Quick answer
Energy Star recommends 78°F when you're home and awake. Set it higher when you're away or asleep, and use ceiling fans to feel cooler without lowering the thermostat.
Why 78°F?
It's the summer setting Energy Star recommends to balance comfort and cost. Every degree lower makes the system run longer — and in a Texas summer, it's already running a lot.
Raise it when nobody's home
The U.S. Department of Energy says turning your thermostat up 7–10°F for 8 hours a day can save up to 10% a year on cooling. A programmable or smart thermostat does it for you, and can cool the house back down before you get home.
Use ceiling fans
A ceiling fan lets you raise the thermostat about 4°F with no loss of comfort. In summer, set it to spin counterclockwise. Turn it off when you leave the room — fans cool people, not rooms.
Don't crank it down to cool faster
Setting the thermostat to 65°F won't cool the house any faster — the AC runs at the same speed either way. It just runs longer and overshoots.
Other ways to keep the heat out
- Close blinds on sunny west- and south-facing windows in the afternoon
- Run the oven and dryer in the morning or evening
- Keep supply vents open and return grilles clear
- Keep the air filter clean
When the setting isn't the problem
- The house never reaches the temperature you set
- Some rooms are much warmer than others
- The system runs nonstop on mild days
- Your bill jumped without a change in habits