The Observatory for the prevention of old buildings in Paris becoming run-down

Aerial view of residential buildings, Paris 9th district © Apur

This observatory takes over from the Observatory of Insalubrity which ceased to be operational in 2011, at the same time as its plan to reintegrate substandard housing reached its end.

The new observatory has preventive objective.

Its aims is to predictively locate old, residential buildings facing difficulties so as to avoid them becoming run-down and insalubrious.

To enable it to carry out a monitoring function the observatory centralises data files on all private residential buildings built before 2000 and extracts six fragility indicators :

  • highly concentrated areas of small rented housing units,
  • dunning relevant to security and fire safety,
  • dunning relevant to salubrity,
  • positive lead diagnoses in communal or private areas of buildings,
  • substantial percentages of people demanding social housing,
  • buildings' water bills being unpaid.

Context mixing and weighting of indicators allow a list of most probable “fragile” buildings to be defined which is communicated to the housing services with a view to more specific monitoring.

This operation is repeated every year.


The observatory monitors private residential buildings built before 1949. It endeavours to define different types of problems linked to the technical aspects of a building, its management and its uses. A list of the most “fragile” buildings is drawn up annually by the observatory so that preventive action can be set in motion. The observatory thus contributes to orientating the checking of properties by technical services and facilitates public authority intervention as early as is possible. This procedure aims to avoid any new cases of buildings falling into the downwards spiral towards insalubrity.


The observatory is a partnership tool set up by the City of Paris (Department of Housing and Living Conditions), the Government (Île-de-France Regional and Interdepartmental Department of Housing and Accommodation -DRHIL-, Police Headquarters) and Apur, which is responsible for running it, by centralising its partners' data files.

In return, it enables the services in charge of housing in Paris (Department of Housing and Living conditions, Paris Police Headquarters and the DRHIL,) and,  in a more direct way, the technical service of City of Paris Housing Department to take action to prevent housing from becoming run-down.