If you’ve ever conducted research to find the right kind of commercial skylights for your building, you have likely come across NFRC skylight ratings. The National Fenestration Ratings Council, or NFRC, is an independent nonprofit group that provides energy-efficiency certifications for windows, doors, and skylights and through its product ratings offers a great guide for skylights that will save you money in utility costs.
As an industry standard, skylight manufacturers rely on NFRC ratings to differentiate their products and indicate the quality of their construction. Reputable brands like Velux utilize this certification in both their residential skylights and commercial skylights to test the performance of their products in four categories:
The U-value of a skylight refers to its ability to resist heat transfer. A low U-value indicates high levels of insulation, which means the skylight will keep heat out in the summer and let in warmth during the winter.
2. Solar Heat Gain Coefficient (SHGC)
This metric is often shortened to SHGC and represents the ratio of transmitted solar radiation to the incident solar radiation of an entire skylight assembly. The SHGC ranges from 0 to 1, and tells you the solar energy transmittance of the skylight as a whole, including glazing, frame, curb, etc. A low SHGC rating means you will spend less on cooling in the summer.
3. Visible Transmittance
Visible transmittance indicates the effectiveness of a material in transmitting radiant energy, and in the case of skylights, it is measuring the effective transmission of natural light. This rating ranges from 0 to 1 and higher numbers mean more daylight is captured and diffused inside. Skylights with high visible transmittance ratings can save you money in electricity costs by replacing artificial light sources.
4. Air Leakage
The most self-explanatory of the NFRC ratings, skylights are rated from 0.1 to 0.3 in air leakage. The more effective the skylight is in acting as an air barrier, the lower its score, and the less you will experience drafts from your skylight.
It is important to note, however, that regardless of how a product performs in these categories, improper installation can undermine its energy efficiency. For this reason, manufacturers like Velux partner with local commercial and home remodeling contractors to provide exclusive installation services based on the quality and thoroughness of their work and their and commitment to providing the best job possible. As you move forward with your commercial skylight project look for one of these Velux appointed skylight specialists in your area.