U-Factor and R-Value: How to Read Window Energy Ratings
When shopping for windows, it’s important to understand how to read the energy ratings to ensure that you’re getting the most energy-efficient option for your home. Two key ratings to understand are U-factor and R-value. In this post, we’ll explain what these ratings mean and how to use them to make an informed decision.
U-factor is a measure of how well a window can prevent heat from escaping. The lower the U-factor, the better the window is at insulating. U-factor values typically range from 0.20 to 1.20, with lower values indicating better insulation. Look for windows with a U-factor of 0.30 or lower for maximum energy efficiency.
R-value is a measure of how well a material can resist heat flow. The higher the R-value, the better the material is at insulating. R-value is typically used for insulation materials like fiberglass or foam, but it can also be used to rate windows. Look for windows with an R-value of 3.0 or higher for maximum energy efficiency.
It’s important to note that U-factor and R-value are not interchangeable, as they measure different aspects of energy efficiency. However, both ratings are important to consider when shopping for windows.
In addition to U-factor and R-value, there are other energy ratings to consider when shopping for windows, such as solar heat gain coefficient (SHGC) and visible transmittance (VT). SHGC measures how well a window can block heat from the sun, while VT measures how much visible light can pass through the window.
By understanding how to read and interpret these energy ratings, you can make an informed decision when shopping for windows. Look for windows with a low U-factor and high R-value, as well as other energy-efficient features like low-E coatings and gas fills, to ensure that you’re getting the most energy-efficient option for your home.
