LEED rates all buildings across five major categories of concern, using key environmental attributes in each category. LEED collects and incorporates a wide variety of best practices across many disciplines including architecture, engineering, interior design, landscape architecture, and construction. It is a mixture of performance standards (e.g., save 20 percent of the energy use of a typical building) and prescriptive standards (e.g., use paints with less than 50 grams per liter of volatile organic compounds), but leans more toward the performance approach. In other words, LEED believes that best practices are better shown by measuring results (outcomes) not by prescribing efforts alone (inputs).

Each LEED rating system (see Table 2.5) has a different number of total points, so scores can only be compared within each system; however, the method for rewarding achievement is identical, so that a LEED Gold project for New Construction represents in some way the same level of achievement (and degree of difficulty) as a LEED Gold project for Commercial Interiors (tenant improvements). Figure 2.3 shows how the LEED-NC rating system splits points into the five major categories of concern.