What temperature should a house be during a big freeze? HVAC pros reveal why this 'Goldilocks' temperature is so important for your health and home

When temperatures outside plummet, things indoors can feel like a struggle between staying cozy and keeping heating costs low. It begs the question, what temperature should a house be during a big freeze?

HVAC experts agree that running your heating between 68-70° Fahrenheit is ideal for most homes, claiming it’s essential not only for your own health but also for the health of your home.

Here’s why this Goldilocks temperature range is so important for your property during a big freeze, and how you can keep a home warm all day without breaking the bank in terrible weather.

What temperature should a house be during a big freeze?

When preparing a home for a freeze, Kevin Goude, HVAC expert and owner of First Choice Heating & Air begins, ‘The standard advice is 68°F, but I'd say that you need to keep in mind your home's insulation and layout. Poorly insulated areas or homes with drafty windows, will "feel" better at 70°F as it will protect vulnerable spots like basements or near exterior-facing pipes from freezing. And if you have a zoned type of heating system, prioritize rooms with plumbing to prevent freezing in areas like kitchens or bathrooms.’

Robert Hamerly, principal and CEO at GreenSavers agrees with the best temperature for a thermostat in winter, saying, ‘We recommend keeping your home somewhere between 68 and 72 degrees, and if it’s going to be below freezing for a prolonged period, you’ll want to stay at the lower end of that range, perhaps as low as 65 degrees. Sure, lower temperatures in general use less energy, but steady temperatures use way less energy.’

There is one exception to this rule, Robert Hamerly adds, ‘If we’re talking about heating an unoccupied house, turn your thermostat way down to save energy. We recommend setting the thermostat in an unoccupied home to 50 degrees – cool enough to lower your bills, but warm enough to keep pipes from freezing and plants from dying.’

Why it’s so important

A 2018 study by the WHO found that these minimum temperatures are essential for protecting the health of the elderly, children, and those with chronic illnesses during cold seasons, but this is not the only benefit.

Kevin Goude explains, ‘Beyond avoiding frozen pipes, maintaining a steady temperature protects hidden systems, like water heaters and HVAC duct work, which often run through unheated spaces. If the temperature drops too low, you risk condensation inside your HVAC ducts, which can lead to ice blockages, risk of mold growth, or reduced airflow when the freeze thaws.’

How to keep a home above 68°F for less

There is no denying that keeping a home warm all day is costly. Luckily, there are a few ways you can keep your house warm without turning up the heat:

• Draft-proof: Brooke Greenwood, director of residential product management of Carrier says, ‘Seal gaps around windows and doors with weather stripping to keep warm air inside and cold air out. You can also use thermal curtains to help retain heat and reduce energy use.’
• Close internal doors: Smaller spaces are easier to heat than large ones, Brooke says. She recommends, ‘Closing doors to rooms you're not using will help focus warmth on the spaces you do occupy, reducing wasted energy on unheated areas.’ Our detailed guide explores whether you should close vents in unused rooms in detail, but the consensus from our HVAC experts is not to do it, as it will create more problems than it solves.
• Check your duct work: Brooke continues, ‘Blockages, missing insulation, or poor seals in your duct work can lead to uneven heating, energy loss, and temperature imbalances. Make sure your ducts are properly maintained to keep your home warm efficiently.’ There are ways to eliminate hot and cold spots in your home if there is a persistent issue.
• Make your heating more efficient: There are several mistakes that could make your heating system work harder, from covered vents and radiators to improperly serviced HVAC systems and forgotten water heater maintenance. Fixing them could quickly save you money on energy bills.

FAQs

How cold is too cold for a house?

For an inhabited house, anything below 62°F is considered too cold. Below this, you risk cardiovascular and circulatory complications. Structurally, prolonged cold periods below 50°F put your home at a higher risk of mold and frozen pipes.

Should I leave the heating on all night in freezing weather?

When the temperature outside drops below freezing for a prolonged period of time, it can be helpful to leave the heating on low through the night or schedule it to come on intermittently to keep your home at a consistent temperature. This is especially important in homes with elderly and young children.

How many hours a day your heating should be on to achieve this Goldilocks zone of 68-70°F will depend on which home heating type you have, your home’s insulation, and the temperature outside. Using a smart thermostat can help you to control your heating more precisely so you can save a little money without over or under-heating your space in a freeze.