In the recent controversy over the energy efficiency of LEED-rated buildings, most commentary placed blame on glass, users, the LEED credit system, ASHRAE, expectations, models, etc.  Few people mentioned simple design decisions. Take a look at this picture of 4250 Connecticut Avenue:

Designed by Hartman+Cox before they went traditional, it’s pretty unremarkable – except that it shows an uncommon sensitivity to site particulars. In the picture, you can see that about 3/4 of each wall is window space and mullions. Elsewhere on the building, however, less than half of the floor height is glass. Why? The above side faces North-Northwest, with the angled shape exposing most of the wall area to due north. The primary energy problems with glass walls cresults from solar heat gain and glare, but daylighting can also save a lot of energy. On the north side of the building, where there is rarely any direct light, the offices can get some daylight but not catch too much heat.