Low U-Factor ratings show the energy efficiency of a window.

What are U-Factor Ratings?

One of the most important factors to look for when choosing a replacement window is the U-Factor rating.  The U-Factor is an indication of the window’s energy efficiency, and affects the money you spend (and save) on your energy bill.

U-Factor ratings are issued by the National Fenestration Rating Council (NFRC), a third party, non-profit organization that administers the only uniform, independent rating and labeling system for the energy performance of windows, doors, skylights, and attachment products.  A U-factor rating is typically between 1.20 and 0.20, and the lower the number the more energy efficient the window is.  Our Premium Vinyl Windows combine energy efficient glass and foam filled extrusions, giving this window an exceptional U-factor rating of 0.21, one of the lowest in the industry.

How U-Factor Ratings are Measured

While the U-Factor does rate the energy efficiency of a window, it’s only accurate if the measurement is a “whole window” value.  In order to qualify for Energy Star, a window’s heat-transfer measurements must be taken at 20 different places on the glass and window frame to give an accurate measure of a window’s energy efficiency.  However, some underhanded companies selling low-quality windows try to “boost” their window’s rating by taking the measurement from only the center of the glass.  If a U-Factor rating seems suspiciously low, be sure to ask the window representative to prove it’s a “whole window” measurement.

You can be assured that the U-Factor ratings presented for all of our windows are whole window values.  All our windows are Energy Star certified, and our windows would not be able to qualify if we weren’t presenting honest, accurate, whole window ratings.

The More Layers The Better

Did your mom ever say to you, “Before you go outside, put on an extra layer to stay warm!”  Adding an extra layer of clothing adds more insulation to keep you warm, and the same is true for windows.  Most standard windows have two layers of glass, but our Premium Vinyl Windows line features three.  That extra pane of glass helps lower the Premium Vinyl Windows’ U-Factor rating to 0.21, one of the lowest in the industry, which will help you save even more money on your fuel bill.  Additionally, a triple-pane window helps greatly with noise reduction, reducing outside noise within your home.