What if architects could make CAD models of their buildings that would automatically tell them how much energy structures would use at what times of day and year; where sunlight streams into rooms, and how bright it is; and how much air conditioning they need? Well, they can, within limits.
Simulation and modeling is one of the keys to a sustainable future. Otherwise progress can only happen by trial and error, which on the architectural scale is a horribly slow process. Simulating a building's energy use is a hard problem, requiring not only a model of the building and the materials that make it up (including insulation, windows, foundation, etc.) but also a model of the building's location, with the path of the sun through the year and weather data that is accurate and detailed, including humidity, wind, simple daytime-nighttime temperatures, and a host of other information. And of course, the challenges are compounded when you want to make a simulation that will work in any part of the world.
For almost fifteen years now, researchers like those at Lawrence Berkeley National Lab have been working on green building simulation systems. They are far more accurate and easy to use than they were, but the pace of change has not been fast--in fact, their state-of-the-art analysis tool, EnergyPlus, is still written in Fortran, and has no graphical interface. However, several other programs have been written that create interfaces to EnergyPlus. LBL's software is open-source, and they have a great network of developers throughout the country, but the project has never gotten as much budget as it should. LBL also helped develop Radiance, a tool that quantitatively renders daylight in building models to provide not just pretty pictures but luminance numbers so you can determine how much artificial lighting you need in a room (or how much you need to change the room to eliminate the need for artificial light).
The leader of the building simulation industry now may be a relative newcomer, Square One research. their program Ecotect is a whole-building simulator that "combines an interactive building design interface and 3D modeller with a wide range of environmental analysis tools for a detailed assessment of solar, thermal, lighting, shadows & shading design, energy & building regulations, acoustics, air flow, cost & resource performance of buildings at any scale." (And don't worry, you don't have to use their CAD engine, you can import from AutoCAD.)
There are other tools out there, as well. IES's "virtual environment" software can act as a plugin to AutoCAD's Revit, calculating heating and cooling loads from within Revit. Green Building Studio has gotten a lot of press for their eponymous web-based program, which is one of the many interfaces to EnergyPlus (or the older DOE-2 analysis engine). It also helps suggest (read: advertises) materials from manufacturers; this got it dubbed "a Google for green building products" by C|Net, though they may not be familiar with Building Green's GreenSpec directory. Green Building Studio does appear to be a great tool, though, with helpful features like telling you how easy it would be to make your building carbon neutral. Architects at HOK have brief but good summaries of some programs on their blog. If you really want to dive into the field, the DOE's Energy Efficiency and Renewable Energy division has an enormous directory of building analysis software, with scores of programs covering everything from whole-building analysis to fenestration, life-cycle analysis, hydronic heating, and multi-building analysis. Perhaps Google's SketchUp people should make an integrated analysis program. That would elevate SketchUp from a toy to an industry-leading tool, and would let the folks at Google.org claim a big impact--after all, the building industry is the single largest energy-user (and thus carbon emitter) in the world.
Simulating a building before it's built is only half the battle. Once the building exists and people are using it, it should be measured to check that it is performing as expected. This is called commissioning, and is crucial to the green building industry. Thousands of buildings around the world perform poorly without anyone knowing -- they just pay the energy bills and get on with their work. But when you monitor a building's performance, you can keep it in peak shape, like an Olympic athlete, to keep its occupants in comfort at minimal expense and environmental impact. Data from commissioning can also feed back into simulation programs, to make their models more accurate and complete.
Image courtesy HOK, from IES.
