Why Does Condensation Form On Windows?

Why Does Condensation Form on Windows?
Hi, I’m Frank G from Jantek windows and in this episode I’m going to answer the most common questions about how and why condensation can form on windows and what you can do about it.
So let’s get right to it!
First I want to tell you that if you are experiencing Condensation between the insulated panes of Glass, there is a problem with the windows themselves. This condition is an indication that the windows seals have failed or are damaged allowing outside air to enter through the breach in the factory seal. Most likely and the insulated glass units are no longer functioning as insulators and depending on the circumstances, the window, or at the very least, the insulated glass unit, may need to be replaced.
In most cases, Condensation appears on the surfaces of windows and is not an indication of a defect in the window. In fact, by replacing drafty windows and doors or installing a new roof or siding, you are reducing air flow in your home or building and making it tighter. Tighter homes and buildings retain more humidity which is actually a big factor in the formation of condensation. The humidity was always there… but your old windows never caused it to showing that was not present before your new windows were installed.
So, what causes condensation? Condensation is caused by excess moisture in the air. When moist humid air comes into contact with cooler surfaces and the moisture condenses into liquid form, this is referred to as reaching “Dew Point” or the temperature at which the water vapor in air liquifies into dew.
Condensation can form on the glass surfaces inside or outside of the home. Whenever there is excess humidity or water vapor in a home, it manifests itself in the form of condensation on the coldest area of a wall, which is normally the windows. The warmer the air, the more moisture or water vapor it will retain, so when air in your home comes in contact with the colder glass surface, it is subsequently cooled, and moisture or vapor is released in the form of condensation on the glass of windows.
So now lets talk about where on the window condensation usually forms and why.
Condensation on windows often forms at the meeting rail and at the bottom of the lower sash on the interior of the glass. This is because when warm air cools, it falls across the interior surface of the window at the same time the temperature of the air is falling. The air contacts the horizontal surface of the meeting rail, which acts like a dam, slowing the air's rate of fall and creating the perfect opportunity for the trapped water vapor to escape and form on the meeting rail's surface. The air then rolls over the edge of the meeting rail and again gains speed until it encounters the lower handle of the sash. At this point, the water vapor again makes its exit and lies at the bottom of the sash.
The two main things you can do to reduce condensation are to control sources of moisture and increase ventilation. You should try taking these steps:
1.) Use exhaust fans in your kitchen, laundry, and bathrooms.
2.) Vent gas burners, clothes dryers, etc. to the outdoors.
3.) Shut off or reduce the output of furnace humidifiers and other humidifying devices in your home.
4.) Be sure that the ventilating louvers in your attic, basement or crawl spaces are open and amply sized.
5.) Open fireplace dampers to allow an escape route for moisture-laden air.
6.) Air out your house a few minutes each day.
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Thank you for watching! I am Frank G from Jantek Windows… and remember… Save Energy…Capture Comfort.