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Part One: Replacement Windows

Below is Part One of a two-part series on windows in your home.  Stay tuned for Part Two on February 21st!

Have you heard the window advertisements that claim that they will save you 20% or more on your energy bills? Do not believe everything you hear.

While replacing windows can increase your comfort and save you energy in certain cases, the energy savings are generally much smaller than those claimed by the window companies. And, the comfort improvements might occur with new windows, but those same improvements might be achievable with your existing windows.

How much energy can you save with new windows? Windows in general are energy-inefficient. They are glass holes within insulated walls. You will always feel cold when sitting near windows during the Winter even when they are not leaking air and they are good quality newer windows. This is because windows have a very low insulation value compared to the rest of the structure.

Insulation values are gauged in terms of the materials’ resistance against heat transfer (loss or gain) or “R” value.  The R-value for windows is generally somewhere between R-2 and for the very highest quality, most expensive windows available today, R-6. For comparison, the lowest minimum wall insulation value that new homes can have today per the building code is R-13 and the roof of the house has to be at least R-38. So, if your windows are likely an R-2 or R-3 and your walls are R-13, you will feel much colder sitting next to the window than a solid wall.

Now if your current windows have an R-2 insulation value and the newer ones you could purchase will have an R-3 or even an R-4 value, you are not gaining much efficiency and you will not save much money on your energy bills with the new windows. You are also still going to feel cold sitting next to them. A couple of simple things you can do to increase the R-value of your windows is to install thermal curtains or even better are cellular shares, especially if you can install ones that come with side tracks that will hold the shade in place. Low-e window films can also be installed to older windows to reduce the amount of heat that can be absorbed by them to increase summer comfort and lower energy bills.

The bigger question is if the windows are leaking from within the window assembly or more likely, from around the edges of the window? Older wooden windows need to be reglazed from time to time. This refers to the practice of replacing the putty that holds the glass into the wooden frame and seals those joints. Over time that substance can crack and cause air leaks in the assembly. It is fairly easy to replace the glazing yourself or you can have a handyman do it for you. You can also purchase “pulley seals” to block air that may be entering through the holes where sash cords disappear into the frames.

In terms of leaking from around the outer edges of the window, this occurs because there is a space between the window unit and the wall that has often not been air sealed.  When windows are installed in new walls, there is a gap that can range anywhere from a ¼ of inch to about an inch between the rough opening in the wall and the window frame. This is where the comfort issue with most windows comes into play. When this gap is not sealed with something that will actually stop air from coming in, then you feel the air coming in from around the window whenever it is breezy outside or whenever there is a negative pressure inside your home. The pressure situation in your home can be negative whenever you are running your dryer, exhaust fans, or even running your heating or cooling systems, so that is a lot of the time!

So, is it possible to seal these leaks without getting new windows? Yes. Do we think about replacing doors because we feel a draft coming in around them? Not usually, because people figure out how to seal them. The same can be done for windows.

Stay tuned for more information on how to seal leaks around windows in Part Two of this blog on February 21st!


By: Helen Reinecke-Wilt



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