This document is created as result of the works and tasks made on “VAM Arquitectes” study and becomes on Final Degree Project (PFG from now on) as “Practicum” modality. All the task I have made during this period has been different, but this project would focus on two of them and how I related them. In the first step, I learnt how to analyse energy efficiency in the construction, making several Energy Efficiency Certificates. After that, I started to collaborate actively in an Executive Project based on Rehabilitation and Usage Change in a Barcelona local in Napols street. It would be the new “Ateneu” for the neighbourhood. The last stage, in order to include what I learnt during these months, I have done an energetic study before and after the rehabilitation of the local. This allowed me to extract environmental, energetic and economic conclusions. In resume, this internship has helped me to settle all the academic knowledge learnt during my degree. It also help me to have a real professional experience. This last point was the main reason I preferred to make a “Practicum” for my PFG.