On this page
A warmer cooling schedule can reduce air-conditioning use, but there is no universal dollar saving for raising the thermostat by one degree. Outdoor weather, humidity, house leakage, equipment and time at the new setting all change the result. The budget question is how much cooling energy is avoided while the home remains safe and comfortable.
DOE’s thermostat guidance supplies a broad setback example. The calculations below use an assumed electricity rate and monthly cooling use to show how a percentage becomes dollars. They are estimates to test against consumption data, rather than temperature instructions for a particular person or a promise that every summer schedule saves ten percent.
Key figures
- $14 Example: monthly saving with 5% less cooling
- $28 Example: monthly saving with 10% less cooling
- $42 Example: monthly saving with 15% less cooling
DOE’s setback figure has a defined scope
DOE describes saving as much as ten percent a year on heating and cooling by setting the thermostat back seven to ten degrees Fahrenheit for eight hours a day from its normal setting. The statement combines heating and cooling over a year. It does not establish a fixed summer saving per degree in every climate.
For cooling, a setback means allowing a higher indoor temperature when conditions and occupants permit. For heating, the direction is reversed. Quoting the temperature difference without explaining that distinction can turn an efficiency tip into the wrong control setting.
The starting temperature also matters. A seven-degree change from one baseline is a different indoor condition from a seven-degree change from another. Use the guidance to understand scheduling, not to choose an absolute temperature without considering the people, equipment and humidity in the home.
| Example monthly cooling calculation | Assumed use reduction | Saving at $0.20 per kWh |
|---|---|---|
| Cooling baseline: 1,400 kWh | None | Baseline cooling energy cost: $280 |
| Modeled 5% cooling reduction | 70 kWh | $14 |
| Modeled 10% cooling reduction | 140 kWh | $28 |
| Modeled 15% cooling reduction | 210 kWh | $42 |
Source note: DOE publishes the setback guidance and “as much as 10%” annual heating-and-cooling example. Every monthly-use, rate and percentage scenario in this table is hypothetical; the 15% row is sensitivity analysis rather than a DOE promise.
- 5% less cooling energy70 kWh
- 10% less cooling energy140 kWh
- 15% less cooling energy210 kWh
Source note: DOE publishes the setback guidance and “as much as 10%” annual heating-and-cooling example. Every monthly-use, rate and percentage scenario in this table is hypothetical; the 15% row is sensitivity analysis rather than a DOE promise.
Cooling savings are smaller than whole-bill savings
Suppose total household electricity use is two thousand kilowatt-hours and air conditioning accounts for fourteen hundred. Reducing that cooling portion by ten percent saves one hundred forty kilowatt-hours. Whole-house consumption falls from two thousand to 1,860, a seven-percent reduction.
At the assumed twenty-cent rate, energy charges fall from $400 to $372. If a hypothetical $25 monthly fixed charge remains, the bill changes from $425 to $397. The twenty-eight-dollar saving then represents about 6.6 percent of the original bill, rather than ten percent.
This distinction matters when cooling is only part of the load. Refrigeration, water heating, cooking and other appliances may continue consuming the same electricity after a thermostat change. The household electricity-use guide helps identify which loads belong in the cooling comparison.
Use the local avoided kilowatt-hour rate, including variable delivery charges where they apply. If the tariff changes by time of day, the value of avoiding afternoon cooling can differ from avoiding overnight cooling. The time-of-use guide explains that price difference.
Schedule and controls affect what can be saved
A thermostat schedule works only when the higher setting remains active for the planned period. An early override, an unexpected occupied day or a sensor in a hot location can change runtime. Record schedule changes when comparing consumption instead of assuming the programmed hours were always followed.
DOE notes that programmable thermostat recommendations for heat-pump systems differ, particularly where heating setbacks can trigger less efficient backup heat. Modern compatible controls can behave differently. A summer cooling calculation should not be copied into a winter heat-pump schedule without checking the equipment and control instructions.
ENERGY STAR’s smart-thermostat information explains that certified products demonstrate energy-saving performance and provide control features. Buying a thermostat alone does not establish the saving in one home. Compatibility, installation and the schedule used still determine whether the device addresses the problem.
If a hypothetical new thermostat and installation cost $200 and save $28 during each of four cooling months, that is $112 in modeled annual cooling savings. Simple payback is about 1.8 years before other costs. If the schedule saves only $14 in those months, annual savings are $56 and payback is about 3.6 years. These are cost and savings assumptions, not product prices or certified household outcomes.
Weather and humidity complicate a bill comparison
A lower bill after changing a thermostat does not by itself prove the setting caused the reduction. A cooler month, fewer occupied days or a tariff change may explain some of it. Compare kilowatt-hours, billing days and weather rather than only the dollar total.
For example, nine hundred kilowatt-hours over thirty days averages thirty per day. The same monthly total over twenty-five days averages thirty-six per day. A shorter billing period can make the total look lower even while daily consumption rises.
Humidity can also change comfort at the same temperature. A cooling system’s cycling and moisture removal are affected by equipment sizing and controls. Avoid assuming a portable fan or a higher thermostat setting removes moisture in the same way as the air conditioner.
The air-leak guide addresses unwanted air paths that can add cooling load. Shade, window coverings and closing doors or windows while using air conditioning can support a schedule, but their savings should not be added mechanically to an overlapping thermostat estimate.
Heat safety sets a limit on bill-cutting experiments
CDC guidance describes heat-related illness and groups that can be more vulnerable to heat. A budget calculation cannot establish a safe indoor temperature for every occupant. Pay attention to heat alerts, indoor conditions and people who cannot easily respond to rising temperatures.
Follow public-health heat guidance and seek medical help for concerning symptoms. If there is uncertainty about an occupant’s vulnerability, obtain advice from a health professional. Do not use an energy-saving percentage as permission to leave someone in an unsafe hot home.
An unoccupied home also has conditions beyond personal comfort: pets, moisture-sensitive materials and equipment can limit how far a setting can change. Consider those conditions before extending a schedule simply because the utility’s peak hours are expensive.
Start with a schedule that meets the home’s safety and comfort requirements, then observe consumption. Record the setting, hours, weather and tariff assumptions used for the estimate. A measured reduction in cooling energy is more informative than repeating a universal per-degree saving that the cited guidance does not provide.
Questions people ask
Does raising the thermostat one degree always save a fixed percentage?
No. The cited DOE guidance gives a 7–10°F setback for 8 hours and an annual heating-and-cooling saving of as much as 10%. It does not promise a fixed saving per degree.
Does 10% less cooling mean 10% off my entire bill?
No. In the example, cooling is 1,400 of 2,000 kWh. A 10% cooling reduction saves 140 kWh, or 7% of total use; a remaining fixed fee makes the whole-bill percentage smaller.
Can a smart thermostat guarantee the table's savings?
No. The table is an assumed monthly calculation. Equipment, climate, compatibility, occupied hours and overrides determine the result in a home.
What should be compared after changing a schedule?
Compare consumption, billing days, weather and the hours the setting was followed. Dollar totals alone can confuse a rate change or a shorter billing period with lower cooling use.
Where these figures come from
- Home Upgrades: Programmable Thermostat Setback Guidance US Department of Energy · energy.gov
- Smart Thermostats ENERGY STAR · energystar.gov
- About Heat and Your Health Centers for Disease Control and Prevention · cdc.gov
Figures last checked October 2026.
