GLOSSARY-N

Nailing fin

A vinyl or aluminum extension attached to the frame of a window or door which creates a positive seal between the window and the framed wall. Acts as an additional barrier against air and water leakage. Screws or nails are fastened through the fin to hold the unit in the opening.

Natural convection

A heat transfer process involving motion in a fluid (such as air) caused by difference in density of the fluid and the action of gravity This is an important part of heat transfer from the glass surface to room air. See: Forced convection.

NFRC

National Fenestration Rating Council® -a non-profit organization that provides fair, accurate and credible energy performance ratings for windows and doors.