Brand new replacement windows and patio doors come with ENERGY STAR® certification labels and energy performance labels from the NFRC. In today’s post, Renewal by Andersen® of Denver shares a look at the differences between these labels, and how they can help you choose the right replacement windows.
Energy Performance Label
The National Fenestration Rating Council is a non-profit organization that sponsors ratings for fenestrations, or windows, skylights and entry doors. Unlike the popular notion of ratings systems, the NFRC does not categorize products into “good” or “bad”. They simply rate products based on their energy performance. NFRC ratings are printed on a white label and are divided into four categories:
U-Factor — U-factor or U-value measures a product’s insulation, particularly in how a product keeps heat from escaping the room. A lower U-factor means better insulation. Some product literature may rate insulation based on R-value, but it measures resistance to thermal transfer. Therefore, a product rated with a low U-factor will have a correspondingly high R-value.
Solar Heat Gain Coefficient — Solar heat gain coefficient, or SHGC, measures resistance against heat gain from direct sunlight. Window replacement options that feature Low E coatings typically have low—therefore good—SHGC.
Visible Transmittance — Visible transmittance measures how well a product allows natural light through. Another feature of glass with Low E coatings is, unlike tinted glass, it allows as much natural light as clear glass does. Higher visible transmittance means more natural light.
Air Leakage — Air leakage measures how much air can pass through a product. Products with low air leakage values help prevent drafts.
ENERGY STAR Label
ENERGY STAR’s labeling system is established as a way for consumers to easily identify energy-efficient products. Unlike the energy performance label described above, ENERGY STAR certification applies to a diverse selection of products, from computers to washing machines. The ENERGY STAR label is aimed at consumers who are not as concerned with specific energy ratings but nevertheless in need of energy-efficient products such as windows.