“If I set my A/C to 80 while I’m out, does it use more energy to cool my home back down when I return? Or should I just keep it at a lower temperature all day?”
It’s a great question, and one that surprises a lot of people.
Short answer: Raising your thermostat while you’re away and lowering it when you get home is the more energy-efficient choice.
Why adjusting your thermostat works:
It might seem like your A/C has to “work harder” to cool your home back down. But in reality, your system uses more energy maintaining a lower temperature all day than it does letting the temperature rise when no one is home.
Think of it this way. The bigger the difference between indoor and outdoor temperatures, the harder your system has to work to keep your home cool. By setting your thermostat higher when you’re away during the hottest part of the day, you reduce that difference for several hours, which lowers overall energy use.
When you return, lower the temperature gradually instead of lowering it all at once. A good approach is to drop it about 2°F at a time, giving your system a chance to cool steadily and efficiently. You’ll still get comfortable, just without making your A/C work harder than necessary to catch up all at once.
What temperature should you use?
A good rule of thumb:
- When you’re home, set your thermostat between 75°F and 78°F for a balance of comfort and efficiency.
- When you’re away, adjust the temperature to around 80°F to 82°F.
- If your schedule changes throughout the week, a programmable (or smart) thermostat can handle these adjustments automatically—so you can set it and forget it. You can schedule the temperature to rise while you’re away and then step down in small increments (like 2°F at a time) before you get home, so the house is comfortable when you walk in without overcooling all day.
Quick tip: For every degree you raise your thermostat above 75°F, you can save up to 5% on your monthly cooling costs, depending on your home and system.
Don’t wait until it’s too late
If your A/C unit is more than 10 years old, upgrading to a high-efficiency model can make a big difference in both comfort and energy use.
Start your install with a participating independent contractor and you can receive a $200
Meet Sonia
Sonia is an energy expert with 30 years of experience. She conducts residential energy assessments, educates customers on energy-saving tips and collaborates with communities to schedule Community Energy Saver events.
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