Towards a sustainable transition of peri-urban neighborhoods?

Since the Industrial Revolution, urban spaces have undergone a profound reorganization in parallel with a transformation of society and lifestyles. Urban sprawl has become widespread in Switzerland, as in countless countries, due to continuous innovations in transport, exponential population growth, land speculation, and the ubiquitous desire to live in a single-family house. This process has led to a dispersion of the city in rural areas, which today raises multiple questions regarding sustainability aspects. In response to the negative consequences of urban sprawl, the model of the polycentric compact city sets a reference for the expression of ambitious spatial planning policies. The context, very favorable to inward densification processes in areas well served by public transport, changes the perception of neighborhoods of single-family houses by providing them with a status of unexploited land reserve. A growing number of projects is investing this emerging field of research to address the challenges of under-occupancy of housing, energy insecurity or the production of new residential areas. However, some neighborhoods, located in peri-urban areas benefiting from a relatively poor public transport service, are on the margins of current investigations. Proactive approaches are still rare to provide answers to the challenges faced in these existing residential sectors.

The aim of this doctoral thesis is to develop a decision-support framework to consider the future of peri-urban residential areas and their participation in the sustainability transition. Anchored within the European and Swiss contexts, the work questions the transformation potential of neighborhoods by 2050. The approach is divided into four phases, the first of which consists in developing a typology of peri-urban neighborhoods of single-family houses. This typology is the result of a method based on the successive reduction of the analysis scale, from the theoretical definition of peri-urban residential municipalities to the census of representative neighborhoods in the Greater Lausanne area. The design of prospective transformation scenarios is part of the second phase of the research. The five scenarios – Caducity, Exclusivity, Opportunity, Urbanity, and Mutuality – are derived from stagnation or transition trends of peripheral sectors, identified during interviews conducted among about twenty experts. The third phase consists in applying the scenarios to six existing neighborhoods over a 35-year time horizon. The thesis does not have as its sole objective to carry out forward-looking work applied to concrete cases, by proposing a medium/long-term vision. Its innovative character also lies in the implementation of an experimental tool of building information modelling (BIM) at the neighborhood scale to deal with the complexity related to the constraints of individual ownership. Considering assumptions of demographic and temporal calibration of projects, the fourth phase, of multi-criteria assessment, is enhanced by a dynamic analysis of evolutions.

This assessment, developed in light of sustainability issues, shows a considerable potential for improving peri-urban neighborhoods, through energy-saving building renovations and the preservation of quality living standards. The path towards more sustainable futures also depends on the coordination of decisions at the neighborhood level to go beyond the mere juxtaposition of individual interests.

This thesis was produced as part of the LIVING PERIPHERIES research project, with the support of the Swiss National Science Foundation (SNSF).