We have a bedroom with single glazing and poor ventilation. Opening windows during the day is of course an option, but if you both work that is sometimes a bit more difficult. The single glass and condensation of moisture created damp spots, especially in the window frames. Bowls of rice don't help, so I looked at a dehumidifyer. The Eurom DB 20 works fine, but too noisy to sleep with. That is why we set it during the day to the humidity we require. Sleep well at night, no more humid, nasty air in the bedroom and no more wet windows.