ᐅ Condensation on all windows

About a year and a half ago, we built a wooden house designed to KFW-60 standards. However, starting from this winter season, we have been struggling daily with moisture on our windows. Every morning before leaving the house, we ventilate every room thoroughly for about 15 minutes, but even that is not enough.

Could the problem be due to poor vacuum sealing in our double-glazed windows? During the installation, the windows had to be reinstalled by the construction company—I won’t name them here—because they were initially installed incorrectly. Could the vacuum seal have been compromised during this adjustment?

To clarify, we lower the heating between 11:30 PM and 5:00 AM and heat the entire house with underfloor heating.

Can someone please help me with this issue before I consider hiring an expert?

Best regards,
Marc

Condensation is basically a sign of excessive indoor humidity, which tends to settle as moisture at the weakest points, usually the edge seals of window panes. This is especially noticeable during the cold winter months, particularly when temperatures fall below freezing.

What you describe also sounds like a ventilation issue. Is there no mechanical ventilation system in the house?

Ventilating once a day for 15 minutes is definitely not enough! You should ventilate for at least 15 minutes both in the morning and in the evening.

Regards, Rustico