The Autodesk® Green Building Studio® web-based energy analysis service can help architects and designers perform whole building analysis, optimize energy efficiency, and work toward carbon neutrality earlier in the design process. With faster, more accurate energy analysis of building design proposals, architects and designers can work with sustainability in mind earlier in the process, plan proactively, and build better.
The best explanation for this program is are the videos on Autodesk's Website: See them here.
Very cool program. Autodesk offers a sixty day free trial for students that are part of the Autodesk Student Community.