According to the US Green Building Council, buildings (in the United States) account for:
Green and sustainable building technologies can provide a variety of benefits, including improved air and water quality, reduced waste streams, reduced operating costs, enhanced comfort of building occupants. To obtain these and additional benefits, obtaining varying levels of Leadership in Energy and Environmental Design (LEED) certification is a top priority in any major building project.
LEED is a third party certification program of high-performance green buildings. LEED certification gives building owners and operators the tools they need to have an immediate and measurable impact on building performance by promoting a whole-building approach to sustainability. LEED is a broad-scope set of guidelines and performance factors used by everyone from architects to construction managers, lenders, and interior designers to create sustainable building environments.