How To Compare The Insulation Value of Wood, Metal, Vinyl and Composite Window And Patio Door Types and Brands

Of course Energy Savings and Comfort are two very important criteria as you determine the best replacement window and patio door type and brand for your project.  But how do you compare the ability of the different types, styles and prices of windows to deliver on that important objective?  Vinyl clad wood windows, Metal windows, and Vinyl windows vary greatly in how they provide energy savings and comfort. In fact windows made of the same frame materials, like the vinyl windows we design and manufacture here at Jantek Windows can vary greatly in energy and comfort performance from those of other manufacturers. So how do you compare your options with regard to this important criteria?  In this article I will give you a simple way to compare the insulation value of any window or patio door your are considering. All you need is one number and a calculator. Let’s get started.

It doesn't matter if your home or building is located in Burlington County New Jersey, South Central New Jersey, Philadelphia or anywhere else on the planet. One of the most important factors in determining how well your new windows and patio doors will perform in terms of saving energy and keeping you warm in winter and cool in summer, is the window or patio door’s insulation value. This is formally known as “R-Value.”   R-Value is the common measurement of the insulation value of any product whether it is a window, patio door, or a bat of insulation for your attic or walls.

The R-value of windows and patio doors is very easy to determine.  That said, it is important to understand that the R-value of any window or patio door is greatly impacted by the:

  • Frame and sash material (vinyl clad wood, vinyl, metal)
  • Glass package (double/triple pane, LowE type, spacer type, gas fill)

 Here are the steps to follow in determining and comparing the R-value of any of the different types and brands of windows and patio doors that you may be considering.

  • Ask your contractor provide you with the Energy Star® NFRC Certified “U-factor” for each specific configuration of window or patio door in your estimate. All Energy Star certified windows and patio doors are required to have this, and other, certifiactions.
    1. The “U-Factor is the standard measurement used in the window industry to state how well the window or patio door resists the transfer of heat from interior to exterior in the heating season and from exterior to interior in the cooling season.
  • Calculate the R-value by dividing the U-Factor into the number 1. So, for the formula 1/U-factor= R-value (round the outcome up or down to the nearest whole number), will give you’re the number you need to compare any two windows or patio doors for insulation value.


  • Let’s do an example:

The U-factor for a Jantek American Classic Double Hung Vinyl Replacement  window with Triple pane EnergyMiser IIÔ glass package is .22.  The R-value would be determined by 1/.22= 4.545 rounded to R-value = 5 (R5). 

If you want to compare the Jantek double hung to a window from XYC Company with a U-factor of .25 you would use the same formula: 1/.25 = 4.0 the R-value = 4 (R4). 

The Window or Patio Door with the higher R-value will insulate better. That translates into better energy savings and comfort for you.

You knew that the energy savings and comfort performance of your new windows and doors is important to your decision. I hope that this article has given you an easy tool to use in comparing the insulation value of your replacement window and patio door options  Remember to check out our large library of information and tips on windows and patio doors on our website at and remember… Save Energy…Capture Comfort!

Next Up:

How Do Windows and Patio Doors Impact Energy Consumption

The Case for High Performance Vinyl Energy Star Windows

How To Use NFRC Factors To Compare Energy And Comfort Performance