Is it better to turn off your AC when you aren’t home, or should you run it all day?

A home’s HVAC system is generally uses more electricity than any other appliance, so it’s no surprise that people want to turn it off as often as possible to save a bit during hot summer months. This has led to a long running debate: Is it better to turn off the system or to leave it running all day?



The “Working Harder” Myth

The first thing it’s important to note is that contrary to a popular myth, your system does not “work harder” to catch up if you turn it off. A homes AC system runs at the same speed all the time, so the only thing that might happen is it runs for a little longer to cool your home down to a normal temperature after being off in the middle of the day. So this means if you leave it running all day, it will frequently turn on and off in shorter bursts to keep the home cool. If you turn it off on your way out of the door, and on when you get home, it will have been off for hours, and might run for longer to reach your home’s set normal temperature.

Does Turning off the AC Save Money?

As stated above, the only thing that changes if you turn your AC off when you leave and on when you get home, is it will run for longer during the period when you get home. This is important to keep in mind, as some energy providers do charge a premium for high usage times like 5pm – 11pm. If you have a provider with this pricing method, and you are turning on your system to run during a peak pricing time, you could be costing yourself money in the long run. However, if your energy provider had a flat rate, or if the peak time charges are not wildly expensive, in almost all cases it should save you money to turn off your AC when you are not at home. (Be sure and check your rate plan before assuming anything.)

Is Turning the AC Off Bad for My HVAC System?

AC system replacements can be pricey, so it makes sense that people would worry that running the system continuously will “burn out the motors” or any other number of issues people tend to worry about. Fortunately, unless you are literally running your AC system nonstop all day and night, you shouldn’t have to worry about this. Running an air conditioning system for a couple of hours in the evening to cool your home will not put enough strain on your system to cause any major issues. In fact, may experts believe operating your system this way in beneficial for the machine. Since it actually runs for less time overall, you will put less wear and tear on the system. As long as it is well maintained, your HVAC system should be at its most stable when running at full speed. The more common breakdowns happen during start up or shut off, since these processes require more smaller moving parts.

So Should I Definitely Turn Off My AC When I Leave?

Unfortunately, it’s not that simple. Yes, you may see some savings by turning off your HVAC system, but cooling isn’t the only thing that happens when you run your AC. Your system also will remove humidity from your home, so if you leave the system off for extended periods, your home will get very humid inside. Mold and mildew will be more likely to start growing. You may notice papers around the house have wrinkled or maybe wood is beginning to warp. Also, the heat resulting from leaving your AC system off can be bad for your plants and pets.

Finding Balance: Turn Up, Not Off

The smartest solution may be to invest in a programmable thermostat. Giving yourself the ability to automatically move the thermostat between 75 and 85 degrees in the middle of the day will allow you to still cool your home to a comfortable temperature quickly when you get home, and prevent your pets and home from any of the issues that may arise from turning the system all the way off. Raising the temperature of your thermostat by 1 degree results in a 5% efficiency increase, which can result in big savings at the end of the month.