It is usually cheaper to turn your AC up, not off, when you leave. Set the thermostat 7 to 10 degrees higher while you are out. That saves energy without the downsides of a full shutdown. In a humid Arkansas summer, turning the AC all the way off lets moisture build up. The system then works harder to clear it when you get home. The real money-loser is leaving it at full cool in an empty house.
This question starts more thermostat arguments than almost any other. One person swears it is cheaper to leave it running. The other is sure that turning it off saves more. The honest answer sits in the middle. It depends on how long you are gone and how humid it is. Here is how it actually works.
Does Leaving the AC On All Day Cost More?
Leaving your AC at full cool all day costs more than it needs to. While you are at work, the system keeps cycling to hold a cold, empty house. It holds the same temperature you want when you are home. That is hours of cooling that nobody is there to enjoy. It is the single most common way people overspend on summer cooling.
But there is a catch that trips up the simple answer. Turning the system fully off is not automatically the cheapest move either. When the house bakes for eight hours, heat and humidity pile up. The AC then has a lot to remove when it kicks back on. The smarter play splits the difference, and we will get to exactly how.
Is It Better to Turn the AC Up or All the Way Off?
Turning the AC up is the safer bet for most Arkansas homes. Turning it off works only in the right conditions. Raising the thermostat 7 to 10 degrees while you are out shrinks the gap between indoor and outdoor temperature. The smaller that gap, the less heat leaks in, so the system runs less. You capture most of the savings without an empty, sweltering house.
A full shutdown can save a bit more on paper, but it carries a risk here. Our summers are humid, and a closed-up house with no AC turns muggy fast. That moisture is the problem, not just the heat. So as a rule, turn it up for a normal workday, and save the full-off move for longer absences.
How Much Can a Setback Actually Save?
A thermostat setback can save real money, and the amount depends on your home and system. According to the U.S. Department of Energy, you can save about 10 percent a year with a setback. The rule is 7 to 10 degrees for 8 hours a day. That is the bedrock number behind this whole strategy.
The savings are not the same for everyone, though. A team of building engineers writing for PBS News modeled this exact question. They found a clear pattern. Let the house warm up while you are out, then cool it when you return. That uses less energy than holding it cold all day. They also found the savings shrink if your home is well insulated or your system is very efficient. So the better your house holds temperature, the less a setback gains you, but it still helps.
Why Does Humidity Change the Answer in Arkansas?
Humidity is the reason the easy “just turn it off” advice can backfire here. Your AC does two jobs at once. It lowers the temperature, and it pulls moisture out of the air. When you shut it off for hours on a humid day, that moisture creeps back in.
A muggy house feels warmer than a dry one at the same temperature. It also invites mold and can warp wood floors and trim over time. When the AC restarts, it has to wring all that moisture back out. That takes extra run time and extra energy. A system that runs harder than it should also wears out faster, and our air conditioning services keep it running right. Keeping the system on at a higher setting holds the humidity in check. You come home to a house that is drier and easier to cool down.
When Does It Make Sense to Turn the AC Fully Off?
Turning the AC all the way off makes sense in a few specific cases. Most of them come down to how long you will be gone. For a quick errand or a normal workday, leave it on and set it higher. For longer stretches, a full shutdown or a deep setback saves the most.
Full-off works well in a few cases. A multi-day trip or vacation is one. A mild day with outdoor temperatures in the 60s or low 70s is another. So is any time you would rather open the windows than run the system. On a vacation, raise the thermostat well up or shut it down. No one is home to feel the humidity for a few days. Just plan to give it time to dry the house out when you return.
What Is the Cheapest Way to Run My AC All Summer?
The cheapest approach pairs a smart setback with a system that runs efficiently. Set the temperature higher when you are away. Bring it back to comfort before you return. You get savings and a cool homecoming both. A programmable or smart thermostat does this for you, so you never forget to adjust it on the way out.
A few habits stack more savings on top:
- Set the thermostat to around 78 degrees when home, and 7 to 10 degrees higher when away.
- Use ceiling fans so you stay comfortable at a higher setting.
- Close blinds on sun-facing windows during the day to block heat.
- Change the air filter regularly so the system breathes and runs efficiently.
The thermostat strategy only pays off if the system underneath it is healthy. A clean filter, clear coils, and a yearly tune-up keep your AC running efficiently. Our AC maintenance service handles that side, so your setback savings actually show up on the bill.
Run Your AC Smarter With a Fort Smith Pro
The short version: turn it up when you leave, not off, and let a thermostat handle the timing. Save the full shutdown for trips and mild days. That habit alone trims your summer bill without leaving you in a hot, muggy house.
If your AC strains to keep up even with smart settings, the problem may be the system, not your habits. Our veteran-owned team serves Fort Smith, Van Buren, and Greenwood, and we keep systems tuned so they sip energy instead of guzzling it. Cooling falling behind this summer? Book AC repair with Riverside Heating Air Plumbing to get it sorted fast.
