NFRC Window Energy Ratings: Important Tools for Meeting Project Specs and Building Codes

 As sustainable building becomes increasingly popular, developers, architects, builders and homebuyers  need to be confident that green components, like energy-efficient windows, perform as advertised. Just as cars have Miles-Per-Gallon ratings, the National Fenestration Rating Council (NFRC) provides uniform fenestration ratings that can be used for comparison.   

NFRC is a nationally recognized and trusted source of energy performance ratings for windows, doors, skylights, and other fenestration products. Its independent procedures are utilized in the 2009 International Energy Conservation Code (IECC) and ASHRAE 90.1-2007, the basis of Nebraska’s building energy codes. Officials enforcing these building codes rely on NFRC’s independent ratings.   

NFRC provides straightforward performance ratings for heat loss (U-Factor), heat gain (Solar Heat Gain Coefficient or SHGC), and Visible Transmittance (VT). The U-Factor measures how well a fenestration unit can prevent heat from escaping, typically ranging between 0.09 and 1.20. The SHGC, demonstrated in a number between 0 and 1, measures how well the product blocks solar heat. The smaller the U-Factor and SHGC ratings, the better the performance. VT measures how much light is transmitted through the product. It is rated between 0 and 1, and the higher the rating, the more light comes through.  

NFRC provides ratings for both the residential and non-residential sectors. For residential fenestration, NFRC lists energy performance values on temporary labels attached to products it rates. NFRC doesn’t attach labels to non-residential products built or assembled on the project site. NFRC’s Component Modeling Approach (CMA) program for non-residential fenestration can provide certified ratings on a project-specific document called a Label Certificate. The CMA program provides an innovative way for users to configure variations of fenestration products online, compare preliminary energy performance values and then certify those ratings.  

Fenestration performance values also play an important role in calculating building energy performance. NFRC provides accurate, reliable energy values that users can input into energy modeling software to determine building efficiency.   

Having an understanding of NFRC’s independent ratings can help architects, designers, contractors, and consumers select the right fenestration products for their green building projects to increase their sustainability and value.

By Tom Herron, NFRC’s senior manager, communications and marketing. You can reach him at therron@nfrc.org.