Why is There Condensation on My Windows? 

Are you having an issue with condensation on your windows? While window condensation is a natural phenomenon that occurs under the right conditions of humidity and temperature, condensation on windows can also indicate the quality of them. Usually, you may find condensation inside closed environments on days when the outside air is cold. Condensation often occurs in fall and winter when steam is released into the air, and windows are some of the most common spots for condensation to form. This is because window panes generally have the coldest surface inside your home. While condensation is most noticeable on glass panes, moisture can also be found on your window frames and fixtures. While it might seem counter-intuitive, condensation on windows can actually be a good thing as it indicates your windows are insulating well. So is condensation a cause for concern? It depends. 

Condensation vs Seal Failure 

It is important to first understand the difference between basic condensation, and window seal failure. Interior condensation is caused from humidity inside your home and will normally occur in the winter months when the temperature outside is low and the inside moisture levels are too high. This is not a failure of the window, but rather a function of there being too much trapped moisture in the home. Exterior condensation is a function of dew point. It is the same thing you see when there is dew on your car windshield when you go outside in the early morning. If you are seeing exterior condensation on your windows after having them replaced, it means your windows are working better than before. This is because the Low-e coat is keeping the interior heat (i.e. 72 degrees) from migrating to the exterior surface of the glass. 

However, if you are finding moisture between the panes, this would indicate a potential seal failure. This is the worst case scenario. Double-and triple-paned windows are made to insulate your home. The space between is filled with an insulating gas like argon and then is sealed air-tight. The benefit of double and triple-pane windows is they help to keep your home energy efficient and secure. However, if the seal fails and condensation forms on the inside the panes, it is permanent (it will not come and go throughout the day.) When a window suffers a seal failure, it is no longer providing any insulation, leaving it vulnerable to wasting the energy used to heat and cool your home. The only solution when you have condensation between window panes is to replace the  window. 

The Science Behind Condensation 

If the issue you are having is simply interior condensation, while this is not bad, it can be frustrating. Windows may not cause condensation, but they historically have been the first and most obvious place it occurs. This is because windows generally have a lower thermal resistance than insulated walls, ceilings, and floors. As a result, their inside temperatures are usually lower than those of other surfaces in a home during cold weather. If the air in a home is humid enough, water will condense from it when it is cooled at a window surface.

While interior condensation is not too much cause for an alarm, if left unchecked it can damage window frames, sills and interior shades. Water can deteriorate the surrounding paint, wallpaper, plasterboard, and furnishings. In severe cases, it can seep into adjoining walls, causing damage to the insulation and framing. Furthermore, the indoor air coming in contact with energy-efficient windows is less likely to be cooled to its dew point temperature because the inside surface temperatures remain higher during cold weather than those of windows with single glazing, traditional metal spacers, and metal frames.

Reducing Window Condensation 

If you are having an issue with interior window condensation, there are a few measures you can take, including: 

• Use a moisture eliminator like a dehumidifier
• Simply turn off or lower your existing humidifier
• Use fans every time you cook or take hot baths or showers
• Circulature your rooms by running ceiling fans clockwise during the colder months to circulate the warm air downward
• Open a door to release some of the steamy indoor air outside
• Replace your windows to double-paned windows