract: Photoluminescence measurements are used to determine the strain in GaN thin films grown by Molecular Beam Epitaxy. The strain which originates from growth on lattice mismatched substrates and from differences in thermal expansion coefficients is found to be greatly relaxed. Residual strains are shown to depend on the thickness of GaN buffer layers and the III/V flux ration during main layer growth. The results strongly suggest that the residual biaxial strain caused by the post-growth cooling can be modified by the incorporation of point defects during the main layer growth which introduce an additional hydrostatic strain field. The effect allows for strain engineering of GaN crystals.

Abstract: This paper presents the results of a study investigating the energy performance of three newly developed prototype electrochromic devices. The DOE-2.1E energy simulation program was used to analyze the annual cooling, lighting, and total electric energy use and peak demand as a function of window type and size. We simulated a prototypical commercial office building module located in the cooling-dominated locations of Phoenix, AZ and Miami, FL. Heating energy use was also studied in the heating-dominated location of Madison, WI. Daylight illuminance was used to control electrochromic state-switching. Two types of window systems were analyzed; i.e., the outer pane electrochromic glazing was combined with either a conventional low-E or a spectrally selective inner pane. The properties of the electrochromic glazings are based on measured data of new prototypes developed as part of a cooperative DOE-industry program.

Our results show the largest difference in annual electric energy performance between the different window types occurs in Phoenix and is about 6.5 kWh/m2 floor area (0.60 kWh/ft2) which can represent a cost of about $.52/m2 ($.05/ft2) using electricity costing $.08/kWh. Much larger differences exist when electrochromic windows are compared to conventional glazings in use today. At large window sizes, such energy savings can be as large as 90 kWh/m2 (8.4 kWh/ft2). Specific electrochromic performance varies with window-to-wall area ratio; i.e., at low ratios, one type electrochromic performs best, while at large ratios, another type performs best. In general, an electrochromic glazing combined with a spectrally selective glazings is better than one combined with a low-E glazing; however, at low-window-to-wall area ratios, this situation reverses slightly. There is almost no difference in peak electric demand for the different electrochromic windows analyzed.

In heating-dominated locations, the electrochromic should be maintained in its bleached state during the heating season to take advantage of beneficial solar heat gain which would reduce the amount of required heating. This also means that the electrochromic window with the largest solar heat gain coefficient is best. The largest heating energy performance difference in Madison for the various window types is 43 MJ/m2 floor area (4.0 kBtu/ft2). This represents a cost of about $.26/m2 floor area ($.024/ft2) using gas costing $0.60/therm ($5.69/GJ, $6.00/MBtu). However, a non-switching electrochromic will not provide desired glare control so that a control strategy that minimizes winter heating use may not be routinely desirable in many buildings.

Abstract: When combined with appropriate electric lighting dimming controls, the use of daylight for ambient and task illumination can significantly reduce energy requirements in commercial buildings. While skylights can effectively illuminate any part of one-story buildings, conventional side windows can illuminate only a 15 ft - 20 ft (4.6 m - 6.1 m) depth of the building perimeter. Even so, the overall efficacy of daylight is limited, because side windows produce uneven distributions of daylight. Achieving adequate illumination at distances further away from the window results in excessive illumination near the window, which increases cooling loads from the associated solar heat gain. As a result, the use of larger apertures and/or higher transmittance glazings, to introduce daylight deeper than 15 ft - 20 ft (4.6 m - 6.1 m), may prove ineffective with respect to saving energy, because cooling load penalties may exceed the electric lighting savings.

The need for more uniform distribution of daylight admitted through side windows has stimulated significant research and development efforts in new fenestration designs and glazing technologies. Many of these approaches, including holographic glazings, rely on the common strategy of redirecting sunlight and reflecting it off the ceiling towards the back of the room. Prior studies on the daylight and energy performance of holographic glazings have been disappointing, however inconclusive because of poor hologram quality, low diffractionsefficiency and inadequate hologram design and building application considerations [Papamichael et al 1994].

Abstract: A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bidirectional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient.

This paper describes the method of measuring the spatially averaged bidirectional optical properties using an automated, large-sample gonio-radiometer/photometer, termed a Scanning Radiometer. Property measurements are presented for one of the most optically complex systems in common use, a venetian blind. These measurements will form the basis for optical system calculations used to test the method of determining performance.

Abstract: Energy efficiency improvements in domestic refrigeratorlfreezers are directly influenced by the overall thermal performance of the cabinet and doors. An advanced system for reducing heat gain is Gas-Filled Panel thermal insulation technology. Gas-Filled Panels contain a low-conductivity, inert gas at atmospheric pressure and employ a reflective baffle to suppress radiation and convection within the gas. This paper presents energy use test results for a 1993 model 500 liter top mount refrigerator/freezer operated with its original doors and with a series of alternative prototype doors. Gas-Filled Panel technology was used in two types of prototype refrigeratorlfreezer doors. In one design, panels were used in composite with foam in standard metal door pans; this design yielded no measurable energy savings. In the other design, special polymer door pans were fitted with panels that fill nearly all of the available insulation volume; this design yielded a 6.5% increase in energy efficiency for the entire refrigerator/freezer. The EPA Refrigerator Analysis computer program has been used to predict the change in daily energy consumption with the alternative doors. The computer model also projects a 25% energy efficiency improvement for asrefrigerator/freezer that would use Gas-Filled Panel insulation throughout the cabinet as well as the doors.

Abstract: Infrared scanning radiometers are used to generate temperature maps of building envelope components, including windows and insulation. These temperature maps may assist in evaluating components" thermal performance. Although infrared imaging has long been used for field evaluations, controlled laboratory conditions allow improvements in quantitative measurements of surface temperature using reference emitter techniques.

This paper discusses issues associated with the accuracy of using infrared scanning radiometers to generate temperature maps of building envelope components under steady-state, controlled laboratory conditions. Preliminary experimental data are presented for the accuracy and uniformity of response of one commercial infrared scanner. The specified accuracy of this scanner for temperature measurements is 2 deg. C or 2% of the total range of values (span) being measured. A technique is described for improving this accuracy using a temperature-controlled external reference emitter. Minimum temperature measurement accuracy with a reference emitter is estimated at ?0.5 deg. C for ambient air and background radiation at 21.1 deg. C and surface temperatures from 0 deg. C to 21 deg. C.

Infrared imaging, with a reference emitter technique, is being used to create a database of temperature maps for a range of window systems, varying in physical complexity, material properties, and thermal performance. The database is to be distributed to developers of fenestration heat transfer simulation programs to help validate their models. Representative data are included for two insulated glazing units with different spacer systems.

Abstract: Until the 1970s, the thermal performance of windows and other fenestration technologies was rarely of interest to manufacturers, designers, and scientists. Since then, however, a significant research and industry effort has focused on better understanding window thermal and optical behavior, how windows influence building energy patterns, and on the development of advanced products. This chapter explains how fenestration technologies can make a positive impact on building energy flows, what physical phenomena govern window heat and light transfer, what new products have been developed, and what new products are currently the subject of international research efforts.

Abstract: This paper documents efforts currently being undertaken by the National Fenestration Rating Council"s Annual Energy Rating Subcommittee to develop procedures to quantify the energy impacts of fenestration products in typical residential buildings throughout the United States. Parallel paths focus on (1) the development of simplified heating and cooling indices and (2) the development of a more detailed methodology to calculate the cost and energy impacts of specific products in a variety of housing types. These procedures are currently under discussion by NFRC"s Technical Committee; future efforts will also address commercial buildings.

Abstract: Vacuum glazing is a form of low-conductance double glazing using an internal vacuum between the two glass sheets to eliminate heat transport by gas conduction and convection. Ansarray of small support pillars separates the sheets; fused solder glass forms the edge seal. Heat transfer through the glazing occurs by radiation across the vacuum gap, conduction through the support pillars, and conduction through the bonded edge seal. Edge conduction is problematic because it affects stresses in the edge region, leading to possible failure of the glazing; in addition, excessive heat transfer because of thermal bridging in the edge region can lower overall window thermal performance and decrease resistance to condensation.

Infrared thermography was used to analyze the thermal performance of prototype vacuum glazings, and, for comparison, atmospheric pressure superwindows. Research focused on mitigating the edge efects of vacuum glazings through the use of insulating trim, recessed edges, and framing materials. Experimentally validated finite-element and finite-difference modeling tools were used for thermal analysis of prototype vacuum glazing units and complete windows. Experimental measurements of edge conduction using infrared imaging were found to be in good agreement with finite-element modeling results for a given set of conditions. Finite-element modeling validates an analytic model developed for edge conduction.

Abstract: Infrared thermography is a non-invasive, non-destructive technique for measuring surface temperatures of an object. These surface temperatures can be used to understand the thermal performance of window components and complete window systems. Infrared (IR) thermography has long been used for qualitative field assessment of window thermal performance, and is now being used in the laboratory for quantitative assessments of window thermal performance. As windows become better and better, more refined test methods and/or simulation tools are required to accurately detect performance changes and make comparisons between products. While hot box calorimetery has worked well to characterize the thermal performance of conventional insulating products, differences in the thermal performance of new highly insulating systems are often less than the resolution of conventional hot box calorimeters. Infrared imaging techniques offer the opportunity to resolve small differences in the thermal performance of components of highly insulating window systems that hot box measurements are not able to identify.

Lawrence Berkeley Laboratory (LBL), a U.S. national research laboratory, is currently using infrared thermography to develop a database of measured surface temperature profiles for a number of different fenestration products for use in validating both basic and advanced two- and three-dimensional finite element method (FEM) and finite difference method (FDM) fenestration heat transfer simulation programs. IR surface temperature data, when taken under controlled laboratory conditions, can be used to direct the development of these simulation codes, identify their strengths and weaknesses, set research priorities, and validate finished modeling tools. Simulation of fenestration heat transfer is faster and less expensive than hot box testing of fenestration products, and forms the basis of window energy codes being implemented, developed, or considered in the US, Canada, the Former Soviet Union, Europe, and Australia. The National Fenestration Rating Council (U. S.) has developed a simulation-based standard which is used to rate and label window U-values for a published directory of over 10,000 different window products.

Abstract: A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bi-directional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient.

The method has been applied to one of the most optically complex systems in common use, a venetian blind in combination with multiple glazings. A comparison between the scanner-based calculation method and direct system calorimetric measurements made on the LBL MoWiTT facility showed good agreement, and is a significant validation of the method accuracy and feasibility.

Abstract: Researchers participating in IEA/SHC Task 18 on advanced glazing materials have as their primary objective the development of new innovative glazing products such as high performance glazings, wavelength selective glazings, chromogenic optical switching devices, and light transport mechanisms that will lead to significant energy use reductions and increased comfort in commercial and residential buildings. Part of the Task 18 effort involves evaluation of the energy and comfort performance of these new glazings through the use of various performance analysis simulation tools. Eleven countries (Australia, Denmark, Finland, Germany, Italy, Netherlands, Norway, Spain, Sweden, Switzerland, and the United States) are contributing to this multi-year simulation study to better understand the complex heat transfer interactions that determine window performance. Each country has selected particular simulation programs and identified the following items to guide the simulation tasks: (1) geographic locations; (2) building types; (3) window systems and control strategies; and (4) analysis parameters of interest. This paper summarizes the results obtained thus far by several of the research organizations.

Abstract: Calorimetric measurements of the dynamic net heat flow through a complex fenestration system consisting of a buff venetian blind inside clear double glazing are used to derive the direction-dependent beam SHGC of the fenestration. These measurements are compared with calculations according to a proposed general method for deriving complex fenestration system SHGC"s from bidirectional layer optical properties and generic calorimetric properties. Previously published optical measurements of the same venetian blind and generic inward-flowing fraction measurements are used in the calculation. The authors find satisfactory agreement between the SHGC measurements and the calculation.

Significant dependence on incident angle was found in the measured SHGC"s. Profile angle was not found to be a useful variable in characterizing the system performance. The predicted SHGC was found to be inherently dependent on two angles, although only the incident angle variations were observable under the test conditions.

Abstract: This paper presents a calorimetric measurement of layer-specific inward-flowing fractions of absorbed solar energy for a number of geometric configurations common in fenestrations with shading. The inward-flowing fractions are found to be relatively insensitive to exterior conditions. Results for an interior venetian blind over double glazing agree with thermal model calculations in the literature, and are the first layer-specific verification of these calculations. It is argued that a data base of these inward-flowing fractions for a suitably broad class of geometries will make possible the determination of solar heat gain coefficient from non-calorimetric measurements of solar-optical properties of complex fenestration components, a procedure termed solar-thermal separation.

Abstract: This paper presents the results of a study investigating the energy performance of electrochromic windows in a prototypical residential building under a variety of state switching control strategies. We used the DOE-2.1E energy simulation program to analyze the annual cooling energy and peak demand as a function of glazing type, size, and electrochromic control strategy. A single-story ranch-style home located in the cooling-dominated locations of Miami, FL and Phoenix, AZ was simulated. Electrochromic control strategies analyzed were based on incident total solar radiation, space cooling load, and outside air temperature. Our results show that an electrochromic material with a high reflectance in the colored state provides the best performance for all control strategies. On the other hand, electrochromic switching using space cooling load provides the best performance for all the electrochrornic materials. The performance of the incident total solar radiation control strategy varies as a function of the values of solar radiation which trigger the bleached and colored states of the electrochromic (setpoint range); i.e., required cooling decreases as the setpoint range decreases; also, performance differences among electrochromics increases. The setpoint range of outside air temperature control of electrochromics must relate to the ambient weather conditions prevalent in a particular location. If the setpoint range is too large, electrochromic cooling performance is very poor. Electrochromics compare favorably to conventional low-E clear glazings that have high solar heat gain coefficients that are used with overhangs. However, low-E tinted glazings with low solar heat gain coefficients can outperform certain electrochromics. Overhangs should be considered as a design option for electrochromics whose state properties do not change significantly between bleached and colored states.

Abstract: This paper explores three significant software development requirements for making the transition from standalone lighting simulation/analysis tools to simulation-based design aid tools. These requirements include specialized lighting simulation engines, facilitated methods for creating detailed simulatable building descriptions, and automated techniques for providing lighting design guidance. Initial computer implementations meant to address each of these requirements are discussed to further elaborate these requirements and to illustrate work-in-progress toward fulfilling them.

Abstract: In this letter, we report the results of ion implantation of GaN using 28Si and 23Mg species. Structural and electrical characterizations of the GaN thin films after thermal annealing show that native defects in the GaN films dominate over implant doping effects. The formation energies of the annealing induced defects are estimated to range from 1.4 to 3.6 eV. A 30 keV10^14 cm-2 Mg implant results in the decrease of the free-carrier concentration by three orders of magnitude compared to unimplanted GaN up to an annealing temperature of 690 deg. C. Furthermore, we have observed the correlation between these annealing-induced defects to both improved optical and electrical properties.

Abstract: The optical and electrochemical properties of sol-gel spin coated Ce02-TiO2 (50% CeO2) films were investigated for electrochrornic applications. The coating solutions were prepared by using mixed organic-inorganic | Ti(OC2H5)4 and Ce(NH4)2 (NO3)6 | precursors. X-ray bffraction studies showed the sol-gel spin-coated films were composed of an amorphous matrix of titanium oxide containing nanocrystallites of cerium oxide. The coating solar transmission value was Ts=0.8 (250 nm thck). The refractive index and the extinction coefficient were derived from transmittance ineasurements in the UV-VIS-NIR regions. These films had refractive index value of n=2.18 and extinction coefficient value of k=8x10-4 at l=550 nm. Cyclic voltametric measurements showed reversible electrochemical insertion of lithium ions in a CeO2-TiO2/LiClO4-propylene carbonate electrochemical cell. During cycling the films maintain high optical transmittance. Spectrophotometric and electrochemical investigations performed on CeO2-TiO2 films revealed that these films are suitable as an optically passive counter-electrode in lithium electrochromic devices.

Abstract: Measurements of the net heat flow through four selective glazings in comparison with clear double glazing under late summer outdoor conditions are presented. The solar heat gain coefficient (SHGC) for each glazing is extracted from the data and shown to be angle-dependent. Good agreement is found between measured properties and calculations with WINDOW 4.1.

Abstract: The science and technology of chromogenic materials for switchable glazings in building applications is discussed. These glazings can be used for dynamic control of solar and visible energy. Currently many researchers and engineers are involved with the development of products in this field. A summary of activities in Japan, Europe, Australia, USA and Canada is made. The activities of the International Energy Agency are included. Both non-electrically activated and electrically activated glazings are discussed. Technologies covered in the first category are photochromics, and thermochromics and thermotropics. A discussion of electrically activated chromogenic glazings includes dispersed liquid crystals, dispersed particles and electrochromics. A selection of device structures and performance characteristics are compared. A discussion of transparent conductors is presented. Technical issues concerning large-area development of smart windows are discussed.

Abstract: Proton conducting tantalum oxide films were deposited by spin coating using a sol-gel process. The coating solutions were prepared using Ta(OC2H5)5 as a precursor. X-ray diffraction studies determined that the sol-gel films, heat treated at temperatures below 400 deg. C, were amorphous. Films heat treated at higher temperatures were crystalline Ta2O5. The solar transmission values (Ts) of tantala films on glass generally range from 0.8-0.9 depending on thickness. The refractive index and the extinction coefficient were evaluated from transmittance characteristics in the UV-VIS-NIR regions. The refractive index values calculated at l=550 nm increased from n=1.78 to 1.97 with increasing heat treatment from 150 to 450 deg. C. The films heat treated at different temperatures showed low absorption with extinction coefficients of less than k=l x 10-3 in the visible range. Spectrophotometric and impedance spectroscopic investigations performed on Ta2O5 films revealed that these films have protonic conductivity of 3.2 x 10-6 S/cm. The films are suitable for proton conducting layers in electrochromic (EC) devices.

