This post has been updated. It originally published on August 29, 2024.
On sweltering days, the temptation to crank the air conditioner can be as hard to resist as the siren song of the ice cream truck. But finding ways to keep your home cool without AC can ease both energy bills and emissions. In the U.S., AC alone accounts for about 17% of a home’s electricity consumption, and the average utility bill can jump by 8% as temperatures climb between June and September.
Blasting cool air from a conventional condenser is also one of the biggest contributors to greenhouse gases. About 3% of global emissions trace back to AC, nearly twice as much as those generated by the airline industry. And, as human-caused climate change spurs more frequent and intense heat waves, demand for indoor chillers could triple by 2050, according to a 2023 report from the United Nations.
Even when the temperature outside makes shutting off AC a hard “no,” it is totally feasible to dial down the thermostat a few notches. It might not always be possible to physically lower the temperature of your home, but making it feel cooler is. Doing so comes down to two things: harnessing the physics of airflow and heat transfer, and leaning into tactics that leverage your body’s natural cooling system. Many of these tricks are especially handy for renters looking to make their homes more efficient.
1. Block sunlight
The U.S. Department of Energy estimates that about 76% of the rays that hit your windows become heat. Keeping panes covered during the day, especially when the sun is at its hottest, can reduce your need for a cooling aid.
Blackout treatments or blinds might seem like the most-obvious move here, but there are options that won’t make you live in darkness. Peel-and-stick solar film, for instance, can block up to 78% of the sun’s warmth from entering a dwelling; in one case study, homeowners saw a temperature drop of more than 10 degrees F. Cellular shades, whose folds form an internal honeycomb pattern that acts as an insulator, can cut unwanted solar heat by up to 60%. Other coverings, like slat-style louvered blinds or rolling roman shades, can also help, though they’re less effective.
2. Create a cross breeze
Keeping air moving doesn’t necessarily lower the mercury, but it does create a chilling sensation as it helps sweat evaporate off the skin—your body’s natural cooling mechanism. If it’s decent enough outside to have the windows open, cross-ventilation can let you feel the breeze, while also pulling cooler air inside and pushing warmer air out.
To generate a breeze, open a door and/or window on opposite sides of your home, creating an inlet and an outlet. Then position fans—either box, floor, or table—to direct air from one side to the other. This will work best if you take advantage of the natural tendency for hot air to rise (aka convection): Place the inlet at a lower level than the outlet, which can be as simple as lowering the top sash of a window instead of raising the bottom. One study conducted in India found that good cross-ventilation can have a cooling effect of around 11 degrees F at the hottest point in the day.
3. Optimize your ceiling fans
Like cross-breezes, a gentle waft of air coming off a ceiling fan can help sweat evaporate more quickly. While the level of cooling depends on how fast the air is moving and how humid it is, a fan can let you adjust the thermostat up by 4 degrees F. Most fans are bidirectional, so glance up at yours and make sure it’s spinning counterclockwise, which creates a downdraft. If it’s going the wrong way, turn it off and find the switch that reverses the spin.
A wobbly or dirty fan is also an inefficient one. Dusty blades may not slice through the air as well as clean ones—and they’ll also fling crud around the room. Add wiping down the blades to your cleaning routine, and while you’re up there make sure to check and tighten up any fasteners. We’ve got the guide on what to do if your ceiling fan isn’t acting up to scratch.
4. Keep humidity in check
On steamy days, the air is simply too saturated for sweat to evaporate efficiently, making you feel even hotter. When it’s damp out, a dehumidifier can be your hero. These appliances condense and collect water vapor, and then release drier air back into the room. (According to the EPA, the ideal indoor humidity is between 30% and 50%.) Another reminder: If you have a bathroom fan, be sure to run it to dissipate the effects of steamy showers. Lower humidity will not change the temperature of your home, but can make it seem cooler.
5. Use appliances wisely
Appliances like ovens, dishwashers, and refrigerators need a lot of energy and generate a lot of heat as they do their jobs. In some cases they are responsible for more than 16% of the heat in a home. While you can’t do much about your refrigerator, make sure to use things like ovens, dishwashers, and clothes dryers during cooler hours—if you turn them on at all.
You can, for example, line-dry your clothes, opt to grill, or tap another alternative cooking method like an induction burner. Baking a pie in the oven, for instance, could raise the temperature in your home by 1 to 10 degrees F, while using a smaller appliance like a toaster oven or air fryer will do less to kill your chill. One more tip: Unplug devices when not in use––they can generate heat, even on standby.
Home upgrades to cut your cooling bills
If you’re interested in more than these nifty tricks, there are options for larger HVAC updates that’ll help cool (and heat) your home more efficiently.
Switch to a heat pump
According to the Department of Energy, heat pumps use about 65% less energy to cool a home than a traditional air conditioner. A heat pump-based HVAC system replaces both AC and heating, and works by moving thermal energy (that’s heat) from one place to another via a refrigerant. The only electricity required to run a heat pump is used to push this refrigerant around so that this thermal transfer can take place throughout the home. “If it is something that you can afford to do, [a heat pump] is going to improve your thermal comfort,” says Megan Plog, who works on the Energy Star scoring program at the Department of Energy. Check out our guide to see if a heat pump might be the right call for your home.
Install a whole-house fan to blow air through your home
A whole-house fan can cool down the entire home by generating bigger air currents. They are capable of using as little as 10% of the electricity consumed by a traditional AC unit––and produce stronger breezes than ACs. These are best installed in a central location, like your hallway ceiling, and should be connected to the attic space, so that warm air can rise up and leave through the attic ducts.
Seal hot air out with better insulation
If your home gets too hot during summer days and too cold during winter, poor insulation might be the culprit. “The most important thing is to make sure that that heat is not penetrating your home in the first place,” says the DOE’s Plog. “Air leaks are a really big source of energy loss.” Effective insulation can help you reduce your energy costs by about 11%, according to Energy Star, because it reduces any “heat leaks” going either in or out of the house. “Heat can either escape in the winter or come in through the summer. When you’re trying to cool your home and your AC is on full blast and the heat from outside is coming in, it’s going to increase your energy cost,” says Alison Knasin, lab manager at Indiana University’s Energy Justice Lab. “Insulation is good year round.”
Use a smart thermostat to control indoor temperatures
A programmable thermostat can allow you to cool your house according to pre-set schedules––not only saving you the struggle of repeatedly changing your room temperature but also keeping your energy bills low by turning off when not needed. Doing so can help save about 10% on your heating and cooling bills. Some models also allow you to set different schedules for different rooms in your house as well as different days of the week.
Cool your home from the outside with landscaping and roofing
The intense heat of the sun can increase the temperatures in your house by warming up your roof and walls of your home. There’s a lot you can do to keep the inside of your home cool from outside. It’s no secret, for instance, that homes surrounded by trees are cooler than homes that are not. In fact, trees can reduce a household’s air conditioning needs considerably based on location (for instance, one study found that an additional 25% increase in tree cover can save 40% of annual cooling energy use of an average house in Sacramento). Covering the roof of your house in lighter shades that reflect sunlight more efficiently and absorb less heat can also keep your home cooler.
Additional reporting by Audrey Chan