You can save as much as 10% a year on your heating and cooling bills by simply turning your thermostat back 10% to 15% for 8 hours. You can do this automatically by installing an automatic setback or programmable thermostat.
Using a programmable thermostat, you can adjust the times you turn on the heating or air-conditioning according to a preset schedule. As a result, the equipment doesn't operate as much when you are asleep or when the house, or a part of it, is not occupied. Programmable thermostats can store and repeat multiple daily settings (six or more temperature settings a day) that you can manually override without affecting the rest of the daily or weekly program. When shopping for a programmable thermostat, be sure to look for the ENERGY STAR label.