Leadership in Energy and Environmental Design. Spell out on first reference. The LEED rating system is a third-party certification program by the U.S. Green Building Council for the design, construction and operation of environmentally friendly buildings. Platinum is the highest level (most “green”), followed by gold, silver and simply “LEED certified.” WashU committed in 2008 to meet or exceed LEED Silver certification for all new construction or major renovations. For more on the system, see the Green Building Council website.