The ups and downs of thermostats
You can tell winter has arrived when customers start calling about thermostats. They want to know whether they’ll really save energy by turning their thermostats down at night. Some have the erroneous belief that because an electric furnace runs longer in the morning to bring a home back to a comfortable temperature, it costs more to recover from a nighttime setback than it saves.
Here’s the skinny: You almost always save by turning down your thermostat, regardless of how long you sleep or are away from home. A typical furnace runs 20 minutes per hour to heat your home. If you set the thermostat to 60 degrees before you go to bed and leave it there for eight hours, the furnace will not need to run 20 minutes each hour. The furnace may have to run some during the night, depending on how cold it is outside, but it certainly won’t be 20 minutes per hour.
According to the U.S. Department of Energy, you can save energy in the winter by setting the thermostat to 68°F while you’re awake and setting it lower while you’re asleep or away from home. By turning your thermostat back 10°-15° for eight hours, you can save about 5 percent to 15 percent a year on your heating bill—a savings of as much as 1 percent for each degree if the setback period is eight hours long.
This doesn’t apply if you have a heat pump. In its cooling mode, a heat pump operates like an air conditioner, so turning up the thermostat (either manually or with a programmable thermostat) will save energy and money. But when a heat pump is in its heating mode, setting back its thermostat can cause the unit to operate inefficiently, thereby canceling out any savings achieved by lowering the temperature setting. Maintaining a moderate setting is the most cost-effective practice.
Bottom line: If you have a heat pump, turn the heat down just a couple degrees when you go to bed at night. If you don’t have a heat pump, turn the heat down to about 60°.
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