How often should you open windows during winter? The experts’ guidance

Keep rooms fresh when the weather turns cold. This is how often interiors professionals recommend windows are opened

window three image split
(Image credit: Future)

Ventilation is a crucial factor for interiors that are healthy and feel fresh, too. Stale air is unpleasant and, if it’s musty, can even be a sign that something’s amiss.

Opening the windows is an important part of letting fresh air in and stale air out, and will make your home smell nice to boot but, while it’s natural to do so in the warmer months, in winter isn’t it just letting the heat out?

The answer is that it is still vital to open windows during the winter and we asked the experts to share their knowhow on how frequently to do so and how to stay cozy, too.

The rules on opening windows during winter

Before the ‘how often’, it’s important to establish why we’re talking about opening windows in the coldest months of the year. ‘Opening windows in the winter allows fresh air to circulate, helping to improve indoor air quality by removing pollutants, odors and moisture,’ explains Jeramy Sibley, president of Glass Doctor, a Neighborly company.

‘Opening windows in winter is important for improving indoor air quality,’ agrees Josh Mitchell, HVAC technician at Air Conditioner Lab. ‘Homes are generally sealed more tightly during cold months, leading to a buildup of indoor pollutants. Fresh air helps dilute and displace harmful indoor air contaminants like CO2, VOCs, and allergens.’

Josh Mitchell
Josh Mitchell

Josh Mitchell is, an HVAC technician and the owner of

living room with white sofa and colourful armchair and accessories

(Image credit: Assignment / Polly Wreford / Claudia Bryant)

How often should you open windows in winter?

Worried you’re going to get cold? Don’t be. While you do need to open windows in winter, it doesn’t have to be for long.

‘Open your windows for about 10 minutes each morning to help the stagnant, humid air out,’ says licensed home inspector and owner of Property Inspection Pros in Baltimore MD Sol Kruk.

‘Ideally, windows should be opened briefly each day, even in winter,’ agrees Josh Mitchell. ‘A daily airing of around five to 15 minutes can significantly improve indoor air quality without causing a substantial loss of heat.’

Be influenced by the particular circumstances, however. ‘The frequency depends on factors like the size of your living space, the number of occupants, and daily activities,’ says Jeramy Sibley.

Josh agrees. ‘It’s important to consider the room’s occupancy and activities,’ he says. ‘Rooms with high occupancy or activities like cooking might require more frequent airing. Also, use curtains and blinds effectively; opening them during sunny days can help warm the room naturally, making it more comfortable to open windows briefly.’

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Factor in the weather

living room ideas in green and white with rattan

(Image credit: Future/Jan Baldwin)

What it’s like outside your home on a particular winter day is definitely going to affect your willingness to open windows in winter.

‘Weather conditions should certainly influence window-opening practices,’ says Josh Mitchell. ‘On milder winter days, it’s more feasible to air out your home without significant heat loss. During extreme cold or inclement weather, the duration should be reduced to minimize heat loss and prevent discomfort.’

And inevitably the cost of heating a home will play into window-opening decisions. ‘The outside temperature is a significant factor,’ says Jeramy Sibley. ‘Opening windows for an extended period in colder climates may lead to heat loss, potentially increasing your heating costs. On milder days, short bursts of window opening can be more effective.’

You can ensure windows retain heat when closed by insulating them with weatherstripping foam, at Amazon. There are also magnetic window insulation kits, available at Amazon, if you are concerned about energy being lost through older windows.

Location counts

Gauze and brass rod window treatment in kitchen

(Image credit: Sara Story Design)

Where you live matters when it comes to opening windows in winter, of course. ‘If you live in a colder climate, you might need to be more cautious about the duration and extent of window opening to avoid excessive heat loss,’ says Jeramy Sibley. ‘In milder climates, you may have more flexibility.’

‘Geographical location plays a significant role,’ agrees Josh Mitchell. ‘In regions with milder winters, windows can be opened more frequently and for longer periods. In contrast, in areas with harsh winters, openings should be shorter and less frequent to maintain a comfortable indoor temperature.’

How wide open do windows need to be?

Bay window with original solid wood shutters

(Image credit: Future / Rachel Smith)

When we’re talking about how often you should open windows during winter, you might also wonder exactly how open the window needs to be. And the answer is not very.

‘Windows don’t need to be wide open to achieve effective ventilation,’ explains Josh Mitchell. ‘Cracking them slightly is often sufficient to allow for air exchange. The aim is to create cross-ventilation without causing a significant drop in room temperature.’


What happens if you don’t open windows in winter?

If windows aren’t opened during winter, there’s a risk of condensation as well as a threat to indoor air quality. A house that smells musty can be a giveaway. ‘Be mindful of condensation,’ explains Jeramy Sibley, president of Glass Doctor, a Neighborly company. ‘In colder weather, moisture from indoor activities can condense on cold surfaces, potentially leading to issues like mold. Controlled ventilation can help manage this.’

If you’re concerned about indoor air quality in your home, you might want to invest in one of the best air purifiers, which can help improve the atmosphere. And if condensation is a problem, the best dehumidifiers can also make a home healthier by preventing mold growth. And practice the other ways to reduce your home’s humidity, too, if it’s an issue.

Sarah Warwick
Contributing Editor

Sarah is a freelance journalist and editor. Previously executive editor of Ideal Home, she’s specialized in interiors, property and gardens for over 20 years, and covers interior design, house design, gardens, and cleaning and organizing a home for H&G. She’s written for websites, including Houzz, Channel 4’s flagship website, 4Homes, and Future’s T3; national newspapers, including The Guardian; and magazines including Future’s Country Homes & Interiors, Homebuilding & Renovating, Period Living, and Style at Home, as well as House Beautiful, Good Homes, Grand Designs, Homes & Antiques, LandLove and The English Home among others. It’s no big surprise that she likes to put what she writes about into practice, and is a serial house renovator.