If you draw walls in the wrong order you can end up in a situation where Revit interrupts south facing glass in a north facing wall. I'm sure you're all aware that glass orientation has a considerable impact on the building loads.
Steps to reproduce:
1. Open a new file in Revit MEP 2011 x64 w/ web update 2 service pack
2. Draw a rectangle room with 4 generic 8” walls 20’ tall.
3. Draw 10’ tall curtain wall into the north wall FROM LEFT TO RIGHT, in other words start in the northwest corner of the building and draw to the northeast corner.
4. Cut the curtain wall out of the generic 8” wall.
5. Place a space in the room and change the upper limit offset to 12’.
6. Open gbxml export and change export complexity to Complex and click Save Settings.
7. Open Heating and Cooling Loads and click Analytical Surfaces. Notice the generic 8” wall to the north is considered a north wall, however the curtain wall cut out of the generic 8” wall to the north is considered south facing glass.
8. Change the Report Type to Detailed and click calculate. Scroll down to the space summary and notice there is a huge south window load although there is no south facing glass. Notice there is no north window load although there is north facing glass.
I contacted my reseller and Autodesk a couple times and neither responded, so just beware that using Revit's load calculator is still in need of refinement.