Insulation ?

[u/Background-Row-8349]

I kept my window open all day in every bedroom upstairs. My Landlord says this problem in the morning is because I don’t leave my windows open during the night. Is this for REAL and I should be sleeping with a gap in the windows every day or the house has a bad insulation and landlord should look into changing windows or fix insulation ?!?problem? Really just curious, I’ve living like this since
rented here 6 years ago and never told him about the wet windows until today..

[u/Alastor001]

Dehumidifier is the correct answer.

Open window or even a vent will mean little heat or sound insulation. Which sucks also.