Abstract: Thin films of tin-doped indium oxide are widely used for transparent conductors. One application of In2O3:Sn (ITO) is transparent contacts for electrochromic electrodes. Opticalsdesign of electrochromic devices requires knowledge of the optical constants for each layer from the near ultraviolet and visible to the Inid infrared. Determination of the optical constants of the electrochromic layer cannot be made in isolation; a complete device or at least a half-cell including a layer of ITO is required to change the optical state of the electrochromic material. Measurements on ITO were made using variable-angle spectral ellipsometry, and spectral transmittance and reflectance. A series of structural models were fit to this data. The problem is complicated because of inhomogeneity in the films, variability in the manufacturing process, and sensitivity to environmental conditions. The spectral dependency was modeled by a single Lorentz oscillator and a Drude free-electron component. This data was then used as the basis for a model to extract the optical constants for a tungsten oxide electrochromic film.

Abstract: This paper discusses the application of Gas-Filled Panels to the building thermal envelope. Gas-Filled Panels, or GFPs, are thermal insulating devices that retain a high concentration of a low-conductivity gas, at atmospheric pressure, within a multilayer infrared reflective baffle. The thermal performance of the panel depends on the type of gas fill and the baffle configuration. We present computer simulation results showing the improvement in thermal resistance resulting from using an argon-GFP in place of glass fiber batt insulation in wood-frame construction. This report also presents estimates of the quantity and cost of material components needed to manufacture GFPs using current prototype designs.

Abstract: Data are presented for the distribution of surface temperatures on the warm-side surface of seven different insulated glazing units. Surface temperatures are measured using infrared thermography and an external referencing technique. This technique allows detailed mapping of surface temperatures that is non-intrusive. The glazings were placed between warm and cold environmental chambers that were operated at conditions corresponding to standard design conditions for winter heating. The temperatures conditions are 21.1 deg. C (70 deg. F) and -17.8 deg. C (0 deg. F) on the warm and cold sides, respectively. Film coefficients varied somewhat with average conditions of about 7.6 W/m2K (1.34 Btu/hft2F) for the warm-side and 28.9 W/m2K (5.1 Btu/hft2F) for the cold-side. Surface temperature data are plotted for the vertical distribution along the centerline of the IG and for the horizontal distribution along the centerline. This paper is part of larger collaborative effort that studied the same set of glazings.

Abstract: In this work we report on the preparation of tantalum oxide and niobium oxide films by the sol-gel method for use as proton ion conductors in electrochromic devices. Measurement of the proton conductivity was derived from impedence spectroscopy measurements. The proton conductivity for Ta2O5 and NbO5 films was 4.6 x 10-6 Scm-1 and 3.2 x 10-7 Scm-1 respectively. The structural and chemical properties of the films were investigated by X-ray diffraction, X-ray photoelectron spectroscopy and scanning electron microscopy. These films were found to be amorphous and close to the stoichometry of Ta2O5 and NbO5 respectively. In order to estimate the compatibility of these sol-gel deposited layers as ion conductors for EC devices, we investigated tantalum oxide and niobium oxide films deposited on sputtered WO3 films. Charge balance and coloration characteristics were investigated during voltammetric cycling in a pH 2 liquid electrolyte. Spectral transmittance was measured for colored and bleached conditions. The photopic weighted transmittance change and solar weighted transmittance change were Tp=35.2% - 21.8% and Ts=75.7% - 14.2% for tantala films on tungsten oxide. For niobia on tungsten oxide the values were Tp=85.3% - 35.2% and Ts=75.8% - 28.1%.

Abstract: Electrochromic devices have increasing application in display devices, switchable minors and smart windows. A variety of vacuum depition technologies have been used to make electrochromic devices. The sol-gel process offers an alternative approach to the synthesis of optical quality and low cost electrochromic device layers. This study summarizes the developments in sol-gel deposited electrochromic films. The sol-gel process involves the formation of oxide networks upon hydrolysis-condensation of alkoxide precursors. In this study we cover the sol-gel deposited oxides of WO3, V2O5, TiO2, Nb2O5 and NiOx.

Abstract: Inorganic LiNbO3 ion conducting films were prepared by sol-gel process involving two alkoxides, lithium ethoxide and niobium ethoxide. The films were analyzed by ellipsometry, X-ray diffractometry, scanning electron microscopy and impedance spectroscopy. Impedance spectroscopy indicated that the Li conductivity values were in the range of 6-8 x 10-7 S cm-1. The morphology and thickness of these films played an important role in the insertion of lithium ions. Spectrophotometric investigation showed that LiNbO3 films exhibit very weak cathodic coloration from 350 to 900 nm spectral region. The previous termelectrochemical and opticalnext term properties clearly indicate that sol-gel deposited LiNbO3 films can be used as lithium ion conducting layers for electrochromic device application.

Abstract: Electrochromic niobia (Nb2O5) coatings were prepared by the sot-gel spin-coating and d.c. magnetron sputtering techniques. Parameters were investigated for the process fabrication of sol-gel spin coated Nb2O5 films exhibiting high coloration efficiency comparable with that d.c. magnetron sputtered niobia films. X-ray diffraction studies (XRD) showed that the sot-gel deposited and magnetron sputtered films heat treated at temperatures below 450 deg. C, were amorphous, whereas those heat treated at higher temperatures were slightly crystalline. X-ray photoelectron spectroscopy (XPS) studies showed that the stoichiometry of the films was Nb2O5. The refractive index and electrochromic coloration were found to depend on the preparation technique. Both films showed low absorption and high transparency in the visible range. We found that the n, k values of the sot-gel deposited films to be lower than for the sputtered films. The n and k values were n = 1.82 and k = 3 x 10-3, and n = 2.28 and K = 4 x 10-3 at 530 urn for sot-gel deposited and sputtered films, respectively. The previous termelectrochemicalnext term behavior and structural changes were investigated in 1 M LiClO4/propylene carbonate solution. Using the previous termelectrochemicalnext term measurements and X-ray photoelectron spectroscopy, the probable electrode reaction with the lithiation and delithiation is Nb2O5 x Li x e-? LixNb2O5. Cyclic voltametric (CV) measurements showed that both Nb2O5 films exhibits previous termelectrochemicalnext term reversibility beyond 1200 cycles without change in performance. In situ previous termopticalnext term measurement revealed that those films exhibit an electrochromic effect in the spectral range 300 < l, Greek < 2100 nm but remain unchanged in the infrared spectral range. The change in visible transmittance was 40% for 250 nm thick electrodes. Spectroelectrochemical measurements showed that spin coated films were essentially electrochemically equivalent to those prepared by d.c. magnetron sputter deposition.

Abstract: The preparation and properties of Nb2O5 coatings made by the sol-gel process were investigated. The films were deposited by spin coating on In2O3:Sn/glass and quartz substrates from a polymeric solutions of niobia derived from niobium ethoxide. The films were characterized by investigation of the stoichiometry, refractive index, optical transmission, electrochemical behavior, and the microstructure. X-ray diffraction studies showed the films to be amorphous for heat treatments below 450 deg. C. X-ray photoelectron spectroscopy (XPS) measurement revealed the O:Nb atomic stoichiometry to be 5:2. Cyclic voltammetric measurements showed that the Nb2O5/1 M LiClO4-propylene carbonate system exhibits electrochemical reversibility beyond 1200 cycles without change in performance. In situ UV-Vis-NIR spectroelectrochemical measurement revealed that Nb2O5 films exhibit an electrochromic effect in the spectral range 300 < l, Greek < 2100 nm and remain unchanged in the infrared spectral range. The change in visible transmittance was 40% for a 250 nm thick electrode. XPS spectra indicate that Nb(V) is reduced to a lower valence state Nb(IV) in a colored state with injected Li . The bronze coloration is due to a simultaneous injection of electrons and Li ions into Nb2O5. The sol-gel-deposited Nb2O5 films are useful for cathodically coloring electrochromic electrodes in electrochromic devices.

Abstract: Electrically activated switchable glazing and their use as smart windows and other large-area applications are discussed. Electrochromic devices are compared to dispersed liquid crystals and dispersed particle glazing systems. A selection of device structures and performance characteristics are compared. A disctlssion of transparent conductors is presented. The characteristics of prototype and commercial devices from commercial and university labs in Japan, Europe, Australia, and USA are covered. A discussion of thesfuture of this technology is made including areas of necessary development for the realization of devices in excess of 1 m2.

Abstract: The most recent version of the DOE-2 building energy simulation program, DOE-2.1E, provides for more detailed modeling of the thermal and optical properties of windows. The window calculations account for the temperature effects on U-value, and update the incident angle correlations for the solar heat gain properties and visible transmittance. Initial studies show up to a 30% difference in calculating peak solar heat gain between the detailed approach and a constant shading-coefficient approach. The modeling approach is adapted from Lawrence Berkeley Laboratory"s WINDOW 4 computer program, which is used in the National Fenestration Rating Council (NFRC) U-value rating procedure 100-91. This gives DOE-2.1E the capability to assess the annual and peak energy performance of windows consistent with the NFRC procedure. The program has an extensive window library and algorithms for simulating switchable glazings. The program also accounts for the influence of framing elements on the heat transfer and solar heat gain through the window.

Abstract: This report summarizes five collaborative research projects on glazings performed by participants in Subtask C of IEA Solar Heating and Cooling Programme (SHC) Task 10, Materials Research and Testing. The projects include materials characterization, optical and thermal measurements, and durability testing of several types of new glazings. Three studies were completed on electrochromic and dispersed liquid crystals for smart windows, and two were completed for low-E coatings and transparent insulation materials for more conventional window and wall applications. In the area of optical switching materials for smart windows, the group developed more uniform characterization parameters that are useful to determine lifetime and performance of electrochromics. The detailed optical properties of an Asahi (Japan) prototype electrochromic window were measured in several laboratories. A one square meter array of prototype devices was tested outdoors and demonstrated significant cooling savings compared to tinted static glazing. Three dispersed liquid crystal window devices from Taliq (USA) were evaluated. In the off state, these liquid crystal windows scatter light greatly. When a voltage of about 100 V ac is applied, these windows become transparent. Undyed devices reduce total visible light transmittance by only .25 when switched, but this can be increased to .50 with the use of dyed liquid crystals. A wide range of solar-optical and emittance measurements were made on low-E coated glass and plastic. Samples of pyrolytic tin oxide from Ford glass (USA) and multilayer metal-dielectric coatings from Interpane (Germany) and Southwall (USA) were evaluated. In addition to optical characterization, the samples were exposure-tested in Switzerland. The thermal and optical properties of two different types of transparent insulation materials were measured. Samples of the polycarbonate honeycomb (supplied by Arel in Israel) and monolithic aerogel (supplied by Airglass in Sweden) were evaluated. Discrepancies in the round robin thermal measurements for the honeycomb material pointed out some measurement problems due to different equipment and procedures used. Overall, these glazing studies were successful in improving the understanding and use of advanced glazings. Follow-on work on most of these glazings will be continued in the new IEA SHC Task 18, Advanced Glazing Materials.

Abstract: We present results from the design and evaluation of three advanced daylighting systems: a light shelf, a light pipe, and a skylight. These systems use optical films and an optimizedsgeometry to passively intercept and redirect sunlight further into the building. The objectives of these designs are to increase daylighting illuminance levels at distances of 4.6-9.1 m (15-30 ft) from the window, and to improve the uniformity of the daylight distribution and the luminance gradient across the room under variable sun and sky conditions throughout the year. The designs were developed through a series of computer-assisted ray-tracing studies, photometric measurements, and observations using physical scale models. Comprehensive sets of laboratory measurements in combination with analytical routines were then used to simulate daylight performance for any solar position. Results show increased daylight levels and an improved luminance gradient throughout the year - indicating that lighting energy consumption and cooling energy due to lighting can be substantially reduced with improvements to visual comfort. Future development of the designs may further improve the daylighting performance of these systems.

Abstract: WINDOW 4.1 is a publicly available IBM PC compatible computer program developed by the Windows and Daylighting Group at Lawrence Berkeley Laboratory for calculating total window thermal performance indices (i.e. U-values, solar heat gain coefficients, shading coefficients, and visible transmittances). WINDOW 4.1 provides a versatile heat transfer analysis method consistent with the rating procedure developed by the National Fenestration Rating Council (NFRC). The program can be used to design and develop new products, to rate and compare performance characteristics of all types of window products, to assist educators in teaching heat transfer through windows, and to help public officials in developing building energy codes.

WINDOW 4.1 is an update to WINDOW 4.0. The WINDOW 4 series is a major revision to previous versions of WINDOW. We strongly urge all users to read this manual before using the program. Users who need professional assistance with the WINDOW 4.1 program or other window performance simulation issues are encouraged to contact one or more of the NFRC-accredited Simulation Laboratories.

Abstract: The light diffraction properties of holographic diffractive structures present an opportunity to improve the daylight performance in side-lit office spaces by redirecting and reflecting sunlight off the ceiling, providing adequate daylight illumination up to 30 ft (9.14 m) from the window wall. Prior studies of prototypical holographic glazings, installed above conventional view windows, have shown increased daylight levels over a deeper perimeter area than clear glass, for selected sun positions. In this study, we report on the simulation of the energy performance of prototypical holographic glazings assuming a commercial office building in the inland Los Angeles climate.

The simulation of the energy performance involved determination of both luminous and thermal performance. Since the optical complexity of holographic glazings prevented the use of conventional algorithms for the simulation of their luminous performance, we used a newly developed method that combines experimentally determined directional workplane illuminance coefficients with computer-based analytical routines to determine a comprehensive set of daylight factors for many sun positions. These daylight factors were then used within the DOE-2.1D energy simulation program to determine hourly daylight and energy performance over the course of an entire year for four window orientations.

Since the prototypical holographic diffractive structures considered in this study were applied on single pane clear glass, we also simulated the performance of hypothetical glazings, assuming the daylight performance of the prototype holographic glazings and the thermal performance of double-pane and low-e glazings. The results of our analyses show that these prototypical holographic glazings did not save significant electric energy or reduce peak electricity demand compared to conventional energy-efficient window systems in inland Los Angeles office buildings, mainly because of their low diffraction efficiency. Finally, we address various design and implementation issues towards potential performance improvement.

Abstract: The last several years have produced a wide variety of new window products aimed at reducing the energy impacts associated with residential windows. Improvements have focused on reducing the rate at which heat flows through the total window product by conduction/convection and thermal radiation (quantified by the U-factor) as well as in controlling solar heat gain (measured by the Solar Heat Gain Coefficient (SHGC) or Shading Coefficient (SC).

Significant improvements in window performance have been made with low-E coated glazings, gas fills in multiple pane windows and with changes in spacer and frame materials and designs. These improvements have been changes to existing design concepts. They have pushed the limits of the individual features and revealed weaknesses. The next generation of windows will have to incorporate new materials and ideas, like recessed night insulation, seasonal sun shades and structural window frames, into the design, manufacturing and construction process, to produce an integrated window system that will be an energy and comfort asset.

Abstract: This paper presents the results of a study investigating the energy performance of electrochromic windows under a variety of state-switching control strategies. We used the DOE-2.1E energy simulation program to analyze the annual cooling, lighting, and total electricity use and peak demand as a function of glazing type, size, and electrochromic control strategy. We simulated a prototypical commercial office building module located in the cooling-dominated location of Blythe, California. Control strategies analyzed were based on daylight illuminance, incident total solar radiation, and space cooling load. Our results show that when a daylighting strategy is used to reduce electric lighting requirements, control algorithms based on daylight illuminance results in the best overall annual energy performance. If daylighting is not an design option, controls based on space cooling load yield the best performance through solar heat gain reduction. The performance of incident total solar radiation control strategies varies as a function of the switching setpoints; for small to moderate window sizes which result in small to moderate solar gains, a large setpoint-range was best since it provides increased illuminance for daylighting without much cooling penalty; for larger window sizes, which provide adequate daylight, a smaller setpoint-range was best to reduce unwanted solar heat gains and the consequential increased cooling requirement. Of particular importance is the fact that reduction in peak electric demand was found to be independent of the type of control strategy used for electrochromic switching. This is because the electrochromics are generally in their most colored state under peak conditions, and the mechanism used for achieving such a state is not important.

Abstract: The performance factors which will influence the market acceptance of electrochromic windows are reviewed. A set of data representing the optical properties of existing and foreseeable electrochromic window devices was generated. The issue of reflective versus absorbing electrochromics was explored. This data was used in the DOE 2.1 building energy model to calculate the expected energy savings compared to conventional glazings. The effects of several different control strategies were tested. Significant energy and peak electric demand benefits were obtained for some electrochromic types. Use of predictive control algorithms to optimize cooling control may result in greater energy savings. Initial economic results considering annual savings, cooling equipment cost savings, and electrochromic window costs are presented. Calculations of thermal and visual comfort show additional benefits from electrochromics but more work is needed to quantify their importance. The design freedom and aesthetic possibilities of these dynamic glazings should provide additional market benefits, but their impact is difficult to assess at this time. Ultimately, a full assessment of the market viability of electrochromics must consider the impacts of all of these issues.

Abstract: Crystalline aluminum nitride (AlN) thin films were formed on various substrates by using RF magnetron sputtering of an Al target in a nitrogen plasma and also by ion-assisted molecular beam epitaxy (IAMBE). Basal-oriented AlN/(111) Si showed a degradation of crystallinity with increased substrate temperature from 550 to 770 degrees C, while the crystallinity of AlN/(0001) Al2O3 samples improved from 700 to 850 degrees C. The optical absorption characteristics of the AlN/(0001) Al2O3 films as grown by both deposition methods revealed a decrease in sub-band gap absorption with increased substrate temperature.

Abstract: The hollow-anode discharge is a special form of glow discharge. It is shown that a drastically reduced anode area is responsible for a positive anode voltage drop of 30-40 V and an increased anode sheath thickness. This leads to ignition of a relatively dense plasma in front of the anode hole. Langmuir probe measurements inside a specially designed hollow anode plasma source give an electron density and temperature of ne = 10^9-10^11 cm-3 and Te = 1-3 eV, respectively (nitrogen, current 100 rnA, flow rate 5-50 scc/min). Driven by a pressure gradient, the anode plasma is blown through the anode hole and forms a bright plasma jet st~earningw ith supersonic velocity (Mach number 1.2). The plasma stream can be used, for instance, in plasma-assisted deposition of thin films.

