Just as it doesn't make sense to let your car engine run all night long on the belief that this will use less fuel than turning it off at night and on in the morning, it doesn't make sense to let your home's heating or cooling system run continuously when no one is there. During the heating season, for instance, lowering your thermostat by ten degrees for eight hours at night can reduce your energy costs by as much as seven percent, with no sacrifice in comfort. A programmable themostat will ensure that your heating/cooling system runs less often during the day when the house is unoccupied, and less at night after everyone has gone to bed. They will also turn your heating or cooling system back on before you wake up or come home, so you may never notice a change (except when you get lower heating or cooling bills). See the ENERGY STAR Programmable Fact Sheet (pdf) for more information.
