What Two Degrees on Your Thermostat Is Actually Worth

Everyone has heard that turning your thermostat up a couple degrees in summer saves money. Most people nod, change nothing, and keep paying the same electric bill. That's because "saves money" is vague, and vague doesn't change behavior. So here's the actual math: every degree you raise your thermostat in summer (or lower it in winter) cuts your heating and cooling costs by roughly 1 to 3 percent. That sounds small until you run it across a whole summer.

Start with the size of the bill. Heating and cooling is usually about half of a home's energy bill. If your summer electric bill is $200 a month, roughly $100 of that is air conditioning. Raise the thermostat 3 degrees — say from 72 to 75 — and you save roughly 3 to 9 percent of that cooling cost. Take the middle: about $6 a month. That doesn't sound like much either. But stretch it across a six-month cooling season and it's $36, and across a full year of heating and cooling adjustments it's $70 to $100 a year, every year, for pressing a button.

But the real savings aren't in the thermostat alone — they're in the habits around it. The biggest waste is cooling an empty house. If you leave the AC at 72 all day while nobody's home, you're paying to keep furniture comfortable. A programmable thermostat, or just the habit of bumping it up 7 to 10 degrees while you're at work, can cut cooling costs by up to 10 percent on its own. On that same $200 summer bill, that's $10 a month just for letting the house be warmer while it's empty. Combine that with a couple degrees at night and you're looking at $100 to $150 a year without ever feeling uncomfortable.

The reason people resist this is comfort, and that's fair — nobody wants to sweat in their own house. But there's a difference between 72 and 75 that your body mostly stops noticing after a day or two, especially if you use fans. A ceiling fan makes a room feel 4 degrees cooler for about a penny an hour in electricity, because moving air pulls heat off your skin. The trick is that fans cool people, not rooms — turn them off when you leave, or you're paying to cool an empty room twice.

There are a few traps to avoid. First, don't turn the AC completely off on a hot day and then blast it when you get home. Air conditioning is most efficient running steadily; the "blast" approach forces the system to work hardest at the hottest part of the day, and it takes hours to pull the humidity back out of the house. A setback of 7 to 10 degrees is the sweet spot — more than that and the recovery cost eats the savings. Second, don't close vents in unused rooms. Modern systems are balanced for the whole house, and closing vents raises pressure and can actually damage the system. Third, change your air filter. A clogged filter makes your system work harder for the same cooling, and a $5 filter every couple months is one of the cheapest efficiency upgrades that exists.

If you rent and can't change the thermostat or the system, you still have moves. Blackout curtains on sun-facing windows can drop a room's temperature several degrees in the afternoon. A $25 fan in the bedroom lets you sleep fine at 76 instead of 72. And if your landlord controls the building's temperature, the same math applies to space heaters in winter — one small heater in the room you're actually in beats heating the whole apartment.

Nobody's getting rich off thermostat math. But $100 a year, every year, for the rest of your life, is $3,000 over thirty years — and that's before counting the programmable thermostat savings on top. It's the easiest money you'll ever make, because the work is just deciding once that 75 is fine.

Disclosure: This article was drafted with AI assistance and reviewed by the author.