How Do I Eliminate Window Condensation in My Home?

If you recently replaced your windows and you're noticing more condensation you probably replaced your old windows because they were drafty. Slight gaps and cracks around the sashes and frames allowed air to travel freely between the outside and inside. This air movement actually prevented condensation in two ways. Primarily, the warm moist air was able to escape from the house without resting on a cold surface. Secondly, enough cold air was allowed to enter the home to create a thick blanket of cold air across the window. This layer was thick enough to prevent the warm moist air from touching the cold window surface.

Energy Efficient Replacement Windows

Your new windows improve the energy efficiency of your home, lower your energy bills, and add to your comfort by blocking air movement through your windows. Blocking this movement however may raise the humidity levels in your home causing condensation. Condensation is created from high indoor humidity and low outdoor temperatures. Since we cannot control the outside temperature, our only hope of curing or eliminating condensation is to control the indoor humidity.

In today’s modern building and construction, we continually search for a “tighter” home that retains our winter heat and summer cooling. Vapor barriers, high performance doors and windows, tile, and plastic wall coverings all conspire to keep whatever air is inside...inside. By building an energy efficient home, we create other problems that may need special attention. One of these problems is the control of moisture (humidity) in the air. The “tighter” the home, the less likely moisture will escape.

Controlling Indoor Humidity

Simply said, moisture is caused by everyday living. Dishwashers, clothes washers, furnaces, humidifiers, cooking, and showering are all major contributors to humidity. Cooking for a family of four releases 4.5 lbs. of moisture daily into the air. Each shower adds 1/2 lb. of water, weekly laundry 30 lbs., and human occupancy 6 to 8 lbs. Some studies show that a family of four can easily release more than 18 gallons of water per week into a typical household.

Exterior Condensation

Exterior condensation on glass can occur at any time, especially in warm, humid climates where the interior temperatures are cooler than outdoor conditions. Condensation on the outdoor surface of an insulating unit is not an indication that the glass or insulating glass unit is defective. Condensation on the exterior of windows occurs primarily in the morning when days are warm and humid, but nights are cool. When the temperature of the exterior surface of the glass is cooled below the dew point of the outside air, moisture forms on the exterior side of the glass. Then, as the day warms, the glass temperature rises above the dew point and the moisture evaporates back into the air. The three main conditions that promote exterior condensation are 1. High outdoor humidity, 2. Very limited or no wind and 3. Clear night sky While unsightly, there is not much that can be done to prohibit exterior condensation. One suggestion that may help reduce the incidence of exterior condensation would be to trim back outdoor shrubbery near the glass to promote better air circulation near the window. Crick the button below to learn more ways to reduce indoor humidity.