Make sure you look at the NFCR rating as well, not just the Energy star label. NFRC label will have rating for your climate area. My contractor has this on his site:
Energy saving windows are rated based on four properties, U-factor, Solar Heat Gain Coefficient (SHGC), Visible Light Transmittance (VT), Air Leakage, and Condensation Resistance. All criteria for energy star windows are based on these properties.
Energy efficient windows with an Energystar label will also show the regional zone its more suited for. Northern regional areas will require a window with different U-factor, SHGC, VT, Air leakage, Condensation Resistance rating than a window for a southern regional area.
NFRC labeling provides a guide for consumers based on independent research to help understand how a window performs. NFRC energy efficient windows will carry a label showing the window properties for you to validate the type of energy saving product you will install.
If you’re energy conscious, you need to make sure the NFRC label is good for your area.
