ᐅ Very wet windows overnight.

Good morning!

Since this is my first post, I hope it’s in the right subforum...

I haven’t built myself, but I’m hoping to find some ideas here about the cause of my problem. It’s really stressful...

Now to the problem: Especially during the cold season, my windows get completely covered in condensation (see pictures/video below). Overnight, they become extremely wet, and you need 1-2 large towels to dry them off.
In addition, the water collects along the bottom edge, creating the perfect conditions for mold to develop.

There is frequent and prolonged ventilation during the day and morning, but this doesn’t help. The windows don’t feel very airtight either; you can especially feel drafts at the edges on windy days.

What causes this? Is it an insulation issue? Are the windows to blame? Or the walls? Unfortunately, I’m no expert...

Thank you very much in advance for your answers!

You are responsible because you are ventilating incorrectly and heating too little.

Please measure the indoor air quality and change your ventilation habits.

How should proper ventilation be done? Should I leave the window open overnight so that I wake up really cold in the morning?

Apart from that, the heating here is electric storage heating, which means it has a limited heating capacity and consumes a lot of electricity.

Indoor air quality was measured here about a year ago; as far as I remember, the humidity was quite high, but I don’t recall the exact number.

I ventilate several times a day with fully opened windows, not just tilted. Especially in the morning and evening.
The windows remain closed overnight.

The problem does not occur throughout the whole day, only in the morning. To what extent is this considered incorrect ventilation behavior?

First, get a moisture meter. Then always try to keep humidity below 50%, which you can only achieve if the heating is on and the room does not cool down. When I hear "storage heater," it usually means things will get difficult and expensive.

How big is the room? How many people sleep there? How far away are the kitchen and bathroom?

I still need to get a measuring device, but I am quite sure that the humidity level is usually between 60-80%, at least at night.
As mentioned, heating a lot is not really possible because the heating system gets exhausted after a while and then needs to "recharge." This often results in the room cooling down since it simply cannot be heated further.

The room (the video shows the windows in the kitchen) is about 14m² (150 sq ft) in size, and there are three of us living here. The bathroom is adjacent to the kitchen on one side.