top of page

Why Windows Fog

One of the most frequently asked questions we receive is "Why have my units failed ?"

 

There is no simple answer. The life of a sealed unit depends on a number of factors, but the 2 most important are exposure to temperature and Humidity levels in the home. Also, No window is ever completely sealed. Depending on the type of window, on average, 75% of failed windows do not have a seal failure but instead are simply fully saturated from years of Solar Pumping.

 

Solar Pumping image

Solar Pumping naturally occurs during the change from day to night. Sunlight heats the inner airspace of the thermal window cavity during the day and causes the window to pressurize, which forces out small amounts of air within the window cavity through the semi-permeable seal. In the evening, as the temperature drops, the window cools and creates a low pressure area causing small amounts of air to be drawn back into the inner window cavity. The air being drawn back into the window naturally holds moisture, mostly from inside the home, and this moisture is absorbed by the windows desiccant material.

 

Solar Pumping activity over a period of time saturates the Silica desiccant material in the thermal window cavity until eventually fog, condensation or moisture appear on the inside surface of the window. This moisture is trapped within the window and an endless cycle of heating, fogging, cooling, and condensing occurs. Eventually every thermal pane window will lose the ability to absorb condensation and fog up.

foggy window

The average age of windows we restore is 12 years.

As the saturation point of the moisture absorbing materials is further exceeded, the dangers begin. Moisture becomes permanent. This progressively leaves deposits, strips the insulating properties of the unit, and scars the window glass.

Once scarred, the window unit may not be salvageable.

Visible fog, condensation or moisture is a sign that the sealed window unit has simply reached Its threshold to absorb moisture, causing foggy window or condensation problems. This is a repairable and preventable condition.

bottom of page