The National Fenestration Rating Council has designed an energy-performance label to help guide contractors and homeowners in their search for the perfect window to meet their needs. Since the climates in different parts of the United States differs widely, examining the labels before ordering any window can make a difference in how much the window will help the client keep energy costs to a minimum. Do not feel intimidated about reading the label. Once you know what to look for, you will be able to find exactly what you are looking for in new windows.
Here are a few tips to get you started.
When you see NFRC Certified this indicates that the National Fenestration Ratings Council has licensed the window’s manufacturer and certified the window’s performance in accordance with NFRC’s standards. On the upper right corner it identifies the window’s manufacturer, model, style and the materials used in its construction.
Energy Performance Ratings include the following:
The U-Factor ratings for windows generally fall between 0.20 and 1.20. The lower the U-value, the greater a window’s resistance to heat flow and the better its insulating value. Keep in mind that the window’s insulating value is indicated by the R-value.
In addition, the solar heat gain coefficient (SHGC) specifies how well a product blocks heat from the sun. The SHGC is expressed as a number between 0 and 1. Once more, the lower the number the better. A low SHGC means the window transmits less solar heat.
Visible transmittance shows the amount of visible light transmitted. VT is expressed as a number between 0 and 1. The higher the VT, the more light is transmitted.
Air leakage is expressed as the equivalent cubic feet of air passing through a square foot of window area. Heat loss and gain happen by infiltration through cracks in the window assembly. The lower the AL, the less air will pass through cracks in the window.
Condensation resistance is the ability of a product to resist the development of condensation on the interior surface of that product. The higher the CR rating, the better that product is at stopping condensation formation.