Energy Saving Ideas

Lower Energy Bills with a Set-back Thermostat

Myths about Setbacks | Types and Features | More Information

According to the U.S. Department of Energy, turning down the thermostat 8 degrees F for eight hours a day will save 8-10 percent on home heating costs. An easy way to take advantage of these savings is to lower the thermostat temperature while away from home or sleeping.

Any thermostat, even a digital electronic model, is essentially an on/off switch for the heating system. When it senses the room temperature has dropped, it signals the furnace to provide heat until the temperature rises to the selected temperature.

Some older thermostats may be inefficient, allowing temperature variations of up to 5 degrees F. Inefficient thermostats cause the furnace to cycle on/off frequently, wasting a great deal of energy. If it's time for a replacement, consider installing an automatic "setback" or programmable thermostat. While you might forget to turn down the heat before you leave for work in the morning, a programmable thermostat won't.

Programmable thermostats help save energy because they store and repeat multiple daily temperature settings, which you can manually override without affecting the rest of the daily or weekly program. Many models can even store six or more temperature settings a day. New programmable thermostats are also usually highly accurate—within .5 degrees F of the actual setting.

On a winter night, for example, when the house doesn't need to be heated to 72 degrees F, simply setting back the thermostat can save money. It is simple to program the thermostat to 65 degrees F from 11 p.m. to 5 a.m., and then bring it back to 72 degrees F so it is nice and warm to wake up to. In a well insulated home the temperature change may go unnoticed.

Myths about Setbacks
A common misconception associated with programmable thermostats is that a furnace works harder than normal to warm the home back to a comfortable temperature after the thermostat has been set back, resulting in little or no savings. Years of research and numerous studies have shown that the fuel required to reheat a home is roughly equal to the fuel saved as the home drops to the lower temperature. This will result in fuel savings between the times the temperature stabilizes at the lower level and the next time heat is needed. The longer the house remains at the lower temperature, the more energy saved.

Another misconception is that the higher the thermostat is raised, the more heat the furnace will put out or the faster the house will warm up. Furnaces put out the same amount of heat no matter how high the thermostat is set. The difference is the length of time it must stay on to reach the set temperature. In the winter, a significant amount of money can be saved by setting back the thermostat for as little as four hours per day. The savings can be attributed to a building's heat loss in the winter, which depends greatly on the difference between the inside and outside temperatures. By turning the thermostat back 15 degrees F for eight hours; it is possible to save 5-15 percent a year on the heating bill.

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Types and Features
There are a variety of setback thermostats, which range in fuction and price. The most versatile set back thermostats allow different comfort and setback-periods for each day of the week. It is possible to override the settings at any time in case heating needs change.

When purchasing a setback thermostat, consider a model with a backup battery pack to eliminate the need to reprogram the clock in case of power failure. Programmable thermostats are available from a heating or cooling contractor and at some home stores. Check to see if your local retailer carries Energy Star® labeled programmable thermostats, which are designed for easy use and can significantly improve heating and cooling efficiency. The Environmental Protection Agency estimates that Energy Star® labeled programmable thermostats, when used properly, can save consumers 20-30 percent on heating and cooling bills.

CAUTION
Before removing or replacing a thermostat, determine the type of power supplied to it. Power must be turned off first to avoid injury. Deadly high voltage conditions could exist. Call your heating and cooling contractor to install a programmable thermostat to ensure it’s done safely.

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More Information and Additional Resources
Additional information on home energy savings can be found in the Home Series booklet available on the Iowa Energy Center’s web site or by calling (515) 294-8819.

Some information in this press release was adapted from the U.S. Environmental Protection Agency’s web site www.epa.gov, the Air Conditioning Contractors of America’s web site www.acca-ncc.org/thermost.htm and from www.warmair.net/html/thermostats.htm.

The Iowa Energy Center is a nonprofit organization dedicated to improving Iowa’s energy efficiency and the use of renewable fuels.

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