Abstract: Since the growth of GaN using molecular beam epitaxy (MBE) occurs under metastable growth conditions, activated nitrogen is required to drive the forward synthesis reaction. In the process of exciting the nitrogen using a plasma or ion-beam source, species with large kinetic energies are generated. Impingement on the growth surface by these species can result in subsurface damage to the growing film, as well as an enhancement of the reverse decomposition reaction rate. In this study, we investigate the effect of the kinetic energy of the impinging nitrogen ions during growth on the resulting optical and structural properties of GaN films. Strong band-edge photoluminescence and cathodoluminescence are found when a kinetic energy of ~10 eV are used, while luminescence is not detectable when the kinetic energies exceeds 18 eV. Also, we find that the use of conductive SiC substrates results in more homogeneous luminescence than the use of insulating sapphire substrates. This is attributed to sample surface charging in the case of sapphire substrates and subsequent variation in the incident ion flux and kinetic energy across the growth surface.This study clearly shows that the quality of GaN films grown by MBE are presently limited by damage from the impingement of high energy species on the growth surface.

Abstract: Gallium nitride is one of the most promising materials for ultraviolet and blue light-emitting diodes and lasers. Both Molecular Beam Epitaxy (MBE) and Metal-Organic Chemical Vapor Deposition (MOCVD) have recently made strong progress in fabricating high-quality epitaxial GaN thin films. . In this paper, we review materials-related issues involved in MBE growth. We show that a strong understanding of the unique meta-stable groivth process allows us to correctly predict the optimum conditions for epitaxial GaN growth. The resulting structural, electronic and optical properties of the GaN films are described in detail.

Abstract: Niobium pentoxide films, fabricated by the sol-gel process, were spin coated onto conductive indium tin oxide (ITO)/glass, and microscope slides. These films were cycled in a 1M LiClO4 propylene carbonate (PC) solution, and exhibited electrochromic behavior upon the electrochemical insertion (reduction) and extraction (oxidation) of lithium. In-situ optical transmittance measurements were investigated in the ultraviolet/visible/near-infrared wavelength regions (250-2100 nm). Niobium pentoxide films showed reversible optical switching from 320 to 870 nm, but were found electrochromically inactive in the infrared region. Surface analysis using X-ray photoelectron spectroscopy (XPS) indicated little difference in the chemistry of Nb2O5 films as deposited and lithiated LixNb2O5 films, as XPS binding energies of Nb and O showed no appreciable shifts. These films were found to be amorphous by X-ray diffraction. Optical transmittance measurements combined with cyclic voltamograms and XPS spectra, revealed that the electrochromic behavior of these films occurs due to the insertion of Li cations into niobium pentoxide films. The bronze coloration of the niobium pentoxide films could make them useful as an electrochromic counter electrodesfor electrochromic devices.

Abstract: Tantalum oxide films were prepared by sol-gel process using tantalum ethoxide Ta(OC2H5)5. The dependence of deposition conditions (i.e. composition of polymeric solutions and spinning rate) on ionic conductivities for tantalum oxide films were studied. The best results achieved for films fabricated by the spin coating technique were from clear polymeric solutions. These films had low packing density p=3.2 g/cm3 and good proton conductivity (about 104 a-1 cm-1). X-ray photoelectron spectroscopy (XPS) was used for studying the compositions of the tantalum oxide films. We report on the use of tantalum oxide films as ion conductors in devices consisting of WO3/Ta2O5/H ion storage polymer structure. We found tantalum oxide to have very good properties for proton device applications.

Abstract: The use of polyorganodisulfides as optically passive counterelectrodes in a variety of electrochromic devices are discussed. Characteristic data is presented for electrochmmic devices using proton, and lithium coloration ions with polyethylene oxide electrolyte and polydimercaptothiadiazole positive electrodes. Solid state devices consisting of molybdenum doped W03, amorphous polyethylene oxide electrolyte (a-PEO), and a polyorganodisulfide counter-electrode colored rapidly from a pale yellow to a deep blue-green, upon application of 1.2 V d.c. The photopic transmittance changed from 61 to 98, and the solar transmittance from 45 to 5% during the coloration process. Also, our experiments with polyimidazole are detailed. This family of compounds due to its unique electrical and ion conduction properties allow a single composite ion storage and ion conductor electrode to be made, simplifying the device construction. Devices rnade from this family of compounds color to deep blue-gray upon application of 1.2-1.5 V. Bleaching occurs at -0.4 to -0.5 s. The photopic transmittance changed from 55 to 9%. and the solar transmittance from 34 to 4% during coloration. Both coloration and bleaching are quite rapid.

Abstract: WINDOW 4.0 is a publicly available IBM PC compatible computer program developed by the Building Technologies Group at the Lawrence Berkeley Laboratory for calculating the thermal and optical properties necessary for heat transfer analyses of fenestration products. This report explains the calculation methods used in WINDOW 4.0 and is meant as a tool for those interested in understanding the procedures contained in WINDOW 4.0. All the calculations are discussed in the International System of units (SI).

Abstract: A new method to simulate the daylight performance of fenestration systems and spaces is presented. This new method, named IDC (Integration of Directional Coefficients), allows the simulation of the daylight performance of fenestration systems and spaces of arbitrary complexity, under any sun, sky and ground conditions. The IDC method is based on the combination of scale model photometry and computer-based simulation. Physical scale models are used to experimentally determine a comprehensive set of directional illuminance coefficients at reference points of interest, which are then used in analytical, computer-based routines, to determine daylight factors or actual daylight illuminance values under any sun, sky and ground conditions.

The main advantage of the IDC method is its applicability to any optically complex environment. Moreover, the computer-based analytical routines are fast enough to allow for hourly simulation of the daylight performance over the course of an entire year. However, the method requires appropriate experimental facilities for the determination of the Directional Coefficients. The IDC method has been implemented and used successfully in inter-validation procedures with various daylight simulation computer programs. Currently, it is used to simulate the daylight performance of fenestration systems that incorporate optically complex components, such as Venetian blinds, optically treated light shelves and light pipes.

Abstract: Heating and cooling energy lost through windows in the residential sector (estimated at two-thirds of the energy lost through windows in all sectors) currently accounts for 3 percent (or 2.8 quads) of total US energy use, costing over $26 billion annually in energy bills. Installation of energy-efficient windows is acting to reduce the amount of energy lost per unit window area. Installation of more energy efficient windows since 1970 has resulted in an annual savings of approximately 0.6 quads. If all windows utilized existing cost effective energy conserving technologies, then residential window energy losses would amount to less than 0.8 quads, directly saving $18 billion per year in avoided energy costs. The nationwide installation of windows that are now being developed could actually turn this energy loss into a net energy gain. Considering only natural replacement of windows and new construction, appropriate fenestration policies could help realize this potential by reducing annual residential window energy losses to 2.2 quads by the year 2012, despite a growing housing stock.

Abstract: The NFRC U-Value Procedure Validation Project was undertaken by a collaborative group of industry, public utility, trade associations, and government researchers in order to validate the testing and calculational methods of the NFRC 100-91: Procedure for Determining Fenestration Product Thermal Properties (Currently Limited to U-Values). This paper summarizes the validation project"s goals and test methodology, the results of the data analysis, and the recommendations following completion of Phase I of the project. Simulations performed according to NFRC 100-91 are shown to agree with each other, to within the NFRC tolerance, in 100% of the cases. Window test results with perpendicular wind performed according to NFRC 100-91 are shown to agree with each other, to within the NFRC tolerance, in 84% of the cases. Simulations and perpendicular wind window test results are shown to agree with each other, to within the NFRC tolerance, in 80% of the cases. Testing of skylights was shown to be problematic under the procedure as written at the time. Agreement between tests and simulations will improve as a result of a strong NFRC education and accreditation program.

Abstract: The validity of a method to reduce the total number of computer simulations which must be run to determine the U-values of a window product line with multiple glazing options is examined. The accuracy and limits of this method, which uses the WINDOW4 and FRAME simulation programs, is evaluated by comparing the edge, frame, and total window U-values calculated on the basis of single point FRAME simulations to those U-values as calculated on the basis of four point FRAME simulations combined with linear interpolation of frame and edge U-values by WINDOW4. The accuracy of this procedure is examined for two frame types, a low thermal conductivity wood-framed casement and a high thermal conductivity aluminum-framed casement, using both aluminum spacers and insulating spacers over a wide range of glazing types. The effect of center-of-glass U-value, overall glazing thickness and spacer type on frame and edge-of-glass U-values is discussed. It is shown that the agreement between total window U-values as calculated by the single point and four point simulation methods is better than 1% for double and triple-glazed windows with aluminum spacers, better than 1% for double-glazed windows with insulating spacers, and better than 2% for triple-glazed windows with insulating spacers.

Abstract: Gallium nitride is one of the most promising materials for ultraviolet and blue light-emitting diodes and lasers. The principal technical problem that limits device applications has been achieving controllable p-type doping. Molecular beam epitaxy assisted by a nitrogen ion beam produced p-type GaN when doped via ion implantation, diffusion, or coevaporation of Mg. Nearly intrinsic p-type material was also produced without intentional doping, exhibiting hole carrier concentrations of 5 x10^11 cm-3 and hole mobilities of over 400 cm2/V/s 250 K. This value for the hole mobility is an order of magnitude greater than previously reported.

Abstract: This paper presents the results of a study investigating the effects of window U-value changes on residential cooling loads. We used the DOE-2.1D energy analysis simulation program to analyze the hourly, daily, monthly, and annual cooling loads as a function of window U-value. The performance of a prototypical single-story house was examined in three locations: hot and humid, Miami FL; hot and dry, Phoenix AZ; and a heating-dominated location with a mildly hot and humid summer, Madison WI. Our results show that when comparing windows with identical orientation, size, and shading coefficient, higher U-value windows often yield lower annual cooling loads, but lower U-value windows yield lower peak cooling loads. This occurs because the window with the higher U-value conducts more heat from inside the residence to the outside during morning and evening hours when the outside air temperature is often lower than the inside air temperature; and, a lower U-value window conducts less heat from outside to inside during summer afternoon peak cooling hours. The absolute effects are relatively small when compared to total annual cooling which is typically dominated by window solar heat gain effects, latent loads, and internal loads. The U-value effect on cooling is also small when compared to both the effects of U-value and solar heat gain on heating load. Our modeling assumed that U-value and solar heat gain could be independently controlled. In fact, reducing window conductance to the levels used in this study implies adding a second glazing layer which always reduces solar heat gain, thus reducing annual cooling. Thus, when we compare realistic options, e.g., single pane clear to double pane clear, or single pane tinted to double pane tinted, the double pane unit shows lower annual cooling, as well as lower peak loads.

Abstract: A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bidirectional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient. In this first in a series of related papers describing the project, the assumptions and limitations of the calculation method are described and the derivation of the matrix calculation technique from the initial integral equations is presented.

In this first in a series of related papers describing the project, the assumptions and limitations of the calculation method are described and the derivation of the matrix calculation technique from the initial integral equations is presented.

Abstract: A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure theA new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bi-directional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient. A preceding paper outlined the method and provided the physical derivation of the calculation. In this second of a series of related papers the detailed development of the matrix layer calculation is presented.

A preceding paper outlined the method and provided the physical derivation of the calculation. In this second of a series of related papers the detailed development of the matrix layer calculation is presented. bi-directional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient. A preceding paper outlined the method and provided the physical derivation of the calculation. In this second of a series of related papers the detailed development of the matrix layer calculation is presented.

Abstract: The MoWiTT field facility is used to measure the convective film coefficient over the exterior surface of a window. The MoWiTT-measured data is compared to some commonly-used experimental and theoretical models. The comparison shows that the MoWiTT data disagrees with the previously used models such as the ASHRAE/DOE-2 model. The reasons for these disagreements are discussed. An experimental model, based on the MoWiTT data, is presented to correlate the film coefficient with the difference in temperatures of the exterior glass surface and the ambient, in the natural convection region, and with the site wind speed, in the forced convection region. The wind speed is considered both in windward and leeward hemispheres. The validity of the MoWiTT model for low-rise buildings is then discussed.

Abstract: This paper traces the development of quantitative office lighting standards from its beginnings to the present. It discusses the sources of recommended lighting practice, the nature of the quantitative recommendations, and trends in recommended values on a comparative basis. A critical assessment of contemporary standards is provided within this historical context.

Abstract: Gas-Filled Panels, or GFPs, are an advanced theimal insulation that employ a low-conductivity, inert gas, at atmospheiic pressure, within a multilayer reflective baffle. The thermal performance of GFPs varies with gas conductivity, overall panel thickness, and baffle construction. Design parameters of baffle constructions that have a strong effect on GFP thermal resistance are (1) cavities per thickness, (2) cavity surface emittance, and (3) conductance of the baffle materials. GFP thermal performances, where the above parameters were varied, were modeled on a spreadsheet by iterative calculation of one-dimensional energy balances. Heat flow meter apparatus measurements of prototype GFP effective conductivities have been made and are compared to results of the calculations. The costs associated with varying baffle constructions are estimated based on the prices of commercial material components. Results are presented in terms of cost per area per unit thermal resistance ($/Area*R-Value) and are usefid for optimizing GFP designs forsair, argon, or krypton gas fills and a desired effective conductivity and thickness.

Abstract: The technology of optical switching devices for dynamic glazings and other applications is discussed. The status of the state of the industry and its developments is detailed. The technical emphasis will be on the properties of chromogenic materials covering electrochromic, phase-dispersed liquid crystals and dispersed-particle systems. Such technologies can be used for dynamic control of solar energy through building and vehicle glazings. Both visible and solar control can be obtained from these devices. Switching ranges can be from as high as 80% to 5-10% transmittance in the visible region. The energy and daylighting benefits of such glazings are discussed. Also, chromogenic glazings can be used for other product applications such as the modulation of reflector surfaces and large electronic information display systems. The science of selected electrochromic devices is covered. Technical issues concerning large-scale chromogenic devices are discussed.

Abstract: This investigation covers two technologies which have different applications but have many similar characteristics. One is the nanocell photoelectrochemical solar cell, the other is the electrochromic window. At first it is hard to see what they have in common other then that they both interact with light.

Abstract: Although primarily designed for studying the dynamic net energy flows through fenestration systems over the full diurnal cycle, the Mobile Window Thermal Test (MoWiTT) Facility is also frequently used to measure nighttime U-values. These measurements have the advantage of incorporating the exterior film coefficient resulting from the true ambient conditions at a particular time and location, rather than relying on a laboratory simulation of some assumed average or extreme condition. On the other hand, the MoWiTT is a much more complicated facility than a laboratory hot box, and the number of potential error sources is correspondingly larger. The method of deriving the nighttime U-value from directly measured data and the effect of random and systematic errors are discussed.

Abstract: The future holds many challenges for the fenestration industry. Just as new types of coated glass are becoming common place today even more advanced wonders await in the future. This industry has the opportunity to redefine the function of the window and to advance its technology into the electronic age. The key to the future appears to be the use of intelligent control systems in home and businesses. This will increase along with advances in a very wide range of appliances and office products. Now the big question remains is the fenestration industry ready to plan for these products? Some changes are certainly being made, but probably too slowly. The future will definitely see further integration of glazings into the building skin and the building skin becoming a dynamic element. The future building skin will be dynamic, incorporating sensors to determine a variety of information. It is notsunreasonable to expect the building to sense human presence and a variety of climatic factors. One of the key growth areas over the next 10-20 years will be in sensor technology. Many types of distributed neural net sensors will be developed along with multipurpose intelligent discrete sensors. Sensors will use microprocessors locally coupled to the sensing region.

Steady movement will be made to integrate microelectronics and photonics with the macro glazing or building skin. If we look back, building technology and electronics have had very little in common. In the future, the glazing and the building skin will become one large electroprocessor or photoprocessor. Another important issue is the increased attention to safety and more stringent frre codes concerning fire resistance. Increased litigation cost and insurance rates make issues of safety even more important in the future.

Abstract: This report presents the results of a California Institute for Energy Efficiency (CIEE) exploratory project to develop a new high-performance insulating material, gas-filled panels (GFPs), that is not based on chlorofluorocarbons (CFCs). Applications for GFPs are widespread, with a primary focus on refrigerator/freezer appliances and building walls. While this project has proven the thermal performance potential of GFPs, further development is necessary to optimize designs for cost, manufacturing, and performance.

Abstract: Spectrally selective solar control films can greatly reduce solar heat gain from the infrared while admitting a high fraction of visible daylight. Single-crystal tungsten bronzes of general formula MxWO3, where M is a metal, can have sharp spectral selectivity, but this property is difficult to obtain in thin films. Reversible electrochromic coloration caused by insertion of alkali metal or hydrogen ions has been extensively studied in WO3. Polycrystalline films were made by reactive magnetron sputtering of WO3 together with substrate heating and/or ion bombardment. Bronze forming elements were introduced after deposition either by electrochemical injection of H or Li or by ion implantation of Ag and Cu. During deposition, HxWO3 or substoichiometric WOx could be formed by controlling the sputtering atmosphere. Films treated by ion bombardment had optical properties approaching those of single crystals.

Abstract: Experimental studies using the Mobile Window Thermal Test (MoWiTT) Facility were undertaken to compare the performance of low-E windows manufactured with two different technologies, sputter-coated (soft-coat) and an improved pyrolytic chemical vapor deposition (hard-coat). The two technologies produce coatings with different emissivities and solar absorptions. The tests showed that from the standpoint of winter average daily performance, the higher solar transmission of the pyrolytic coatings tends to offset their higher emissivity, making the average performance of windows with the two coatings more similar than one would predict on the basis of either property alone. The tradeoff between the two window types is both orientation and climate dependent. Differences between the two windows were within the small experimental uncertainty of the measurement for all orientations except south, where the pyrolytic coating produced a larger net heat gain. Summer tests in a west-facing orientation showed that both windows produced large solar heat gains if unshaded, and that shading with an interior white venetian blind was not a very effective way of reducing these heat gains.

