How to Properly Cool Your Home With a Fan

Hot weather is a major threat to health, and this summer is on track to be even hotter than usual. Air conditioning is a lifesaver in these conditions, but a much older technology could protect your safety, your budget, and even the planet. Keeping cool over the next few months could revolve around the blades of a refreshing fan.

“Fans are a great way to save money and energy,” says Nicole Miranda, a senior researcher on sustainable cooling at the University of Oxford. Whereas ACs work by chilling the air around you and making it less humid—a very energy-intensive task—fans require much less electricity as they move air across the body to keep you cool.

To get the most out of these devices, it helps to experiment with several ways of using them. Every home is different, and comfort is subjective, says Patricia Fabian, professor of environmental health at Boston University. “It isn’t one-size-fits-all.”

Here’s how to best use a fan in your home.

Try fans plus AC 

If you have working AC, a worthwhile experiment is to adjust it for less cooling while turning up your fans. This approach could do wonders for your summer electricity bill. Plus, you might feel exactly the same as if the AC were cranked up. Ollie Jay, a professor of thermal physiology at the University of Sydney, points to research showing that people don’t notice any difference when fan cooling is combined with a less chilly AC, compared to ACs set to arctic blast on their own, without fans.

“You’d feel just as cool in an 80-degree room with fans, as a 72-degree room with AC and no fans,” Jay says.

Read More: What's the Best Kind of Sunscreen?

Dialing back on ACs will ease the strain on the power grid, meaning fewer blackouts. And it could help break a vicious cycle, Jay says, where heat causes people to ratchet up their ACs, which generates carbon that results in an overall warmer climate—thereby creating even more demand for AC. This escalation has already happened in recent decades, with the contribution of ACs to carbon emissions more than doubling.

“When it is very hot, people need to use fans together with an air conditioner to be sure that they are safe, and they will still save money on their utility bill,” says Stefano Schiavon, a professor of architecture and engineering at UC Berkeley. 

Pick fan favorites

When it comes to fan types, there’s no shortage of options, but many experts say the ceiling fan blows the competition away—for cooling, if not necessarily style. These fans push down a column of air that flows “across all surfaces of the body,” Jay says. They also help circulate stagnant, hot air stored in the upper parts of the ceiling. “They’re very effective,” Miranda says, “though some are very 1970s.” Getting a ceiling fan doesn’t mean your home will resemble a Brady Bunch episode; they now come in many modern looks.

Meanwhile, Schiavon studies fan types and finds few differences in effectiveness. “If you use normal sized fans in their typical condition, many provide more or less the same cooling effect,” he says. But he notes that ceiling fans may not work during a power outage, whereas some standalone fans are battery-operated. Look for standalone options with DC motors; they’re affordable and more energy-efficient than AC motors, Schiavon says. His team developed this free book with more guidance.

Read More: What's the Most Refreshing Drink That's Not Water?

You may feel cooler if you point fans to the right spots of the body, such as the torso, and personal fans worn around the neck can complement stationary fans, Miranda says. To get the most physical cooling, though, cover as much of your body with airflow as possible, especially the parts not covered by clothing, Schiavon adds.

Another consideration is fan speed. “When it’s too fast, it can dry your eyes out,” Jay says. You could wear protective goggles—no style tips for that one—but there’s a point of diminishing returns where you won’t feel any cooler despite higher speeds. This threshold is usually the medium setting on a typical pedestal fan, when it’s about a meter away, Jay says.

Window fans to the rescue

The heat can be life-threatening if ACs break down, which may happen when the demand for electricity exceeds supply. Severe storms this spring and potentially record-setting ones over the summer carry similar risks. Meanwhile, 12% of Americans lack AC even when the power grid is up and running.

In these no-AC scenarios, your savior could be the option we relied on back in the 1950s: the window fan. But it requires more strategy than just sticking the fan in a window. 

Timing is a major consideration. You want to use a window fan when it’s cooler outside the home than inside, typically overnight or early morning, says Pravin Bhiwapurkar, an associate professor of architecture at the University of Cincinnati. Direction is also key: the fan should face inward, so it draws the cooler air into your abode and blows it in your direction. 

Try putting a separate window fan on the other side of your home as well, if you have a window there. This additional fan should face out, so it helps pull the hot air out of the home and increase the overall airflow. The two fans will combine to create a soothing crossbreeze, Bhiwapurkar explains. (You wouldn’t want both window fans facing into the home because that would increase air pressure and reduce the cooling efficiency.) And you can place a third blower, such as a box fan, on the floor to give this breeze some extra oomph.

Another trick is for homes with multiple stories: face the window fan into the house on your lowest story to bring in the cooler air. The warmer portion of this air will naturally rise to the top floor, so place a window fan up there, too—on the other side of the home, facing out—to expel the heat. To assist the process, put standalone fans, ones that are capable of tilting, on the lower levels, pointing upward if possible.

Check air quality indices and don’t use window fans if they’ll be sucking in fumes from rush-hour traffic or wildfire pollution, for example. As the day goes on, outdoor heat will also exceed indoor temperatures. When that happens, try shutting all windows to keep the cooler air inside, and crank up your arsenal of standalone fans.

Try other fans with no AC

The strategies for expelling heat from a top floor can also work with fan types other than window fans, Bhiwapurkar says. When it’s warm outside—but not blazing hot—you could turn off the AC, open a ground floor window on the side the wind is blowing toward, and point your pedestal or tower fans to direct the airflow upward. Open a window on the top floor to let out the heat as it rises.

These approaches work especially well when using windows on the side of your home that’s coolest, since the incoming air will be more refreshing. It’s usually the most shaded side of your home, maybe near some trees.

Read More: I Hate Summer—and You Should Too

In areas that don’t have many trees or other natural shade, try to curate a space outside your window to source cooler air, supporting the job of your indoor fans. When developing this space, think green and blue; plants and running water will help chill the air. “First and foremost, try to increase the vegetation” outside your window, says Khaled Tarabieh, the university architect and associate professor of sustainable design at the American University in Cairo, Egypt. If possible, install a fountain with flowing water outside this window, or fans that spray water there, creating a cool mist that acts as a buffer from the heat, Tarabieh adds.

Don’t fan the flames

If you don’t have AC or it isn’t working, turn off fans when outdoor and indoor temperatures are extreme, because they’ll simply blow hot air at you. According to the EPA, this threshold is 90°F. The WHO says 95°F, while Jay thinks the cutoff for fan use is even higher: 102°F for healthy people, and 98°F for older people with chronic illnesses. In these scenarios, it might be worth seeking out assistance from a local cooling center.

Experiment

Your indoor cooling strategy should go beyond fans and AC to include shading your sunny windows and hydrating well with liquids. When it’s very hot inside (and outside), wearing a wet shirt is also effective. “You can couple wet shirts with fans to optimize their effectiveness,” Jay says.

It’s good to experiment with how different approaches to home cooling affect the thermometer, but individual characteristics matter as well. Some people are more sensitive to heat stress, notably babies and those who are older, pregnant, or diabetic. “See what works best for you,” Fabian says.