Brad Hartnagle has posted a 'how to' on his Blog Green Revit for exporting Revit information to Green Building Studio. Green Building Studio will give you some great preliminary energy analysis numbers, all for registering on their website.
This just happens to be the same process you would use to export heating and cooling information to Trace 700. Exporting to Trace will of course give you much more valuable information.
Michael Dakan wrote a great gbxml article in Cadalyst if you would like more information on just what the heck is gbxml and what can you expect to get out of using it with ABS and Revit Systems.