Parents lie to kids about a lot of things. For instance, my dad told me he put cinnamon on my hamburgers growing up. Total lie. But it did work: I’d eat those “cinnamon” burgers but not the regular kind. One thing he didn’t lie to me about, though, was the air conditioning in our house. My parents have run an HVAC company in North Georgia for almost 40 years now (our family dogs are the mascots), and my dad has been a licensed technician for just as long, so it was always plenty cold in our house. Sometimes too cold for me, but I’m not going to complain about that in the middle of the summer.
Central air conditioning has been a common feature in newly built American homes since the late 1960s, but that doesn’t mean most adults understand it. In fact, we don’t usually think about it very much at all until it breaks down or we need to buy a new one—unless we’re thinking about how much it costs to run it. That’s usually where the lies begin.
It’s funny how many of the lies most people’s parents tell them center around running the AC in the summer, intending to keep their electrical bill down. But a lot of that thinking is upside-down or just plain wrong. I asked my dad to fact-check the most common misconceptions on this topic, including ones my colleagues’ parents leaned on when they were kids. Keep reading to debunk the lies your parents told you about air conditioning and find out which ones actually contain a nugget of truth.
Lie: It’s Better to Run the Air Conditioning Only at Night
Growing up in India (where it’s even hotter than in North Georgia) House Beautiful digital designer Soumi Sarkar’s parents allowed the air conditioning to be used only at night or, on absolutely sweltering days, in the afternoon.
Truth: It does cost more to run your air conditioning than it does a fan. You pay the utility company for the amperage you use, and an air conditioner draws more amps than a fan does. But that doesn’t mean it’s better to do this. Your air conditioner has to work harder to cool the house when you let the temperature go to extremes. “If you let your house get hot, everything in it gets hot, even the chairs,” my dad says. It takes longer to cool all those things down. That can also cause wear and tear to happen more quickly—and replacing an air conditioner is pretty expensive.
Big swings in temperature from hot to cold aren’t great for anything you own—including other appliances, like your fridge, and the structure of your house itself, which is affected by humidity. My dad recommends not letting your home get hotter than 80 degrees Fahrenheit.
Lie: The AC Won’t Help the Humidity
South Florida native and House Beautiful executive content editor Jess Teves knows damp, hot heat from experience. Unlike a lot of Floridians, though, her parents weren’t big on air conditioning. They told her that it was still going to be humid anyway.
Truth: “Air conditioning is actually all about dehumidification,” my dad says. That’s how it works, by pulling the warm moisture out of the air, cooling that air, and then pushing it back out into your house. The condensation that accumulates from this process typically drains into an outgoing pipe or a pan, which is why leaks in attics are more common when it’s super hot outside—more condensation is building up and can overflow. It’s important to get your system checked for clogs in the spring to ensure the water can drain out.
Lie: Air Conditioning Will Make You Sick
There are lots of variations on this one: Going from hot air to cold air is bad for you. It’s bad to sleep near the draft from an air-conditioning vent.
Truth: The draft itself isn’t going to make most people sick—although my dad (like anyone who has a modicum of common sense) wouldn’t recommend positioning a baby’s crib right under an air conditioning return. “Clean drains and clean filters are a must,” he says. “This applies to most everything in life. If everything is clean, health should not be an issue.”
He recommends changing your air conditioning filters once a month all year and being especially vigilant about it in the spring and summer when allergens and temperatures peak or if you have pets that shed a lot. In his opinion, there’s no need for most people to buy special and expensive HEPA or similar filters—the most important thing is changing them regularly.
Lie: The Lower the Thermostat, the Faster It‘ll Cool Down
You might have heard your parents arguing about this one—for instance, if your dad felt hot and cranked the dial down to 60 instead of the 70 your mom preferred.
Truth: “Turning down the temperature from, say, 70 to 60 when it’s 80 degrees in the house will not help it cool down faster,” my dad says. The only exception might be if your system has a two-stage or variable-speed compressor—and you’ll likely crank up your energy costs since it takes more BTUs to get that going.
Lie: Live by the 20-Degree Rule
You may have grown up hearing some version of this household mandate: The thermostat should never be set to a temperature more than 20 degrees hotter or colder than the outside temperature.
Truth: “I never heard of that one,” my dad says. Still, he says, it’s the temperature inside your house that matters, not outside. “A typical air-conditioning system will change the intake temperature”—aka the temperature of the air it’s pulling in from the rooms in your house—“by 20 degrees,” he adds. If you don’t run the air consistently, it’s actually pretty easy for it to get hotter inside than it is outside.
Lie: Turn Off the AC When You Go Out of Town
This money-saving move appears on many a family’s vacation prep list, along with unplugging the TV and turning off the water supply.
