There is only one reliable way to compare windows and that is by asking for the NFRC* rating for each window that you are considering. NFRC labels are independently certified and rate the whole window performance by U-Factor and Solar Heat Gain Coefficient (SHGC). The lower these ratings are the better the window will perform. The priority of U-Factor versus SHGC depends on your climate. You should ignore all the sales hype and choose the best NFRC ratings for your climate at the best cost.
Energy Star is a window certification program administered by the Federal Government to help you select energy efficient windows optimized for your climate. A window must meet minimum performance criteria to qualify. These criteria are based on NFRC whole window performance ratings and are different for each of four climate zones as follows:
Northern Zone (blue): U-Factor of .30 or less, SHGC any
North Central Zone (yellow): U-Factor of .32 or less, SHGC of .40 or less
South Central Zone (orange): U-Factor of .35 or less, SHGC of .30 or less
Southern Zone (red): U-Factor of .60 or less, SHGC of .27 or less
Yes, any window or patio door ordered with a LowE glass upgrade will qualify for the Energy Star guidelines for the climate zone where purchased. This guarantee always comes in writing on your contract specifications so you will be assured of ordering and receiving the best LowE glass that is optimized for your particular climate zone.
The Window Source provides you with extremely affordable prices on premium vinyl windows because of our large national buying power. also our low prices and easy purchasing process allows us to be extremely efficient and pass the savings along to you.
Yes, a window needs to be properly measured to fit the opening and allow adequate tolerance for pluming and squaring the new window. If the new window is not properly plumbed and squared it will not seal and operate properly no matter how good the quality of the new window.
Every Window Source job comes with a Limited Lifetime Warranty and Labor Warranty. Every window is delivered with an NFRC independently certified label and will qualify for Energy Star for your climate zone if ordered with the LowE glass upgrade. You will also receive a written best price guarantee at participating locations.
*The National Fenestration Rating Council (NFRC) U-Factor is a certified measurement of the resistance to conduction of heat and cold by the entire product (frames and glass). The Solar Heat Gain Coefficient (SHGC) is a certified measurement of the ability of a product to keep out unwanted solar heat gain in the cooling season.