Abstract: A new method of predicting the solar heat gain through complex fenestration systems involving nonspecular layers such as shades or blinds has been examined in a project jointly sponsored by ASHRAE and DOE. In this method, a scanning radiometer is used to measure the bi-directional radiative transmittance and reflectance of each layer of a fenestration system. The properties of systems containing these layers are then built up computationally from the measured layer properties using a transmission/multiple-reflection calculation. The calculation produces the total directional-hemispherical transmittance of the fenestration system and the layer-by-layer absorptances. These properties are in turn combined with layer-specific measurements of the inward-flowing fractions of absorbed solar energy to produce the overall solar heat gain coefficient.

The method has been applied to one of the most optically complex systems in common use, a venetian blind in combination with multiple glazings. A comparison between the scanner-based calculation method and direct system calorimetric measurements made on the LBL MoWiTT facility showed good agreement, and is a significant validation of the method accuracy and feasibility.

Abstract: We describe LBL"s involvement with multimedia concepts by discussing several modules of an advanced computer-based building envelope design tool. The qualitative and quantitative aspects of the building design process are accommodated within the same design tool which uses object-oriented programming procedures. This computer-based concept utilizes images (buildings, landscapes, models, documents, etc.), expert systems (knowledge bases, i.e., lighting design, site planning, WAC design, etc.), and data bases (design criteria, utility rates, climatic data, etc.) in addition to more traditional simulation models to evaluate building design alternatives.

Abstract: Gallium Nitride films were grown on (111) Gallium Arsenide substrates using reactive rf magnetron sputtering. Despite a 20% lattice mismatch and different crystal structure, wurtzitesGaN films grew epitaxially in basal orientation on (111) GaAs substrates. Heteroepitaxy was observed for growth temperatures between 550-600?C. X-ray diffraction patterns revealed (0002) GaN peak with a full-width-half-maximum (FWHM) as narrow as 0.17?. Possible surface reconstructions to explain the epitaxial growth are presented.

Abstract: During the 1980s, the availability of energy-efficient window components and products grew at a rate faster than the window and building industry"s ability to analyze their performance accurately and efficiently. As a result, a coalition of industry and public sector groups formed the National Fenestration Rating Council (NFRC) in an effort to provide standard methodologies to rate the thermal performance of windows. The NFRC"s first task was to develop a methodology for evaluating the thermal transmittance (U-values) of fenestration products. This procedure, published in 1991 as NFRC 100-91 (NFRC 1991) and already referenced by state codes in Alaska, California, Idaho, Minnesota, Oregon, and Washington, allows the manufacturer to use a unique combination of advanced computer simulation tools coupled with improved laboratory test methods. Since most manufacturers offer dozens, and often hundreds or thousands, of individual products, each with significantly different U-values, these simulation tools are an essential component of the rating system"s cost effectiveness. This paper discusses this procedure and its intended use in more detail, and outlines the NFRC"s future plans for developing rating procedures for solar heat gain coefficients, optical properties, infiltration, condensation resistance, and annual energy impacts.

Abstract: We report on the fabrication and use of new ion storage layers as counter electrodes for completely solid state electrochromic windows. The ion storage layers are transparent composites of a room temperature ion-conducting polymer and an electroactive material based upon the polyorganodisulfide/dithiolate redox couple. Solid state devices consisting of molybdenum doped WO3, a polymer ion conductor layer and the new ion storage layers colored rapidly from a pale yellow to a deep blue-green, upon application of 1.2 V d.c. The photopic transmittance changed from 61 to 9%, and the solar transmittance from 45 to 5% during the coloration process, for a typical sample. Because the counter electrode does not change optical proprties as a function of redox state, problems with color imbalance can be avoided completely. The large number of polyorganodisulfides that may be used for this application allows for flexibility in device design and properties, and the use of solid state components ensures improved stability of windows incorporating this technology.

Abstract: This document presents the framework and foundation for an optical properties database undertaken as part of Subtask A.l, High-Performance Glazings, of Task 12 of the IEA Solar Heating and Cooling Program.

At the start of the Task, the participants agreed that a database of glazing optical properties would prove invaluable in the performance modeling of windows. The compilation of an optical properties database for glazing materials is intended to provide researchers with a common set of data for modeling fenestration systems and their components. The database also serves as a cross-reference for materials and products produced in different countries, and can be used for hourly annual building energy simulations programs such as DOE-2.1 E.

The WINDOW program for calculating the thermal performance of fenestration systems was used to establish the optical properties database. WINDOW 4.0 calculates the total window system thermal and optical properties. The format of the database is consistent with WINDOW 4.0 libraries that are directly accessible by WINDOW. The database contains the optical properties of commonly-found glazing systems and glazings, and is included in the appendices.

Future work on this database could include glazing and glazing system optical property data from each country, the collection of spectral data, the development of guidelines for reporting and methods for evaluating optically complex materials, and the establishment of a mechanism for maintaining the database.

Abstract: This document presents the work conducted as part of Subtask A.l, High-Performance Glazing, of Task 12 of the IEA Solar Heating and Cooling Program. At the start of the task, the participants agreed that chromogenic technology (switchable glazing) held considerable promise, and that algorithms to accurately model their dynamic behavior were needed.

The purpose of this subtask was to develop algorithms that could be incorporated into building energy analysis programs for predicting the thermal and optical performance of switchable windows. The work entailed a review of current techniques for modelling switchable glazing in windows and switchable windows in buildings and methods for improving upon existing modeling approaches. The proposed approaches correct some of the shortcomings in the existing techniques, and could be adapted for use in other similar programs. The proposed approaches generally provide more detailed calculations needed for evaluating the short-term (hourly and daily) impact of switchable windows on the energy and daylighting performance of a building. Examples of the proposed algorithms are included.

Abstract: Windows have very significant direct and indirect impacts on building energy consumption, load shape, and peak demand. Electrochromic switchable glazings can potentially provide substantial reductions in all aspects of cooling and lighting electricity usage. The solar-optical properties of electrochromic coatings vary over a wide range in response to an applied electrical signal. This control signal can be driven by a combination of occupant needs, external environmental conditions, building operating strategies, and electricity demand minimization requirements. The impact of an electrochromic glazing depends on the intrinsic properties of the coating, the placement of the coating within a window system, and many parameters related to building type, operating strategy, orientation, and location.

This study explores the potential benefits of electrochromics in comparison to other currently available and emerging glazing technologies. These effects are explored in office buildings in several climates as a function of window size, orientation, and building operating characteristics. The DOE-2 building energy simulation program was used to model the performances of these dynamic coatings, accounting for both thermal and daylighting impacts. Very substantial savings are demonstrated compared to conventional glazings, but specific impacts on component and total energy consumption, peak demand, and HVAC system sizing vary widely among the options analyzed. In a hot, sunny climate, probably the first niche market for electrochromics, simple payback periods of three to ten years were calculated based on an incremental glazing first cost of $15/ft2 to $25/ft2.

Electrochromic glazings appear to represent a very important future building design option that will allow architects and engineers a high degree of design freedom to meet occupant needs, while minimizing operating costs to building owners and providing a new and important electricity demand control option for utilities. Utility demand-side management programs can accelerate the market penetration of electrochromics by offering incentives to reduce net first cost and payback periods.

Abstract: Over the last five years, vinyl-framed windows have gained an increased market share in both new and retrofit residential construction. This success has been mainly due to their low manufacturing cost and relatively good thermal performance (i.e., total window U-values with double glazing between 0.50 Btu/h.ft2.?F [2.86 W/m2.K] and 0.30 Btu/h.ft2.?F [1.70 W/m2.K]). Turning such windows into superwindows, windows with a U-value of 0.20 Btu/h.ft2.?F (1.14 W/m2.K) or less that can act as passive solar elements even on north-facing orientations in cold climates, requires further significant decreases in heat transfer through both the glazing system and the frame/edge. Three-layer glazing systems (those with two low-emissivity coatings and a low-conductivity gas fill) offer center-of-glass U-values as low as 0.10 Btu/h.ft2.?F (0.57 W/m2.K); such glazings are being manufactured today and can be incorporated into existing or new vinyl frame profiles. This paper focuses on the use of a state-of the-art infrared imaging system and a two-dimensional finite-difference model to improve the thermal performance of commercially available vinyl profiles and glazing edge systems. Such evaluation tools are extremely useful in identifying exactly which components and design features limit heat transfer and which act as thermal short circuits. Such an analysis is not possible with conventional whole-window testing in hot boxes where testing uncertainties with superwindows are often greater than proposed improvements.

Abstract: Our experimental results using reactive magnetron sputtering, combined with earlier literature, are used to understand the thermodynamic and kinetic processes involved in GaN film growth and the limiting factors involved in the incorporation of nitrogen during the growth process. We show that GaN films fabricated with low pressure growth techniques (< 0.1 Torr) such as sputtering and molecular beam epitaxy W E ) are formed under meta-stable conditions with a non equilibrium kinetically limited reaction. For these methods, the growth process is controlled by a competition between the forward reaction which depends on the arrival of activated nitrogen species at the growing surface and the reverse reaction whose rate is limited by the unusually large kinetic barrier of decomposition of GaN. In practice, the thermally activated rate of decomposition sets an upper bound to the growth temperature.

Abstract: We present a method for analyzing the annual cooling and lighting electricity use and peak demand associated with varying fenestration and lighting strategies in commercial office buildings. A prototypical office building module consisting of four perimeter zones and a central core zone was defined and a series of DOE-2 bidding energy simulations were completed to create a data base for varying fenestration and lighting system parameters. Using regression analysis procedures, we characterize electric energy and peak performance patterns as a function of solar aperture, defined as the product of shading coefficient and window-to-wall ratio, and efective daylighting aperture, defined as the product of visible transmittance and window-to-wall ratio. Optimum performance consists of defining the solar and effective daylighting aperture values that minimize annual energy consumption and peak demand, a process easily facilitated by the methods described herein.

Abstract: This paper discusses the use of gas-filled panel technology as a high-performance, non-CFC insulation for building applications. Gas-filled panels (GFPs) combine low-emissivity surfaces and multiple, low-conductivity gas-filled cavities to minimize radiation, convection, and conduction. The thermal performance of some GFP designs has been independently tested (ASTM 1989) at a national laboratory. Measurements on first-generation prototypes yielded R-5.2/in. (5.2 h.ft2.?F/Btu.in. [36 m.K/W]) with an air fill, R-7.1/in. (49.3 m.K/W) with an argon fill, and R-12.5/in. (86.8 m.K/W) with a krypton fill. This paper discusses technical aspects of GFP barrier materials and their gas transmission rate requirements, baffle component characteristics, and potential gas fills. We present examples of potential GFP products for various building applications with cost and performance estimates.

Abstract: This assessment examines several lighting technologies that have the potential to significantly impact the energy use for lighting in commercial buildings over the next five to ten years. The technologies are divided into four categories: sources, controls, and lighting quality. This is not a comprehensive list of every available new lighting technology. Energy-efficient technologies that are currently considered standard practice (e.g. energy efficient core coil ballasts for fluorescent lamps) are not included. In addition, technologies that are not projected to reach the market before 10 years are not included. The intent of this assessment is to highlight some of the most promising new technologies that appear to the have the largest widespread applicability in most commercial buildings. The fact that a particular technology does not appear on the list should not be construed to mean that the technology has no potential.

Abstract: Proper building envelope design is the most direct and efficient way to reduce cooling loads, by controling the radiative, convective and conductive heat transfer through the building envelope.

The most effective way to reduce cooling loads is to prevent their generation by controlling the output of the heat sources and the heat transfer through the building envelope. Heat sources can be either external, i.e., direct and diffuse solar radiation along with the associated convective and conductive heat transfer, or internal, i.e., electric lighting, equipment and building occupants. From these sources, only the electric lighting system can be partially controlled by the building designer with respect to output. The strategies to control the generation of cooling loads from the rest of the sources concentrate on the heat transfer modes through the building envelope, focusing on reducing heat transfer from the exterior to the interior and increasing heat transfer from the interior to the exterior.

Abstract: This review addresses a technology area of interest for the future. Current systems falling into the category of dynamic envelopes are rare, of unknown cost effectiveness on a general basis, and probably most useful in climates harsher than in California. However, the concept of a dynamic envelope holds great promise for building optimization and perhaps even for a zero energy building perimeter. Future building technology developments are likely to include systems in this category, potentially leading to cost effect integrated systems that include the building skin as well as internal building systems. This technology section discusses rationale behind development of a dynamic building skin and presents the few existing examples in this category.

Building envelope design to date has addrcssed the combination of various materials and components to produce a building skin that will act primarily as a static banier to the extremities of the climate outside the envelope. This is in contrast to the dynamic behavior of an analogous system, our own skin. In the human body, the interface between internal and external environments is dynamically controlled through the complex interactions between the internal loads of the body, the thermal resistance of the clothing, and the conditions of the external environment such as air temperature, mean radiant temperature, air velocity and vapor pressure. Human beings have several means at their disposal to modify their comfort conditions, either through conscious thermo-regulatory control (e.g., removing clothing layers or changing locations) and/or through involuntary responses (e.g.. sweat secretion or vasoconstriction). Our ability to dynamically use a variety of regulatory tools enables us to survive through a wide range of adverse conditions.

Abstract: Conventional daylighting design components (i.e. fenestration systems) can normally provide adequate daylight in the perimeter of buildings, i.e. within 15 feet of windows or skylights. To provide daylight in a larger fraction of the building area requires one of two approaches. One option is to increase the fraction of the floor area that is adjacent to fenestration using architectural design strategies to alter floor plans from rectangular to reentrant forms, use of atria, stepping back upper stories of the building, etc. The second option is to use daylighting optical systems to deliver light to building locations beyond the perimeter zone. In this section, we present several technical approaches for introducing daylight and sunlight deeper within buildings. We consider situations where light transmission is desired over longer distances (15" - 100") and where it may be desirable to penetrate either horizontally or vertically through the core of a building. These includes daylighting techniques based on the use of light shelves, wide window sills, special reflectors, louvers, baffles, reflective blinds, and other ways to direct light deep into the building"s plan. These methods are intended to avoid the glare and the strong modulation (intense light near the window, rapidly falling off with increasing depth) of direct-beam daylighting.

Abstract: Glazing is a primary factor in the radiative, convective and conductive heat transfer through the building envelope and can be used to control or limit each of these energy flows. It is also the primary component in fenestration systems affecting the admission of natural light into buildings and thus critically affects the potential of energy savings through daylighting. Glazing is perhaps the building material with the broadest range of impact; its selection will affect all of the issues below.sGlazing impacts:

Operating costs: Energy use, Peak electrical demand.

Developer concerns: First costs for HVAC and lighting, Floor space required for HVAC.

Market value: Occupant comfort, Facade appearance, Window area, View.

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Abstract: The impending phase-out of chlorofluorocarbons (CFCs) used to expand foam insulation, combined with requirements for increased energy efficiency, make the use of non-CFC-based high performance insulation technologies increasingly attractive. The majority of current efforts are directed at using advanced insulations in the form of thin, flat low-conductivity gas-filled or evacuated orthogonal panels, which we refer to as Advanced Insulation Panels (AIPs). AIPs can be used in composite with blown polymer foams to improve insulation performance in refrigeratorlfreezers (R/Fs) of convent.iona1 design and manufacture. This AIP/foam composite approach is appealing because it appears to be a feasible, near-term method for incorporating advanced insulations into R/Fs without substantial redesign or retooling. However, the requirements for adequate flow of foam during the foam-in-place operation impose limitations on the allowable thickness and coverage area of AIPs. This restriction, combined with thermal bridging effects associated with elements such as steel outer shells and surrounding foam, generally allow only relatively small improvements in overall thermal resistance as a result of incorporating ATP/foam composite insulation into conventional foam core R/Fs.

Abstract: A large fraction of California"s energy consumption and peak demand results from the need to cool residential buildings with high levels of solar heat gain transmitted through windows. For example, single family residences with central air conditioning built before 1978 consume from approximately 800 kWh per household in the Sacramento Municipal Utility District (SMUD) territory to 2,000 kwh per household within the northern Pacific Gas and Electric (PG&E) and Southern California Edison (SCE) central valley and inland territories. For a new demonstration home being built in the Sacramento area, SMUD reported that 52% of the peak summer cooling load was due to solar heat gain from windows. In cooling-dominated portions of California, where this energy problem is most severe, clear single-pane glass having the highest solar heat gain of any glazing type, is the most prevalent glazing found in existing residences.

Abstract: This paper studies the effects of a large area light source of variable but uniform luminance surrounding a video display terminal (VDT) on the perceived glare discomfort and visual performance of computer operators. A set of criteria was established for rating the discomfort from glare as either intolerable, disturbing, noticeable, or imperceptible. Source luminance adjustments by means of a variable transformer to match the subjective glare criteria, as well as ratings of preselected lighting conditions on a visual analog scale with the same criteria, were used to determine comfortable lighting conditions. Results from the experiment indicate that subjects reliably selected a preferred lighting condition at any time when asked to adjust the luminance to produce optimum visual comfort. There was considerable between-subject variation in the range of luminances over which the surround field was neither noticeably too dim nor noticeably too bright. Comfortable luminance ranges also varied with initial presentation luminances immediately preceding the adjustment. Subjects preferred higher luminances following high initial presentation luminances. Performance speed at a difficult letter-counting task suggests that visual performance was slightly impaired by the presence of glare discomfort. Counting errors also occurred slightly more frequently under higher surround source luminances. There was a tendency for subjects to become more susceptible to glare over the course of the experiment.

