When we turn on our home heating systems each fall, many of us experience condensation, or steam, on windows. Condensation requires a cool surface and moisture in the air. When the temperature of the glass drops below the dew point of the inside air, invisble water vapor in the air condenses on the cool glass.
Over the summer, moisture slowly accumulates in furniture, walls, woodwork, cloth and other surfaces. In the fall, as the exterior temperature drops for the first time, some of this moisture condenses on cold window glass.
Most moisture leaks out of your home as your furnace runs and vent fans are used. Eventually, all the materials in your home dry out and moisture stops condensing on the windows. This normally takes a few weeks. Keeping drapery and window treatments away from the glass area allows a good flow of air over the windows and helps reduce condensation quicker.
If condensation continues to form on windows after several weeks, your home may have excessive moisture. Most moisture problems can be solved by limiting sources of moisture and improving ventilation.