How thermostat settings affect your electric bill

How much does one thermostat degree change a Texas electric bill?

Raising your thermostat by one degree makes the air conditioner run less. A reasonable starting estimate for a Texas summer is about 5% to 8% less air-conditioning energy for each degree, not 5% to 8% off the whole electric bill.

For example, suppose your home uses 1,600 kilowatt-hours (kWh) in July and the air conditioner accounts for 800 kWh. Raising the setting one degree might save about 40 to 65 kWh. At 16¢ per kWh, that is roughly $6 to $10 for the month. The lights, refrigerator, water heater, and other uses on the bill do not change with the thermostat.

That estimate is a starting point, not a promise. A field study of 204 homes in a hot, humid climate found about 7% less annual cooling energy per degree, while models produce a wider range because weather, shade, insulation, air leaks, equipment, and household routines differ. In Texas, air conditioning is large enough to matter: the 2020 federal Residential Energy Consumption Survey found that it accounted for 28% of home electricity across the year, and a study of 40 Austin homes measured heating and cooling at about two-thirds of summer electricity use.

Why does one degree save more in some homes than others?

Because the thermostat is only one part of the cooling picture. Outdoor temperature, direct sun, humidity, insulation, air leaks, and the air conditioner itself all affect how much energy the home needs.

Start with the difference between the indoor and outdoor temperatures. Heat moves into a cool home faster when that difference is larger. The examples below show the arithmetic for the same five-degree thermostat change on a warm day and an extremely hot day.

Three other factors change the result:

• Homes collect heat in different ways. Afternoon sun through west-facing windows, humid outside air, cooking, people, and appliances all add to the cooling load. A shaded apartment with shared walls will respond differently from a detached house in full sun.
• Air conditioners lose efficiency in extreme heat. Performance curves that NREL built from manufacturer data imply that a typical single-stage air conditioner at 105°F provides about 6% less cooling and needs about 18% more electricity for that cooling than it does at its 95°F rating point.
• An air conditioner has a maximum capacity. Once it is running nearly continuously, it cannot add much more cooling. The indoor temperature may drift above the setting instead. If the thermostat reads 78°F while set to 74°F on a 106°F afternoon, the system may simply have reached that limit.

Should you keep one temperature or turn the thermostat up while away?

For cooling, turning the thermostat up while the home is empty usually uses less energy than holding one temperature all day. A warmer home absorbs heat from outside more slowly. The later run that cools the home back down does not erase the energy saved during the warmer hours. Department of Energy guidance explains the same effect, and the National Research Council Canada measured about 11% cooling savings from a daytime away schedule in matched research houses.

Four practical limits determine how far to raise it:

• Occupants come first. People who are elderly, ill, or heat-sensitive, pets, medications, and instruments set the ceiling before the bill does.
• Humidity needs runtime. In humid parts of Texas, an air conditioner that barely runs barely dehumidifies. A Florida Solar Energy Center study of vacant homes found that even an 85°F setting produced too little runtime to control moisture, and sustained humidity above about 70% invites mold. That is a concern during a long absence, not a typical workday: ordinary daily temperature changes in the same climate showed no measurable humidity change.
• Cooling back down takes time. If you want the home comfortable when you return, schedule the change early enough. If your electricity plan charges different prices by hour, check whether the recovery would fall in an expensive period.
• Winter works differently for some heat pumps, covered below.

Setting the thermostat lower than you want does not cool the home faster on common single-stage systems; it only overshoots the target. Schedules beat repeated manual overrides for the same reason: they capture the away hours without relying on anyone remembering.

What temperature should you set your air conditioner to?

There is no single correct temperature. Start with the highest setting that keeps the people and pets in your home comfortable and safe, then raise it during hours when no one is home. In humid weather, the air conditioner also needs enough runtime to control indoor moisture.

The familiar 78°F recommendation came from a sample schedule in a 2009 ENERGY STAR guide. The guide called it a starting point, not a requirement. The Department of Energy later recommended setting the thermostat as high as is comfortable, with humidity control where needed. The 2020 federal survey found that 74–76°F was the most common daytime summer setting in U.S. homes, but comfort and home conditions matter more than matching a national average.

How does lower air-conditioning use reduce your bill?

Your meter records electricity in kilowatt-hours (kWh). To estimate the bill reduction, multiply the kWh saved by the energy and delivery charges that apply to each kWh. Fixed monthly charges stay the same.

For example, saving 60 kWh at a combined energy and delivery price of 16¢ per kWh lowers the bill by $9.60.

If your plan includes a usage-based bill credit or different prices at different times, the exact result may vary. Your Electricity Facts Label shows the formula, and the bill-credit and free-nights guide explains those plan types.

What changes in winter if you have a heat pump?

