Discoloration in the parquet, who has an idea?

Heating and ventilating is always necessary, even in 8 years.

That is probably clear, but if you go on vacation for two or three weeks, you probably turn down the heating and don’t ventilate every day, right? We just took over the property last week and for logistical reasons won’t move in until early May. For now, we have turned down the heating because it didn’t make sense to heat it for me at first. However, I’m happy to be proven wrong. Ventilation is currently done daily.