You should always look for the ENERGY STAR® label while shopping for an energy-efficient window replacement. Only windows that have complied with the EPA’s stringent energy requirements are certified by ENERGY STAR. Of course, not all ENERGY-STAR-certified windows have the same level of energy-efficiency. How can you pick an energy-efficient window from dozens that were certified by ENERGY STAR? By checking the National Fenestration Rating Council (NFRC) label.
What do the ratings on the NFRC label mean?