Truth: “We don’t recommend turning the AC off,” my dad says. “Quickly accumulating a lot of humidity isn’t good for a house.” As a family with indoor dogs and cats, we’d personally never do this. Pets need to stay cool too. (My parents also leave on Animal Planet for their dogs, but that’s strictly optional.) It also goes without saying that you should never leave a pet in a hot house, car, or yard.
What you can do if you want to reduce your electric usage while you’re away is turn the thermostat up to 78 degrees, my dad suggests. That’s enough to keep the humidity in control and the house relatively comfortable.
Lie: You Should Close the AC Vents in an Empty Room
You might’ve seen your mom or dad use the little dial on the register in the guest room to close it as soon as your aunt or grandma went home from a visit, the idea being that’d keep overall costs down and/or make other rooms cool faster.
Truth: “Closing vents is not good for an AC system,” my dad says. “If it has been installed properly, the air is sized accordingly for the entire house.” A closed vent can throw off the balance. You also don’t want to close the door and let humidity build up in just one room. It’s bad for paint, furniture, windows—you name it.
Lie: A Ceiling Fan Is Just as Good as AC
This one is for all the New Englanders who grew up without central air.
Truth: Naturally my dad is a bit biased since he gets paid to install air-conditioning systems, but it’s objectively false to say a fan does the same thing as air conditioning. It simply does not. “Having the fan on only helps move the air around,” he explains. “It has nothing to do with dehumidification, so it’s no help with cooling or humidity.”
What a ceiling fan can do is help distribute cold air. Pro tip: In the summer, set your ceiling fan to reverse so it runs counterclockwise. (You may not have noticed before, but most ceiling fans have this feature.) “Cool air molecules are heavier than hot ones, so running your ceiling fan counterclockwise will help move some of the cool air around the room.”
Lie: An Open Window Lets All the Cold Air Out
This one applies in the car and at home. Parents love to tell kids they’re wasting anything, AC included.
Truth: This is actually (and frankly pretty obviously) true. We pay good money to insulate our houses to keep cold air from escaping in the heat of summer—and the inverse is true in the winter. The more tightly a house is sealed, the easier and more efficient (not to mention less expensive) it is to control the climate. An open window is essentially a leak—what passive house experts would call a thermal bridge.
Lie: You Don’t Need AC If You Have a Cross Breeze
Senior digital editor Melanie Yates’s Italian landlords in Astoria, Queens, love to tell her this when it’s especially hot out.
Truth: This one is a partial truth that depends on your tolerance for heat and humidity. Homes and apartment buildings built before air conditioning (or even electricity) were designed to help them stay cool in the summer and warm in the winter. Windows were sized and positioned strategically to allow cross breezes to flow through. Moving air helps dissipate humidity and feels nicer than hot, stagnant air. If you live near water, the breeze may be cool too. My dad points out that transom windows served a similar purpose. “They’re actually an old-school way to try to cool houses and buildings,” he says. “Hot air rises, and any cross ventilation pushes the hot air from front to back.”
But there’s only so much a cross breeze can do, and the heat simply wasn’t as extreme or extended back then as it is now. Modern weather patterns make air conditioning essential now, especially in many urban environments. That’s why the federal Department of Housing and Urban Development recently agreed to help public housing residents pay their cooling costs (although not pay for the air-conditioning units themselves).
Lie: Always Turn Off the AC During a Storm
When the sky starts to look like something out of Twister (or Twisters, coming soon to a theater near you), one of your parents might’ve headed down to the basement to cut the power to the AC unit, hoping to protect it from a power surge or outage. You probably remember feeling pretty sweaty while you were ducking and covering in the hallway or the bathtub.
Truth: Welp, they were right on this one. “Yes, you should turn your AC system off during a storm—at the panel box if you can get to it safely,” my dad says.
Lie: It’s Too Hot to Cook
It’s the best excuse to order takeout—turning on the stove will make it even hotter in the house—but is there anything to it? How much can turning on one burner really affect the overall temperature?
Truth: Generally, and this depends on the exact stove you have and the burner you might use, but “one stove burner of heat is roughly equal to one ton of AC cooling: 12,000 BTUs,” my dad says. “So cook quickly or little to none on very hot days.” (The exception is an induction stove, which heats only the pot you’re cooking in, not the surrounding air.) You could also opt to do as he does and take some burgers or steaks out to the grill and hang out with the dog while you do your cooking there.
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Elyse (she/her) is the Senior Features Editor at House Beautiful, where she oversees print and digital house tours and coverage of all things design and has worked since 2023. She has more than a decade of experience as a writer, editor, and product tester, previously at Martha Stewart Living and Weddings, where she edited the iconic Good Things section and led home and entertaining content for five years; O, The Oprah Magazine; and ELLE. She has built her own interior design skills by studying at Parsons School of Design and tackling the (endless) renovation of her 1907 Tudor, for which she won a . When she’s not obsessing over or , this Georgia native loves hanging out with her family and beloved cat, hitting estate sales, and reading murder mysteries.
