The U.S. Green Building Council has recognized nearly 100 schools as eco-friendly under the Leadership in Energy and Environmental Design program. For the LEED program, schools are rated on a point system and given a designation reflecting the environmental elements they incorporate. The highest score is 79 Certified = 29-36 points Silver = 37-43 points Gold = 44-57 points Platinum = 58-79 points. Only one school, Sidwell Friends in Washington, has achieved platinum certification status. The scoring system is divided into six categories: Sustainable Sites (criteria such as proximity to public transportation, maximizing open space and controlling pollution during construction). Water Efficiency (criteria such as landscaping that needs relatively little water, reduced water usage in the building and innovative water system designs). Energy and Atmosphere (elements such as on-site renewable energy sources or use of refrigerant that doesn't employ ozone-depleting chemicals). Materials and Resources (criteria such as storage and collection of recyclable waste, renovation of existing buildings rather than new construction, and use of recycled materials during construction). Indoor Environmental Air Quality (elements such as increased ventilation, large windows that bring in natural daylight and motion sensors that control artificial lighting). Innovation and Design Process (elements such as a green curriculum that showcases environmental aspects of the building and use of cleaning agents and methods that minimize noise and air pollution).