Last time we talked about the different between a pocket replacement windows and a full replacement windows.

Now we will cover U-factor and how to use it to your advantage when buying windows.

U-factor in replacement windows or any window for that matter is a rating that measures the heat loss through a window as a whole.

The lower the U factor the less heat loss through the window. The U-factor measurement was created by the National Fenestration Rating Council as a universal measurement to compare the energy efficiency of different replacement windows from different window manufactures or even from the same manufacturer.

How to use U-factor rating

U-factor rating is measured on a scale from 0.10 (the best) to 1.20 (the worst). Simply put, the lower the U factor, the less heat is lost through the window, thus a more energy efficient window that will save you money on your heating cost year after year.

U-factor rating is a handy tool when you are shopping for your new replacement windows because it allows you to compare one window to another window with a universal measurement that all window manufacturers use.

You see, window manufactures like to use different branded buzz words to market their windows as the best. Meaning manufacturer “x” and manufacturer “y” will use different terms to describe the same exact thing. This can make it very difficult to compare one window to another.

What should the U-factor be in your replacement windows?

Depending on the part of the country you live in will influence what your minimum U-factor should be in your replacement windows. You see, to get an Energy Star rating on your window the U-factor will need to be at a certain level depend on the climate of the area you live in. Now in the Northern States of the U.S. a 0.30 U-factor or lower will get you an Energy Star rating.

Now in the Southern States the U-factor can be a bit higher, but, there is another qualifier for Energy Star in these areas. SHGC or (solar heat gain coefficient) typically needs to be 0.30 or lower. Take a look at the Performance Guidelines chart to see what your replacement window needs to be in your region.

How U-factor makes replacement window shopping easier?

In a nutshell what U-factor does for you when window shopping is allow you to comparison shop and know that you are comparing apples to apples. What I mean by that is that every window manufacturer is going to have a different name for their energy efficient features on their window. This can be very confusing when trying to compare one window to another.

So what the U factor does is clear the murky waters of fancy professional marketing terms and gives you a universal baseline rating on a replacement window. Now you can look at one window and say okay this window has a U-factor rating of 0.30 along with this other window and now it takes the guess work out of which window is more energy efficient. Make sense.

Got a Question?

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Next Time

We will talk about 5 must know things about buying replacement windows.