These buildings were identified by cross-referencing a dozen or so indicators that indicate problems, often only minor or involving a single housing unit, such as procedures undergone relating to the safety of a building or hygiene, interventions by the Paris Fire Brigade, the proportion of vacant housing units over a long period or a building's unpaid water bills. The principle is then to retain only those buildings accumulating several of these issues. The addresses identified for the most part corresponded to old, co-owned buildings located in the north-eastern districts of Paris.
Carried out in collaboration with the City of Paris Department of Housing and Habitat (DLH), this initiative is part of an operational approach to monitoring residential buildings and preventing their degradation. The aim is to direct a small proportion of the on-site inspections carried out by municipal services, as complementary to responding to the 5,000 reports submitted to them each year by individuals or co-ownership bodies.