Abstract: Windows have typically been the least efficient thermal component in the residential envelope, but technology advances over the past decade have helped to dramatically improve the energy efficiency of window products. While the thermal performance of these advanced technology windows can be easily characterized for a particular building application, few precise estimates exist of their aggregate impact on national or regional energy use. Policy-makers, utilities, researchers and the fenestration industry must better understand these products" ultimate conservation potential in order to determine the value of developing new products and initiating programs to accelerate their market acceptance. This paper presents a method to estimate the conservation potential of advanced window technologies, combining elements of two well-known modeling paradigms: supply curves of conserved energy and residential end-use forecasting. The unique features include: detailed descriptions of the housing stock by region and vintage, state-of-the-art thermal descriptions of window technologies, and incorporation of market effects to calculate achievable conservation potential and timing. We demonstrate the methodology by comparing, for all new houses built between 1990 and 2010, the conservation potential of very efficient, high R-value superwindows in the North Central federal region and spectrally-selective low-emissivity (moderate R-value and solar transmittance) windows in California.

Abstract: Electron-beam-evaporated nickel oxide films were shown to have a microcrystalline cubic nickel oxide structure. The pressure in the chamber during the film deposition has a large effect on the crystal size and the stoichiometry of the films. The redox currents, the efficiency of these films to color, and their optical properties were influenced by the processing conditions employed and the resulting microstucture. A model is proposed based on the observed microstructure that explains the source of overstoichiometric oxygen and ion transport in these films.

Abstract: Tungsten oxide and molybdenum doped tungsten oxide electrochromic films have been electrochemically prepared from a metal peroxide bath and experimentally tested. They were characterized by electrical and optical methods, using cyclic voltammograms and calculating the charge capacity as a function of the number of deposition cycles.

The color of the electrochromic WO3 film is strongly altered by doping it with molybdenum. Electrochromic W---Mo oxide films were fabricated by adding different percentages of molybdenum to tungsten oxide, ranging from 0.5% to 7% weight of deposition solution. Normal optical transmittance was also measured and evidence is given of different behavior if the switching for oxidation and reduction cycle, so that coloration occurs in a shorter time than the bleaching. The time constant of the process tends to increase as a function of the molybdenum oxide doping concentration.

Abstract: Heat transfer through building envelope components is typically characterized by one number, the conductance. Such a characterization is best suited for homogeneous samples since it does not quantify or illustrate spatial variations within a sample. However, the growing use of advanced wall and window insulations with existing framing materials has increased the importance of understanding spatial heat transfer effects within building envelope components. An infrared thermography laboratory has been established to provide detailed quantitative and qualitative infor-mation on the spatial heat transfer effects of building envelope materials. The use of this facility for more effective product development and more accurate product characterization is discussed.

Abstract: Electrochromic nickel oxide films were deposited by radio-frequency magnetron sputtering of a Ni target in gas mixtures of Ar and O2. When electrochemically cycled in 0.1 N KOH solution, large reversible changes in visible absorption were obtained within the first 10 bleach/color cycles. Films which showed the greatest changes in optical properties and charge capacity were produced within a narrow range of oxygen flow rates. The coloration efficiency was found to be insensitive to the sputtering conditions and stoichiometry, with a value of 34 -4 cm2C-1 at 550 nm. This indicates that microstructure and charge capacity determine the absorption coefficient. The reaction rate was found to depend on the concentration of OH- in the electrolyte, indicating that OH- diffusion in the electrolyte limits the rate of reaction.

Abstract: This paper introduces a new high performance non-CFC based insulating material with primary applications for refrigerator/freezer and building walls. Characteristics of these gas-filled panels, projected and experimental thermal performance levels, cost estimates, and manufacturing/installation issues for this material are discussed. Independent testing of prototypes has yielded R-values of 36 m-K/W (5.2 hr-ft2-F/Btu-in) or air filled panels, 49.32 m-K/W (7.1 hr-ft2-F/Btu-in) for argon filled panels, and 86.8 m-K/W (12.5 hr-ft2-F/Btu-in) for krypton filled panels. Target R-values values are 36 m-KLW (5.2 hr-ft2-F/Btu-in), 55 m-K/W (8 hr-ft2-F/Btu-in), and 105 m-K/W (15 hr-ft2-F/Btu-in) for air, argon, and krypton filled panels, respectively. Manufacturing costs depends strongly on gas-fill, and structural requirements and are estimated at 42 to 850 $/m3 (0.10 to 2.00 $/ft2-in). This insulation system can be fabricated using commercially available materials and equipment.

Abstract: The Mobile Window Thermal Test facility (MoWiTT) predicts the energy efficiency of windows by continuously measuring the net heat transfer into and out of two room-sized calorimeters. The system consists of a data acquisition/control unit which communicates through a General Purpose Interface bus (GPIB IEEE-488) with an LSI-11/23 computer. We wrote the software in FORTRAN 77 and run it under TSX using detached jobs, the message facility, and shared run time systems to execute nine 64KB jobs which simultaneously take data and store it on disk. We arbitrate the access to a single scanner on the GPIB by running a SERVER task which acts as a virtual machine to serialize the requests. We can control and monitor the system remotely and run a number of interactive jobs without interfering with the data collection tasks. We cover a description of the hardware; the software requirements, including the libraries to control the data collection and drive the hardware; the system architecture, including a block diagram; design considerations to meet real-world requirements; and the problems we discovered along the way and the solutions we found either to correct or to bypass them.

Abstract: In the standard process for sputtering of YBCO, the substrate is located off the axis of the target. High pressures are used to avoid and slow bombardment of the growing film by high-energy oxygen atoms. Using a particle shield and dc bias, we have deposited high quality YBCO films on axis at significantly reduced pressures. Typically these films have better and more repeatable electrical properties than off-axis films, and deposition rates are 2 to 3 times faster. Even more important is the return to a geometry that is inherently scalable to large-area deposition.

Abstract: We report on the prepation, electrical and optical analysis of eIectrodes and prototype electrochromic devices using a solid polymer ion conductor. For these devices we developed electrodes consisting of cobalt-doped nickel oxide, manganese-nickel oxide, and niabium oxide. Optical and voltammetric data was obtained for each electrode. Solid polymer electrolytes were synthesized from modified amorphous poly(ethy1ene oxide) [a-PEO] complexed with a metal silicate. Electrochromic devices were made using cobalt-doped nickel oxide/niobium oxide, and cobalt-doped nickel oxide/manganese-nickel electrode laminations. Optical spectra as a function of voltage was obtained for each device. Our best cobalt-doped nickel oxide/a-PEO/rnanganese-nickel oxide device showed photopic transmittance to be Tp(bleached)=0.76 and Tp(colored)=0.44. The corresponding integrated solar transmittance was Ts(bleached)=0.64, Ts(colored)=0.46. Our best cobalt-doped nickel oxide/a-PEO/niobium oxide device had photopic transmittance of Tp(bleached)=0.65 and Tp(colored)=0.16. The corresponding integrated solar transmittance was Ts(bleached)=0.45 andTs(colored)=0.15. Of the two devices, the nickel/niobium oxide device had the best combination of electrical and optical properties. Better device properties are expected with improvements in the solid polymer electrolyte and lamination process.

Abstract: This paper describes the development of a prototype PC-based computer program called RESFEN. The program calculates the heating and cooling energy performance and costs of residential fenestration systems. Regression analysis of a data base of DOE-2 building energy simulations of single- and two-story residential buildings was used to develop algebraic expressions that form the basis of the calculation procedure. The user can vary geographic location, electricity and gas cost, infiltration and internal load levels, HVAC and wall type as well as window size, U-value, and shading coefficient for the four cardinal orientations of north, east, south, and west. Incremental changes in energy use due to obstructions, overhangs, and interior shades can also be calculated.

Abstract: Gallium nitride films were grown by reactive rf magnetron sputtering on sapphire substrates. Crystalline (1120) GaN films were obtained on (0112) sapphire at substratestemperatures between 640-680 OC. High N2 partial pressures are required to crystalize the GaN films. Nitrogen incorporation and crystal quality of GaN films are examined as a function of substrate temperature and nitrogen partial pressure. Band gaps of 3.4 eV, and photoluminescence peaks as narrow as 11 meV are reported for sputtered GaN films.

Abstract: This paper presents an algorithm to determine the angular dependence of the transmittance and reflectance of homogeneous glazing layers given the reflectance and transmittance at normal incidence, the wavelength, and the thickness. For the commonly used solar and visible properties, typical wavelengths are presented that can be used with this procedure to approximate these wavelength integrated properties. Theoretical calculations have shown that the absolute error of this approximation is less than 1.5% for most clear, low-iron, and absorbing glasses. Existing approximations can yield absolute errors up to 15%. This new approximation can be used with computer programs that calculate energy fluxes through glazing(s) based on the glazing thickness and optical properties at normal incidence.

Abstract: We report the growth conditions necessary for highly oriented wurtzite GaN films on (111) GaAs, and single crystal GaN films on (111) GaAs using AIN buffer layers. The GaN films and AlN buffers are grown using rf reactive magnetron sputter deposition. Oriented basal plane wurtzite GaN is obtained on (111) GaAs at tempertures between 550-620?C. However, using a high tempertaure 200 A AIN buffer layer epitaxial GaN is produced. Crystal structure and quality is measured using x-ray diffraction (XRD), reflection electron diffraction (RED), and a scanning electron microscope (SEM). This is the first report of single crystal wurtzite GaN on (111) GaAs using AlN buffer layers by any growth technique. Simple AlN/GaN heterostructures grown by rf reactive sputter deposition on (111) GaAs are also demonstrated.

Abstract: Glass plays a significant role in the design of building envelopes today. Since its emergence during the last century as asmajor building material, glass has evolved into an ubiquitous and versatile building design element, performing functionsstoday that would have been unimaginable a few years ago. The optical clarity and transparency of glass that we take forsgranted is one of its most unique features. Glass windows keep out the cold wind and rain without blocking the view, butsalso perform many more complex functions which require variable properties and tradeoffs between conflicting conditions.sThe glazing that provides view must also provide visual privacy at other times and must sometimes become totally opaques(for audiovisual shows, for example). Transparent glass admits daylight, providing good color rendition and offsetting electricslighting energy needs, but it can also create discomfort and disability glare conditions. The sun provides desirable warmth inswinter but its heat is unwelcome in summer when it contributes to thermal discomfort and cooling energy requirements. Andsglass is an important element in the appearance and aesthetics of a building, both interior and exterior.

The problem confronting a building designer is one of tremendous variability in the environmental forces that impinge on thesbuilding exterior and the rapidly changing needs inside the building. For example, the intensity of sunlight varies on severalstimescales: by the seconds or minutes on a day with scattered clouds; by the hour as the sun follows its diurnal cycle; andsover months as the seasons change. Since exterior daylight illuminance can vary by a factor of 10 to 20 during a day, fromsapproximately 5000 lux (approx. 500 fc) under overcast sky to 100,000 lux (approx. 10,000 fc) in direct sun, optical controlssmust operate over this wide dynamic range.

There are many building envelope options to extend the intrinsic degree of optical and thermal control exhibited by glasssalone. The glass selection will influence total transmittance, spectral properties, and directional properties. But these will besfixed properties and will satisfy some, but not all, of the performance requirements. In order to provide a wide range ofsperformance responses, dynamic control of one or more of the glazing properties is essential. This is not a new thought; asvast array of window accessories can be added to glazing to alter its properties in response to changing external conditionssand/or internal needs. Current research in a new field, large area chromogenics, is leading the way toward development of asnew generation of glazing materials that will provide an intrinsic dynamic and responsive optical control capability within thesglazing. A recent approach is to provide this dynamic control using thin film coatings deposited on the glazing.

Abstract: When designing a fenestration system, it is often required to determine its luminous performance,sthat is the way it allows daylight to enter the space and contribute to the requiredsillumination levels. This can be achieved either through use of scale models orsthrough computer simulation. Each approach has advantages and disadvantages.

On one hand, scale models allow the simulation of the luminous performance of any fenestrationssystem, including consideration of outdoors and indoors parameters, such as exteriorsand interior obstructions, space geometries and surfaces" reflectance. However, thesconstruction of scale models is time consuming and expensive. Parametric studies requiresthe use of many models, or a sophisticated, changeable one. Moreover, the use ofsscale models requires appropriate luminous source(s) to simulate the light from the sun,ssky and ground, dictating testing under real or simulated sky conditions, which introducessadditional limiting issues: real sky conditions are beyond the designer"s control and simulatedsones require highly sophisticated and expensive facilities.

Abstract: For six windows the U-values measured with the MoWiTT under field conditions arescompared with detailed U-value calculations for the same conditions using the programssWINDOW and ANSYS. There is good agreement between measurements andscalculations.

Abstract: Amorphous carbon films were deposited on glass by d.c. magnetron sputteringsfrom a graphite target in mixtures of argon and hydrogen. Hydrogen flow and othersdeposition parameters affected the optical and mechanical properties of these films.sIncreasing hydrogen content caused the average visible transmittance to vary froms16% to 86% for 500-A thick films. Maximum compressive stress and hardness occursbetween 0-1% hydrogen flow, resulting in rapid delamination. Low sputtering powersmoderately increases transmittance and hardness while relieving stress. Transparency is induced in both the high-hydrogen and low-power films by formation of sp3 C-C bonds. In the case of the hydrogenated films, however, a softer polymeric structure issformed.

Abstract: Lawrence Berkeley Laboratory (LBL), with support from Southern California Edisons(SCE), a major utility in the Los Angeles area, has developed a prototype electronicsinteractive Energy Information Kiosk: a personal computer with touch screen providessinformation linked to video images stored on an optical disc. The kiosk uses text,sgraphics, animation, sound, and video to communicate effectively. This project"s goalsswere: to demonstrate SCE"s commitment to provide relevant, useful energy services to itsscustomers; to highlight specific incentive programs; to provide users with contacts tospeople and resource materials at SCE; and most importantly, to provide technical guidancesfor building design professionals who want to improve the energy efficiency of buildings.

Abstract:

Abstract: This paper presents the design, material characteristics, and thermal performance of a new insulating material. Development of this material is motivated by the need for non-CFC based high performance insulations with applications for refrigeratorlfreezer and building walls. This suyr insulating gas filled panel technology achieves R-values of between 8 hr-ft2-F/Btu per inch and 15 hr-ft2-F/Btu per inch (one to two times that of CFC blown foams and two to four times that of fiberglass insulations) at estimated costs of $0.40 -$1.50/in-ft2. Prototypes have been built using commercially available materials and components, tested by the developers, and sent to an independent laboratory for independent thermal performance testing.

Abstract: Glazing materials with variable optical properties (switchable glazings) offer the ultimate in control over the light and energy entering a building. Products of this kind are in their initial stages of development, and guidelines that relate window energy performance to glazing material properties are needed. Though the use of a computer program for calculating window thermal and optical performance parameters, we evaluated (1) the relative performances of three switchable glazings prototypes with differing solar transmittance spectra; (2) the differences between glazings that switch from transmitting to reflecting and those that switch from transmitting to absorbing; and (3) the effects of positioning the switchable glazing in a window. We focused on design conditions for cooling-dominated buildings, since switchable glazings are expected to reduce cooling and lighting loads. We conclude that the differences in thermal performance between absorbing and reflecting switchable glazings can be eliminated through proper placement of the glazing in a window system and through the use of other spectrally selective glazings.

Abstract: We describe the preparation, electrical and optical analysis of prototype electrochromic electrodes and solid polymer electrolyes and complete switching devices. The electrodes studied are nickel oxide, nickel-manganese oxide, nickel-cobalt oxide, and tungsten-molybdenum oxide. These electrodes were found to be useful as active electrochromics or ion storage layers. Solid polymer electrolytes were synthesized from poly(ethylene oxide), a PEO, and poly(ethyleneimine). Also, an inorganic borate silicate glass was used as an ion conductors. The best performing devices were made with a-PEO electrolytes. Electrochromic devices were made using nickel oxide/tungsten-molybdenum, and nickel oxide/nickel manganese electrode combinations. Optical spectra as a function of voltage was obtained for each device. Our best nickel oxide/a-PEO/tungsten-molybdenum device showed the photopic transmittance (Tp) to be Tp(bleached)=0.79 and Tp(Colored)=0.39. The corresponding integrated solar transmittance was (Ts) to be Ts(bleached)=0.55, Ts(colored)=0.35. Our best nickel oxide/nickel-manganese device showed the photopic transmittance to be Tp(bleached)=0.71 and Tp(colored)=0.23. The corresponding integrated solar transmittance was Ts(bleached)=0.52, Ts(colored)=0.44. Better device properties are expected with improvements in the solid polymer electrolyte.

Abstract: The window industry"s commercialization of low-emissivity coatings and low-conductivity gas-filling over the past few years has helped to drastically reduce heat transfer rates through the glazed areas of windows. However, few changes have taken place in the design and construction of window frames and edges, leaving these elements to account for most of the heat transfer through today"s state-of-the-art windows. This paper presents design and material requirements for the manufacture of low conductivity window frames obtained through the use of finite element computer modeling. Such frames will compliment and not degrade today"s most-energy-efficient insulated glass units.

Abstract: Lockheed Building 157 is one of the United States" largest experiments in contemporary daylighting. Built in 1983, the five story structure houses 3,000 employees and uses daylight for ambient illumination throughout its 56,000-m2 office interior. A continuously dimmable fluorescent lighting system supplements interior daylight under the control of open-loop ceiling-mounted photosensors. In 1985 Lawrence Berkeley Laboratory (LBL) began a year-long program to measure lighting system performance in the building. Data from this study indicated that architectural features of the building performed admirably, admitting significant daylight to large areas of the open plan interior. Operational savings, however, were limited by inappropriate performance of the control system in many of the building"s lighting circuits. LBL recently completed a follow-up investigation of the lighting systems in Building 157 addressing the interaction between daylight and the lighting control system with the goal of improving control system performance. We modified a 1,700-m2 test zone by relocating the photosensors, attenuating, the photosensor control signal, changing the response pattern of the photosensors, and implementing a LBL-developed calibration procedure. Following these modifications, we installed four data-acquisition systems and collected detailed data describing illuminance and lighting power demand during two week periods in the summer, equinox, and winter seasons. This paper presents a comparison of lighting system performance before and after the LBL modifications. Analysis of the data indicates our modifications were successful in maintaining the interior illuminance at the target of 350 lux with minimal electric energy consumption.

