The question sounds like it should have a number for an answer. Search for it and plenty of pages give one, and the numbers differ. The more useful answer is about how the setting changes through the day, because that is where the savings are, and about the situations where turning the heat down is the wrong move.
This guide covers what the U.S. Department of Energy says about setting the thermostat back, why it works, how a heat pump changes the picture, and the three exceptions: pipes, people, and an empty house.
The number, and why this guide does not pick one
None of the federal sources checked for this guide sets a single “right” winter temperature. What they describe is a method: a comfortable setting when you are home and awake, and a lower one when you are asleep or away. The comfortable setting depends on the household. The lower one is where the money is.
That also answers the question of whether any particular number is “good”. A setting is good if the people in the house are warm enough and safe at it, and it is cheaper the lower it is and the longer it stays there. The exceptions below matter more than the choice between two comfortable numbers.
What DOE says setbacks save
The Department of Energy’s advice is direct. “If you have a thermostat, set it lower by 7–10 degrees for 8 hours a day while you are away or asleep,” a 2022 DOE article on winter savings says. “Doing so can shave as much as 10% per year off your heating bills.”
Two things about that figure. It is an upper bound, “as much as”, not a promise. And the Building America Solution Center, a Department of Energy resource run by Pacific Northwest National Laboratory, adds a caveat about climate: “The percentage of savings from thermostat setback is greater for homes or buildings in mild climates than for those in more severe climates.” A setback still saves in a cold winter, but the percentage is not the same everywhere.
Why turning the heat down saves energy
One worry is that the furnace works so hard to warm the house back up that a setback costs more than it saves. DOE’s explanation is the reason it does not: “In winter, the lower the temperature inside your home, the slower the loss of heat. So, the longer you keep your thermostat at the lower temperature, the more money you save because your home has lost less energy than it would have at a higher indoor temperature.”
Put simply, a house leaks heat faster when it is warmer inside. A cooler house for eight hours leaks less heat for eight hours, and the energy spent warming it back up is less than the energy the warmer house would have lost in that time.
Night and daytime setbacks
The two natural setback periods are overnight and during the working day, if the house is empty. DOE’s advice covers both: “while you are away or asleep.”
A programmable or smart thermostat does this without anyone remembering. The Building America Solution Center notes that “programmable thermostats allow the home owner to set setback times so the system will automatically turn down heating or cooling when occupants are away or asleep,” and it recommends that “in homes with central HVAC equipment, a programmable thermostat should be installed.” Changing the schedule on the thermostat is a homeowner’s job. Replacing or rewiring the thermostat is not.
DOE adds one more lever that costs nothing: “lower your heating costs by layering up in the winter. You can significantly reduce the amount of heat needed to keep your family cozy and comfortable by dressing in warm clothes and layers and throwing on blankets to retain body heat so you can lower those thermostats.”
Manual, programmable and smart thermostats
A setback does not need new equipment. The Building America Solution Center notes that “homeowners with conventional thermostats can save energy and money just by remembering to adjust their thermostats every day.” The catch is the remembering.
A programmable thermostat removes that step with a fixed schedule. A smart thermostat goes further. ENERGY STAR describes one as “a Wi-Fi enabled device that automatically adjusts heating and cooling temperature settings in your home for optimal performance,” and lists what they can do:
- Learning. “Many smart thermostats learn your temperature preferences and establish a schedule that automatically adjusts to energy-saving temperatures when you are asleep or away.”
- Geofencing. It “allows your smart thermostat to know when you’re on the way home and automatically adjusts your home’s temperature to your liking.”
- Remote control. “Wi-Fi enabled thermostats allow you to control your home’s heating and cooling remotely through your smartphone.”
ENERGY STAR’s context for why this matters: “For the average American household, almost half of the annual energy bill goes to heating and cooling.” Its buying advice starts with one check: “Make sure the smart thermostat you purchase is compatible with your heating and cooling system.” That is a question to settle before buying, not after, and the wiring of a new thermostat is a job for a technician.
A learning thermostat also needs time. For the adaptive-recovery thermostats used with heat pumps, the Building America Solution Center says they “‘learn’ from experience how soon to turn on the heating or cooling system,” and that “within a week or so of installation, a programmable thermostat with adaptive recovery technology will have adjusted to the home’s specific heating and cooling system, construction type, and local climate.” The first week’s behaviour is not the thermostat’s settled behaviour.
The heat pump exception
A heat pump changes the setback question, because of what happens when the house is warmed back up after a deep setback.
The Building America Solution Center is specific: “If the home has a heat pump for heating and cooling, the programmable thermostat should have adaptive-recovery technology.” It explains why: these thermostats are “equipped with an adaptive-recovery technology that directs the heat pump to minimize the use of costly auxiliary heating, which is typically electric resistance heat, when returning the space from a set-back temperature to the desired temperature.”
It gives an example: “the owner may input a temperature setback to 62°F during the day in the winter while they are at work with the temperature returning to 68°F at 5 pm.” The thermostat “senses the temperature difference to be overcome and triggers the heat pump earlier allowing it to bring up the space temperature gradually over a longer period of time. This allows the heat pump alone to provide the temperature increase and minimizes the use of the more costly electric resistance auxiliary heat.”
The practical point for a heat pump owner: a setback is not ruled out, but the thermostat doing it needs to be one that recovers gradually. If you are unsure whether yours does, that is a question for the thermostat’s manual or a technician.
