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Innovation in Urban Transition Practice: Putting Transition in Place in Arcueil and the Plateau de Saclay

To focus our view even more strongly in the practice of urban ecological transition, the Vice Mayor of Habitat for the Town of Arcueil, Carine Delahaie, and urban and landscape designer for the Plateau de Saclay Anthony Cara, provided insights into their work. The Arcueil that we visited on July 3rd, 2025 was an inner-ring Parisian suburb that had undergone a remarkable transition from the 1960s, when it was a site of concentration of thoroughfares and rundown, squalid buildings, where residents faced severe public health challenges. Notably, tuberculosis affected residents of the 13 ha of decrepit older public housing. The transition pathway that Arcueil has travelled has led to today’s image of a modern and green city, with new social housing buildings, sited adjacent to rich greenway and community gardens, with protected pedestrian pathways. Delahaie is proud to consider Arcueil a laboratory of innovation in urban habitability.

Delahaie also noted that the wholesale importation of technologies of ecological innovation had not always served their efforts well. The strongest example of the challenges faced was that the national climate law had come down to impose the resdesign of social housing building operations to ensure a maximum of 19 degrees in public housing, in order to avoid heat-related illnesses. While Arcueil complied with the national direction, they immediately faced two problems in implementation. First, they found that energy consumption increased, contrary to climate change mitigation targets. Second, and more immediately concerning given the special local public health history of Arcueil, at a temperature of 19 degrees in the humid summer, building managers observed mould growing in dank and cold interior building spaces, raising the fears of residents and operators alike. The solution that they were able to arrive at, through negotiation and consideration of local conditions as well as willingness to innovate, was geothermal heat exchangers instead of conventional air conditioners to achieve indoor comfort during summer heat.

The case of Arcueil was a shining example of a town with modest economic means that rose to the challenge and opportunity of embracing what resonated with the specifics of the local landscape, socioeconomic context and built environment, to situate aspects of the ecological transition that could meet multiple goals and improve the habitability while protecting local specificity.

For Anthony Cara, whose work as a development consultant on the large ZAC de Corbeville on the Plateau de Saclay exposes him to a host of terms and technologies to employ in the design of a new demonstration site for ecological transition, finding the intersection point of cultural, ecological and urbanist demands is key. While excited by opportunities to uncover the medieval culture of the place through preparatory archaeological works, to demonstrate engineering efficiencies including on-site ecological urine treatment and fertilizer generation, constructed wetlands and the use of on-site landscaping materials, the true work of innovation is not in the pure technologies of ecological urbanization. Instead, according to Cara, it is the rendering of social and cultural visibility and legibility of the site, over time and in place, that gives him the greater sense of satisfaction amidst the complexity of the effort.