One of the most common calls we get every winter is for drafty windows. While it is very common for your old windows to become drafty, what you are often feeling is not actually cold air from outside getting into your home. Many times what you are actually experiencing is the convection of air. Let’s go back to our middle school science class that we slept through. (I know, I didn’t think I needed it either!)
What happens in your home when the temperature is very cold outside is fairly predictable. The exterior surfaces of your home become very cold. Your walls are very thick and well-insulated compared to your windows. So, naturally, no matter how well insulated our windows are, they are going to become the coldest surface in the home. Now, when the interior surface of that glass starts to become colder than the air inside your home, that air falls towards the ground (cold air falls, hot air rises). If you happen to be sitting on a couch in front of that window, you would swear the outside air is rushing into your home. What is actually happening is that the air in the room is starting to circulate during the process of convection. Cold air displaces warm air on the floor, the warm air rises, and as it cools again, it starts to fall back down the window where the cold air is rushing downward. This process will actually continue completely unchecked if there is no intervention.
Fortunately, we have modern heating systems in our home that introduce warm air back into the room. Most homes use forced air that comes out of our heating ducts. If you pay attention to where your heating ducts come out of the floor, it is almost always in front of a window. Even if it is in the ceiling, it is usually near a window. This is an ingenious design as it is meant to send the warm air to the coldest surface, your window. Unfortunately, most of us are trying to maximize the usage of space in our homes. This often means we put our furniture over these ducts. Now the air doesn’t get to that window before it has circulated through the whole room.
It can help a great deal to move your furniture slightly away from the walls near cold windows to allow this air to get to the glass. Window coverings will help to keep that cold air from getting circulated through the room as easily, but this can also lead to a “freezer” effect on the window, where it continues to get colder and colder until it freezes. That is a topic for a later post though.
The number one thing you can do to help keep this process from freezing you off of your couch in winter is higher energy efficiency glass. Glass coating technology has come a long way and allows us to offer glass that can have an enormous impact on the comfort inside your home. In most cases, you don’t need completely new windows. Glass is usually the most important factor in a window’s performance. The good news is most windows are designed to have the glass removed. This means you can have your glass upgraded without the expense of complete window replacement.