This study aims to analyze how the energetic efficiency can be included inside the phases of Public Procurement, since its beginning, with particular reference to the Public Procurement for existing buildings. This sector, despite the actual economic crisis, continues to maintain consistent dimensions and to move huge economic resources involving various sectors of market. The Environment health cannot remain out of the factors considered in this circle and more and more we are invited from European Community to have a green approach also in this sector. In fact, if before the European Community Directives aimed to guarantee the general principles of free competition, impartiality, not discrimination and transparency, today the further aim is to improve this old approach, to come to another one based on energetic efficiency aspects, that leads towards goods and respectful services to the environment, socially responsible and innovative. This Job, through the study of the European and Italian laws for Public Procurement, wants to investigate on the causes that have lead to the birth and the development of the concept of “Green Public Procurement”, trying to trace its route and analyzing its different applications in Europe, but, above all, in Italy. Public Procurement will be analyzed, focus on that ones which have as object existing buildings, to try to formulate green rules to include in public announcements since the beginning.