To keep the thermostat steady, the walls and ceilings contain four to six inches of insulation, including a rigid plastic foam called polyisocyanurate (for sources, go to pima.org). That is more than the thickness of the average home's insulation. I also use a ductless heat pump from Sanyo. This system runs on recycled refrigerant fluid that can be heated or cooled. All the light fixtures in the office take compact fluorescent bulbs, which use only a fraction of the wattage of incandescents, and high-efficiency LED bulbs.