Is it easy being green? It sure seems so for the D.C.-metro area, according to new federal energy rankings.

With 686 buildings totaling 154 million square feet, the District and its surrounding jurisdictions came in first this year for their number of Energy Star-certified sites—buildings that are more efficient and produce fewer carbon emissions than others. (The EPA uses the Census Bureau’s definition of metropolitan areas; D.C.’s includes Arlington, Alexandria, Silver Spring, Frederick, Md., Rockville, Md., Bethesda, Gaithersburg, and Reston, Va.)

The District Department of Energy & Environment says the D.C. area overtook Los Angeles for the top spot last year. It adds that in 2015, there were 200 more buildings certified than in 2014, and that these helped save the District “$179 million in total energy costs.”

As one might expect, many of the District’s Energy Star-certified buildings are situated downtown (the majority are office buildings). According to a map that uses 2015 data, no such buildings exist east of the Anacostia River.

According to DOEE, there are more than 27,000 Energy Star-certified buildings in the U.S. as of the last December certification.

Graphs and map via EPA