I once had a solar home. It was the most comfortable home I've ever lived in. It used a combination of passive solar energy and earth berming to stay comfortable all year round without either a furnace or an air conditioner. And this was in southern New Mexico. This was way back in the 80s, when saving energy and reducing your carbon footprint wasn't exactly front page news. If you are looking for energy saving ideas, there are plenty to be found in the 20 homes that were in competition in this year's solar decathlon.