Does ventilation increase the humidity in winter? Answers to the most frequently asked questions about humidity in winter

Find out in this article

• Humidity in winter: does ventilation in winter increase humidity?
• How do I measure the humidity and what is the optimum humidity in the home in winter?
• Humidity and heated air in winter: how are they related?
• Why is humidity important for the body?
• What do I need to consider when ventilating the bedroom?
• Correct ventilation in winter – why shouldn't windows be tilted in winter?
• How long should you opening windows in winter?

Humidity in winter: does ventilation in winter increase humidity?

No, ventilation does not increase humidity in winter. People often get the impression that the air outside is more humid than the air inside the home – but this is not always true. If the outside air is colder than the air in the home in winter and the window is opened, the cold air enters and the humidity automatically drops. 

To illustrate this, here is a brief numerical example: If there is a relative humidity of 69 per cent outside at 0 degrees, this corresponds to just 18 per cent relative humidity inside at 20 degrees. This is due to the air's ability to absorb water at different temperatures. To summarise, airing in winter lowers the humidity indoors. A glance at the hygrometer before and after airing shows the effect at a glance.

How do I measure the humidity and what is the optimum humidity in the home in winter?

The optimum humidity level is between 40 and 60 per cent. To find out whether there is optimum humidity in your home, you should use a hygrometer. This is a smart helper in everyday life and measures the humidity. 

You can find more information about the ideal humidity level and how to measure it in this video.

Humidity and heated air in winter: how are they related?

Cold air in winter can absorb less moisture. If this outside air gets indoors, it becomes even drier with the heating. This is due to the fact that the cold air from outside contains very little water vapour. A humidifier can help here. You can find humidifier tips as well as questions and answers about humidifiers in our blog article. Read more here.

Why is humidity important for the body?

If the room air is below 40 per cent of relative humidity for a long period of time, this has unpleasant effects on the body. This dries out the mucous membranes and can lead to coughing and breathing difficulties. Skin problems and an increased susceptibility to infections are also possible. You can find out more about the effects of dry indoor air on the body here. A humidifier can help here and ensure that it doesn't get that far. It ensures an optimal indoor climate in which you can feel more comfortable. 

Excessive humidity also has an impact on our health. You can find more information here.

What do I need to consider when ventilating the bedroom?

After purchasing a humidifier, the question often arises as to whether you can continue to sleep with the window open or tilted. The answer is no, because that would be counterproductive. The humidifier constantly supplies moisture to the room air. At the same time, the cold, very dry outside air enters the room through the window. We therefore recommend the well-known "shock ventilation" for the bedroom as well, so that fresh air enters your own four walls. The window should be opened for a few minutes in the morning and in the evening.

Correct airing in winter – why shouldn't windows be tilted in winter?

It is not advisable to leave the window permanently tilted in winter. The air exchange is low and a permanently tilted window leads to high heat loss. This can also increase the risk of mould because the wall and ceiling along the window cool down considerably. This can lead to condensation and mould growth. 

The tilt position is not fundamentally bad and can still be helpful in some situations and for a short time. For example, if you want to remove food odours, this can be useful if it is not possible to shock-ventilate the room at the moment.

How long should you opening windows in winter?

Ideally, you should open the windows wide for a few minutes in the morning and evening, allowing fresh air to flow into the rooms and then close the windows again completely after airing. This way the humidifier continues to work effectively.

Would you like to find out more about how a humidifier can help you feel better or what different humidifier systems are available? You can find more information on our information page about humidifying the air.

More about humidifying the air

If you have questions related to indoor room climate, please get in touch with us. Or subscribe to our newsletter to regularly get informed about current topics regarding indoor climate, experience reports or Stadler Form insights.