Key Takeaways
- The Department of Energy recommends 78°F when you are home and awake — the balance point between comfort and a reasonable energy bill.
- Adjust by time of day: push it into the low-to-mid 80s when the house is empty, and set it a few degrees cooler for sleep.
- A programmable or smart thermostat makes those changes automatically, so you save without thinking about it.
- Every degree lower raises your bill — and a ceiling fan lets you sit comfortably at a higher setting.
The short answer: the U.S. Department of Energy recommends setting your air conditioner to 78°F when you are home and awake. That is the number that balances staying comfortable with not overpaying to cool the house. The longer answer is that the best setting changes through the day — and there are a few ways to stay comfortable while nudging it higher. Here is how to think about it.
The Ideal Summer Setting: 78°F
The Department of Energy points to 78°F as the sweet spot for a summer day when you are home. That said, plenty of households here in the Midwest run cooler — somewhere in the 70 to 74°F range is the most common real-world setting. There is nothing wrong with that; just know that the lower you go, the more you pay. Think of 78°F as the efficient baseline and adjust from there based on your own comfort.
Adjust the Temperature by Time of Day
You do not need one setting for the whole day. The biggest savings come from letting the temperature drift up when no one benefits from keeping it cool.
While You Are Away
When the house is empty during work hours, there is no reason to cool it to a comfortable living temperature. Letting it rise into the low-to-mid 80s — around 82 to 85°F — cuts energy use while still protecting the home from excess heat and humidity. The AC then has less work to do to bring it back down when you return.
While You Sleep
Most people sleep better a little cooler. Setting the thermostat around 4°F lower than your daytime number at night is a common approach — comfortable for sleeping without cooling an empty, awake house. Many homeowners land somewhere between 75 and 78°F overnight, depending on preference.
Let a Programmable or Smart Thermostat Do the Work
Remembering to change the thermostat four times a day is not realistic, which is exactly why programmable and smart thermostats exist. You set the schedule once — warmer while away, cooler for sleep, comfortable when you are home and awake — and it handles the rest, preventing the unnecessary cooling that quietly runs up your bill. Smart models go further, adjusting automatically based on your habits. For the full picture, see our guide on how smart thermostats save money and improve comfort.
What Affects Your Comfortable Temperature
The right number is not the same for everyone. Personal preference, age, and how much humidity is in the air all change how warm a given temperature feels. Humidity is a big one — damp air feels warmer, so a system that manages moisture well lets you stay comfortable at a higher setting. Ceiling fans help too: running them lets you raise the thermostat a few degrees and still feel just as cool, since moving air makes your skin feel cooler even when the temperature has not changed.
The Bottom Line: Every Degree Counts
Every degree lower can noticeably increase your cooling costs over a summer, so the goal is to find the highest setting that still feels comfortable and let it rise whenever you can. If your home will not hold a comfortable temperature even at a reasonable setting — or one room is always warmer than the rest — that usually points to an airflow, insulation, or system issue rather than the thermostat, and our guide on uneven cooling covers why.
Stay Comfortable and Efficient With Degree of Comfort
If your AC is struggling to hold the temperature you set, or you want a smart thermostat installed and dialed in, Degree of Comfort can help. We service, repair, and tune air conditioning systems and install thermostats across Cincinnati and the surrounding Tri-State, including Northern Kentucky and Southeast Indiana. We are family-owned, licensed and insured, with upfront, flat-rate pricing and a satisfaction guarantee.
Want a cooler, cheaper summer? Call (513) 586-5107, ask about a thermostat upgrade or AC maintenance, or request a free estimate and let our team handle it.
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