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Bild-IT: An Integrated Design Tool for the HVAC Industry

EETD is involved in an international joint development project to create a computerbased tool called Bild-IT that supports integrated building design. The tool will link an architectural CAD system, a computational fluid dynamics (CFD) program and the building energy simulation program EnergyPlus, which is currently being developed by the U.S. Department of Energy. The structure of a prototype version of the tool is shown in Figure 1. Standard methods of exchanging design information within the tool and with other software tools will be developed, based on the International Alliance for Interoperability's Industry Foundation Classes, in order to provide an open, interoperable environment for equipment selection and HVAC system analysis. The other partners are the Canadian branch of AEA Technology, a UK-based CFD developer, the Halton Group, a Finnish manufacturer of HVAC equipment, and Olof Granlund, a Finnish building services consulting firm. The work is being supported by the U.S. Department of Energy and the Finnish research agency TEKES.

Structure of the Bild-IT: links an architectural CAD system, a computational fluid dynamics (CFD) program and the building energy simulation program EnergyPlus

Figure 1. Architecture of the integrated design tool.

The first phase of development will concentrate on understanding the requirements for tools to support the integrated design of commercial buildings and demonstrating a prototype tool to the industry. Successive phases of the project will involve developing and implementing the tool for specific applications. As an example, in the food service industry, this software package will permit the user to make a floor plan, define food preparation requirements and then equip a kitchen according to manufacturers' specifications. With this information, the designer will then perform an energy analysis on the building envelope and HVAC system performance, use an CFD tool to resolve indoor air quality/comfort/control issues, compare different equipment package performance and make easy-to-understand presentations on results to both building owners and architects.

This tool is intended to accelerate the pre-design and design phases in building projects and to improve communication between key players from various disciplines. It will provide the comprehensive computational capabilities required to address complex IAQ, comfort, energy conservation and productivity issues. This project will make advanced technology that is already widely used in other industries available to the HVAC industry.

In order to enhance the capabilities of the tool, the development team is collaborating with MIT-School of Architecture, Fisher Consultants, and the International Facility Manager's Association. Together, this group provides the wide distribution of complementary skills and expertise necessary to achieve the goal of an integrated design tool. Throughout the project, industry input will be solicited through a dialogue with the key players and feedback from product performance testing.

EETD's role is focussed on the use of standard methods to couple energy simulation programs such as EnergyPlus to CAD programs and to CFD programs. Automatic transfer of geometrical and other information from CAD systems is expected to overcome one of the main barriers to the use of simulation in building design, namely the time-consuming and error-prone process of entering the necessary input data. This automatic transfer requires the adoption of a standard way of describing buildings and building systems, which requires the definition of data models and the development of interfaces to simulation and other analysis programs that support these data models. EETD is currently developing an interface for EnergyPlus that will allow it to read files from leading CAD programs that are compatible with the Industry Foundation Classes.

EETD is also working on methods of coupling EnergyPlus to CFD programs, in collaboration with MIT. This will allow the simulation of systems in which the operation of HVAC equipment and the heat flow through the building envelope influence the temperature and flow fields in the space, and vice versa. This coupling is complicated by the fact that CFD programs are much more demanding computationally than building energy simulation programs such as EnergyPlus. The coupled programs will be run at selected full and part load operating conditions and the results characterized in some way, possibly by means of a simplified model, for use in simulating the long term system performance using EnergyPlus on its own.

— Philip Haves

For more information, contact:

  • Philip Haves
  • (510) 486-6512; fax (510) 486-4089

This research is sponsored by the U.S. Department of Energy, Office of Building Technologies, State and Community Programs.

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