The Efficient Windows web site is sponsored by the Efficient Windows Collaborative (EWC) with support from the U.S. Department of Energy's Windows and Glazings Program and the participation of industry members. This web site provides unbiased information on the benefits of energy-efficient windows, descriptions of how they work, and recommendations for their selection and use. EWC members have made a commitment to manufacture and promote energy-efficient windows. Take a look to learn more!