What are Energy Performance Ratings?
How do you know if you’re getting an energy efficient product? The simplest answer is to check out the ENERGY STAR® label on qualifying replacement windows. By understanding the criteria used by the National Fenestration Rating Council (NFRC) for its ENERGY STAR® rating system, you can easily see a product’s potential for gaining and losing heat, as well as transmitting sunlight into your home. The ENERGY STAR® label enables consumers to easily identify NFRC-certified products that have superior energy performance.
There are five main categories for NFRC performance ratings:
- U-Factor – Ranging from 0.25 to 1.25, the lower the u-factor the better the window insulates.
- Solar Heat Gain Coefficient (SHGC) – from 0 to 1, the lower the number, the less solar heat the window transmits.
- Air Leakage (AL) – The rate at which air passes through joints in the window. From 0 to 1, the lower the AL, the less air leakage.
- Visible Transmittance (VT) – The amount of light the window lets through. The higher the VT the more light you see.
- Condensation Resistance – How well the window resists water build-up. From 0 to 100, the higher the number, the less build-up the window allows.
By understanding the ENERGY STAR® rating system, you can rest assured that you made the right choice.