The U.S. Green Building Council established Leadership in Energy & Environmental Design (LEED) in 2000 to assess buildings by key sustainability standards that include energy conservation, indoor air quality, the use of recycled and recyclable materials, support for reduced-carbon commuting solutions and long-term sustainability. LEED is the most widely used third-party verification standard for green buildings in the Americas. Public buildings, especially office buildings and educational and governmental facilities, are among the most frequent participants in the LEED certification program.