The pipes exception
A setback that lets the house get cold in a hard freeze can cost far more than it saves. The American Red Cross’s frozen-pipe guidance says, for very cold weather: “Keep the thermostat set to the same temperature both during the day and at night. By temporarily suspending the use of lower nighttime temperatures, you may incur a higher heating bill, but you can prevent a much more costly repair job if pipes freeze and burst.”
It names the pipes at most risk: “water supply pipes in unheated interior areas like basements and crawl spaces, attics, garages, or kitchen cabinets,” and “pipes that run against exterior walls that have little or no insulation.” In a cold snap, those are the reason to suspend the night setback.
The people exception
A setback is for a household that can be comfortable and safe at the lower setting. The CDC’s hypothermia guidance names those who are most at risk: “Victims of hypothermia are often,” it says, “older adults with inadequate food, clothing, or heating” and “babies sleeping in cold bedrooms.”
If an infant, an older adult or anyone with a health condition that cold could worsen is in the house, their comfort and safety set the minimum, and the savings come second. A deep night setback in a baby’s room is not the place to save 10%.
The empty house
Going away for a few days in winter is the biggest setback opportunity, and the one with a floor. The Red Cross says: “If you will be going away during cold weather, leave the heat on in your home, set to a temperature no lower than 55° F.” Below that, the risk to the pipes starts to outweigh the saving.
Where the thermostat is matters
A thermostat can only control the temperature where it sits. One manufacturer’s furnace installation manual lists what to keep a thermostat away from, including “radiant heat from the sun”, “hot or cold air from registers” and “light fixtures or other appliances”. A thermostat warmed by a lamp or a sunny window stops calling for heat before the rest of the house is warm, and every setting on it is off by the same amount.
Keeping heat sources away from the thermostat is a homeowner’s check. Moving the thermostat is a wiring job.
The homeowner checks
The safe thermostat-related checks are short:
- The thermostat. Confirm the mode is heat, the schedule matches the household, and nothing is warming it.
- The filter. A clogged filter restricts airflow through the whole system. The furnace manual says that “improper filter maintenance is the most common cause of inadequate heating or cooling performance.”
- Clearances. Registers and return grilles open and clear, and nothing stored against the furnace.
- The carbon monoxide alarm. Test it.
If the house cannot reach the setting on the thermostat, the problem is not the setting. See furnace blowing cold air and furnace short cycling, or heating maintenance and tune-ups. For the wider picture of heating costs here, see the guide to winter heating costs and safety in Boulder.
Frequently asked questions
Is 68 a good temperature for heat in the winter? It is the setting PNNL’s Building America Solution Center uses in an example of a heat pump returning from a 62°F daytime setback. No federal source checked for this guide sets 68 as the right number. The saving comes from how far and how long you set it back, not from the daytime setting itself.
Should you turn the heat down at night? Yes, unless one of the exceptions applies. DOE says setting the thermostat “lower by 7–10 degrees for 8 hours a day while you are away or asleep” can “shave as much as 10% per year off your heating bills.” The exceptions are a hard freeze with pipes at risk, anyone at higher risk from cold, and a heat pump without a thermostat that recovers gradually.
What is the cheapest temperature to keep your house in winter? The lowest one at which the people in the house are safe and comfortable, for as long as possible. DOE explains that the lower the indoor temperature, the slower the house loses heat. The Red Cross’s floor for an empty house in cold weather is 55°F.
Does turning your heat on and off raise your bill? Setting the heat back does not. DOE says the longer the thermostat stays at the lower temperature, “the more money you save because your home has lost less energy than it would have at a higher indoor temperature.”
Why does my house feel cold at 69 degrees? One reason is where the thermostat reads. If it is warmed by sun, a register, a lamp or an appliance, it reads higher than the rooms around it and stops calling for heat early. One furnace manual lists “radiant heat from the sun”, “hot or cold air from registers” and “light fixtures or other appliances” among what to keep a thermostat away from. If the house still feels cold with the thermostat well placed, the cause is in the rooms or the system, not the number.
What is a setback on a thermostat? A scheduled lower temperature for times when the house is empty or everyone is asleep. PNNL’s Building America Solution Center describes programmable thermostats that let the homeowner “set setback times so the system will automatically turn down heating or cooling.”
What should an unoccupied house be set at during winter? The Red Cross says to “leave the heat on in your home, set to a temperature no lower than 55° F” if you will be away during cold weather.
Sources
- U.S. Department of Energy, Office of Indian Energy, Six Simple Steps To Save Energy and Money This Winter (January 25, 2022) – https://www.energy.gov/indianenergy/articles/six-simple-steps-save-energy-and-money-winter
- Pacific Northwest National Laboratory for the U.S. Department of Energy, Building America Solution Center, Thermostat Controls – https://basc.pnnl.gov/resource-guides/thermostat-controls
- ENERGY STAR, Smart Thermostats – https://www.energystar.gov/products/smart_thermostats
- American Red Cross, Preventing & Thawing Frozen Pipes – https://www.redcross.org/get-help/how-to-prepare-for-emergencies/types-of-emergencies/winter-storm/frozen-pipes.html
- Centers for Disease Control and Prevention, Preventing Hypothermia (page dated August 25, 2026) – https://www.cdc.gov/winter-weather/prevention/index.html
- Goodman, Installation Instructions for *M9S80 & *C9S80 gas furnaces (thermostat location, filter maintenance) – https://documents.alpinehomeair.com/product/goodmangm9s8gc9s8installationmanual.pdf
