How often should you open windows in winter? It might be more than you think

When winter rolls around, we are focused on keeping heat in and staying cozy. This means our windows and doors stay firmly shut whenever possible. However, this can lead to musty, stale air and reduced air quality. This begs the question, how often should you open windows during winter?

While we don't want to freeze or undermine our heating efforts, it is still important to open your windows at least once per day.

Here, air quality experts have explained why opening your windows in winter is a must, and how long to open them to improve indoor air quality while staying cozy.

How often should you open windows during winter?

Josh Mitchell, HVAC technician at Air Conditioner Lab says, 'Ideally, windows should be opened briefly each day, even in winter. A daily airing of around five to 15 minutes can significantly improve indoor air quality without causing a substantial loss of heat.

‘Windows doesn’t need to be wide open to achieve effective ventilation,’ he adds. '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.’

The frequency at which you open your windows can vary however depending on the room and how it's used, Josh adds. ‘Rooms with high occupancy or activities like cooking might require more frequent airing.'

‘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. A house that smells musty can be a sign your air needs a refresh.

‘Be mindful of condensation,' Jeramy adds. 'In colder weather, moisture from indoor activities can condense on cold surfaces, potentially leading to issues like mold. Controlled ventilation and opening windows in winter can reduce condensation.'

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.

Prices correct at time of publication.

Exceptions to the rule

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.

'Geographical location also plays a significant role,’ he adds. ‘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.’

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 Walmart. There are also some highly-rated magnetic window insulation kits, available at Amazon, if you are concerned about energy being lost through older windows.

Tips for opening windows in winter

Opening windows is not rocket science, but there are a few steps you can take to ensure you get maximum benefits in winter without freezing.

When your goal is to improve air quality, it is helpful to open two windows on opposite sides of the house. This will create a thorough draft that will help to push stale air out and refresh your home's air. This should be done on all levels of your house.

It is also helpful to open your windows before you turn your heating on for the day. This is likely first thing in the morning. This helps you make the most of your heating system to help cut energy bills.

Finally, before opening your windows in winter, it can be a good idea to turn your heating off or turn the thermostat down as a sudden rush of cool air can make your heating system work hard with none of the benefits. This is a great quick way to make heating more efficient.

Opening your windows for a few minutes per day in winter is more than enough to air out your home. However, you can also consider sleeping with your windows open in winter to help improve sleep hygiene (so long as you don't live somewhere dangerously cold). This can also help stop condensation on windows overnight.