With a programmable thermostat, you can stay comfortable and save energy – without lifting a finger. A programmable thermostat adjusts the temperature according to a preset schedule, so in the summer, your house uses less energy during the day while you're at work, yet is cool when you get home.

Some thermostats allow you to set different schedules for each day, while others offer programming for weekdays and weekends. Heat pumps need programmable thermostats specifically designed for them.

According to the U.S. Department of Energy, you can reduce your annual heating and cooling expenses by 5 to 15 percent by turning your thermostat down or up at least 8° F for at least eight hours a day. Here's an example of how you could set your programmable thermostat to save during the week:

Here are some tips for the most efficient use of your programmable thermostat:

• Once the settings on your thermostat are working for you, leave the thermostat alone. If you get home early, just change the temperature and the thermostat will go back to its regular setting at the next period. Only use the "Vacation" or "Hold" setting when you're planning to be away for an extended period. If you use it to override the programming for a short period of time, the odds are you'll forget to switch back.
• Change the batteries at least once a year. Most thermostats run on low-voltage power with a battery backup, but if the batteries are dead and your power goes out, your thermostat will lose its programming.
• Don't forget to check your thermostat regularly. Some thermostats have indicators that show heating and cooling system problems and when it's time to change filters or batteries. If you have a heat pump, one indication of a problem is if the "Emergency" heat stays on for an extended period of time.
• Setting the energy saving temperature for at least eight hours is most effective.
• Use your programmable thermostat effectively and you'll save energy painlessly.