Glossary - N

A Glossary of window terminology

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Nailing Fin (or Flange)
The section of siding or accessories where the nailing slots are located.

National Fenestration Rating Council (NFRC)
The NFRC is an independent third-party certification organization with industry-accepted standards for evaluating and certifying energy performance. The NFRC Certificate contains U-factor, SHGC (Solar Heat Gain Coefficient), and VT (Visible Transmittance) values. These values form the basis for the ENERGY STAR® Door and Window Program.  

Non-Removable Operator Cover
A fixed cover which conceals the operating hardware on a casement or awning window.