There is no universal perfect setting
Comfort, humidity and energy use set the answer
Comfort depends on humidity, air movement, clothing, activity, radiant temperature of nearby surfaces, age and health - Not only the thermostat number. Two homes set to 72°F can feel very different if one has humid air and hot sunlit walls while the other has dry air and shaded windows.
For efficiency, the U.S. Department of Energy recommends the lowest comfortable setting in winter and highest comfortable setting in summer, with setbacks when appropriate. Treat familiar numbers as starting points, then observe comfort and indoor humidity.
Practical starting points
| Situation | Starting point | Then adjust for |
|---|---|---|
| Winter, occupied | Around 68°F (20°C) | Comfort, clothing, drafts and vulnerable occupants |
| Summer, occupied | Around 76–78°F (24–26°C) | Humidity, shade, fans and activity |
| Sleeping | Often 60–67°F (16–19°C) | Bedding, age, health and personal comfort |
| Away for hours | Set back heating or raise cooling | Pets, plants, humidity, freeze and heat risks |
Why a setback can save energy
Heat transfer increases with the temperature difference between indoors and outdoors. Lowering the indoor target in winter - Or raising it in summer - Reduces that difference while you are away or asleep. A programmable or smart thermostat can restore comfort before you return.
DOE says a setback for eight hours can reduce annual heating and cooling energy use, though savings vary. Heat pumps, radiant floors and high-mass buildings may need different strategies because recovery can be slow or activate less-efficient backup heat. Follow the system manufacturer or installer rather than copying a schedule blindly.
Humidity changes both comfort and safety
In summer, an oversized air conditioner may cool quickly without running long enough to remove moisture. Raising the setpoint while allowing humidity to climb can feel clammy and encourage condensation on cool surfaces. In winter, very dry air can make occupants uncomfortable even at a higher temperature.
Measure humidity with a reliable hygrometer and use the humidity and dew-point tool. If windows, ducts or walls sweat, solve the moisture source and cold-surface problem rather than only changing the thermostat.
A better way to find your setting
- Choose a conservative starting point and leave it long enough for the home to stabilize.
- Check temperature and humidity in occupied rooms, not directly beside a vent.
- Adjust by 1°F at a time and use fans, blinds, clothing and bedding before large HVAC changes.
- Create modest schedules, then review comfort and energy use over comparable weather.
For bedrooms and special occupants, continue with the broader room-temperature guide. Never let an efficiency target override medical needs or local extreme-weather advice.
Diagnose comfort before moving the setpoint again
If one room is uncomfortable, compare its measured temperature with the thermostat area before changing the whole home. Sun, drafts, closed doors, blocked returns and unbalanced supply airflow can create a local problem that a lower or higher setpoint merely hides.
Use a schedule that reflects when the home is occupied and how quickly the system responds. Large last-minute changes do not necessarily heat or cool a room faster. Heat pumps and other systems can have controls that behave differently from a simple furnace, so follow the equipment guidance when choosing setbacks.
Review humidity, filters and maintenance when comfort or energy use changes unexpectedly. Keep the thermostat clear of direct sun, lamps, vents and other heat sources. For a household member with a medical need, prioritize professional guidance and safe indoor conditions over a generic efficiency recommendation.
After a change, compare similar days rather than judging one hour. Note outdoor weather, occupancy and system runtime. A short record can show whether the new schedule solved the problem or shifted discomfort to another part of the day.