What is the National Fenestration Rating Council (NFRC)?

NFRC is a non-profit organization that administers a uniform certification and labeling process for windows, doors, and skylights.  Their goal is to provide the public fair, credible, and accurate information related to fenestration performance.  NFRC is widely accepted as the standard certification for thermal performance in the window and door industry.

The resulting testing and certification results in the measuring of a units performance in four key areas:

1. U-Factor or U-Value - The amount of heat energy that will flow through the product from inside to outside. Lower values are better.

2. Solar Heat Gain Coefficient (SHGC) - The amount of heat energy from the sun that will flow through the product from outside to inside. Higher = more Solar Heat; Lower = less Solar Heat

   • Heating climates want passive solar heat gain

   • Cooling climates want to lower solar heat gain

   • Results are between .01 and 1.0

3. Visible Transmittance (VT) - The amount of the visible light that is transmitted through an insulated glass unit. The lower the number, the less visible light that passes through.

4. Air Leakage Rating - A meausre of how much outside air comes into the home or building through the window or door product. The lower the air leakage number the better the product is at keeping air out.

All NFRC certified products should have labels detailing the individual unit’s performance.  In addition, all certified products are listed on their website at www.nfrc.org and are searchable by performance criteria and manufacturer.

Complete NFRC Ratings

• Cornerstone Complete NFRC Ratings

• Apex Complete NFRC Ratings

To find the permanent NFRC label on your WeatherBarr Products, use the WeatherBarr NFRC Label Location document.

To see how our WeatherBarr products perform, take a look at our Energy Efficiency Ratings.

If you need more help with window jargon, then check out our glossary of technical window terms.