Julien Salingue: A longitudinal analysis (1978–2013) of the French housing system: continuity and discontinuities

This thesis begins with the observation that poor housing conditions have persisted over the last 30 years. By adopting a supply-side economic approach, public policy has proved incapable of responding to successive ‘crises’. An interdisciplinary review shows that few studies address the issue of housing within the joint dynamics of households (residential mobility) and housing stock (construction, demolition and renovation). Drawing on the concept of the filtering process and the vacancy chains method, our thesis proposes to overcome this limitation by creating new concepts (social position, function and demographic profile) that enable a comprehensive and dynamic analysis of the housing system. To this end, we have developed the Housing Systems Analysis (ASHA) model, which simulates the impact of variations in housing supply on the entire system based on household mobility (turnover rates) between housing types (vacancy chains).

This model was used, drawing on data from the eight Housing Surveys (INSEE, ENL, 1978 to 2013), to analyse, using a retrospective, prospective and experimental approach, the evolution of the housing system over a longitudinal period of 35 years. Through simple empirical observation, the initial analysis identified the functioning of the current system (2013), structured into residential sectors that mirror the hierarchy of society as a whole. Simulations of the continuation of successive supply policies (between 1978 and 2013) showed that the real break in the system stems from the continuation of the planning logic of the 1977 reform (enacted in the context of the Trente Glorieuses) up to 2013. Far from completely abandoning housing subsidies, the reform established a subsidised home ownership scheme for the upper, middle and solvent working classes, to the detriment of vulnerable households, often young people.

The prospective analysis, meanwhile, simulated the extension of the 2013 system through to 2050. The results reveal its high level of instability. The collapse of the private rental market drives households into early home ownership, which leaves them vulnerable and excludes them from the system. Furthermore, it highlights significant pressures within the social housing sector. The ASHA model also offers the possibility of conducting experimental prospective simulations of alternative housing policies: large-scale construction of social housing and attempts to build housing with a view to improving the fluidity of the system (adaptation to residential dynamics). The results do not fundamentally alter the organisation of the system, which remains highly socially unequal. In this sense, they show that resolving poor housing conditions requires recognising that a supply-side policy alone cannot address residential vulnerability caused by the effects of increasing precariousness in society as a whole. In this context, an overhaul of the system will likely require a reform that incorporates the profound transformations of the current and future social context.

Composition of the jury

Rapporteurs:

• Marc Dumont, Professor at the University of Lille
• Yankel Fijalkow, Professor of Social Sciences at ENSAPVS

Examiners:

• Jean-Claude Driant, Professor Emeritus at the Paris School of Urban Planning
• Véronique Flambard, Professor of Economics at the Catholic University of Lille
• Arnaud Simon, Senior Lecturer at Paris-Dauphine University (PSL)

Guest:

• Manuel Domergue, Director of Research at the Abbé Pierre Foundation