There's a common belief that you can save energy by leaving your thermostat at a constant temperature rather than turning it up (in the summer) or down (in the winter) when a comfortable interior temperature is unnecessary. This little article is my attempt to set the record straight on that.
During warm or hot weather, setting your air-conditioning thermostat higher (or off) while you're away saves energy versus leaving the thermostat set at a constant temperature. During cool or cold weather, the same is true if you set your thermostat lower when heat isn't needed because you're asleep or away.
Save Energy and Equipment Wear
Leaving an air conditioning thermostat set to a constant, comfortably-low temperature when you're asleep or away causes your air conditioner to work more (longer total time) and harder (because running continuously for a certain amount of time causes less wear than starting and stopping, even if it runs for the same total time).
The same is true in Winter, of course, with one possible exception. Leaving your heater or furnace set unnecessarily warm while you're away is wasteful and wears out your heater/furnace prematurely.
The exception is for heat pump furnaces, but not all of them. Some heat pumps use electric resistance heat to quickly raise the indoor temperature (or when temperature outside drops too low for a heat pump to be effective). When the heating element turns on it will use extra energy. This saves wear and tear on your heat pump unit, but sometimes it uses enough extra energy to offset what you would have saved otherwise.
Automate The Process: Set-back Thermostats
Consider installing a programmable thermostat if you don't have one already. They're inexpensive and they conserve enough energy to recover their expense in a short time.
If you have a heat pump there are models especially designed for heat pumps. They avoid using the supplemental electric-resistance heat feature by warming the interior temperature more gradually.
References
- Thermostats | Department of Energy
- You can save money on your heating and cooling bills by simply resetting your thermostat when you are asleep or away from home. You can do this automatically without sacrificing comfort by installing an automatic setback or programmable thermostat.
- How to Save Money On Energy and Stay Cool This Summer: Organic Gardening
- A common myth about the way air conditioners work may be wasting your money and contributing to global warming.
- If You Think Thermostat Setbacks Don't Save Energy, You're Wrong!
- Recently I ran a guest post here in the Energy Vanguard Blog by Ted Kidd, [...] Two simple and definitive reasons stand in his way: Physics and studies of energy savings from thermostat setbacks. Let's take a look at each of them.
- Energy Conservation Myths | Campus Operations
- Myth #2: Keeping your thermostat at the same temperature day and night uses less energy than turning it down at night and heating your room up again in the morning. Truth: It takes less energy to warm up a cold room in the morning than it does to maintain a constant temperature throughout the night.
- Take control of your home's energy use with programmable thermostats | U.S. Green Building Council
- Programmable thermostats help minimize energy consumption by making sure your home's heating and cooling system is working hard only when it absolutely needs to.
- Winter Time Energy Saving Tips
- Install a programmable thermostat. If you have a heat pump, select a model designed for heat pumps. Set-back thermostats can save up to 15 percent on energy costs.