When buying energy-efficient windows, it’s imperative to pay attention to the anatomy of the unit. Understanding the fancy terms can help you understand the unique features of the product. But at the end of the day, energy performance ratings count the most.
To choose the most energy-efficient replacement windows for your home based on their ratings, you should know the answer to these important questions first:
What Is U-Factor?
This rating measures how good the window is at thermally insulating rooms. Ranging from 0.20 to 1.20, a lower number means it’s better at keeping the heat inside. In Nassau, Suffolk, Kings, and Queens counties, ENERGY STAR® recommends products with a U-factor of 0.30 (or less) to meet the energy efficiency requirements in the North-Central Climate Zone.
What Is Solar Heat Gain Coefficient (SGHC)?
While U-factor is about trapping indoor heat, SGHC pertains to the ability of the unit to prevent unwanted heat gain because of the sun. Ranging from 0 to 1, a lower number means a more efficient unit. Any windows installation expert, though, would say that an SGHC of 0.40 (or less) is the optimum complement to a 0.30 U-factor. Anything more than that affects the overall product’s energy efficiency when used in the North-Central Climate Zone.
What Is Visible Transmittance (VT)?
VT is about measuring daylighting. Also ranging from 0 to 1, the higher it is, the better the product is at admitting sunlight. Products with high VT values help increase the potential artificial lighting savings.
What Is the NFRC Label?
The National Fenestration Rating Council is a non-profit organization that independently tests and rates casement, double-hung, bay, bow, picture, specialty and sliding windows. The ENERGY STAR seal tells you which products are energy-efficient, but the NFRC label helps you compare your best options. It contains information about the product’s performance ratings, including U-factor, SHGC and VT.
At Renewal by Andersen of Long Island, all of our windows are ENERGY STAR–certified with excellent NFRC ratings. To learn more about our products, call us at (866) 609-5033 or fill out our contact form to schedule your free, in-home consultation. We serve clients in Massapequa and nearby areas.