Abstract: This report was undertaken to provide NYSERDA with information from which to initiate a research program in daylighting. The intent was to review the state of the art in this broad field, identify current trends and directions in both design/practice and research, develop a quantitative basis from which to estimate the magnitude of potential benefits, and then to identify actions that might be helpful to accelerating implementation and utilization of daylighting strategies.

Our report draws heavily from past and ongoing daylighting research at LawrencesBerkeley Laboratory, from contacts with other research and professional groups, from extensive contacts with building designers and engineers, and from technical and design-oriented publications. Additional support for this study was provided by the U.S. Department of Energy as part of our ongoing research program; portions of this work were then expanded and appear elsewhere as technical publications.

Abstract: New window technologies are reducing heat transfer through the glazed areas of windows.sLow-emissivity (low-E) coatings reduce radiative heat transfer and low-conductivity gas fillss(which replace the air between glazing layers) reduce conductive heat transfer. Given thesesadvances in insulating glass technology, researchers and manufacturers are now beginning tosfocus their attention on reducing heat transfer through window edges. Old edge designs aresnow under scrutiny and new designs are being proposed.

This paper explores window material and design parameters which influence heat transfer usingstwo-dimensional heat-transfer modeling with an advanced finite-element computer codes(ANSYS). A comprehensive set of correlations, based on ANSYS parametrics, is thensdeveloped. These correlations are compared, whenever possible, to experimental results and willsbe incorporated into future versions of the WINDOW program. Glazing edge designs analyzedsinclude both double-glazed and triple-glazed options with aluminum, steel, wood, fiberglass,sbutyl, and insulated spacers. Single and double seal design are also analyzed.

Abstract: Of all building envelope elements, windows always have had the highest heat loss rates. However, recent advances in window technologies such as low-emissivity (low-E) coatings and low-conductivity gas fillings have begun to change the status of windows in the building energy equation, raising the average R-value (resistance to heat flow) from 2 to 4 h-ft2-F/Btu. Building on this trend and using a novel combination of low-E coatings, gas-fills, and three glazing layers, the authors developed a design concept for R-6 to R-10 super windows. Three major window manufacturers produced prototype superwindows based on this design for testing and demonstration in three utility-sponsored and -monitored energy-conserving homes in northwestern Montana. This paper discusses the design and tested performance of these three windows and identifies areas requiring further research if these window concepts are to be successfully developed for mass markets.

Abstract: We show the development and implementation of a new methodology that can be used to evaluatesthe energy and comfort performance of fenestration in non-residential buildings. The methodologysis based on the definition of a fenestration system figure of merit. The figure of merit issdetermined by considering five non-dimensional performance indices representing heating energy,scooling energy, cooling energy peak, thermal comfort, and visual comfort. These indices weresderived by performing a regression analysis of several thousand hour-by-hour building heatstransfer simulations of a prototypical office building module using the DOE-2 simulation program.

The regression analysis resulted in a series of simplified algebraic expressions that relatedsfenestration configuration variables to performance parameters. We implemented these equationssin a hypermedia environment ? one that integrates graphics, sound, animation, and calculationssequences ? and created a prototype fenestration performance design tool. Inputs required by thesprogram consist of geographic location, building type, perimeter space, and envelope definition.sOutputs are the calculated performance indices for electricity and fuel use, peak electric load, andsthermal and visual comfort.

Abstract: Daylighting is an energy-conserving strategy and a lost architectural art. The Windows and Daylighting Group has extensivelysresearched the energy implications of daylighting, and after developing a number of conventional design tools, has recently been consideringsnew electronic design tools to promote its practice. Daylight as a topic sits at the junction of key quantitative and qualitative design issues andsworks well as an energy-conserving strategy when incorporated into buildings early in the design process.

The application of microcomputer tools in building design has been limited to date, as has been acceptance of such tools among architecturalsprofessionals. While computer-aided drafting systems are becoming more and more popular, computer-based design tools are rarelysseen. This reluctance in the design world towards the use of computers in the design process itself may begin to turn around with the developmentsof friendlier computers and software, and particularly with the increasing interest in and use of hypermedia. The arrival of both thesMacintosh microcomputer and its accompanying hypertext program HyperCard opens new opportunities for design applications. The Macintoshshas been successful in dispelling computer phobia, and hypermedia has potential as a replacement for traditional methods of presenting,saccessing, synthesizing and evaluating information pertinent to the design process.

HyperCard can be described as a new electronic information system, more powerful and flexible than traditional written methods. It isscharacterized by its unique abilities to interlink data in non-linear sequences, radically altering how we use reference tools. Part of the genesissof this software is in a recognized global need for the sharing of information; the parallel to architectural design is immediately seen, as ever increasingsdemands on the profession highlight a growing need for accessible reference information.

The Windows and Daylighting Group is currently developing a daylight design guide in HyperCard. The intent is to first supplement,sand eventually replace, written manuals and other references, which, by their size or structure, are too cumbersome or otherwise forbidding tosbe used in a typical design process. The tool is intended to be a guide for both design and educational tasks. Currently in the early stages ofsdevelopment, the tool will ultimately take advantage of state-of-the-art multimedia hardware while the software will combine data and expertsguidance into a fluid and dynamic design tool.

Abstract: For over a decade research work in the Windows and Daylighting Group has focused onsidentifying and quantifying the architectural and energy impacts of daylighting. We have lookedsat the energy-saving potential of daylighting, its role as an enhancement or supplement for electricslighting systems, and its effect on the quality of interior spaces. Convinced that daylighting canshave a beneficial impact in all of these aspects, we have over the last few years turned oursattention to the application of daylighting design knowledge. Existing methods to facilitate bettersdaylighting design appear to have had little impact in the built environment. We are thereforesdeveloping new design tools to encourage the use of daylighting by making the necessarystechnical information and design data more accessible and useful for designers than traditionalsreference materials and design tools.

Some recent advances in the computer world are helping us bridge the gap between the promisessof research and the reality of design application. The friendly environment of currentsmicrocomputers and new software implementations of a concept in electronic information systemssknown as hypertext present new possibilities in the realm of technology transfer. Unlikestraditional written information systems, hypertext has the ability to flexibly link data in a nonlinearsfashion, allowing different users to move through the information differently. These newselectronic systems may also include sound, animation and video as well as traditional text andsimages, expanding the hypertext concept to hypermedia. Part of the genesis of this software is insa recognized global need for the sharing of information; the parallel to architectural design issimmediately seen, as ever-increasing demands on the profession highlight a growing need forsaccessible reference information.

The Windows and Daylighting Group is currently developing a daylight design tool usingshypermedia tools. The intent is to first supplement, and eventually replace, written manuals andsother references, whose size or structure are too cumbersome or otherwise forbidding to be usedsin a typical design process. The tool is intended to be a guide for both design and educationalstasks. Currently in the early stages of development, the tool will ultimately take advantage ofsstate-of-the-art multimedia hardware while the software will combine data and expert guidancesinto a fluid and dynamic design tool.

Abstract: Vanadium oxide films were deposited by reactive dc magnetron sputtering from a vanadium target in argon-oxygen gas mixtures. The composition and structure of these films were investigated by X-ray photoelectron spectroscopy and X-ray diffraction. Films with the approximate composition V2O5 were amorphous when deposited at room temperature and had a reversible color change when lithium was electrochemically injected. Because the color change is slight, these films could be used as a counterelectrode to a more strongly coloring material.

Abstract: This paper describes the development of asnew concept for analyzing the performance ofsfenestration systems. We show the derivationsof five indicators that can be combined in asvariety of ways so that both qualitative andsquantitative judgements can be madesregarding total fenestration performance. Thesfive indices consist of three related to energy:sfuel (heating), electric (cooling), and peakselectric demand; and two to comfort: thermalsand visual. Performance comparisons ofsdifferent systems are made possible bysintroduction of a non-dimensional user-definedsweighting function that specifies thesrelationship between the five indices. Asfigure of merit is then calculated byscombining the index values and weightingsfactors to provide a direct comparison betweensfenestration systems.

The indices were derived by performing asmultiple regression of several thousand hour-by-shour building heat transfer simulations of asprototypical office building module using thesDOE-2 simulation program. From thissregression analysis, we derived a series ofssimplified algebraic expressions that relatedsfenestration performance to configurationsvariables. We then incorporated thissmethodology as the computational engineswithin a prototype fenestration design tool onsa microcomputer using hypermediasconcepts for the user interface. Ashypermedia environment is one thatsintegrates computer graphics, video, sound,sanimation, etc. with calculation sequences.sThis first prototype represents a significantsdevelopmental step toward our longterm goalsof an overall building envelope design tool.

Abstract: Advances in window technologies and the desire to standardize the reporting of standardswindow heat transfer indices have necessitated the development of a comprehensivesanalytical procedure for calculating heat transfer through windows. This paper showsshow complete window heat transfer can be considered as the area-weighted sum of thesthree window component areas: the center-of-glass area, the edge-of-glass area, and thesframe area. Algorithms for calculating heat transfer through each of these areas and forscombining these to calculate total window indices are presented.

Abstract: In this study we report on our investigation of the microstructure of nickel oxide films produced byse-beam evaporation, sol-gel deposition, and sputtering techniques. We give characteristic cyclicsvoltammetry, current-voltage relationships, and optical transmission data for films made by eachstechnique. Data is shown for electrodes, both uncycled and cycled, for 17-20 hrs. We found allssamples have at least one phase corresponding to cubic nickel oxide (NaC1 structure). Othersphases, such as nickel hydroxide, may exist but are not immediately identifiable. The structure ofsthe films ranges from fine polycrystalline to amorphous and varies over the surface of the sample.sFilms that were cycled for 17-20 hours all tended to have improved transmittance, as high as as20% change. The highest transmission range from bleached to colored was for the evaporatedsfilms, which showed delta T=60%. The sol-gel films showed a large residual coloration in thesbleached state after cycling (about a 40% decline was noted). Overall, after cycling the filmssappeared to be slightly more crystalline. In all films, after cycling there were increases in thescoloration and bleaching current. Also, peak shifts were noted after cycling; the coloration peakstended to shift to higher and the bleaching peak shifted to lower potentials. The overall colorationsefficiency (550 nm) for these films ranged from 26-36 cm2/C.

Abstract: It is widely known that most materials used in solar energy conversion and buildingsenergy control applications suffer from two major restrictions, the first being the costseffectiveness of the material in a particular use and the second being durability. In thessolar field, cost has been a very important factor and has restricted development of moresexpensive but efficient materials. The issue of durable lifetime is coupled to the cost;ssince in many cases a more expensive material might have greater durability or operationalslifetime. This investigation looks into selected solar materials and how theysdegrade, fail or cease to function in their specific solar application, and explores methodssby which certain materials can have their operational life extended. This report documentsswork conducted as part of Task 10: Solar Materials RSGD of the IEA Solar Heatingsand Cooling Program.

Abstract: A Fresnel lens"s imaging performance can be seriously impaired by chromatic dispersionswhich typically doubles the diameter of the focused sun image in a solar concentrator. Thissproblem can be alleviated by means of a molded diffraction grating whose diffraction-inducedsdispersion offsets and substantially cancels the lens"s intrinsic refractive index dispersion. Thesgrating lines would comprise a second tier of small-scale, Fresnel-type facets superimposed on theslens facets, with a typical grating facet height of about 40 microinches and a facet width rangingsfrom about 1 milliinch at the edge of the lens to around 5 or 10 milliinches near the center. In itssprimary intended application the grating would function in a core daylighting system to improve thesoptical performance of a collector which focuses direct sunlight into fiber optic couplers. For thissapplication chromatic dispersion would be reduced by an order of magnitude with only a 2% losssin optical efficiency.

Abstract: This paper extends an existing heat transfer model of multipane windows filled with gasses to include the effects of infrared absorption within the gasses. A one-dimensional, finite-element, control-volume approach for calculating the heat transfer across a horizontal window filled with an infrared absorbing gas is presented. This model includes the coupled effects of conduction and radiation but not convection. Experimental data on the heat transfer rates through windows filled with infrared absorbing gasses and heated from above (to minimize convection) agree with results from this model. Infrared absorbing gasses are shown to have a small effect on reducing heat transfer through common window systems and are not as effective as low-emittance coatings for reducing radiative heat transfer.

Abstract: Over the last few years, hydrated nickel oxide or hydroxide has gained interest as an electrochromic material. It has many important features. First it shows a transparent to bronze coloration which isssuitable for a number of architectural, vehicle and aerospace glazing applications. This material is stable insan alkaline environment and colors and bleaches at potentials below 1.0V and below the oxygen andshydrogen evolution potentials. It can be deposited by a wide range of processes, including anodic andscathodic electrodeposition, r.f. and d.c. sputtering, vacuum evaporation, chemical vapor deposition, andssolgel processes. In this work we will discuss films made chiefly by anodic electrodeposition. Some of thesbest characteristics are seen in films made by electrodeposition. The properties of films made by othersdeposition processes will be discussed in subsequent chapters. Much of the electrochemical knowledgesabout hydrated nickel oxide comes from studies of metallic nickel electrodes used in batteries. The studysof hydrated nickel oxide based electrochromic devices is just emerging, and so far very few devices havesbeen reported. Some of the work by my group on nickel based devices will be outlined later in thisschapter.

Abstract: Traditionally, lighting designers and architects have designed using only theirown experience and assumptions. In increasing numbers, they are turning to CAD systems and design tools. Radiance is a design analysis tool for electric lighting and daylighting. The program was conceived as a research tool to study illumination, and has been used to prepare general guidelines and instruct designers in qualitative and quantitative aspects of lighting. The first part of this report will show the importance of lighting simulation in designing for energy efficiency, visual comfort, and aesthetics. Radiance takes a scene description with light sources, sun, sky, other buildings, rooms, furniture, etc. and produces spectral radiance values which can be collected in a color image. Its specialty is providing both realistic images and numerical data. Designer can see what their work will look like and simultaneously, use the numercal data (luminance or illuminance values) to check the deisred amount of light, or to compare the values with those given by other light sources.

Abstract: We present a detailed consideration of the energy flows entering a building spacesand the effect of random measurement errors on determining fenestration performance.sEstimates of error magnitudes are made for a passive test cell; we showsthat a more accurate test facility is needed for reliable measurements on fenestrationssystems with thermal resistance 2-10 times that of single glazing or with shadingscoefficients less than 0.7. A test facility of this type, built at Lawrence BerkeleysLaboratory, is described. The effect of random errors in this facility is discussed andscomputer calculations of its performance are presented. The discussion shows that,sfor any measurement facility, random errors are most serious in nighttimesmeasurements, and systematic errors are most important in daytime measurements.sIt is concluded that, for this facility, errors from both sources should be small.

Abstract: Many of our current national concerns are linked to the quality of our built environment.sEnergy use in buildings accounts for almost 40% of total U.S. consumption, a muchshigher fraction of U.S. electricity use, and requires expenditures of $140 billion/year.sAlthough we have made significant advances since the energy shocks of the early 1970s, ifswe compare our energy use to other industrialized nations we find that much of oursenergy consumption today is still unnecessarily wasteful. Energy waste has other unfortunateseconomic and environmental consequences. It diverts scarce economic capital tospay fuel bills or to invest in new energy supply infrastructure and it contributes directlysto serious long-term adverse environmental effects such as global warming due to CO2semissions.

Substantial energy reductions can be achieved in the building sector. However, thisswill require the concerted action of tens of thousands of individual designers and decisionsmakers, rather than a small number of centralized actions. It is clear that this can besachieved only if each decision maker is well informed, well equipped with proper tools tossupport the design process, and is strongly motivated to take effective action. Fortunatelysthere are other sound reasons to pursue such strategies. Building design issuessthat influence energy use also affect the habitability of buildings. Many energy-relatedselements of the work environment (e.g. air quality, thermal and visual comfort) can raisesor lower the level of satisfaction and productivity in our workplaces. In the increasinglyscompetitive global markets, the resourcefulness and productivity of our workforce issimportant.

Abstract: We present results from the first phase of a project to develop a fenestration performance design tool to besused by builders, designers, architects, utility auditors, etc. In phase 1 we defined the design tool conceptsand the experimental and analytical methodologies required to achieve the project goal. We defined fivesfenestration performance indices, which when combined with user-specified weighting factors yield a singlesfigure of merit. Three of the indices are related to the effects of fenestration on building energy performance:sfuel and electric use and peak electric demand. The other two are related to thermal and visualscomfort. We derived index values and correlations to window design parameters by creating a data basesconsisting of a large number of building energy simulations for a prototypical o5ce building module usingsthe DOE-2 computer simulation program. Four glazing types and two shading devices were combined insseveral ways so that a representative sampling of realistic fenestration systems was analyzed.

Abstract: The daylighting performance of the Pacific Museum of Flight in Seattle,sWA, has been analyzed using the DOE-2.1C building energy simulation program.sThe main exhibit areas of this museum are enclosed on three sides by glass wallssand the 48,000-ft2 roof is completely glazed. Because of the large glass areas, asdetailed thermal simulation of the building was carried out during its designsphase in order to select glazing parameters that would avoid excessive summerssolar heat gain, reduce winter heat loss and, at the same time, provide enoughsnatural light to significantly reduce electric lighting loads. Glazing choices consideredsincluded conventional glass, heat mirror, and glass with a low-emissivityscoating. On/off, stepped and continuous dimming lighting control systems weresanalyzed. Daylighting was found to be very effective in reducing annual electricslighting load, peak electrical demand, and the overall annual energy consumption.

Abstract: Five commercial windows were studied using the MoWiTT (MobilesWindow Thermal Test) facility, an accurate new field test apparatus. Bothsoverall diurnal performance and U-values were measured. The latter werescompared to test laboratory hot box measurements for the same fiveswindows, and to calculations made with the program WINDOW-2.0.sCalculations, MoWiTT and hot box measurements agreed for three of theswindows; for one of the others, the calculations agreed with the MoWiTTsmeasurement but not with the hot box. For the fifth, a low-E window, thescalculations may be made to agree with either measurement but not both,sdepending on assumptions about the frame. The authors suggest a possiblesexplanation for the conflict, and advance an interpretation of the data whichswould allow a consistent understanding of calculated, field and laboratorysU-values.

