Operation Cour Gaillard in Bourg en Bresse and built in 1957, consists of the thermal rehabilitation of collective housing in occupied site. Several stages of work were carried out in 1988-89 and then in 2018-2020 on the built structure, the common areas and housing, the zinc roofing, heating and exterior joinery. A programme of additional works is aimed in particular at improving the thermal and energy efficiency of buildings. The objective of this heavy rehabilitation is to guarantee all tenants a better comfort of use and thermal of their homes, to control the energy expenditure of buildings and greenhouse gas emissions.