According to the Department of Energy1, 78° Fahrenheit is the sweet spot for air conditioners to balance energy savings and comfort when people are at home and need cooling. But in reality, this is a question that doesn't have a “one size fits all” answer.
This is more of a personal question, as different people feel comfortable at different temperatures. Since 72 degrees is generally agreed upon to be an ideal indoor temperature, most people would probably still feel comfortable setting their AC units slightly higher than this, perhaps at around 75.
What is the Best Thermostat Setting for Summer Air Conditioner Use? Energy Star recommends the following thermostat temperatures for your air conditioner in the summer: 78°F during the day if people are home. 82°F at night if people are home.
What should my AC be set at if it's 90 degrees outside? If the outdoor temperature is 90 degrees, it's recommended to set your thermostat between 75-78 degrees.
Best AC Temperature Settings While You Are Home
As you consider the most comfortable room temperature for your lifestyle and family, keep in mind that for each degree that you set your thermostat above 72 degrees, you can save up to 3% on your energy bill.
Most people work better and are more productive when with a temperature setting in the 72–74-degree range. This setting is low enough to keep the house cool and dry and keep you and the kids awake during the afternoon hours.
According to the Department of Energy1, 78° Fahrenheit is the sweet spot for air conditioners to balance energy savings and comfort when people are at home and need cooling. But in reality, this is a question that doesn't have a “one size fits all” answer.
For many of us, 70 degrees is the ideal indoor temperature, but when it is close to 100 degrees outside, your AC unit will be working quite hard to meet these expectations. Consider setting your thermostat at 75 degrees to 80 degrees in your home if the outside temperature is approaching triple digits.
Your AC might not cool properly due to thermostat issues, an undersized unit, or extremely high outdoor temps—so check those first. Keep an eye on airflow—replace clogged filters every 3 months, and make sure vents and ducts aren't blocked for efficient cooling.
Air conditioners shouldn't generally work all the time unless the thermostat is set to “fan on” (inadvisable). A correctly sized and well-maintained AC system should run for 15 to 20 minutes, two or three times every hour—with longer cycles in the higher temperatures of summer.
Setting your AC to 16°C will cool the room more than setting it to 30°C. However, keep in mind that extremely low temperatures can lead to higher energy consumption and may not be comfortable for occupants. A moderate setting, like around 22–24°C, is often recommended for both comfort and efficiency.
There are benefits to having your air conditioner set to “auto” and “on.” The benefits of the “auto” setting include higher efficiency, lower energy bills, better humidity control, less wear and tear on some components, and quieter running.
During a heatwave, we recommend that you don't lower the AC's setting below 68°F. This is already quite chilly for most people, and many would consider it too cold. An air conditioner set this low risk of its coil freezing—and that's bad news because it indicates that the air conditioner is overworked.
Setting the thermostat below 72 degrees while using an air conditioner can cause the unit to work harder than necessary, leading to higher energy bills and potential damage to the appliance.
The best way to save money is by combining both. The “run” feature lets you preset the temperature when you're not home to prevent wasting money on cooling or heating an empty home. Meanwhile, the “hold” button lets you change the room's temperature without changing your energy-saving, preset schedule.
If the temperature is set to 74°F but the thermometer shows 78°F, you will have to recalibrate the thermostat to account for this 4-degree deviation. Even with older AC units or furnaces, you might have to recalibrate your thermostat from time to time.
Another problem that can cause your house to be hotter than what you've set the thermostat to is if your home's HVAC system isn't sized properly. An HVAC system that's too large for your house will cool your home unevenly. It will only cool some rooms off and then shut off versus cooling down the entire house.
To maintain a comfortable indoor environment during the summer, the American Society of Heating, Refrigerating & Air Conditioning Engineers recommends a range of 73 to 79 degrees Fahrenheit. On scorching hot days, you may want to adjust your thermostat toward the higher end of that range.
When the AC temperature is too low, between 60-67 degrees F (15-19 degrees C), the evaporator coil inside the unit can get excessively cold. If the humidity in the room is high, condensation can accumulate on the coil, which may lead to the formation of frost or ice.
When outside temperatures are pushing 100 degrees, try setting your thermostat at 78-80 degrees. Supplement the indoor airflow with fans and other strategies to maintain cool temperatures inside.
Recommended AC Temperature for Sleeping
The Sleep Foundation says 65° is the best temperature for sleeping. However, if you prefer a slightly warmer or cooler room, that's okay, too. The recommended range is 60–68°, so there is some wiggle room.
Cooling a house from 80 to 72 degrees is a common goal for many, especially during the peak of summer. On average, this process takes roughly two and a half to three and a half hours.
A more moderate setting like 24°C (75.2°F) can achieve comfort with reduced electricity usage.
The best room temperature for sleep is approximately 65 degrees Fahrenheit (18.3 degrees Celsius). This may vary by a few degrees from person to person, but most doctors recommend keeping the thermostat set between 65 to 68 degrees Fahrenheit (15.6 to 20 degrees Celsius) for the most comfortable sleep.
Energy Saver recommends setting your air conditioner to 78 degrees when you wake up, 85 degrees during the day, and 82 degrees when you're sleeping to save the most money. Kureczka suggests bumping the temperature up to the highest setting you're comfortable with.