The Efficient Windows Collaborative (EWC) is a coalition of window, door, skylight, and component manufacturers, research organizations, federal, state and local government agencies, and others interested in expanding the market for high-efficiency fenestration products. Its goals are to double the current market penetration of efficient window technologies, and to make National Fenestration Rating Council (NFRC) labeling a near-universal practice in U.S. markets.

EWC members have made a commitment towards manufacturing and promoting energy efficient windows, and represent manufacturers, suppliers, and affiliates to the window industry.

The Efficient Windows website ( provides unbiased information on the benefits of energy-efficient windows, descriptions of how they work, and recommendations for their selection and use.