Upgrading lighting fixtures to florescent bulbs offers the greatest rate of return. The Home Energy Saver institute estimates that changing all the bulbs in a house would cost about $200 and would save $80 per year. This investment would take 2.5 years to pay itself off, lending to a 41% rate of return. Sealing ducts is estimated to cost about $250 but could save $95 per year, also a 41% rate of return. Energy Star branded appliances such as refrigerators, heat pumps, washing machines, dishwashers, and programmable thermostats will all pay themselves off in less than 6 years and can offer a rate of return between 18-37%.
