“Subsidiary cities” for the 21st century: How the subsidiarity principle can help us design new sustainable settlements in times of climate crisis

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This proposal comes directly from the main results of my doctoral thesis in architecture, recently defended on 14 March 2022, which explores the garden cities model imagined in Great Britain in the late 19th century (Howard, 1898). On the basis of a fieldwork combined with historical and prospective investigations, this work proposes a re-examination of this well-known urbanisation model in order to reveal its relevance for today, and to suggest new forms of territorial organisation able to tackle the contemporary housing crisis in a context of socio-ecological transition. To this end, the proposal that is made aims to develop new approaches by thinking the design of new human settlements from the scale of the living (human and non-human) and its synergistic relationship with the territories.This proposal chooses to focus on the main results of my thesis, and more specifically to pursue my work on the concept of “subsidiary cities”. The notion of “subsidiarity” is usually used in the context of the organisation of public action in order to optimise the scope of action of each political level. However, this principle, when transposed to other fields such as territorial planning and urban development, allows us to explore new urban approaches focusing on habitability, and simultaneously to clarify interactions and spaces of negotiation, whether they are biological (physical) or political (social). Exploring the polysemy of the term "subsidiarity" leads us to investigate in a new light the principles of social organisation, to reconsider spatial scales and to imagine new scenarios based on the interactions between the urbanised space and the biosphere that hosts it.This approach will lead us to explore in more detail several elements, including: spatial distances and the notion of proximity, the interdependence between urban space and the local resources, the challenges of urban metabolism for the built environment (Wolman, 1965; Barles, 2014), the complementarity of territories, and the possible relationships of cooperation and mutual aid (Kropotkin, 1902; Servigne & Chappelle, 2017) that can be established within a shared space. What will be proposed here is not, in the end, a new model, but rather an original method and a tool which can help us to think about sustainable urban planning through a scenario which is both spatial and social and which deals with all the complexity of the issues imposed on us by the climate emergency.