Rating Systems for Replacement Windows

When investigating new replacement windows you want to have a basic understanding of how the various models are rated for there energy efficient proporties. Generally there are two different ways manufactures describe the “rating” of a window:

1. How much heat a particular window glass will allow to pass, which is expressed in the assigned U-Value when the product itself is conductive.
2. How resistant that window frame is to allowing heat to pass, which is expressed in the assigned R-Value when the product such as vinyl is not conductive

So the better a window resists heat transfer (higher number), and the lower it tends to let heat pass, (lowest number) the more energy efficient window you have. Look for the NFRC label and only buy certified NFRC windows.

U-Values (conductance of heat) U=.31 (not good) U=.22 (good) U=.17 (excellent)

R-Values (resistance to heat flow) Only use U values and Not R values when purchasing.

Department of Energy R-5 Volume Window Program only allows windows with a U value of .22 (operating) .20 (fix lite) No .30 -.30 windows are allowed.

How can I find out more information?

You can start by requesting to speak with a licensed local home improvement professional in your area to learn even more about your home improvement options. Go to our map to get started now.