Lowering the thermostat while you are away can also save energy in winter. A heat pump needs special care, however. It normally heats the home by moving heat from outdoors to indoors, but many systems can also switch on electric resistance strips called auxiliary heat.

A large temperature increase can cause those strips to turn on so the home warms faster. Resistance heat can use two to four times as much electricity to provide the same warmth as the heat pump in mild weather. DOE's guidance is to keep heat-pump temperature changes moderate or use a thermostat with adaptive recovery, which starts early and warms the home gradually. If a winter bill spikes after a cold snap, auxiliary heat is one of the first things worth checking in the high-bill diagnosis.

How can you measure the effect in your own home?

A one-week test with your own meter data can give you a more useful estimate than a general percentage. Texas smart meters record usage in 15-minute intervals, but daily totals are enough for this test.

Most customers in competitive areas can get this data from Smart Meter Texas or their electricity provider's usage portal. A smart thermostat can help if you want the temperature to change automatically. ENERGY STAR certification is based on field-measured average savings of about 8% of heating and cooling costs, but results vary. In one Florida field study, savings averaged near 10%, while several homes that already used effective schedules saved nothing. The schedule saves the energy; the smart thermostat makes the schedule easier to follow.

Thermostat settings FAQ

What temperature should I set my air conditioner to in a Texas summer?

There is no single correct number. Use the highest setting that keeps everyone comfortable and safe and controls humidity, then raise it several degrees while the home is empty. The familiar 78°F recommendation began as a starting point in a 2009 ENERGY STAR guide, not a rule.

Is 72 degrees too cold to keep the air conditioner?

It is a choice, not a mistake — but each degree below your comfortable ceiling adds several percent to cooling energy, so 72°F costs meaningfully more than 75°F or 78°F in the same house. On 100°F-plus afternoons, many systems also cannot hold a low setting: the air conditioner runs continuously and the indoor temperature drifts up, which reflects the equipment's capacity rather than a malfunction.

Is it cheaper to leave the AC at one temperature all day?

No. Setting the thermostat up while the home is empty uses less energy than holding one temperature, because a warmer house absorbs heat more slowly and the evening catch-up removes less than the day saved. In humid areas, avoid turning the system fully off for long absences — moisture control needs some runtime — and on a time-of-use plan check when the recovery hours fall.

What is the 20-degree rule for air conditioning?

Two real engineering facts get garbled into a false rule. Air conditioners are designed to cool the air passing through them by roughly 20°F, and residential sizing conventions assume about 75°F indoors on a 95°F-class design day. Neither forbids setting the thermostat more than 20 degrees below the outdoor temperature — but in extreme heat a system may run continuously and the home may hold above the setpoint, which is the capacity limit those conventions describe.

How much does raising the thermostat from 70 to 75 save?

As a range, five degrees might reduce air-conditioning energy by about 25% to 35%. For a home using 800 kWh for air conditioning in July, at a combined energy and delivery price of 16¢ per kWh, that is roughly $30 to $45 for the month. The exact result depends on the weather, the home, and the plan formula, so compare the estimate with your own meter data.

What should the thermostat be at night for sleeping?

Sleep research favors cooler rooms than energy guidance does, and only you can price that tradeoff. Ways to sleep cool without cooling the whole house all night include a ceiling or room fan, lighter bedding, and cooling the bedroom rather than the whole home. A free-nights plan changes the price of night hours only if its formula says so; check the Electricity Facts Label rather than assuming.

Sources and related reading

The Department of Energy's Energy Saver thermostat pages were retired from energy.gov in mid-2026; the DOE Building America Solution Center guide carries the same guidance — the 10% setback figure, the milder-climate caveat, and adaptive recovery for heat pumps — and the archived Energy Saver page preserves the last published wording. Field and laboratory studies cited above: the Florida Solar Energy Center's 204-home monitoring study (about 7% of annual cooling per degree) and vacant-home humidity study, the National Research Council Canada twin-house setback experiment, NREL's air-conditioner performance-curve report, and the Florida Solar Energy Center's smart-thermostat field evaluation. Usage and behavior data come from the U.S. Energy Information Administration's 2020 Residential Energy Consumption Survey state tables and Pecan Street's Austin research; ENERGY STAR documents its smart-thermostat savings basis and the 2009 guide where the 78°F schedule originated.

Reviewed August 17, 2026. Figures marked illustrative are examples, not measurements of your home, and estimates here are educational ranges — not predictions, HVAC sizing, or diagnostic advice. Savings depend on the home, equipment, weather, humidity, occupancy, and plan terms. Use qualified professionals for equipment, electrical, refrigerant, moisture, and health concerns.

Continue with how to lower your electric bill, why your electric bill is so high, bill credits and free nights, how to read an Electricity Facts Label, or how to set up apartment electricity.