In the studies of overall performance, uncertainties arising from wintertimessolar gain were found to overshadow the differences in U-value for allswindow orientations, including north-facing. In some of the windowsstested, improved U-values were offset by decreased solar gain acceptance.sFurther research is suggested to achieve a method of evaluating overallswindow energy performance which would reliably reflect U-valuesimprovements.

Abstract: In most areas of the United States, windows are by far the poorest insulating materialsused in buildings. As a result, approximately 3% of the nation"s energy use is used tosoffset heat lost through windows. Under cold conditions, conventional double glazingsscreate uncomfortable spaces and collect condensation. However, with the recent introductionsof low-emissivity (low-E) coatings and low/conductivity gas filling to respectivelysreduce radiative and conductive/convective heat transfer between glazing layers, somesmanufacturers are beginning to offer windows with R-values (resistance to heat transfer)sof 4 hr-ft2- F/Btu (0.70 m2-C/W). This paper presents designs for and analysis and testsresults of an insulated glass unit with a center-of-glass R-value of 8-10; approximatelystwice as good as gas-filled low-E units and four times that of conventional double glazing. This high-R design starts with a conventional insulated-glass unit and adds twoslow-emissivity coatings, a thin glass middle glazing layer, and a Krypton orsKrypton/Argon gas fill. The unit"s overall width is 1 (25 mm) or less, consistent withsmost manufacturers" frame and sash design requirements. Using state-of-the-art low-emissivity coatings does not significantly degrade the solar heat gain potential or visiblestransmittance of the window. Work to date has substantiated this concept of a high-Rswindow although specific components require further research and engineering development. Demonstration projects, in conjunction with utilities and several major window manufacturers, are planned. This high-R window design is the subject of a DOE patent application.

Abstract: Accurate determination of the luminous and thermalsperformance of fenestration systems that incorporatesoptically complex components requires detailedsknowledge of their radiant behavior. We describe a largesscanning radiometer used to measure the bidirectionalstransmittance and reflectance of fenestration systems andscomponents. We present examples of measured datasobtained for simple non-specular samples. We describesa method of obtaining the overall properties ofsfenestration systems by calculation from scanningsradiometer measurements of fenestration components.sFinally, we describe the application of bidirectionalssolar-optical properties of fenestration systems tosdetermine their luminous and thermal performance withsrespect to building energy consumption and occupants"scomfort. We also discuss the advantages and limitationssof the method, which appears to be promising.

Abstract: U-value measurements made with the MoWiTT field test facility and at a commercial test laboratory for four commercial windows are compared with calculations made with the WINDOW program. Good agreement is found for three of the windows; for the fourth--a double-glazed window with a highly conductive frame--agreement is good between the calculations and the MoWiTT measurements, but agreement with the test laboratory is only marginal. Measurements of overall diurnal performance are presented, and it is shown that, even for a north-facing window, the uncertainties in thermal performance due to solar gain effects overshadow the effects of improved U-value. The author argues the need for better methods of accounting for solar gain effects in window performance comparisons, so that the net benefits of U-value improvements may be correctly assessed.

Abstract: The Lawrence Berkeley Laboratory has performed a preliminary analysis of the effects of glazingsand ventilation on automobile cooling loads and air conditioner capacity limits. The study wassaccomplished as part of the Environmental Protection Agency"s efforts to reduce the release ofschlorofluorocarbons into the earth"s atmosphere from automobile air conditioners. We investigatedsthe characteristics of standard and sports-model sedans using numerical simulations of the heatstransfer processes under static-soak conditions. In addition, an annotated bibliography was createdsthat documents other relevant research relevant to both static-soak and highway driving conditions.

These studies and our own results suggest that:

- Glazing is a major contributor to the cooling loads that dictate the size of automobile airsconditioners.

- The use of new glazing technology in conjunction with other design features, e.g.,sventilative cooling when parked, provides a viable means of reducing cooling system size in many parts of the country.

- Continuing work is needed to perform additional analytical and experimentalsinvestigations under highway driving conditions that will document the magnitude of thescooling unit size reduction possibilities.

Abstract: Materials science properties of optical materials and coatings are discussed for a broad range of solar conversion, architectural glazings and greenhouse energy efficient uses. Transparent low emittance coatings for glazings are discussed for radiative heat transfer reduction. Both interference multilayer and doped semiconductor low emittance coatings are covered. The use of Drude theory to model coatings is discussed. Discussion of various types of selective absorbers include interference multilayer, composite tandem absorbers and selective paints. Effective medium theories are used to describe composite absorbers. The basic properties of radiative cooling materials and antireflection coatings are detailed. Also, the properties of reflector malerials on glass and plastics are covered. Application of fluorescent concentrators, spectral splitting and cold mirror films are outlined. Research on transparent aerogel insulation and optical switching films for windows are introduced.

Abstract: A procedure has been developed for calculating the one-dimensional heat flux through complex windowssystems. A computer program embodying this procedure (WINDOW 2.0) is available to the public. Theswindow may consist of multiple glass or plastic layers, separated by gas-filled spaces. Gases other than airsmay fill the space between solid layers, and the layers may have low-emissivity coatings. Measurementssfrom five different manufacturers and researchers of the overall thermal conductance of various windowssystems confirm the validity of this model for a range of temperatures and layer spacings less than 3 cms(1.2 in). A list of U-values and shading coefficients is given for a representative group of windows.

Abstract: Fenestration is the most significant envelope design determinant of energy use in nonresidential buildings.sThis paper presents our assessment of energy use effects of low-emissivity (low-E) versus conventional glazing for a range of window-to-wall ratios in a daylighted office building, in representative hot and cold climates.sLow-E glazings transmit cooler daylight than their conventional counterparts because, for asgiven visible transmittance, they reflect a much larger fraction of incident solar infrared radiation. Westhus use the ratio of visible transmittance to shading coefficient, which we define as Ke, to compare theseffect of representative glazing characteristics on component and total-building energy use, peak electricalsdemand, and required cooling equipment sizes.

We conclude that insulated glazings with low-E coatings can provide lighting and cooling energy savingssin both hot and cold climates. The most dramatic lighting, cooling, and total electricity energy savingssare achieved for increases of Ke within the range of 0.5 to 1.0; higher Kes provide diminishing savings.sThe increased R-value of low-E insulated glass units provides significant benefits in cold climates and issnot a liability in hot climates.

Low-E glazings also help increase the mean radiant temperature of interior environments in wintersand reduce it in summer, and provide greater architectural design freedom without adverse energy consequences.sFurther, the higher first costs of these glazings may be more than offset by savings from smallerscooling equipment, energy and peak-demand cost savings, long-term financial gains from better rentals,sand increased productivity due to improved occupant comfort.

Abstract: We present a comparative study in which residential heating and cooling energy costs aresanalyzed as a function of window glazing type, with a particular emphasis on the performancesof windows having low-emittance coatings. The DOE-2.1B energy analysis simulationsprogram was used to generate a data base of the heating and cooling energy requirementssof a prototypical single-family ranch-style house. Algebraic expressions derived bysmultiple regression techniques permitted a direct comparison of those parameters thatscharacterize window performance: orientation, size, conductance, and solar transmissionsproperties. We use these equations to discuss the energy implications of conventionalsdouble- and triple-pane window designs and newer designs in which number and type ofssubstrate, low-emittance coating type and location and gas fill are varied. Results arespresented for the heating-dominated climate of Madison, WI, and cooling-dominated locationssof Lake Charles, LA, and Phoenix, AZ. The analysis shows the potential for substantialssavings but suggests that both heating and cooling energy should be examinedswhen evaluating the performance of different fenestration systems. Coating and substratesproperties and the location of the coating in the glazing system are shown to havesmoderate effects as a function of orientation and climate. In addition, with the low-conductancesglazing units, the window frame becomes a contributor to overall residentialsenergy efficiency.

Abstract: Using data obtained in a mobile field-test facility, measured performance of clearsand low-emissivity double-glazing units is presented for south-facing and north-facingsorientations. The changes in U-value and shading coefficient resultingsfrom addition of the low-E coating are found to agree with theoretical expectationssfor the cold spring test conditions. Accurate nighttime U-values weresderived from the data and found to agree with calculations. Expected correlationsbetween U-value and wind speed was not observed in the data; a plausible experimentalsreason for this is advanced.

Abstract: The properties of VO2, thermochromic coatings were investigated forsapplication to building windows. The solar transmittance of V02sdecreases above a certain temperature, blocking excess solar gain. Filmsswere deposited on glass by reactive magnetron sputtering, butsstoichiometric compositions have not yet been achieved. The compositionsand structure of these films have been determined by Auger spectroscopysand x-ray diffraction. Optical properties were measured by photometricsand ellipsometric methods. Using this optical data, composite coatingsswere designed having improved optical characteristics. The high-temperaturesmetallic state of V02 was not found to be suitable as a staticslow-emissivity coating. When this VO2, is used as a thermochromic coating,showever, its moderately low-emissivity would contribute to energyssavings. The ratio of solar transmittance between the high-temperaturesand low-temperature states increases with decreasing average transmittance.sHigher values of this ratio might be obtained by proper choice ofsadditional coating layers.

Abstract: This paper presents a comparative study in which commercial building perimeter zone electricsenergy (cooling, lighting, fan) and peak electric demand are analyzed as a function of windowsglazing type, with a particular emphasis on the use of glazings with wavelength-selective solar opticalsproperties. The DOE-2 energy analysis simulation program was used to generate a datasbase of the electric energy requirements of a prototypical office building module located in Singapore.sAlgebraic expressions derived by multiple regression techniques permitted a direct comparisonsof those parameters that characterize window performance in hot and humid climates:sorientation, size, and solar-optical properties. Also investigated were the effects of exterior andsinterior shading devices, as well as interior illuminance level, power density, and lighting controlssto permit the use of daylighting. These regression equations were used to compare the energysimplications of conventional window designs and newer designs in which the type of coating andssubstrate were varied. The analysis shows the potential for substantial savings through combinedssolar load control and lighting energy use reduction with daylighting.

Abstract: Transparent low-emissivity coatings are commonly used to reduce the thermal conductance ofswindows. It is important to be able to characterize and compare the wide variety of thesescoatings that are now available. The property that best describes the effectiveness of a coatingsin suppressing radiative heat transfer is the total hemispherical emissivity. It is muchssimpler, however, to measure the normal emissivity. This paper shows that a correspondencesexists between these two properties which applies to most types of low-emissivity compositescoatings. An empirical expression for this correspondence is provided.

Abstract: Silica aerogel is a porous insulating material that isstransparent to solar radiation. To understand itssinsulating performance in a window system, it issnecessary to first study component heat transferspaths. Aerogel"s absorption coefficient, a measure ofsthe attenuation of radiation heat transfer, was determinedsover the spectral range 1-200 pm. Althoughsradiation heat transfer is negligible over much of thissregion, there is a transmission window between 3-6spm. At ambient temperatures, for aerogel thicknessessof 0.5-5.0 cm, radiation heat transfer through ansunmodified aerogel window is less than 15% of thestotal heat flux. For evacuated or high-temperaturesfurnace windows, this contribution can be over 50%.sThermal radiative transfer can be somewhatsdecreased by allowing the aerogel to absorb moisture,sbut solar transmission and optical clarity aressacrificed. Absorption of water vapor over timescauses irreversible structural changes that increasesscattering in the solar spectrum. Aerogel"s thermalsperformance can be improved by replacing the poresgas with one of lower conductivity or by evacuatingsthe aerogel to pressures below 0.1 atm. A hypotheticalsevacuated aerogel window has a calculated UValuesof 0.5 = W/m2-K for a gap spacing of 12.5 mm,swhich is four times better than currently availableslow-emissivity gas-filled units of similar size.

Abstract: In this investigation, in-situ spectroscopic studies of anodically deposited electrochromic hydrated nickel oxide electrodes were performed by visible/near-infrared spectroscopy and Fourier-Transform Infrared (FTIR) spectroscopy. All measurements were taken while the nickel oxide thin films were switching between the bleached and colored states, where the electrodes were not removed from the electrochemical cell. Optical transmittance measurements of the nickel oxide film relative to tin oxide coated glass varied during coloring from the integrated solar spectral transmittance, Ts=101%-54%, and average near-infrared transmittance, Tnir, = 101%-83%. The photopic transmission was Tp = 101 - 31%. Transmittance measurements versus time were also performed at selected wavelength values, ranging from 375 to 1100 nm. Also different scan rates (10-100 mV/s) were investigated at each of these wavelengths, where optimum switching rates could be determined. All changes in optical density were achieved by continuously cycling between a potential range of -500 to 800 mV. Coloration occurs at a faster rate than bleaching of the films at every switching rate selected. Also, maximum and minimum transmission measurements at 420 nm do not to correspond to the cathodic and anodic peak current densities. Instead these transmission measurements correspond to the regions past the peak current densities. From these optical experiments, plots of transmission (%) versus voltage (mV) and transmission (%) versus total extracted charge (mC) were obtained. For FTIR spectroscopic experiments, chemical identification of the 10-20 nm thick films showed that the films exhibit different bonding environments for both the colored and bleached states. There exist surface hydroxyl groups associated with nickel oxide in the region of 3600-3800 cm-1 wave numbers. Fundamental water vibrations are also found at 3200-3500 cm-1 and at 1600-1700 cm-1 wave numbers. The nickel oxygen vibration region is at 400-525 cm-1 for both states. The comparison of bleached and colored states exhibits distinctive molecular vibrational states, which correspond to Ni(OH)2 and NiOOH respectively.

Abstract: Electrochromic device testing and durability is discussed in this study. This work begins with a discussionsof performance criteria for switchable glazings used in building applications. This is followed by devicesdesign of several common electrochromic device types. The types are distinguished by structure andselectrolyte type. A number of test methods are used for the analysis of electrochromic devices. Deviceslifetime and degradation covers considerable work on amorphous tungsten oxide. Some degradation andsageing modes are identified for electrochromic devices during static and cyclic testing. The degradationsmodes are film dissolution, transparent conductor etching, gas generation, humidity dependence, secondarysreactions and photoreactions. Many of these mechanisms are specific to the materials, device design, andsthe operating conditions used. Overall, future of electrochromic devices looks very promising, but there aresmany issues in this study that designers need to take into consideration for electrochromic glazings.

Abstract: During the last ten years, daylighting has become an increasinglysimportant consideration for lighting designers,sarchitects, and building owners. Besides the amenities thatsdaylight it may significantly contribute to the reductionsof electric lighting loads, especially in commercialsbuildings, where the largest portion of the lighting requirementssoccurs during the day. However, it is important thatsdaylight admittance is controlled to prevent glare and negativesimpacts on cooling loads.

As with electric lighting design, successful daylightingsdesign requires means for predicting the luminous performancesof fenestration systems. In other words, we need tospredict daylight"s contribution to the illuminance and luminancesof interior surfaces. Daylight must be of sufficientsquantity and quality for building occupants" visual comfort,svisual performance, and aesthetic needs. Consideration ofsadditional design criteria, such as thermal comfort and energy/costsimplications, requires means for predicting the thermalsperformance of fenestration systems, so designers cansbalance and optimize the contribution of fenestration systemssto lighting and thermal loads.

Abstract: Titanium nitride (TIN) shows promise as a low-emittance coating forswindows because it possesses both the optical properties of a metal andsthe hardness and inertness of a ceramic. Titanium dioxide (Ti02) is asconvenient choice for a matching layer to enhance the solar transparency.sTiN and TiO2 films have been deposited on glass by reactive dc magnetron sputtering, which is a standard technique used for production ofswindow coatings. The composition of these films was determined by X-raysphotoelectron spectroscopy (XPS). Incorporation of N and O appearssto follow the Langmuir adsorption isotherm at low partial pressures.sStructure was determined by x-ray diffraction, using both Seemann-sBohlin and conventional Bragg-type geometries. Nonequilibrium phasesdiagrams have been prepared from this information for various depositionsconditions. The properties of these films depend strongly on the sputteringsconditions, especially gas pressures, substrate temperature, and biassvoltage. Emittance values have been achieved that are much lower thansthose of TiN films produced commercially. Multilayer coatings have beensdeposited with greatly improved spectral selectivity.

Abstract: The finite-difference equation method is used to derive expressions for the directional-hemisphericalstransmittance as measured in the integrating sphere; and for the correction factor necessary with a one-portssphere to account for changes in the enclosure caused by substituting the open port (the standard device) forsthe sample. Expressions are also derived for the hemispherical reflectance, since this quantity is necessary toscompute the correction factor. It is also shown that no correction factor is necessary with a two-ports(comparative) sphere.

Abstract: Results are presented that indicate a proportional relationship between building thermal loads for varying configuration parameters. Through the use of numerous building energy simulations using both the DOE-2.1 and BLAST energy analysis computer programs, it is shown that the relationship is independent of climatic location and covers a broad spectrum of those variables that influence a building"s energy use. The theoretical justification associated with such a phenomenon is treated using a multiple regression-derived algebraic expression that clearly establishes the linear independence of a building"s heat gain/loss components. Procedures are defined for the simplification of future parametric studies of the thermal analysis of buildings using a methodology that incorporates the observations reported herein.

Abstract: This paper describes the performance of a 56,000-m2 office building emphasizing the use of daylighting for ambient illumination. Natural light serves 3,000 employees in open-plan offices through the building"s five floors. The architectural scheme includes ceilings that slope from 4.25 m (perimeter) to 2.75 m (center), 3.5-m-deep light shelves at the exterior walls, and a central atrium providing light to interior spaces. An electric lighting system supplements available daylight, when necessary, using fluorescent fixtures with continuously dimming ballasts controlled by photocells. Monitoring during asone-year period has confirmed that the daylighting elements of the buildingsprovide ambient illumination in a pattern predicted by the design studies.sBetween 8AM and 6PM on an average summer day, the building"s southern half canspotentially maintain the target illuminance of 350 lux with an electric lighting load of 44% full power. The northern half of the building would requiresless electrical lighting at 31% of full power. However, actual measuredselectrical power consumption for ambient lighting is higher at 75% of fullspower for the south side and 50% of full power for the north side. The daylighing component of interior illuminance peaks at seven times the target level for ambient light. Proper design and tuning of the electric light control system was determined essential for the realization of projected savingssin electric power consumption.

