The Science of Sustainability

Top Energy (and Money) Saving Thermostat Tactics

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The CCHT twin house facility in Ottawa, CanadaTwo weeks ago in this blog I tried to answer the question, Do compact fluorescent lights (CFLs) save energy overall? Even though CFLs contribute a lot less heat to a house in the winter, compared to incandescents, CFLs still save energy overall, even in places like Anchorage, Alaska. Thanks to the folks at the Canada Centre for Housing Technology (CCHT) who did the research to answer that question.

The Department of Energy, the Environmental Protection Agency, and others recommend that we set our thermostats at 68°F in the winter and 78°F in the summer. Some people are comfortable at home with these temperatures and some or not. So how can we save energy and still be comfortable?

Besides recommending that people replace their incandescent bulbs with CFLs, we at Home Energy also encourage people to turn their thermostats down when they are away from home during the winter, and to set them up when they are away from home in the summer. Both actions are supposed to save energy. But do they? It's not really that clear. For example, if you set your thermostat at 60°F before you leave for work in the morning, and then set it at 68°F in the afternoon when you get back, does your furnace use more energy raising the temperature of your house from 60°F to 68°F, than it saves by having the temperature at 60°F all day?

Once again the Canadians have come up with an answer. Marianne Armstrong and her colleagues at CCHT used the twin house research facility to show that thermostat set backs in the winter and thermostat set forwards in the summer really do save energy.

In the research house where they set the thermostat back to 64°F at night and during work hours, from 72°F, it saved more than 10% on heating costs compared to the house that was set at 77°F all day and night. A 61°F setback saved more than 13%.

In the summer, a set forward to 77°F at night and during work hours from 72°F saved 11% on cooling costs. Now for the big winner: Setting the thermostat up to 75°F all day and all night saved 23% of cooling costs compared to the house set at 72°F. That's a savings of about 8% for every degree adjustment.

If you lower your thermostat a few degrees when you are away from home this winter, or when you are asleep, you'll save energy and money. If you set your thermostat up a few degrees when you are away from home or asleep this Indian Summer, you'll save energy and money. And you won't be uncomfortable.

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Category: Astronomy, Energy, Engineering, Environment, Health, Partners, Physics, Sustainable Health

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Jim Gunshinan

About the Author ()

Jim Gunshinan is the editor of Home Energy, the magazine of sustainable home building and renovation.
  • John

    What about programmable thermostats? I read they can save 10% or so. I found another site which gave some ways to save electricity, http://www.waystosaveelectricity.com but looking for more good advice. Also, what can we do to get help after we use methods to save? Such as gov't aid? Thanks

  • http://www.homeenergy.org Jim Gunshinan

    Hi John,

    Programmable thermostats work, if people use them. The EPA almost canceled its Energy Star labeling for programmable thermostats, because of overwhelming evidence that people weren't using them. EPA decided not to cancel the labeling program, but to focus more on educating homeowners how to use them. And the thermostat manufacturer's are figuring out ways to make programmable thermostats more user friendly. Programable thermostats work, if you use them.

    Other things you can do to save energy this winter?

    You can air seal your attic and add insulation. Congress, along with the Big Bailout for Wall Street, continued some tax incentives for homeowners who do energy saving retrofits at home. Go to the Web site for the Residential Energy Services Network (RESNET) to find about about the tax incentives and other home performance information that will help you save energy and money.

  • betty

    i have a small hourse 1100sq ft. we have two bedrooms, kitchen, bath, livingroom and dining room that are airconditioned and a single thermostat controlling the ac. the termostat is located in the dining room. one bedroom door leads off the dining room. if one window in that particular bedroom has a window that is left open for two,three or four hours a day, can you estimate what additional cost (electricity bill) will be to my family. thank you so much for an answer to this question asap.

  • http://homeenergy.org Jim Gunshinan

    I can't say how much you would waste exactly. I just know that if you are air-conditioning a room with the windows open you are throwing your money away. I don't know if it is 10% of your energy or more, but it is wasted.

    If for whatever reason you need to have the windows open in that room, than keep the door closed and close the register—in other words, separate that room from the rest of the house.

    Hope this helps!

  • Pulamica

    I don't usualy comment, but I have to say, this post is really great. Could you send me some more details?

  • Jim Gunshinan

    Hi Pulamica,

    The Energy Star Web site is a great source of information on thermostats and other energy-related topics (www.energystar.gov). If you want to have a free energy audit of your house, you can do it online at the DOE Home Energy Saver Web site (http://hes.lbl.gov/). Hope this helps!