These pavilions located in the Varizelle district of Saint-Chamond were built in the mid-1980s and have not undergone major modifications since. A social diagnosis was carried out by the departments of Gier Pilat Habitat and the fluid design office. It makes it possible to identify that these dwellings mainly house households with less than the resource ceiling (of which 20 % have less than 60 % of the ceiling). The aim is therefore to improve housing while reducing the rent-load couple: the increase in rents will be offset by a reduction in energy charges (a 50 % reduction in the charges on this project). The buildings do not have remarkable architectural interests and are not subject to particular heritage constraints, so outdoor thermal insulation will be possible. The current walls are weakly isolated and aging. They therefore no longer allow an insulating envelope to play its full role. Their treatment and the replacement of existing carpentry will also significantly improve the airtightness of the operation. This work programme was initially built on the basis of a comprehensive and detailed state of play: study of existing plans, visits, long exchanges with tenants. The contracting authority had an energy audit carried out by an external contractor.