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Green Building Studio: Energy analysis made easy

November 01, 2005 |

With the development of software programs like DOE-2 and EnergyPlus, it's never been easier for Building Teams to evaluate potential energy saving measures for a building project.

However, preparing data that accurately represents the proposed building and its energy-efficient features is a costly, labor-intensive process. As a result, energy analysis is often postponed to a later point in the design process, which can limit the number of cost-effective options for boosting energy efficiency.

Supported with funding grants from the California Energy Commission, Sonoma, Calif.-based Green Building Studio (formerly GeoPraxis Inc.) has developed a free Web-based service that enables Building Teams to integrate whole building energy analysis into the early stages of the design process.

With Green Building Studio, architects and engineers can use their existing computer-aided design systems to communicate a project's building geometry to the GBS website, which conducts an energy analysis of the building design. The program enables the design team to look at the energy impact of early design decisions, compare alternatives, and share information more broadly with other team members.

The product is best suited for use in new construction and major renovation of commercial or residential buildings in the U.S.

Building energy model

The heart of the system is an open data format called Green Building XML that permits the exchange of data between 3-D CAD and energy simulation software.

Using 3-D CAD software from any number of vendors, including Autodesk, Bentley, and Graphisoft, designers construct their early building design model, and then use gbXML and some simple user inputs to export a building energy model.

The gbXML export from CAD feeds an energy model that is automatically developed through the use of regional building standards and codes, which enables the GBS system to make intelligent assumptions about items such as insulation and lighting levels. The resulting building description then goes through a DOE-2.2 hourly simulation using typical-year weather data for the building's location. The simulation generates estimates for annual energy consumption, costs, and a wide range of data on heating and cooling loads.

Designers can revise the CAD model and re-run a simulation to compare the energy impact of design options such as window types, wall insulation levels, building orientation, multi-level versus single-level designs, and other building geometry considerations that come up early in the design process.

The GBS analysis helps ensure that the basic building design meets local codes. For facilities in California, the system also performs an analysis using building equipment assumptions based on the Savings By Design program—a utility-run effort to improve building efficiency. This option can be used to compare a Title 24-compliant building and a high-efficiency alternative.

GBS also creates detailed input files for more-comprehensive energy analysis using DOE-2 and EnergyPlus. The files are created in minutes—a process that could take weeks using plan takeoff or engineering services. Using this capability can reduce the cost of preliminary and downstream building design by $5,000 to $10,000, according to the maker.

The program facilitates direct sharing of detailed project and building data with engineering firms, which can then run the information through detailed design software, use it to specify equipment, and share it with other parties such as bid preparers and manufacturers of building products.

Targeted product ads

To help fund the program's ongoing operation and development, Green Building Studio has integrated a highly targeted advertisement function into the software. Based on the parameters of the building project, the program recommends relevant product information as early in the process as the planning and schematic design stages. Using a building relevance filter, the system sends highly targeted building component ads (and paid ads) to the user's GBS Product Advisor screen. These advertisements are linked to building product libraries online, providing targeted advertising placement for product manufacturers and project-appropriate information for the design team.

Future program upgrades include the development of a "Design Alternatives" feature that will allow users to run parametric studies without entering a new CAD model for each variation. Other plans include adapting the system for use with existing buildings and adding the capability to analyze buildings internationally.

Most CAD systems are compatible with gbXML, including Autodesk Revit 6, 7, and 8; Autodesk Architectural Desktop 3.3, 2004, and 2005; Autodesk Building Systems 2004 and 2005; Graphisoft ArchiCAD 8.0, 8.2, and 9.0; and Bentley Architecture and HVAC. In addition, most HVAC manufacturers accept gbXML input directly into their energy analysis packages.

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