Product Performance Values

What you get with a VELUX

All VELUX Skylights are tested to meet the harshest weather climates around the world. Our entire product program endures rigorous VELUX testing to ensure quality and performance in every box. All products manufactured in North America are not just tested for performance, but also third party certified with unannounced factory inspections.

Testing Data

VELUX residential skylights & SUN TUNNEL® skylights are rated at 20° slope and labelled with NFRC – certified product values and NAFS testing.

Certified Energy Performance Value (NFRC) - Definitions

U-value is the thermal transmittance, the rate of heat transfer through the skylight due to temperature difference. The lower the number the more energy efficient. (U-value is the inverse of R-value.)

Solar heat gain coefficient (SHGC), the fraction of incident solar radiation from the sun that gets through the skylight and into the building at a 0˚ incident angle.

Visual transmittance, the fraction of visual light that gets through the skylight from outside into the building.