Environmentally preferable or "green" building uses optimal and innovative design to provide economic, health, environmental, and social benefits. In 1993 the U.S. Green Building Council (USGBC) was formed by a broad range of building industry stakeholders from the public, private, and nonprofit sectors. It is a committee-based, member-driven, and consensus-focused nonprofit coalition leading a national effort to promote high-performance buildings that are environmentally responsible, profitable, and healthy places to live and work. In 2000, USGBC created the Leadership in Energy and Environmental Design (LEED) rating system. That voluntary standard was intended to transform the building market by providing guidelines, certification, and education for green building. LEED is a comprehensive, transparent, and market-driven framework for assessing buildings' environmental performance. Compared to standard practice, "green" buildings can provide greater economic and social benefits over the life of the structures, reduce or eliminate adverse human health effects, and even contribute to improved air and water quality. Opportunities for reducing both costs and environmental impact include low-disturbance land use techniques, improved lighting design, high performance water fixtures, careful materials selection, energy efficient appliances and heating and cooling systems, and on-site water treatment and recycling. Less familiar innovations include natural ventilation and cooling without fans and air conditioners, vegetative roofing systems that provide wildlife habitat and reduce storm water runoff, and constructed wetlands that help preserve water quality while reducing water treatment costs.