Officials in the Federal Home Energy Efficiency program found that a programmable thermostat paid for itself in six months. The best way to use a programmable thermostat is to set it and leave it. Calculate the temperatures you’re comfortable at while at home: the lowest temperature in winter, the highest in summer. Then, during winter, lower the temperature at night and periods when you’re out of the house. During the summer, raise the temperature when you’re not home. According the American Society of Heating, Refrigerating, & Air-Conditioning Engineers, if you lower the temperature one degree Fahrenheit at night, you’ll save one percent of energy costs. So lowering your nighttime temperature ten degrees will save ten percent off your heating bill. Not bad.