LEED is a system that rates now green a building is. It is a nationally accepted benchmark for the design, construction, and operation of green buildings. LEED certification rates structures based on water and energy efficiency, sustainability of the site, construction materials, and indoor environmental quality. LEED looks at the entire life cycle of a building – its design, construction, and its operations. The idea is to construct commercial and residential buildings to a higher standard that minimizes adverse environmental impacts. Under LEED, a building is evaluated under a multi-level Green Building Rating System. It is an objective set of standards that assigns points. Different levels of certification depend on the number of points earned. The levels from lowest to highest are Certified, Silver, Gold and Platinum. Next: How to LEED.