A green roof helps a lot with that. The only thing I want to change about ours is that I'd like to take the carpet out. The people who built it were retired, so I think they decided they were too old to have cold feet in the winter and the living room, hallway, dining room and bedrooms are carpeted. Well, covering up the concrete floor takes away a LOT of the benefit of the passive solar design. It should heat up in the winter, and release that heat all night long, then in the summer the cool of the earth should keep the temps down. It still is very efficient. Even with the carpeting, our house is total electric, and we spend a bit over a hundred a month average on our electric bill, but it irks me knowing that it could be a lot lower. One of these years we'll do stained, polished concrete floors.
Traci