Expert reveals the best temperature to set your AC during a heatwave — and it might surprise you

Controls with an air conditioning unit
(Image credit: Shutterstock)

With another heatwave predicted for the weekend, things are hotting up. While it’s tempting to escape inside and crank up your AC to stay cool, it’s neither energy-efficient nor cost-effective.

To save you from losing your cool and facing a rocketing energy bill, we asked HVAC experts what the ideal temperature is to set your AC during a heatwave.

Your first instinct might be to turn down the thermostat to pump out more cold air, but this is the wrong approach. Not only does it send your energy bill skyrocketing, but it’s also not energy-efficient.

What is the best temperature to set your AC?

Smart thermostat

(Image credit: Shutterstock)

Rather than constantly yo-yoing with your thermostat, a consistent temperature is the best approach. The U.S. Department of Energy suggests setting your AC to 78°F (26°C) when you’re at home during the day and to 74°F (23°C) while you're asleep.

While you may want to bring your indoor temperature down further, to say, 72°F, Tara Energy explains what impact this will have on your energy consumption and bill, “Because AC units require so much energy, and outdoor summer temperatures tend to be much hotter than 72°F, it takes a lot of energy to bring indoor temperatures down to this level.”

Use a programmable thermostat

The Energy Protection Agency’s ENERGY STAR program recommends using a programmable thermostat to adjust your home’s temperature at times when you’re regularly away or sleeping. Apart from saving you from constantly changing the setting, it will ensure you are not using energy unnecessarily.

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Maintain your AC

Man cleaning air conditioner

(Image credit: Shutterstock)

There are also other measures you can take to prepare your AC for a heatwave and keep it in good working order, ensuring it remains efficient. The EPA recommends changing the AC’s air filter regularly to prevent dust and dirt from accumulating in the system. It suggests replacing the filter every month, especially during the winter and summer months when use tends to be heavier.

It also recommends maintaining proper upkeep with a qualified HVAC technician to prevent future problems.

Make the most of 'dry' mode

Another option to stay cool in a heatwave is to use the ‘dry’mode on your AC unit, if it offers this feature. Stephen Day, Operations Manager at iHeats says, “Humid conditions can make the air feel heavier and more uncomfortable than the temperature alone would suggest. Dry mode doesn’t cool as aggressively as standard cooling, but by removing excess moisture from the air, it can significantly enhance comfort levels while using less energy.”

And he concludes, “Air conditioning should be about creating comfort, not a freezer-like environment, and striking that balance will keep your home pleasant without pushing the unit (or your electricity bill) to breaking point.”

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Camilla Sharman
Staff Writer, Homes

Camilla is the Homes Staff Writer and covers everything to do with homes and gardens. She has a wealth of editorial experience, mounting over 30 years, and covers news and features, tests products for reviews and compiles buying guides. 

Her work has appeared in business and consumer titles, including Ideal Home, Real Homes, House Beautiful, Homebuilding & Renovation, and Kitchen & Bathroom Business. She’s even appeared on the cover of Your Home, writing about her own house renovation.

Although she’s obsessed with decorating her home, she also enjoys baking and trying out the latest kitchen appliances. But when she’s not inside, you’ll find her pottering about in her yard, tending to her vegetable patch or taking in her prized hydrangeas.

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