The building was recently acquired by DAH (1992) and previously had a condominium status, resulting in a certain heterogeneity of the state and the seniority of the private elements (windows, radiators, etc.). The building has never been the subject of energy improvement work since its construction in the 1960s. The programme is dealt with in three main areas: energy performance — Valorisation of heritage — Acceptance and appropriation of works Energy performance The most efficient interventions are defined on the basis of a careful diagnosis. In the event that certain elements cannot be dealt with at a sufficient level of performance, for questions of acceptance by the inhabitants or economic arbitration, care is taken to leave the real possibility of re-intervention in order not to “kill the deposit” of energy savings. Priority is given to insulation, which is the basis for the energy performance of the building, the challenge being to reduce heating needs and improve summer comfort. A high thermal performance partly common is necessary but not sufficient: — treatment of thermal bridges on a case-by-case basis, — Perenniity of performance through the choice of coatings. The intervention on equipment is guided by the research to reduce loads: — issues to be resolved at the end of the audit — integrated energy approach to design