Integrated Environmental Solutions Limited has released a free energy modeling plug-in for Google Sketchup. This looks promising.

Other free energy modeling with a 3-D interface is eQuest and a beta Google Sketchup interface for EnergyPlus.

Of course, the idea of the free back end and plugin is to get you hooked enough to buy the expensive modeling packages. How expensive? I don’t know, you have to call or write for details. Usually this means “If you have to ask, it’s too expensive”. But if the tools are worthwhile I’m not that concerned about the price. Both Carrier and Trane publish prices for their hourly building simulation software, which can result in some sticker shock. But at least the price is known.