Windows become humid inside, what can be done? Old building (2000)

Hello,

we have bought a house, built in 2000, energy certificate C, Ytong masonry, double glazing.

Our problem:

Windows in the kitchen (external corner wall) always get damp in winter (condensation collects at the edges). But this only happens in the kitchen; the living room, children's room, bedroom, etc. remain more or less dry.

Of course, I am aware that this is caused by the temperature difference on the window glass and the humidity in the room.

But what can be done about it besides ventilating and heating properly (which is not necessarily good for the heating bill at subzero temperatures)?

We have considered installing triple glazing, at least in the kitchen... but then the question arises whether this could lead to mold formation on the wall with the existing masonry?

Are there any experts here who can help us:

- From which U-value of the external wall can triple glazing be installed safely (meaning the temperature difference between the wall and the window on the inside is more or less the same)?
- Why does it fog up in the kitchen but not on the other windows of the rooms with external walls?
- Could the windows be defective?
- Is it advisable to install triple glazing only in certain rooms?
- Is it necessary to integrate ventilation for humidity into the wall when using triple glazing?
- Do you have any other ideas?

Thank you!

What can you do about it, except ventilating and heating properly (not necessarily good for the heating bill in freezing temperatures).

Actually, that is THE correct solution especially when it’s cold outside.

We have considered installing triple glazing, at least in the kitchen... but then the question arises whether that might lead to mold formation on the wall with the existing masonry (can happen)?

It can, but it doesn’t have to.

- From which U-value of the exterior wall can you safely install triple glazing (so the temperature difference between wall and window on the inside side is more or less the same)?

Basically, this works for almost all exterior walls. The problem is not the glazing, but the tightness of new windows. Ventilating and heating is then extremely important. Considering your year of construction, I assume the house is already very airtight.

Why does it fog up in the kitchen, but not on the other windows of rooms with exterior walls?

Cooking with high humidity, little heating, little ventilating.

- Could the windows possibly be defective?

Crystal ball says: no idea. Probability says: no.

- Is it recommended to install triple glazing only in certain rooms?

Doesn’t matter.

- With triple glazing, do you necessarily have to integrate ventilation for moisture into the wall?

See above. The glazing doesn’t matter. Even with new double-glazed windows you should observe the same measures.

- Do you have any further ideas?

No. Personally, I would rely on "more" ventilating and heating. Start with measuring temperature and humidity. Possibly also measure the wall temperature with an infrared thermometer as a supplement.

We have been considering installing triple glazing, at least in the kitchen... but the question arises whether with the existing masonry it might lead to mold growth on the wall (could happen)?

If I were to internally calculate what ventilation costs in heating expenses and what the triple-glazed windows cost for purchase and installation, I would assume (even with the glass ball turned off) that you can ventilate for a very long time before you even come close to the costs of replacing the windows...

Ventilate and heat properly and everything is fine. Calling a house built in 2000 an old building is also daring...

Windows in the kitchen (outer corner wall) always get damp in winter (condensation forms on the edges).
But this only happens in the kitchen; living room, children's room, bedroom, etc. all stay more or less dry.

This is a completely normal problem and not critical. The warm air in the kitchen can hold a lot of moisture. If the windowpane has a temperature lower than the dew point, moisture will settle there. The fact that this does not happen evenly across the whole pane has to do with air movement in the room. Where the air "stands still," moisture settles faster.
You basically have three options:
1.: You ensure a warmer pane. This is the effect of double glazing – the inner pane cools down less.
2.: You ensure more air movement at the pane. With "wind," the effect of condensation on a surface is less. This effect is used in ventilated cabinets.
3.: You make sure that the moisture leaves the room. You do this by ventilating. Humid warm air out, cold air in. This works even if it is humid outside because cold air holds less water mass, and as the room heats up, the relative humidity decreases.
Therefore, ventilating is a good option. Shock ventilation is energetically better than the famous tilted window, as shock ventilation extracts less energy from the objects in the room.

In the 2000s, it was common to install radiators under the windows in kitchens. If you have one and have blocked off the area with a kitchen panel, ventilation grilles above the radiator under the window will help to warm the area and create air movement as described above.

Calling a house built in 2000 an old building is also daring...

52 years too late for an old building.

If I were to internally calculate what ventilating costs in heating expenses and what the triple-glazed windows cost for purchase and installation, I would (even with the crystal ball turned off) assume that you can ventilate for a very long time before you even come close to the costs for the window replacement...

Apart from the fact that double glazing (which I prefer to call cavity glazing) is by no means basically outdated, window panes can quite well be replaced individually without having to tear out the frame.