What Should You Set Your Thermostat to When You’re Away?

Quick answer: In summer, raise the thermostat a few degrees instead of turning the AC off, generally no higher than the mid 80s, so the house stays dry while you save energy. In winter, keep the heat no lower than about 55°F to protect pipes. The DOE says a 7 to 10°F setback for 8 hours a day can save up to 10 percent a year.

Why not just turn the AC off while you’re gone?

Because in Central Texas the AC is also your dehumidifier. Shut it off in July and a closed-up house can climb into the 90s, with indoor humidity drifting well past 60 percent. That’s the level the EPA warns about for mold and mildew. You could come home to a musty house, damp closets and a system that runs for hours to catch up.

What should you set it to for a workday?

Raise it a few degrees while you’re out. The DOE suggests 78°F when you’re home and awake in summer, and a 7 to 10°F setback for about 8 hours a day for the biggest savings. Plenty of Austin households use a smaller setback, such as 80 to 82°F, so the house recovers quickly on a 105°F afternoon. A schedule or a smart thermostat handles it for you, and the best summer AC setting post covers the at-home side.

What about a summer vacation?

Set it a few degrees above normal, generally no higher than the mid 80s, and leave the fan on AUTO. If your thermostat shows humidity or has a dehumidify setting, set it around 50 percent. If you have a whole-home dehumidifier, leave it on. Close blinds on west and south windows, and if your thermostat allows it, schedule it to cool down a few hours before you get home.

What about winter trips and hard freezes?

Keep the heat on. The American Red Cross recommends keeping the thermostat no lower than 55°F when you’re away in cold weather. When a hard freeze is forecast, like the ones Austin saw in 2021, keep it a little warmer, open cabinet doors under sinks on exterior walls, and ask someone to check on the house if the power goes out.

Heat pump owners should keep setbacks modest in cold weather. Recovering from a deep setback can bring on backup strip heat, which uses much more electricity. See aux heat vs. emergency heat.

Does the system use more energy catching back up?

Generally no. The DOE notes that a house loses heat (or gains it, in summer) more slowly when the indoor temperature is closer to the outdoor temperature, so the energy saved while you’re away is more than the energy spent recovering. Heat pumps in cold weather are the main exception, for the strip heat reason above.

Related guides: Smart Thermostats: Are They Worth It?, Aux Heat vs. Emergency Heat: What Your Heat Pump Thermostat Is Telling You and Is 79 Degrees Hot or Cold? The Best AC Setting for Summer.

About Gold Eagle Services: This guide comes from the team at Gold Eagle Services, a family-run Austin HVAC, indoor air quality and mold remediation company founded in 2017. We’re licensed (TACLA119235 and RCO1783), insured and bonded, and we serve homes across the greater Austin area.

Need help with this in your home? Learn about our air conditioning repair and installation, or call 512-489-4653 to schedule a visit.

Related Gold Eagle service: AC repair in Austin