What is U-Factor and how is it different from R-Value?
Also known as the U-Value, this measures the rate of heat transfer through a material. The U-Factor is the most effective measurement for window performance. While R-Value measures the performance of the individual parts of a window, U-Factor measures how well the fully assembled window resists heat transfer. Every aspect of a window, from the spacer, to the glass, to the framing material, to the gas fill, affects performance. U-Factor measures all of it. U-Factor is the opposite of R-Value when it comes to measurements. The lower the U-Factor the better. A window with a low U-Factor insulates your home better and has higher heat transfer resistance.
