Programmable thermostats can save up to $160 a year in energy costs. Match thermostat settings to your schedule: cold when you’re away and warm when you’re at home. In winter, set the thermostat to 68 degrees during the day (lower at night when you’re snug in bed). By turning your thermostat down 10 to 15 degrees for at least 8 hours, you can shave 5-15% from your heating costs.
Source: TogetherWeSave.com, U.S. Department of Energy