Abstract: The Industry Foundation Classes (IFC) object data model of buildings is being developed by the International Alliance for Interoperability (IAI). The aim is to support data sharing and exchange in the building and construction industry across the life-cycle of a building.

This paper describes a number of aspects of a major extension of the HVAC part of the IFC data model. First is the introduction of a more generic approach for handling HVAC components. This includes type information, which corresponds to catalog data, occurrence information, which defines item-specific attributes such as location and connectivity, and performance history information, which documents the actual performance of the component instance over time. Other IFC model enhancements include an extension of the connectivity model used to specify how components forming a system can be traversed and the introduction of time-based data streams.

This paper includes examples of models of particular types of HVAC components, such as boilers and actuators, with all attributes included in the definitions. The paper concludes by describing the on-going process of model testing, implementation and integration into the complete IFC model and how the model can be used by software developers to support interoperability between HVAC-oriented design and analysis tools.

Abstract: The Industry Foundation Classes (IFC) model of the International Alliance for Interoperability (IAI)-an object data model of buildings-is in its seventh year of development. The last three re-leases of the model (IFC 1.5.1, 2.0 and 2x) have been implemented by a number of mission critical industry applications. The deployment of such software in real life projects is just starting. The author is exploring lessons from early de-ployment that are related to end user and general industry readiness for software interoperability, project model population with data and issues with compatibility of project data, built-in limitations in applications and in the data model, exchange file size and the selection of interoperable software for a project, as well as benefits attainable today from the use of interoperable software. He concludes that software interoperability is beginning to work in this industry, although not as smoothly as first expected.

Abstract: This paper provides an overview of software interoperability as it relates to the energy simulation of buildings. The paper begins with a discussion of the difficulties in using sophisticated analysis tools like energy simulation at various stages in the building life cycle, and the potential for interoperability to help overcome these difficulties. An overview of the Industry Foundation Classes (IFC), a common data model for supporting interoperability under continuing development by the International Alliance for Interoperability (IAI) is then given. The process of creating interoperable software is described next, followed by specific details for energy simulation tools. The paper closes with the current status of, and future plans for, the ongoing efforts to achieve software interoperability.

Abstract: Building geometry is essential to any simulation of building performance. This paper examines the importing of building geometry into simulation of energy performance from the users" point of view. It lists performance requirements for graphic user interfaces that input building geometry, and discusses the basic options in moving from two- to three-dimensional definition of geometry and the ways to import that geometry into energy simulation. The obvious answer lies in software interoperability. With the BLIS group of interoperable software one can interactively import building geometry from CAD into EnergyPlus and dramatically reduce the effort otherwise needed for manual input.

The resulting savings may greatly increase the value obtained from simulation, the number of projects in which energy performance simulation is used, and expedite decision making in the design process.

Abstract: In this paper we describe the product modeling techniques that we use for the development of a computer-aided decision-making tool for the building industry. We start with an introduction to modeling and a brief description of the goals and scope of the project, and follow with an extensive presentation and discussion of the modeling techniques employed. We conclude with a brief description of our plans for the future.