You’re Using a Box Fan All Wrong

It’s no secret that heat waves have gradually become more intense during the summer months. In the United States alone, data shows that summers in most cities have warmed by an average of 2.6 Fahrenheit since 1970 — and apartments built well before then can’t necessarily keep up. If you don’t have central air conditioning, you might find yourself struggling to keep your home cool during particularly hot days. 

Box fans can offer relief, but too often they only cool down one room — especially if you set them on the floor, point them toward your couch or desk, and let them run. Here’s how to use a box fan properly for maximum cooling (and minimum energy bills). 

Maria, an RA for a dorm with no AC at the University of Maryland, recommends placing a box fan in a windowsill. “During the lowest temperature periods of the day, position the fan with the blades facing inwards to pull cool air in. During the warmer times of the day, position the fan with the blades facing outwards to draw out the warm air,” she explains in this tutorial. 

In peak summertime heat, for example, you’d want to place the fan linked above with the Lasko logo facing outside, and maybe at night run the fan with the logo pointing into your home. 

If there’s a cool breeze outside or at night, you could also try this one-fan, two-window method from a Reddit user in this viral Reddit thread. 

“Blowing inwards makes a ‘jet’ of air that cools one room very well,” user u/spacex_fanny explains, but if you’re looking to make a “corridor of cool,” as they call it, open a window on the cooler, shadier side of your home, then open a second window and put your fan in it to blow warm air out and suck in replacement air from the open window across the entire house. For best results, try running the fan only in the evenings — if you can, a good rule of thumb is using a fan with a timer to run the fan from 8 p.m. to 7 a.m. so the fan doesn’t suck in too much hot air.

The key to making this “corridor of cool” work is to avoid “short circuits” — aka gaps around the fan — by filling them with boxes or towels. This helps ensure circulation that will push warm air out while bringing cool air in.

If you have two box fans, good news! You can up the power of the “corridor of cool” method by using two fans that each serve a different purpose. One can point outside and push hot air out, while another can stay inside and bring cool air around your space. With the right placement, your box fan will have you feeling cooler in no time.

For extra heat relief, use curtains, sheets, or any other shade coverage over windows to reduce the effect of harsh sunlight. You can also keep yourself cool with wet garments, small fans, cool showers, and more.