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Is It Better to Turn Off the A/C While You’re Away?


Have you ever wondered whether or not to turn off the A/C when you leave the house? While the answer to this question obviously depends on how hot it is outside, there are other factors to consider. Cooling systems use a good deal of electricity, and unless it’s excessively hot outside during the day, you generally can save money by turning off the A/C. At the very least, set or program the thermostat temperature eight to 10 degrees higher than your comfort level while you’re gone.

Factors that determine whether you should leave it running or turn it off altogether include:

  • Energy efficiency. If your home has ample attic insulation, efficient windows or window coverings, and low rates of air infiltration, it will resist heating up while you’re gone. Heat always travels to cooler temperatures, but when there’s enough thermal protection to slow the heat transfer, your home won’t get as hot.Single-pane windows have almost no insulating value, but those that are thermal or Energy Star certified will stop much of the heat transfer through the glass. Thermal drapes and solar window films can help inefficient windows. A home with minimal air leaks also will retain cooler temperatures longer.
  • The weather. When temperatures aren’t going to be excessively warm, it’s a good idea to turn off the A/C, since the heat buildup indoors will be minimal. However, if the weather will be scorching, turning the A/C off may not be a good idea if you have energy savings in mind, since the cooling appliance will have to run overtime to catch up. Anything higher than 83 degrees F inside may distress your pets.
  • Air conditioner capacity. If you notice that your cooling system runs in short cycles, it’s probably larger than your home needs. In this case, you’ll get better efficiency if you turn it off during the day. It will have to run longer to cool your home when you return, making it more efficient at both cooling and removing humidity. Short cycling drives up energy bills, increases wear, and leaves humidity behind. By increasing the cooling load, the A/C won’t short cycle.

For more information about whether you’d get more efficiency if you turn off the A/C or let it run at higher temperatures, please contact us at HVAC & Plumbing Unlimited Heating & Air Conditioning, serving homeowners in Fairfax, Loudoun and Prince William counties.

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HVAC Unlimited Inc.
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