On the most-sweltering days of summer, it’s natural to find a new best friend in your air conditioner. But your energy bill probably feels differently. In the U.S., AC alone accounts for about 16% of total electricity consumption in homes, and the average bill can jump by 8% as temperatures climb between June and September.1,2
But blasting cool air from a conventional condenser is also one of the biggest contributors to greenhouse gas emissions. About 4% of global emissions trace back to air conditioning, nearly twice as much as those generated by the airline industry.3 And as human-caused climate change spurs more frequent and intense heat waves, demand for indoor chillers could triple globally by 2050, according to a 2023 report from the United Nations Environment Programme.4
Even when the temperature outside makes shutting off AC a hard “no,” it is possible to dial down the thermostat a few notches. And, if larger, pricier upgrades like installing a heat pump are on the table, there’s plenty you can do there, too.
How to keep your house cool in summer, without blasting the AC
While it might not always be possible to lower the temperature of your home, it is at the very least possible to make it feel cooler. Doing so comes down to 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.
Use shades to block the sun
The U.S. Department of Energy estimates that about 76% of the sunlight that hits your windows becomes heat. Keeping your panes closed and 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, 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 10 to 20 degrees Fahrenheit.5 Cellular shades, which have accordion-like folds that 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. Opt for lighter colors, which are more reflective, and heavier materials whenever possible.
Make a cross-breeze
Keeping air moving doesn’t necessarily lower temperatures, 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 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 create a breeze, open at least two doors and/or windows on opposite sides of your home, providing an inlet and an outlet. For this to work best, you’ll also want to take advantage of convection—the natural tendency for hot air to rise—by placing the inlet at a lower level than the outlet. This can be as simple as lowering the top sash of a window instead of the bottom. You can also help this along by placing table or floor fans on opposite sides of the house to initiate some moving air. One study conducted in India found that good cross-ventilation can have a cooling effect of around 11 degrees Fahrenheit at the hottest point in the day.6
Optimize your ceiling fans
Like cross-breezes, a gentle wind coming off a ceiling fan can help sweat evaporate from your body quicker than still air. While the degree 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 Fahrenheit. 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 allows you to flip 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 check to 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.
Keep humidity in check
Humidity is a measure of evaporated moisture in the air. On days that are hot and humid, 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. Dehumidifiers work by condensing and collecting water vapor, and then releasing drier air back into the room. According to the EPA, the ideal for indoor humidity is 30% and 50%. Bathroom fans and ventilation can also dissipate the heat and humidity generated during steamy showers. Lower humidity will not change the temperature of your home, but can lower the real feel to make it seem cooler.
Time when you use your appliance
Appliances like ovens, dishwashers, and refrigerators use 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 use them at all.
You can, for example, line-dry your clothes and opt to grill or tap another alternative cooking method. Baking a pie in the oven, for instance, could raise the temperature in your home by 1 to 10 degrees Fahrenheit, while using a smaller appliance like a toaster oven or air fryer will do less to kill your chill.
Home upgrades to cut your cooling bills
If you’re interested in more than tiny 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
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.
Improve your 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.”
Install a programmable thermostat
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.
Explore energy-saving landscaping and cool 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 by 30%. Covering the roof of your house in lighter shades that reflect sunlight more efficiently and absorb less heat can also keep your home cooler.
- Residential Energy Consumption Survey (RECS), U.S. Energy Information Administration ↩︎
- Summer Residential Cooling Outlook: Residential Electric Utility
Expenditures Projected to Reach Record Levels, Highest in 10 years, National Energy Assistance Directors Association and Center for Energy Poverty and Climate, Jun. 2024 ↩︎ - Humidity’s Impact on Greenhouse Gas Emissions from Air Conditioning, Joule, Apr. 2022 ↩︎
- Global Cooling Watch 2023, UN Environment Programme, Dec. 2023 ↩︎
- A Place in the Sun, 3M, 2018 ↩︎
- Influence of Cross-Ventilation Cooling Potential on Thermal Comfort in High-Rise Buildings in a Hot and Humid Climate, Building and Environment, Jan. 2024 ↩︎