Google SketchUp 7 + OpenStudio plug-in for EnergyPlus
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OpenStudio
The U.S. Department of Energy (DOE) released OpenStudio, a free energy design plugin that works seamlessly within the Google SketchUp 3D drawing environment. The plugin simplifies use of DOE's award-winning EnergyPlus simulation software, which identifies potential energy savings by modeling lighting, heating, cooling, ventilating, water, and other building energy flows.

OpenStudio makes it easy to create and edit the building geometry in EnergyPlus input files using the Google SketchUp tools. With the native SketchUp 3D capabilities, users can view the geometry from any vantage point, apply different rendering styles and architectural finish details, and perform accurate shadowing studies. OpenStudio also allows users to launch EnergyPlus simulations and view the results without leaving SketchUp.

http://apps1.eere.energy.gov/buildings/energyplus/openstudio.cfm