Green building sometimes called "high-performance building" refers to the practice of reducing the environmental impact of the built environment. Because buildings are visible and are such significant users of energy and materials, applications of sustainability have attracted as much attention as green building, particularly in the commercial real estate sector. Since the introduction of the Leadership in Energy and Environmental Design (LEED) standard in 2000, over 20,000 new commercial buildings have been recognized as LEED-certified. During the recent economic recession, the focus of sustainable real estate in the US shifted somewhat. Other careers in the real estate arena that have a focus on social and/or environmental issues include affordable housing development, community development finance, and urban planning and redevelopment. Some corporate sustainability roles are heavily focused on buildings and real estate; companies like banks, information technologies firms, retailers, and other corporations with large real estate footprints often have roles in their sustainability departments that center primarily on sustainable buildings.