The project focuses on the energy-saving rehabilitation of 289 social rental units in Mont-Gaillard, Le Havre. These 289 units are of a collective type. They are divided into 7 buildings:- 89, 90, 95 avenue Mont Gaillard- 2, 11, 12 and 13 avenue Jacques BrelIls were built in 1975-1976. The buildings have 10 levels. These dwellings are agreed.Their energy performance is not very satisfactory since they are classified as “D”. A thermal study was carried out, the objectives set are to reduce primary energy consumption by at least 80 kwh/m/year and to obtain the BBC Effinergie Rénovation label. After work the 289 dwellings will be classified “B”.