About 70 million of the nation’s more than 118 million single-family homes, apartments  and mobile homes now have double- or triple-pane windows, according to the Residential Energy Consumption Survey (RECS), released this week by the U.S. Energy Information Administration (EIA). That represents roughly 59 percent of all homes in the U.S.

Double-pane windows can be found in 68.5 million U.S. homes, according to the survey, and 1.2 million homes have triple-pane units. Single-pane windows still exist in 48.5 million homes.

Despite the surge in vinyl window sales in recent decades (they were about 70 percent of the U.S. market in 2014, according to the American Architectural Manufacturers Association’s U.S. National Statistical Review and Forecast), metal remains the most popular framing material. RECS reveals that 47.5 million homes have metal-framed windows. About 42 million have wood windows and 25.3 million have vinyl windows. Only about 3.5 million households have fiberglass or composite windows.

Among all U.S. households, 37.7 million have ten to 15 windows. About 28.4 million have six to nine windows, and 17.6 million have three to five windows. Roughly 3.7 million homes have 30 or more windows.

Sliding glass doors might be a popular item for fenestration companies to promote, but 75.6 million U.S. homes still don’t have one. About 32.4 million have a single sliding glass door and 7.3 million have two. Around 2.9 million homes have three or more.

Windows play a vital role in reducing energy use and cutting greenhouse gases. In 2012, the residential sector accounted for 21 percent of total primary energy consumption and about 20 percent of carbon dioxide emissions in the U.S., according to the EIA.

EIA’s 2015 RECS Household Survey examined more than 200 energy-related items from more than 5,600 households.