Each fall, as the weather turns chilly and the first coats of frost paint the world crystalline, customers who have recently had new windows installed call us up with a worried tone in their voice to say, “Oh no, my windows are failing! There’s condensation on them!”

Their concern is justifiable, as most of us have heard at some point in our lives: condensation on the window is bad! It means the windows aren’t doing their job! It means my house isn’t insulated from the cold! —What many of us don’t know to ask about condensation, however, is: where on the glass is it occurring?

Fact is, condensation happens. It’s one of those laws of nature that takes place when warm air (which holds water in gaseous form) contacts a cold surface. Because warm air has the ability to hold much more moisture than does cold air, when warm air cools, the vapor within it condenses back into liquid form.

This is why, for example, cold drinks will sweat on a hot day. The temperature of that cold drink draws water vapor out of the warm air around it, and condenses it onto the cool surface of the glass. (The nature of condensation dictates that there must be a surface present for the water to condense upon). Likewise, when outside temperatures drop, the first place you will see any condensation is on the windows, where the two differing temperatures meet.

This brings us back to the question at hand, then: where on the window surface is the condensation occurring? (Depending on the answer, you may not need be worried at all).

If it’s occurring on the interior part of the windowpane, that is something to worry about! Condensation on a window’s interior is a clear-cut indication that your window is not doing a good job of insulating your home. After all, if your window’s surface is cold enough to cause condensation, then it’s effectively cooling down your living space—and just when you want it be the coziest! It probably need not be mentioned that this continual loss of heat will cause your winter heating bill to skyrocket. But it certainly should be mentioned that interior condensation leads to dampness, which can cause spores to grow inside your home and create dangerous health conditions. No one should be breathing mold!
There are short term solutions that can help reduce condensation within your home (weather stripping and fans, to name a couple), but in the long run, and for the good of your health, comfort, and bank account, nothing short of energy efficient replacements will rectify the situation satisfactorily.

Now, what about cases of condensation occurring on the outside of your windows (which is, invariably, the reason for our customers’ calls)? —With high performing, energy efficient windows, because they work so well at insulating your home, the warmth within your home actually travels all the way through to the exterior. It’s at this location, then, that the warm air meets the cold surface—and that is why condensation takes place on your window’s exterior.

Therefore, if you yourself have been worried about exterior condensation on your recent window replacements, we’d like you to rest assured. As we tell all our customers who call us up, “There is nothing to worry about! Now you have visible proof that your windows are energy-efficient. They’re working extra hard for you and are doing a great job of keeping that heat in. You should be proud of your investment.”