Abstract: Using daylighting in commercial buildings may significantly reduce electric lighting requirements if appropriatesphotoelectric controls are used to adjust the electric lighting output according to the available daylight. Prior analysis andsresults from monitored buildings and scale-model measurements suggest that the selection, placement, and installation ofsthe control photosensor is a difficult task, even with simple non-operable fenestration systems, since the daylightscontributions from sun, sky, and ground change continuously. The problem becomes even more complex forsfenestration systems that incorporate operable shading devices, because every adjustment changes the system"s opticalsproperties. This paper presents results from measurements in a scale model under real skies, designed to bettersunderstand the problem of integrating fenestration and lighting controls. The scale model represented a typical officesspace and was equipped with motorized venetian blinds. Three control photosensors mounted on the ceiling weresconsidered for the operation of the electric lighting system, and two control strategies were considered for the operation ofsthe venetian blinds. Two ground-plane reflectances and two window orientations were examined. Results indicate thatsthe signal from a ceiling-mounted control photosensor shielded from direct light from the window shows the bestscorrelation with daylight work-plane illuminance, regardless of ground plane reflectance or venetian blind slat angle for allsslat angles that do not allow penetration of direct solar radiation. Results also indicate that the control strategies of thesvenetian blinds that were considered for the purposes of this study may result in significantly different slat angles, andsthus different daylighting work-plane illuminances and electric lighting requirements, especially when the ground-planesreflectance is high.

Abstract: This paper presents conclusions from a one-year instrumented study of an innovative daylighted commercial building insthe San Francisco Bay area. The building, a five-story structure housing 3,000 employees, has a series of architecturalsfeatures specifically developed to admit daylight into interior office zones. These are complimented by a continuouslysdimmable fluorescent lighting system that supplements available daylight under the control of open-loop ceiling-mountedsphotosensors. Monitored data indicate that the architectural daylighting features of the building are performing admirablysand contribute significant daylight to most areas of the building"s open plan offices. Field tests have determined that,sunder manual control, the electric light dimming hardware is capable of dimming to 27% of full power consumption.sOperational savings, however, are limited by inappropriate performance of the control system in many of the building"sslighting circuits.

Abstract: When hourly energy simulation models are used to predict the performance of multi-zone buildings, theysmay be required to perform more than 2,000 daylight analyses in a single simulation. The traditionalsapproach is to use a very fast computational model, which of necessity must be a very simple model.sCoefficient of utilization models have been widely used as simple design tools but have been severely limitedsin their applicability to complex and realistic fenestration systems and building designs. This paperspresent a new coefficient of utilization (CU) model for daylighting that combines the ease of use of CUsmodels with the ability to predict illuminance under a wide range of conditions. The model consists ofsseven regression equations normalized to exterior vertical surface illuminance. These equations describesdaylight illuminance as a function of position in a room and are sensitive to all of the significant designsvariables. The equations are derived from parametric analysis using a mainframe daylighting computersmodel (SUPERLITE). We describe how these equations were developed and their physical and theoreticalsbackground. Comparisons between direct calculation and CU results for sample rooms are demonstrated.

Abstract: This paper examines the relationship between lighting energy savings from daylighting and daylight-imposedscooling loads. From DOE2.1C simuIation results for specific commercial buildings and glazingsoptions, we show that for any daylighted or electrically lighted space, the cooling load component fromsnatural or artificial lighting can be broken into three component factors. Each of these factors can besexpressed mathematically as constants that are a function of glazing characteristics and illumination levelsswithin the space. These three constants can then be combined into a single daylight coolness index.sThus, from (model or simulation) illuminance measurements for a proposed daylighted space, a designerscan quickly compare the relative cooling load impacts of different daylighting designs.

Abstract: Traditional computational models predict daylight illuminance in a space by dividing window surfaces into discretesareas and then calculating the apparent luminance of each window element by multiplying the luminance of thesnatural light source in a given viewing direction by the window transmittance in that direction. This approach worksswell for conventional glazing materials but is incapable of modeling commonly used, but complex, window systemsssuch, as those with specular reflective venetian blinds. We describe a new approach that combines measured luminancesdistributions for complex window systems with a flux transfer calculation within the space. This methodsresembles the calculation of illuminance from electric light fixtures where the candlepower distribution of the fixturessis measured and used as an input to the calculation. Based on the variable luminance characteristics of the windowssystem, the SUPERLITE program calculates illuminance at the workplane over the entire space. The measurementstechniques and mathematical implementation in the SUPERLITE program are described. This approach allows aswide range of complex window and shading systems to be evaluated without continuous changes in the computationalsprogram. A special apparatus for measuring the bidirectional transmittance of window systems has been builtsin conjunction with this approach. Sample results from the program are compared to measurements made in scalesmodels in a sky simulator.

Abstract: The bidirectional solar-optical properties of a fenestration system are necessary to accurately determine its luminous andsthermal perfomance. Bidirectional transmittance and reflectance can be determined experimentally for fenestrationssystems of arbitrary complexity using a scanning radiometer, after which the total directional absorptance can bescalculated. However, for the case of multilayer fenestration systems, this approach does not provide information aboutsthe net absorptance of each layer. Moreover, the same layers can be ordered in more than one way, resulting insfenestration systems with different solar-optical properties, the determination of which requires additional experimentalsprocedures. This paper describes a mathematical model for the calculation of the bidirectional solar-optical properties ofsmulti-layer fenestration systems, using the bidirectional solar-optical properties of each layer. The model is based on thesrepresentation of the bidirectional solar-optical properties using matrices. Matrix operations are then used to calculate thesbidirectional solar-optical properties of any combination of layers, considering the interreflections between them. Thissapproach offers two advantages: (1) the reduction of the experimental procedures to those required for the determinationsof the bidirectional transmittance and reflectance of fenestration layers, rather than complete fenestration systems, and (2)sthe determination of the net absorptance of each layer as part of the fenestration system, rather than the total absorptancesof the complete fenestration system.

Abstract: A review of current daylighting design tools indicates that over 30 tools are now available, including nomographs,sprotractors, overlays, and programs for micro-, mini-, and mainframe computers. Computer-based tools allow testingsand analyzing of more design alternatives under a wider variety of conditions than was previously practical with slowerstechniques, but they have not fundamentally changed the information available to the design professional. These tools aresapplicable to certain limited functions of the design process and do not address the varying information needs of thesdesigner at various points in the design process. We describe a concept for a computer-based building envelope designstool that is structured to overcome many of the limitations of the existing tools. The tool would address daylightingsdesign in the context of the overall building envelope design, covering a range of environmental quality issues in additionsto quantitative aspects of lighting and energy use. It would be useful throughout the process of design, construction, andsoccupancy, and is intended to provide important feedback that is often missing between those stages of the building"s lifescycle. A cost-effective tool with these performance features is not technically feasible using today"s hardware technology.sHowever, examination of the development of the necessary technologies provides strong evidence for future feasibility;saccordingly we are developing the tool to be used in a 1990 time frame. To date we have studied the features andscapabilities that such a tool should have, as well as several key areas, such as the design process, computer graphics,simaging systems, expert systems, and building science data bases.

Abstract: A general theory of optical transport systems has been developed that can be used to determine preliminary designsspecifications for light guide systems. Several generic light guide types are analyzed, including hollow reflective lightsguides, prism light guides, solid dielectric and fluid-filled light guides, lens guides, and open light wells. Minimumstheoretical aperture requirements are determined for each type as a function of the specified optical transport efficiency andsdesign parameters (light guide length, transmitted luminous flux, etc.). Generally, a system"s aperture requirement wouldsbe inversely related to its cost. Solid dielectric (e.g., optical fiber) light guides would be very compact and practical forsretrofit applications, but their high cost would preclude their use for long-distance optical transport. Open light wellsswould be the simplest and least costly option, but would require the greatest aperture area. Hollow reflective light guides,sprism light guides, or lens guides may offer the best compromise between cost and space requirements. But in order tosachieve optical concentrations and efficiencies near the theoretical limit, the collector system would need to maintainsoptical and tracking tolerances exceeding the capabilities of existing systems, so further advances in core daylighting willsrequire improvements in collector technology.

Abstract: Electric lighting is a major component of electricalsenergy use in large commercial buildings andshas additional significant impact on the coolingsenergy requirements. This paper evaluates thesmonitored performance of such an integrated lightingsscheme in a recently completed 600.000-ft2soffice structure located in the San Francisco BaysArea. Decentralized data acquisition systemssmonitored 62 different locations in the buildingsbetween May 1985 and January 1986, recordingsaverage illuminance levels and correspondingsambient lighting power usage across the north andssouth building sections. A graphic summary of datascompares the performance of effectiveness of thesbuilding"s lightshelf system for north and southsorientations. One counterintuitive conclusion ofsthe study is that the dimmer north side lightsshelf scheme exhibits a higher potential (69%sreduction from full power) for electric lightsreduction than the brighter south side scheme (56% reduction).

Abstract: The electrochromic properties of hydrated nickel oxide thin films electrochemically deposited by anodization onto doped tin oxide-coated glass have been studied by transmittance measurements, cyclic voltammetry, Fourier-transform infrared spectroscopy, and ion-backscattering spectrometry. The spectral transmittance is reported for films switched in both the bleached and colored states. The photopic transmittance (Tp) can be switched from Tp (bleached) = 0.77 to Tp (colored) = 0.21, and the solar transmittance (Ts) can be switched from Ts(bleached) = 0.73 to Ts(colored) = 0.35. Also reported is the near-infrared transmittance (TNIR), which was found to switch from TNIR(bleached) = 0.72 to TNIR(colored) = 0.55 for a film thickness of 500 A. The bleached condition is noted to have very low solar absorption in both the visible and solar regions. Ion-backscattering spectrometry was performed on the hydrated nickel oxide film, yielding a composition of NiO1.0 (dehydrated). Cyclic voltammetry showed that, for films in the bleached or colored state, the reversible reaction is Ni(OH)2 <---> NiOOH H e-. Voltammetry also showed that the switching of the film is controlled by the diffusion of protons, where OH- plays a role in the reaction mechanism. Analysis of the hydrated nickel-oxide thin films by Fourier-transform infrared spectroscopy revealed that both the bleached and colored states contain lattice water and hydroxyl groups. The surface hydroxyl groups play an important role in the coloration and bleaching of the anodically deposited nickel oxide thin films.

Abstract: The use of daylight for ambient illumination can substantially reduce this energysusage if the electric lighting system is properly controlled in response to available daylight.sThis paper evaluates the monitored performance of an integrated lighting systemsin a recently completed 56,000-m2 office structure in the San Francisco Bay Area.sNatural light serves 3,000 employees in open-plan offices throughout the five-story building.sThe architectural scheme includes: ceilings that slope from 4.25 m high at the perimetersto 2.75 m at the center; 3.5-m light shelves at the exterior walls; and a centralsatrium providing light to the interior spaces. The electric lighting system consists ofsfluorescent fixtures with continuously dimming ballasts controlled by photocells, which supplement available daylight when necessary.

The paper presents a summary of daylighting and electric lighting performance assmonitored in several zones of the building. Analysis of detailed measurements on thesthird floor for four unoccupied days in May indicates that on the brighter south side, thespotential for dimming during occupied periods is to 44% of full power. On the dimmersnorth side of the third floor, the potential for dimming during occupied periods is to 31%sof full power based on an eight-day block of data in July. Analysis of detailed measurementssduring occupied periods indicates that on the third-floor south side the actual averagespower consumption is 75% of full power over nine-days in May. On the third-floorsnorth side, the actual average power consumption during occupied periods is 50% of fullspower for eight days in July. Significant potential for daylighting is not being realized.

The paper discusses the potential benefits of daylighting in the context of the overallsbuilding electrical energy use. Analysis of annual electricity use indicates that thesambient lighting electrical circuits represent 23% of the total building electricity use.sPresent operation of the building is consistent with dimming of the ambient lightingselectrical circuits to 85% of full power. There are significant opportunities for dimmingsthat are not used. Proper integration of the electric light dimming system is essential forsthe realization of projected savings in electric power consumption.

Abstract: The thermal performance of single glazing, clear doublesglazing, and double glazing with a low-emissivity coating wassmeasured in both south-facing and north-facing orientationssunder realistic field conditions using the new MoWiTT fieldstest facility. The time-dependent net heat flow through eachsfenestration was found to be consistent with the predictionssof the standard simplified heat transfer model, provided thatsan angle-dependent shading coefficient is used and diffusessolar gain is included in the calculation. Summer-conditionsaverage U-values were derived for each glazing type and weresfound to agree with the expected values for both types ofsdouble glazing. The measured U-value for single glazing wasslower than predicted.

Abstract: The DOE-2 building energy analysis computer program has been used to study the life-cycle cost and annual energy use for a wide range of glazing and sun-control options in a 25-story office building with 50% glazing. Four climates in the U.S. have been analyzed: Miami, Los Angeles, Washington, D.C., and Chicago. The impact of daylighting in the perimeter zones for the various sun-control options has also been investigated. Double glazing was found t o have little effect on energy use in Miami and Los Angeles, but reduced energy use 11 - 23% in Washington, D.C., and 16 - 32% in Chicago. Daylighting reduced energy use 10 ? 22% and had a simple payback period of 3.7 - 8.9 years depending on climate and type of fenestration. Of the alternatives considered, the lowest life-cycle cost and energy use were obtained with daylighting coupled with clear glazing and exterior sun-control blinds.

Abstract: A comprehensive set of optical constants and a partial set of bulk optical properties are listed for clear, absorbing, and low-iron glasses used for windows. The measurements extend from the near ultraviolet to the far infrared, covering the range of interest for calculating solar and thermal radiative transfer through windows. This information is also needed to calculate the properties of thin-film coatings on glass substrates. Large variations in solar absorption are observed among these glasses, whereas the far-infrared properties are almost constant for all glass types. An important quantity, the hemispherical total emissivity, is 0.837 at 20 degrees C, as determined from reflectance data measured with an IBM Fourier-transform spectrometer. Solar properties are determined from conventional transmission and reflection measurements.

Abstract: Skylight parameters that affect lighting, cooling, heating, fan, andstotal energy use in office buildings are examined using the state-of-the-art building energy analysis computer code, DOE-2.1B. The lightingseffects of skylight spatial distribution, skylight area, skylight visiblestransmission, well factor, illumination setpoint, interior partitions,sceiling height, and glazing characteristics are discussed. Thissstudy serves as the foundation for the creation of a DOE-2.1B databasesand design tools for estimating daylighting energy savings fromsskylights.

Abstract: This study systematically explores the energy effects of skylight systems in a prototypical office building module and examines the savings from daylighting. For specific climates, roof/skylight characteristics are identified that minimize total energy or peak electrical demand. Simplified techniques for energy performance calculation are also presented based on a multiple regression analysis of our data base so that one may easily evaluate daylighting"s effects on total and component energy loads and electrical peaks. This provides additional insights into the influence of skylight parameters on energy consumption and electrical peaks. We use the DOE-2.15 energy analysis program with newly incorporated daylighting algorithms to determine hourly, monthly, and annual impacts of daylighting strategies on electrical lighting consumption, cooling, heating, fan power, peak electrical demands, and total energy use. A database of more than 2000 parametric simulations for 14 U.S. climates has been generated. Parameters varied include skylight-to-roof ratio, shading coefficient, visible transmittance, skylight well light loss, electric lighting power density, roof heat transfer coefficient, and electric lighting control type.

Abstract: A simple and economical phase-sensitive detector circuit is described. The circuit, which was developed for use with large-area heat-flow sensors that employ resistance temperature detection, uses a synchronous rectifier driven by a square wave. It is shown that the circuit has good linearity, resolution, and immunity to external and internal noise.

Abstract: A daylighting calculation has been intergrated grated into the DOE-2 building energy analysis computer program. Users can, for the first time in a widely-accepted, publicly-available program, determine the impact of daylight utilization on heating and cooling loads, energy use, energy cost, and peak electrical demand. We describe the algorithms which simulate hourly-varying interior illuminance, management of windows for sun and glare control, and the operation of electric lighting control systems. Sample DOE-2 daylighting output reports are presented and results of program validation against scale model illuminance measurements using the Lawrence Berkeley Laboratory sky simulator are discussed.

Abstract: This paper presents the results of a parametric study of a prototypical single-family ranch-style house. The DOE-2.1B energy analysis simulation program was used to analyze the variation in heating, cooling, and total energy requirements and resultant energy costs due to changes in the following building characteristics: fenestration orientation, size, conductance, and shading coefficient; and levels of internal heat gain, infiltration, and natural ventilation. Climate sensitivity was established by considering results from Madison, Wisconsin, and Lake Charles, Louisiana. To facilitate simplification of the analysis, multiple regression techniques were used to generate a simplified algebraic expression that relates energy use to the parameters varied. This simplified representation of the performance data could form the technical basis for simplified design tools to define optimal fenestration configuration parameters.

Abstract: A large set of illuminance and irradiance data has been collected for four years at 15-minute intervals in San Francisco. This data set has been used to investigate the impact ofsatmospheric turbidity on daylight calculations. Existing predictive formulae for Linke turbidity,sTL, provide moderate agreement to measured values of TL when using nominal designsvalues for the Angstrom scattering coefficient, P, and precipitable water vapor, w. When averagesmeasured values for p and w are used, the agreement improves. We suggest the use of ansilluminance turbidity, Til, to calculate direct normal illuminance directly. We derive a simplesapproximate solution, Til = 1 21.6 B. Til appears to be a better parameter to describe atmosphericsconditions since, unlike TL, it is insensitive to air mass and thus solar altitude or time ofsday. We present and compare plots of Til and TL vs. solar altitude, tim