Energy Analysis Earlier
In brief, the software works by serving as "translator" between design models and analytical ones. An architect creates a building model within Autodesk or Graphisoft, then either exports gbXML to Green Building Studio or runs GBS within the modeling software environment using a plug-in. GBS uses local building code assumptions, creates a file for input to DOE-2, and runs the analysis.
GBS then summarizes the results and returns a file that can be displayed in the Autodesk or Graphisoft modeling environment. The gbXML files and DOE-2 input files can also be input into engineering analysis systems such as eQUEST, EnergyPlus, or Trane Trace 700. An engineer can then expand the model, adding more detailed assumptions about building equipment and construction.
According to Jim McCray, chief operations officer of GeoPraxis, designers can use Green Building Studio in early schematic design to determine the siting of a building. He explains that the software will estimate the building's energy use, giving the user immediate feedback about siting variations even before the building is designed beyond a massing level.
McCray says: "They can see the building rotated and see if there are significant differences in usage by changing different factors, and play with the model to get that feedback at the earliest design stages. Up until now, designers have had to send the drawings out to specialty engineering analysis firms to get this kind of feedback."
GBS Put to the Test
The large architecture and engineering firm HOK has a major focus on sustainable design, and several HOK designs have been honored as "Top Ten Green Projects" by the AIA's Committee on the Environment.
Mario Guttman, HOK's firm-wide CAD director, is enthusiastic about the GBS Web service. His team has created a model of a project to test with GBS in parallel with the firm's implementation of Autodesk Architectural Desktop and other software.
"It's all experimental at this point," says Guttman. "We haven't used the data from the service in any of the decision making for the project yet. We're just demonstrating how it can work."
For Guttman, the appeal of GBS is to get quick feedback on design alternatives. "For many of our projects we intend to have a full energy analysis anyway, so that in itself is not necessarily of value. But being able to get that analysis done at a very early design stage and look at alternatives before we do the full analysis is very valuable."
Guttman continues: "The other thing I'm really interested in personally is demonstrating ways in which we can use a building model for different purposes. A lot of what we've been studying is whether or not we can use the same model for design visualization that we use for things like the energy analysis or producing working drawings, etc."
GBS in Practice
In theory, this sounds relatively simple, says Guttman, adding that while they are demonstrating that GBS integrates with ADT, "in real life people tend to build different models for different purposes." On their current project, a small laboratory with a sustainable focus, it is requiring some effort to demonstrate that disparate models can be integrated.
He explains that a model created strictly for design visualization is different from one created for energy analysis. For a design model, appearance is more important than true geometry. A model to be subjected to an energy analysis has to be more precise.
HOK's in-house mechanical engineers or outside consultants use DOE-2 and other complex systems for energy analysis, but typically architects do not do the energy analysis. "This is the first time we would expect an architect to do the analysis rather than an engineer," Guttman notes.
"We don't see Green Building Studio as a substitute for the energy consulting; we see it rather as an architect looking at design alternatives early on. Then they would begin to share the process with an engineer as it got more refined." The type of analysis that GBS offers is "definitely a simplified analysis of what you would get with an energy consultant."
Traditionally, sustainable design has been important to the firm, yet it has not overlapped much with CAD department efforts. Now both the engineering energy analysis and CAD departments are interested in these new options. HOK takes these beta tests with building information and energy analysis software very seriously.
Guttman confirms: "The whole business of building information modeling is central to our CAD strategy right now. I definitely see a convergence where we will in fact have models that we use for multiple purposes and I'm certain that we'll be using the Green Building Studio Site for other uses as well."
Currently, he says, although there has been a lot written about building information modeling, "the fact is we're all still learning about how to do it. At HOK, we're now beginning to actually use our models for analysis, more than just for looking at the building."
"And it's not totally there yet," Guttman admits, adding, "we're still having to work on structuring the model in order to make it useful for the energy analysis but have demonstrated it enough to be convinced that it will work."
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Susan Smith is the editor of AECCafe, an online news portal for the architecture, engineering, and construction industry, as well as GISCafe and GISWeekly, an online portal and weekly magazine for the geographic information systems industry. She has been writing about architecture and technology for over ten years and resides in Santa Fe, New Mexico.
Note: Artifice, Inc., publisher of ArchitectureWeek, had a strategic alliance with Geopraxis in 2000 through 2002 and contributed to the development of the Green Building Studio and the gbXML schema.