Choosing a Window Installer
Beware of Misleading Sales Practices
The U-Factor Rating Must Reflect the Whole Window. Be sure the U-Factors you’re comparing are “whole window” values. Energy Star requires heat transfer measurements be taken at 20 places on the window frame and glass, (as shown to the left). Some manufacturers report a “center-of-glass” value only, making their window appear more energy-efficient than it actually is. If the U-Factor seems suspiciously low, ask them to prove it’s a “whole window” rating.
R-Values are Not Recognized for Windows
R-Values are appropriate for wall insulation and roofing, but not for windows. Most consumers are aware that higher R-Values signify better insulating properties, but an R-Value can only be used to measure the window’s center-of-glass, not the entire window unit; therefore it is a rating method not accepted by the NFRC or the Energy Star® program.
Look for the NFRC Label
NFRC stands for the National Fenestration Rating Council; (The word fenestration has roots in the Latin word for window, fenestra. Fenestration defines any object that fills an opening in a building, such as windows, doors, skylights, etc.)
The National Fenestration Rating Council partners with the U.S. Dept of Energy to help consumers compare the energy-efficiency of window products. Manufacturers participating in their program are required to label every window with its thermal performance and U-Factor rating. Rite Window is a participant in the NFRC program.
The NFRC label to the right shows the two most important ratings in determining energy efficiency, the U-Factor, and the Solar Heat Gain Coefficient, (SHGC). Solar Heat Gain is a measure of the interior heat generated by sunlight through the window. For New England climates the SHGC is a trade-off. A higher SHGC rating means more heat from sunlight keeping the house warm in the winter, but also less efficient cooling in the summer.
Look for Low-E Coated Glass
Low-E is short for low-emissivity. It’s a very thin coat of material on the glass that reflects heat and ultraviolet radiation. Low-E coatings have been in use since 1979. Today’s Low-E coatings improve the energy-efficiency of clear glass by 30%. The huge benefit of Low-E versus the small additional cost makes installing new windows without Low-E unwise, therefore all our windows have a Low-E coating.
Look for Argon or Krypton Gas Fill
Window thermal performance is improved by adding argon or krypton gas between the panes. Argon and krypton gas minimizes the convection currents within the space, and the overall transfer of heat between the inside and outside is reduced. Rite Window uses an argon fill. The gas is nontoxic, nonreactive, clear, odorless, and improves the performance of our window by 20-to-30%.