LEED certification was developed and introduced in the US in 1999 by the Green Building Council, the association that brings together representatives of the building industry, of the research institutes and North American government bodies, with the objective of providing a useful tool for all operators in the sector to certify an eco-sustainable development. This certification evaluates and certifies the environmental, social and economic sustainability of buildings, from their project-planning phase to their final execution, thanks to a flexible system featuring different parameters depending