Q & A: Preventing Window Condensation

Posted by Ben Thompson on 11.15.12



Our home has hot water baseboard heating and since adding insulation to the attic whenever there is a temperature change in our home condensation builds up on the windows. Any suggestions?


Factors to consider:

1) Weather – Weather may be the largest contributing factor to your problem. The shift from warm to cold and when it's wet then cold can contribute to window condensation

2) Radiant Response Time - A lot of us keep our homes significantly colder at night, and then in the morning when multiple showers are taken, and breakfast is cooked, a lot of moisture is put back into the air that has a low dew point, and this results in condensation on the windows. Radiant heated homes are fabulous, but the air movement comes from convection vs. air being forced to mix. Radiant heated homes don't respond as quickly as forced air systems. Radiant heated homes benefit from keeping the temperature a bit more constant day to night. Maybe only a 2-3 degree set back vs. a >5 degree set back day to night.

3) Dehumidifier – A dehumidifier will remove moisture from indoor air. They are typically used to address moisture issues such as window condensation but can also help with comfort issues related to high relative humidity. The windows are the barometer of our homes. You may also try opening the door to the basement (if relevant) to condition more of air throughout the house.

If you wanted to do an experiment, consider trying this.

1) Leave the house with the heat set at 70 degrees day and night for multiple days (reducing the variable of interior temperature swing), and see what actions inside the house trigger the condensation. Keep an eye out for prolonged condensation at different times of the day and for multiple days in a row. That would point towards excessive heat loss from the window or door it's happening on.

2) If windows are covered with blinds or window treatments, condensation tends to build up between them. Blinds should be opened up daily to allow the condensation to dissipate.


Topics: Love Where You Live