Washington, D.C. has quickly become a pioneer for environmental sustainability. The new Nationals stadium, for example, is the first baseball stadium in the country to receive LEED certification. Certification for LEED, which stands for Leadership in Energy and Environmental Design, is given by the U.S. Green Building Council, when buildings qualify for a certain number of points in five categories: sustainable site development, water savings, energy efficiency, materials selection and indoor environmental quality. The District......