The US Department of Energy’s standard recommendation is 68°F (20°C) in winter and 78°F (26°C) in summer while you’re home and awake, with the setpoint moved further from that comfort zone while you’re asleep or away. That single pair of numbers covers most ordinary furnace-and-AC systems, but it isn’t the whole answer: a heat pump punishes a deep setback instead of rewarding it, and infants and people over 65 have a narrower safe range than “save energy” advice assumes. The settings below cover all three, with the reasoning so you can adjust them for your own house rather than follow them blindly.
Recommended settings by season and mode
| Season | Mode | Standard furnace/AC | Heat pump note |
|---|---|---|---|
| Winter | Home, awake | 68°F (20°C) | Same setpoint; avoid big swings |
| Winter | Asleep | 60–66°F (16–19°C) | Limit setback to 2–3°F |
| Winter | Away | 60–66°F (16–19°C) | Limit setback to 2–3°F, or use a smart recovery thermostat |
| Summer | Home, awake | 78°F (26°C) | Same setpoint works |
| Summer | Asleep | 82°F (28°C) | Fine; cooling setbacks don’t trigger strip heat |
| Summer | Away | 85°F (29°C), or off with pets/plants considered | Fine |
These are starting points, not fixed rules. Humidity, home age, insulation, and who lives there all shift the number that actually feels comfortable.
What temperature should I set my thermostat in winter?
68°F while you’re home and awake is the Department of Energy’s long-standing figure, chosen as the point where most people stay comfortable in normal indoor clothing without spending more on heating than necessary. You can go a little lower and add a layer, or a little higher if the house runs cold near windows and exterior walls — the number is a starting point, not a safety threshold.
For the hours you’re asleep or out of the house, the DOE’s guidance is to drop the setpoint by about 7–10°F for at least eight hours. In practice that lands most households somewhere in the 60–66°F range overnight. A programmable or smart thermostat handles this automatically; see our guide to installing a thermostat if your current one is still a manual dial with no schedule. One caveat covered below: that full 7–10°F setback applies to furnaces and boilers, not to heat pumps.
What temperature should I set my thermostat in summer?
78°F while home and awake is the figure ENERGY STAR and DOE both point to for air-conditioned homes, and it’s higher than many people expect — a lot of US households run their AC closer to 72–74°F without realizing how much that costs. Each degree below 78°F while cooling means the compressor runs longer and more often.
While you sleep, DOE guidance supports raising the setpoint a few degrees further, commonly cited around 82°F, since a sleeping body generates less heat and a light sheet does the rest. While away for the day, 85°F or shutting the system off entirely both work, as long as humidity, pets, and houseplants can tolerate it; in very humid climates, leaving the AC running on a high setpoint to keep dehumidifying is usually smarter than switching it off completely. A ceiling fan set to spin counterclockwise in summer lets most people raise the daytime setpoint another few degrees without losing comfort, since moving air does the work a lower setpoint would otherwise do.
How much does turning back the thermostat actually save?
The Department of Energy estimates roughly 1% off your heating or cooling bill for every degree of setback sustained for eight hours, which is why an overnight 8–10°F setback is commonly cited as worth about 8–10% a year on heating. The exact percentage depends on climate: homes in mild climates see a bigger proportional saving from a setback than homes in harsh winters, where the furnace has less idle time to recover.
| Setback | Duration | Typical annual heating savings |
|---|---|---|
| 1°F | 8 hours/day | About 1% |
| 7°F | 8 hours/day | About 7–10% |
| 10°F | 8 hours/day | About 10–15% |
These figures assume a standard gas, oil, or electric-resistance furnace. A heat pump behaves differently, which is the next question.
Why is a heat pump thermostat different?
A furnace makes heat by burning fuel or running a resistance element at full output regardless of how far the room has drifted from the setpoint, so a bigger temperature swing before it kicks on just means it runs a little longer — setbacks are close to free. A heat pump moves heat rather than generating it, and it’s most efficient running continuously at a small temperature difference. Recover from a large morning setback and many systems can’t catch up on the heat pump alone; the thermostat calls in backup electric-resistance strip heat to close the gap faster, and strip heat typically costs two to three times more per degree than the heat pump’s normal compressor operation.
The Department of Energy’s heat pump guidance notes that avoiding unnecessary auxiliary-heat operation is one of the most commonly overlooked parts of running these systems efficiently, and that controls should prevent the backup heat from firing when it isn’t actually needed. The practical takeaway: limit a heat pump setback to 2–3°F rather than the 7–10°F that works on a furnace, or use a thermostat designed for heat pumps that recovers gradually on the compressor alone instead of snapping straight to strip heat. If you’re also addressing other seasonal energy loss, our fall winterizing checklist covers the air-sealing and insulation work that reduces how hard any heating system, heat pump included, has to work in the first place.
What’s a safe temperature for infants and older adults?
Energy-saving setpoints assume a healthy adult in normal clothing, and that assumption doesn’t hold for everyone in the house. The National Institutes of Health has warned that older adults can develop hypothermia indoors at temperatures that wouldn’t trouble a younger person, cautioning that a home sitting at 60–65°F can be risky and recommending a thermostat setting of at least 68–70°F where an older adult lives, even during the day. Age-related circulation changes and a blunted sense of cold mean someone can be losing dangerous body heat without feeling uncomfortably cold enough to notice.
Infants have the same vulnerability from the other direction: a large body-surface-area-to-mass ratio and immature temperature regulation mean they lose heat fast in an underheated room and overheat fast in one that’s too warm. A nursery or bedroom with an infant is generally kept in the upper 60s to low 70s°F rather than pushed down to a frugal overnight setback. In summer, the CDC lists older adults and infants among the groups at highest risk of heat-related illness and recommends that anyone in these groups stay in air-conditioned space during hot weather rather than relying on fans alone, since a fan moves air but doesn’t lower its temperature the way a well-set AC does. If your household includes an infant, an older adult, or someone with a chronic illness, treat the standard DOE setback numbers as a starting point to soften, not a target to hit.
Getting more from a programmable or smart thermostat
A schedule only pays off if it actually runs on one. The biggest gap between a thermostat’s potential savings and what a household actually sees is a schedule that gets overridden so often it stops functioning as a schedule at all — set once and never adjusted for the real rhythm of the house. A smart thermostat that learns occupancy, or at minimum a programmable model with separate weekday and weekend schedules, closes that gap for most people better than a single fixed setpoint ever will.
Two other settings matter alongside the number on the dial. First, a wider “deadband” between the heating and cooling setpoints (for example, 68°F heat and 76°F cool rather than 70/72°F) stops the system from switching between modes over a couple of degrees of drift. Second, check whether your thermostat has a dedicated heat-pump or dual-fuel mode and that it’s actually selected; a furnace-profile thermostat controlling a heat pump is a common, invisible source of the auxiliary-heat overuse described above. If the water heater is next on your list of settings to check, see our guide to water heater temperature for the same cost-versus-safety tradeoff applied to hot water.
The bottom line
68°F and 78°F, moved further away from comfort while you sleep or leave, remain the right defaults for most homes with a furnace or standard air conditioner, and the Department of Energy’s figures back both numbers with real savings data. Two exceptions are worth remembering on their own: a heat pump wants a small, steady setback rather than a dramatic one, and a home with an infant or an older adult should hold closer to the comfortable end of the range than the frugal one, especially overnight. Get those two right and the standard numbers do the rest of the work.