In this final degree project proposal will explain what is an environmental certification, what kind of environmental certifications exist in the world, will discuss one of the most important BREEAM-ES (Building Research Establishment Environmental Assessment Methodology - Spain), will be a building of less than 40 years with 16 detached houses located in L'Hospitalet de Llobregat. Be studied to know in what state of certification is under the BREEAM certificate and also will be proposed to make a statement to obtain the BREEAM environmental certificate and submit a proposal for a higher level of certification. Finally, proposals will be analysed from the point of view of economic and sustainable.