• Simulating and analyzing the daylighting aspects of a buildings design are just two of Ecotects capabilities.
    Simulating and analyzing the daylighting aspects of a buildings design are just two of Ecotect's capabilities.

The statistics have been quoted time and time again since they were first released by the U.S. Energy Information Administration in 2005, but they still have the power to shock: In the U.S., buildings account for 40 percent of total energy consumption and 72 percent of total electricity consumption. To bring these numbers down to a level compatible with a sustainable future, architects need to make their buildings perform better when it comes to energy efficiency.

A number of energy-modeling software packages on the market offer various tools to forecast a building’s energy use and predict its performance. Running a schematic design through a rough simulation helps identify energy-saving strategies in building massing, façade components, and orientation. It can also help analyze overall lighting and cooling loads, a boon for clients trying to reduce energy costs.

Energy-modeling software runs the gamut, from quick-and-dirty applications to specialized, data-driven platforms that only an engineer can love, which makes finding the right combination of analysis tools for a given project tricky. Steve Sanderson, a founding partner of Case Design, a New York–based technology consultancy, and Buro Happold’s Matthew Herman helped Architect steer through the offerings.

Free and Fast

EQUEST is an energy simulation tool available for free download (doe2.com/equest). It’s made available and supported as part of the Energy Design Resources program, which is funded by California utility customers. The PC-only program, upgraded to version 3.64 in August, is geared toward compliance modeling for ASHRAE Standard 90.1 (Appendix G), the code that corresponds to LEED certification requirements. Although the software purports to be intuitive and has some tools for inputting and exporting designs, eQUEST is really focused on getting people to build the model in the program itself. “The first thing that will turn an architect away is learning a new software,” Sanderson cautions.

The U.S. Department of Energy offers its EnergyPlus analysis and thermal-load simulation program (version 5.0)—which models heating, cooling, lighting, and ventilation—as a free download for Windows, Mac, and Linux platforms (apps1.eere.energy.gov/buildings/energyplus). The EnergyPlus OpenStudio plug-in for Google SketchUp makes it possible to edit a building’s geometry and launch simulations while in the drawing software. Additionally, the cloud-based EnergyPlus Example File Generator produces a rough analysis based on a few parameters, including building activity, location, and basic form.

Software maker and green consultancy Integrated Environmental Solutions (IES) offers VE-Ware (version 6.1), a free energy- and carbon-usage software for PCs and Macs that works in conjunction with SketchUp and Autodesk’s Revit (iesve.com/Software/VE-Ware). The “VE” stands for “Virtual Environment,” and the program models performance and efficiency. Unlike eQUEST, however, for which the building model has to be within the program, with VE-Ware, users can assign data such as building or room types and HVAC systems within SketchUp and then import the data, rather than the model, into VE-Ware. The full VE-Ware suite, IES VE-Pro (price depends on configuration), combines VE-Ware’s ease of use with the level of quantitative analysis required for high-performance engineering.

  • Ecotect, from Autodesk, can also model a buildings effects on the surrounding environment.
    Ecotect, from Autodesk, can also model a building's effects on the surrounding environment.

Good Graphics

“Ecotect is accessible and gratifying to new users because it gives you so much graphical output,” Sanderson points out. The software, Ecotect Analysis 2011, by Autodesk, offers a whole suite of tools for sustainable building design. These include energy analysis and thermal loads, but also daylighting, solar radiation, and solar position in relationship to the building. Autodesk acquired Ecotect in 2008, and the company’s Green Building Studio works in conjunction with Ecotect to support server-based analysis. Designed for PC platforms, it is $2,995 for a stand-alone license.

Engineering-performance calculations would require more-specific sun data, but Ecotect’s modeling is effective for rough comparisons between different design schemes. “It helps to visualize abstract phenomena,” Sanderson says, “and gives you an intuitive sense of how the sun tracks or how much direct sun a particular surface is receiving.”

Similarly, Graphisoft’s EcoDesigner for ArchiCAD provides users with an idea of their building’s energy performance early in the design process. Launched in April 2009, the software runs on PC and Mac platforms and costs $645 ($275 for ArchiCAD subscribers). Architects can enter the structure’s location, function, orientation, openings, and HVAC and M/E/P systems and get charted estimates in return. “Because the graphics are great for clients, these programs cater toward architects and designers,” Sanderson notes. “You can take the output and show it directly to a layperson.”

Supporting Multiple Systems

“Energy is just one of several factors we look at,” says Buro Happold’s Herman, offering a perspective into how engineers approach environmental modeling. “We think of energy as part of a much larger picture that includes thermal comfort, carbon dioxide emissions, and cost.”

  • Want to know how the mechanical and electrical systems in your building could affect temperature distribution throughout a space? Bentley Systems Hevacomp can tell you that.
    Want to know how the mechanical and electrical systems in your building could affect temperature distribution throughout a space? Bentley Systems Hevacomp can tell you that.

Software such as Bentley System’s Hevacomp and Trane’s Trace 700 is geared to the kind of specificity needed by engineers and consultants. Hevacomp runs on Windows 2000 and XP operating systems and offers integrated mechanical and electrical engineering packages; the full suite runs in the $5,000 range. Hevacomp’s energy analysis and performance tools are designed to support ISO, IEE, CIBSE, and ASHRAE standards, as well as LEED compliance in the U.S. Trane’s explorations into building analysis date back to 1974, and the company’s Trace 700 program can model complex, nuanced mechanical systems, accounting for sustainable design features such as under-floor air distribution, passive chilled beams, or thermal energy storage. A single license for Trace 700 begins at $1,995.

Unlike the graphic-friendly programs described earlier, both Hevacomp and Trace 700 produce data-driven outputs in the form of spreadsheets and quantitative logs. Interpreting the information requires engineering skill and experience. “[These programs] are about the quality of the data, not rainbow diagrams,” Sanderson says.