As summer heat waves grip the U.S. and electricity prices surge, a familiar piece of advice circulates: set your thermostat to 78—or even 81—degrees Fahrenheit. Government officials and corporate websites often tout these numbers as the ultimate hack to stay cool without spiking your energy bill.
But according to Destenie Nock, an energy costs researcher, this one-size-fits-all advice ignores real-world safety and comfort.
Nock learned this lesson firsthand. The summer after her daughter’s first birthday, the toddler began vomiting in the middle of the night, developing small bumps across her chest. Initially suspecting a food reaction, Nock and her husband cut out acidic foods and switched her milk.
At the time, the couple kept their thermostat at 79 degrees. It was a habit from their pre-parenting days, a strategy that successfully kept their summer electric bill under $200.
When the weather finally cooled down one night, the child’s symptoms vanished. Nock lowered the hallway thermostat to get her daughter’s bedroom closer to 74 degrees, and the nighttime vomiting stopped entirely.
The Cost and Complexity of Air Conditioning
There is no universal thermostat setting that works perfectly for every person or every home. Cooling equipment varies wildly in technical design, age, and maintenance history.
Homes themselves differ in size, insulation, sun exposure, and local climate. While starting at 78 degrees might help cap energy costs, it is neither a strict safety threshold nor a comfortable baseline for every household.
Generally, a higher thermostat setting saves money because the system works less. Maintaining a home at 78 degrees when it is 95 degrees outside requires far less energy than hitting 72 degrees, which is the actual average summer temperature most U.S. households prefer.
Air conditioning also plays a critical role in reducing indoor humidity. High humidity prevents sweat from evaporating effectively. According to the National Weather Service, an air temperature of 90 degrees paired with 60% humidity feels like it exceeds 100 degrees.
While running the AC is vital during a heat wave, it can consume over 50% of a home’s summer energy usage. Fortunately, households have alternative strategies to stay cool without breaking the bank.
Low-Cost Strategies to Beat the Heat
Block the sun. Prevent outside heat from infiltrating your home by closing curtains on sun-facing windows. Keep doors and windows shut during the hottest parts of the day, opening them only when the outdoor temperature drops significantly overnight.
Use fans safely. Ceiling and portable fans create moving air that makes a room feel cooler, allowing for a slightly higher thermostat setting. However, the Centers for Disease Control and Prevention warns against using fans when indoor temperatures exceed 90 degrees.
Once the air is hotter than human skin—typically around 90 to 94 degrees—a fan creates a convection oven effect. This drives heat directly into the body and risks pushing body temperatures to dangerous levels.
Target specific rooms. A hallway thermostat rarely reflects the temperature of an upstairs bedroom or a sun-drenched living room. Use an inexpensive thermometer to monitor the exact spaces where your family actually sleeps.
Cool the body directly. A cool shower, a damp cloth, or strategic ice packs offer immediate physical relief. Drinking water consistently is also essential to replace fluids lost to sweat.
When to Seek Outside Help
Never compromise your health to save on a utility bill. Tragic stories frequently emerge of individuals dying indoors because they turned off working air conditioners or failed to repair broken units during extreme heat.
Infants, the elderly, and individuals with underlying health conditions often require longer periods in cooler spaces than healthy adults. Keep a close watch for signs of heat stress, including dizziness, intense thirst, nausea, confusion, or unusual fatigue.
If indoor temperatures become unsafe, call your local 211 resident-services hotline or locate a free municipal cooling center. Spending just a few hours in an air-conditioned public library, splash pad, or movie theater significantly reduces the physical toll of a heat wave.
For households struggling with electricity bills, utility companies often offer payment plans or direct cost subsidies. State and local government weatherization programs can also help residents insulate their homes and upgrade inefficient appliances to lower future bills.
Ultimately, the ideal thermostat setting is one that delivers safe cooling at a sustainable price. As Destenie Nock, an Associate Professor of Engineering and Public Policy at Carnegie Mellon University, discovered, a strict 78-degree recommendation cannot dictate a household’s safety. The true priority is protecting the people inside the home.
