Heating and cooling your home contributes to almost 50% of yearly energy bills. Sounds like a good place to cut energy use, right?
The answer: Avoid doing things with your thermostat that waste energy.
The short version
Heating and cooling make up close to half of a typical home’s energy bill, so your thermostat is one of the easiest places to save money — or quietly waste it. The catch is that a few habits that feel like they should save energy actually cost you more.
Here are the three biggest thermostat myths we run into in Charleston homes, and the simple fixes that genuinely lower your bill:
- Myth 1: Cranking the thermostat way down cools your home faster. It doesn’t.
- Myth 2: Set it once and never touch it. Adjusting it when you’re away saves real money.
- Myth 3: More fiddling means more comfort. Constant changes make your system run less efficiently.
In Charleston, where the AC runs the better part of the year, getting these right adds up fast. Here’s the why behind each one.
Myth 1: Setting it colder cools your house faster
You walk in, the house is 80° and you want 75°. So you set the thermostat to 70°, figuring it’ll cool things down quicker. It won’t.
Your air conditioner only has one speed. It doesn’t cool harder because you asked for a lower number — it just runs longer. Setting it to 70° when you actually want 75° means the system keeps running past the point you were comfortable, burning extra energy and, often, overshooting into too-cold territory before you notice and bump it back up.
Set it to the temperature you actually want and let it work. It reaches 75° at exactly the same pace whether the dial says 75° or 70°.
Myth 2: Set it once and leave it alone all day
Picking one temperature and never touching it feels efficient, but it means you’re paying to cool an empty house. The U.S. Department of Energy estimates you can save around 10% a year on heating and cooling by setting your thermostat back 7–10° for eight hours a day — say, while you’re at work. (Source: U.S. Department of Energy)
The move is simple:
- When you leave for 8+ hours, set the thermostat about 7–10° warmer in summer (or cooler in winter) than your comfort setting.
- Set it back to comfortable when you’re home.
There’s an old worry that letting the house heat up and then cooling it back down costs more than just holding it steady. It doesn’t — a warmer house loses energy more slowly, so you come out ahead overall.
If remembering to do this twice a day sounds like a chore, that’s exactly what a programmable or smart thermostat is for. It runs the schedule automatically. We install and set them up correctly for your system — ask us about thermostat options if you want one handled.
Myth 3: Constantly adjusting it keeps you more comfortable
People who micromanage the thermostat usually use more energy than people who leave it alone. Every time you change the setting, you risk stopping and restarting the system, and short, frequent cycles are where efficiency goes to die.
Picture it set to 75° in summer. The AC cools the house, hits 75°, and shuts off. A few minutes later you still feel warm, so you knock it down to 73° — and the system fires right back up. Do that a few times a day and you’ve turned steady, efficient operation into a series of short bursts.
Think of your car’s gas mileage: you get better mileage cruising on the interstate than stopping and starting at every light in town. Your HVAC system is the same. Longer, steadier runs are cheaper than constant stops and starts. Pick a comfortable setting and give it time to do its job.
Why this matters more in Charleston
In the Lowcountry, your AC isn’t a few-months-a-year appliance — it runs hard from spring well into fall, fighting heat and humidity the whole time. That means every percentage point of efficiency you give away gets multiplied across a long cooling season.
It also means a thermostat habit that wastes a little in a milder climate can waste a lot here. The flip side is good news: getting these three things right pays off more in Charleston than almost anywhere else.
One more thing worth knowing: if you’re doing everything right and your bills are still climbing, the thermostat may not be the problem. A system low on refrigerant, dirty coils, or leaky ductwork all force your AC to run longer for the same comfort. That’s where a quick AC tune-up or service visit pays for itself.
The takeaways
- Don’t crank the thermostat way up or down to change the temperature faster — your system runs at one speed either way.
- Set the thermostat back about 7–10° when you’re away for 8+ hours. It can save roughly 10% a year.
- Pick a comfortable setting and leave it — constant adjusting causes inefficient short-cycling.
- Let a programmable or smart thermostat run the schedule for you.
Want help dialing in an efficient setup, or wondering why your bills are higher than they should be? Call Blanton & Sons at (843) 256-6454 or request a quote. And if you’d like routine tune-ups that keep your system running efficiently year-round, ask about our maintenance plan.
Reviewed by the team at Blanton & Sons — a family-owned HVAC, heating, and plumbing company serving Charleston and the Tri-County area since 1998.