December 12, 2014
It seems like the entire country is steeped in polar temperatures. Even here, in Greater Vancouver, we were hit with an icy blast of frigid air that lasted for days. Brrr!!
Now that winter has set in, and everyone has turned up the heat in their homes, more people are noticing condensation build up on their windows. Condensation seems to strike a chord of fear in people and we get a lot of calls from homeowners worried that this means that the glass in their windows has failed.
Condensation on glass is a common occurrence and can appear on either the interior or exterior window panes. This moisture formation, while annoying, does not usually mean that there is something wrong with your windows.
Modern energy efficient building designs, techniques and products mean that our homes are better sealed against air leakage. High performance windows and doors are doing their job: preventing the cold outside air from coming into your house, and stopping the heated indoor air from escaping outside, keeping you toasty warm and lowering your energy costs. But this reduction in natural air exchange, along with the water vapour from activities such as breathing, cooking, and showering, means that your home will have a high relative indoor humidity level which can result in condensation on the inside of your windows.
The easiest way to control indoor condensation is to lower the relative humidity inside your house. There are several things that you can do to accomplish this, including running your kitchen fan while cooking, and bathroom fans when bathing or showering. Also, opening a window to air out the house on a daily basis and keeping your blinds and drapes open as much as possible will help to lower the indoor humidity.
The same principles that produce indoor condensation also cause outdoor condensation. Certain climactic conditions — a clear night sky with no wind and a high relative humidity — cause the surface temperature of the exterior glass to fall below the dew point of the ambient air. When this happens, moisture from the air condenses on the outside of the window. This is not an indication that your windows are faulty; on the contrary, it is sign that your windows are performing well. The insulated inside pane is preventing the warm air from inside your home from reaching the exterior pane and warming up the glass.
Differences in window orientation and/or objects outside the window (e.g. shrubs, shutters, etc.) can affect the surface temperature of the glass, contributing to exterior condensation.
Exterior condensation is a natural and common occurrence and there is not much that you can do to control this phenomenon. Opening window coverings at night to warm up exterior glass or removing/trimming shrubbery near windows to promote air circulation may help in reducing exterior condensation. However, exterior condensation is not a cause for concern as usually this moisture evaporates quickly after the sun comes up and the temperature of the glass rises.
For more tips on dealing with condensation, please check out our Condensation FAQ on our Resources page.
Check out these links for additional information on condensation.
Moisture Problems – Natural Resources Canada
Exterior and Interior Condensation on Windows – Fenestration Association of BC
Avoiding Condensation Problems – Homeowners Protection Office – Branch of BC Housing
Questions About Windows & Condensation? – National Fenestration Rating Council
If you have excess water on or around your window sills or notice ice forming on the inside, please call your installer, builder or dealer as this may indicate that your windows or doors have been installed incorrectly.
If you find condensation between the panes in an insulated glass unit, the airtight seal may have failed and require replacement.