You can save substantially on your heating and cooling costs by using a programmable thermostat—but how do you know if you’re setting it correctly?
Jude Canchola, an energy advisor with Owen Electric, offers these tips for making sure you’re getting the most efficiency from your thermostat as possible:
1. First, be aware of your heating and cooling system type, as the proper means of adjusting the thermostat differs for electric and gas versus geothermal.
If you have a geothermal system, note that you do NOT want to program large temperature fluctuations on a day-to-day basis while you’re at work or outside the home.
“For a geothermal system, in terms of everyday living, you’re only going to want to do very incremental changes, no more than one degree at a time,” says Canchola. Otherwise, if you bump the heat up 3 degrees or more in the winter, for example, your geothermal system—which is a type of heat pump—will engage the auxiliary heat, which is not nearly as efficient to run.
2. If you are using a gas or electric furnace system, however, Canchola recommends setting the temperature lower by 5-8 degrees in the winter and higher by 5-8 degrees in the summer, during the hours that you are at work or away from home each day.
3. How to program to achieve desired temperature when you return home: For conventional forced-air gas or electric HVAC units, program your thermostat to adjust to the desired temperature 30 minutes before you arrive home. (Making a 5-8 degree temperature adjustment in one step is acceptable for these types of systems.)
For electric heat pump systems, you’ll want to schedule this rise in heat or rise in AC gradually, so as not to engage the auxiliary heat/AC. For example, if your ideal home temperature is 70 degrees, but you drop back to 65 degrees while you’re at work, then you’ll want to program your thermostat to do a gradual rise, 1-2 degrees at a time, in a schedule something like this:
Goal: to have home temperature return to 70 degrees by 5 p.m.
3:30, bump from 65-67 degrees
4:30, bump from 67-69 degrees
5:00, bump from 69-70 degrees
Note that if you purchase a programmable thermostat specifically designed to accommodate a heat pump system—which most energy advisors recommend—you won’t need to go through the steps of manually setting these small, incremental temperature changes in order to avoid setting off your auxiliary heat or AC. Once programmed to a desired start and end temperature, heat pump compatible programmable thermostats will automatically adjust the temperature in your home in small increments, without requiring you to schedule the incremental changes by hand.