Is It Better To Leave Your A/C On Or Turn It Off When You’re Not Home?

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My family recently left the house for the day, and my husband and I debated turning the air conditioning off or leaving it on while we were away.

We ended up leaving it on with the thought that the A/C wouldn’t have to work as hard to keep the house cool when we came home. From an energy-saving perspective, it would have been wisest to turn it off completely or, at least, raise the temperature while we were away.

“Air-conditioning systems run most efficiently when they are running at full speed,” Jennifer Thorne Amann, MES, buildings program director for the American Council for an Energy-Efficient Economy (ACEEE), recently told Rodale’s Organic Life. Rather than charging your A/C unit with performing a number of short cool-downs during the day, Amann said one big cool-down upon returning home will ultimately save more energy and better dehumidify your home to boot.

Now, if you live in a super-hot climate (like Arizona or Florida) or have pets at home, turning off your air conditioning may not be the best or wisest choice.

Other experts advise that using a programmable thermostat to bump up the temperature (to around 85 degrees F) when you are away, then gradually cooling the house down before you arrive home is a smart strategy for maximum energy savings.

The ACEEE estimates that air conditioners use three to five percent less energy for every degree you raise the thermostat. The sweet spot for energy savings seems to be around 78 degrees F.

So it looks like the consensus is to either turn off the A/C completely (as long you aren’t in a very hot climate) or using a programmable thermostat to set the temperature higher while away.

Other simple ways to save energy and money while keeping cool include:

1. Replace or clean A/C filters on a monthly basis

According to “Dirty air filters are the No. 1 cause of air conditioning breakdowns and they cost about 7 percent more in energy costs (or about $45 a year) in hot climates.”

2. Use a ceiling fan in conjunction with your A/C

While a ceiling fan won’t lower the temperature of a room, feeling the air move across your skin will help you feel cooler. Just be sure to turn the fan off when you leave a room to avoid wasting energy.

3. Create a draft

If it’s cool enough, try turning off the A/C and creating “crosswinds” across your house instead. Open windows on opposite sides of the house just enough to create a draft. Avoid opening them too much, as the breeze won’t pull through if the window is opened all the way. Rodale’s Organic Life suggests experimenting with windows on different levels of your house to see which create the best crosswind.

4. Upgrade your air conditioner or thermostat

Upgrading to a newer, energy-efficient air conditioning unit can help keep your home cooler and cut costs at the same time. Likewise, investing in a programmable thermostat can allow you to set different temperatures throughout the day. “Smart” thermostats like the Nest retail for around $220, and work to adjust temperatures automatically, can be adjusted remotely from your phone and will tell you when you hit a temperature that saves energy. Pretty smart, indeed!