Where in the United States was a building project most likely to be environmentally friendly in 2012? According to the U.S. Green Building Council, it's the District of Columbia. The council, whose Leadership in Energy and Environmental Design (LEED) program certifies buildings that have incorporated sustainable elements into their design and construction, says that Washington, D.C., with its abundance of federal facilities, had 36.97 square feet of space per resident that was certified under LEED in 2012. That far outdistances any individual state. Virginia, which also has numerous federal government buildings, was the state with the greatest amount of square feet certified per resident in 2012 under LEED — 3.71.