Should You Turn Off Your Air Conditioner When You Leave Home?

Updated: Oct. 06, 2023

A recent study has the answer, and it's more complicated that a simple "yes" or "no." It depends on several factors, including what kind of air conditioner you have.

Summer may be coming to an end, but many parts of the country will still need air conditioning well into the fall. Mindful of utility bills, some of you may be wondering, “What’s the most efficient way to use my air conditioning?”

Is it cheaper to leave air conditioner on all day?

Two professors and one Ph.D student at the University of Colorado, all engineers, tried to determine whether shutting off your air conditioning during the day when you’re not home actually saves money. According to their study, it depends on how much energy it takes to remove heat from your home.

Multiple factors come into play, like how well your home is insulated, your climate and what kind of AC unit you have. The better insulated your home, the less heat will enter during the day. This will reduce the load on your AC. Likewise, humidity and your system type also have an impact.

The researchers looked at two climates, three systems and three cooling cycles. They also standardized the time of day, making sure to include the hottest part. Accounting for various experiences helped them address the question: Should you leave your air conditioner on when you leave home?

Curiously, the most efficient air conditioning systems did not always yield the highest energy savings. And different factors can affect your specific situation. But generally, the answer is yes.

Overall, by leaving the AC off for eight hours, you’ll see energy savings no matter what type of system you have. Leaving it off for four hours yielded mixed results. Depending on the humidity and the system, it could result in minor energy savings, or take a little more energy than running it all day.

One thing the study didn’t account for was the cleanliness of the system. A dirty air conditioner won’t cool as efficiently. Don’t forget to clean your unit regularly to keep it functioning well.

How often should ac turn on and off?

The frequency with which your air conditioning system turns on and off depends largely on the weather, the temperature you’ve set for your home, and the efficiency of your system. However, during a typical summer day, a properly functioning central AC unit should cycle on and off every 15 to 20 minutes. Each cooling cycle should last for around 10 to 15 minutes.

Keep in mind that this is just a general guideline. There could be instances where the system will cycle more frequently, such as on extremely hot days when your AC needs to work harder to maintain your set temperature.

If your AC unit is constantly turning on and off in quick successions (a process known as short cycling), this could indicate a problem that needs to be addressed. Short cycling can be caused by several issues including an oversized AC unit, a clogged filter, low refrigerant, or a malfunctioning thermostat.

How to turn off air conditioner?

Turning off an air conditioner may differ slightly depending on the type of the system (window, central, or split AC), but generally, you can follow these steps:

  1. Thermostat Method:
    • Locate the thermostat on your wall that controls the temperature of your home.
    • Look for an “off” setting or a power icon. Most thermostats have a switch or button that allows you to turn off the system.
    • Move the switch or press the button to the “off” position. The air conditioning system should then stop running.
  2. Breaker Box Method:
    • Find your home’s breaker box. It’s usually located in a utility room, basement, garage, or outside.
    • Look for the breaker that controls your air conditioning unit. It should be labeled “AC,” “HVAC,” or something similar.
    • Switch the breaker to the “off” position. This will cut power to the air conditioning unit, effectively turning it off.
  3. For a Window AC:
    • You can simply press the power button on the unit or remote control to turn it off.

Remember, if you are going to turn off the AC unit for an extended period (like over winter), you may want to consider having a professional service it before you shut it down to ensure it is in good condition for the next use.

Note: Always consult the manual provided by the manufacturer for accurate information on how to operate and maintain your specific AC unit.