If you have these windows in your home, you are likely spending hundreds of dollars a year more in home heating and cooling costs than you would with the latest ENERGY STAR qualified windows.

Jun 25, 2025 · What is window R-value? See charts for single, double & triple panes, compare U-value, learn what’s a good R-value, and discover the highest R-value windows & doors.

The NFRC label helps you compare between energy-efficient windows, doors, and skylights by providing you with energy performance ratings in multiple categories.

Free window R-value calculator. Determine how well your windows insulate your home and compare different window types for energy efficiency and comfort.

Dec 4, 2025 · What are the highest R-value windows? We define thermal metrics, detail the technology (gas fills, coatings), and show how to reach R-10 performance.

View our glass performance chart for each of our different types of glass.

In the video, Matt and Aaron from 406 Windows talk about the different window gas options and the U-factor of Alpen’s ZR-7 window and give you a sense of what you can achieve with high-performance …

Jan 3, 2021 · R-value measures the performance of a specific material, like insulation, to reduce the transfer of heat. We know that the R-value measures heat resistance, but that implies more than is …

Jun 28, 2023 · The R-value of your windows can tell you how energy efficient they are. Learn more about what a good R-value is for windows on this page.

Aug 26, 2025 · While a single-pane window with an R-value of 1 does not offer great insulation, you get a much better picture of its performance by comparing it to a double-pane window than to an …