What does the NFRC label tell you?

Understanding commercial vinyl window codes and understanding The NFRC label helps you compare between energy-efficient windows & doors by providing you with energy performance ratings in multiple categories.

U-Factor measures how well a product can keep heat from escaping from the inside of a room. The lower the number, the better a product is at keeping heat in.
Range: 0.20-1.20 Look for: Low numbers

Visible Transmittance measures how well a product is designed to effectively light your home with daylight, potentially saving you money on artificial lighting. The higher the number, the more natural light is let in. Range: 0-1 Look for: High numbers


Solar Heat Gain Coefficient measures how well a product can resist unwanted heat gain, which is especially important during summer cooling season. The lower the number, the less you’ll spend on cooling. Range: 0-1 Look for: Low numbers

Air Leakage measures how much air will enter a room through a product. The lower the number, the fewer drafts you’ll experience.
Range:  ≤ 0.3  Look for: Low numbers