snowed-in house

Ventilating properly in the winter

Prevent mould and save energy

Poor ventilation can have a negative impact on the energy efficiency of your home, in addition to providing an excellent environment for mould. Air humidity and your indoor environment have a significant impact on the efficiency of your heating system. There are a number of attractive subsidies available for modern heating and ventilation systems, which can also improve efficiency. Find out how to ventilate your home properly in winter without losing valuable heat.

Moisture is the enemy

Mould loves a damp and wet environment. The warmer the air, the more moisture it can hold. Hot, damp air can be unbearably humid in summer and can make you sweat much more than you otherwise would.


The walls of our homes aren’t particularly fond of moisture either. The moisture in warm air can condense on cooler walls, windows and other surfaces, inevitably leading to mould.

Ventilating properly in the winter

We have to keep our homes warm in the winter, so opening the window isn’t particularly energy-efficient. However, ventilating properly in winter can help retain as much heat as possible while also making sure that air is exchanged efficiently.

A lot of people make the mistake of keeping their windows slightly open for long periods of time. This significantly slows down the speed at which air is exchanged, while giving heat a perfect route to escape. This is particularly true for windows placed directly over radiators. Opening your windows wide for short periods of time is much more efficient and is the best way to exchange air quickly in your home.

Ventilate correctly - misted up window

Intermittent ventilation

  • Open your windows or doors as wide as they will go to maximise the amount of air that can be exchanged.
  • Doing this for around 10 minutes twice a day will be enough for most rooms.
  • You can use a cross breeze or draft to make this even more efficient. Do this by opening windows at opposite ends of a room.
  • If a room doesn’t have windows at opposite ends, you can open windows and doors in other rooms to get rid of moisture quicker.
  • If you live in an older building which isn’t that well insulated, five minutes will probably be enough.

Should all rooms be treated the same way?

Living room

This is the area we spend most of our time, and it’s normally heated to a comfortable level. Ideally, the air humidity level in your living room should be between 40% and 60%. You will need to open the windows wide on a regular basis and heat the room correctly to achieve this.


Most people like to have it a bit cooler in the bedroom. However, air humidity levels in these rooms can be significantly higher than in other areas of the house because of sweating and respiration. If you don’t heat the bedroom at all, you’re at risk of mould. Try to ventilate this room thoroughly in the morning and evening.

Kitchen and bathroom

Along with the laundry room, these are usually the dampest rooms in your home. Showering and cooking create a lot of water vapour to get rid of.


Basements are particularly damp areas and are usually left unheated. Unless there’s frost on the ground, you should keep the windows in the basement open a crack at all times to facilitate the flow of air. When the weather turns cold, we recommend opening the windows in the basement wide at regular intervals.

Basement level living space

These areas tend to have relatively high humidity levels. As a result, they need to be ventilated and heated even if they are rarely used. In fact, the same goes for any room which you use only rarely – never let them get completely cold to avoid heat bridges and condensation.


Insulated lofts are very effective at trapping heat, so keep the heating to a minimum and ventilate on a regular basis to keep moisture levels down. If your loft isn’t insulated, it will be very difficult to heat. On the other hand, it won’t need to be ventilated as often.

The right way to heat your home

Ventilating and heating your home properly in winter will save energy and provide a healthy indoor environment. Instead of constantly fiddling with the thermostat, try and keep your heating at a consistent comfortable temperature throughout the day.


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