an urban model for combating urban sprawl

To explore the multiple issues being questioned by the actors of the urban fabric in the context of climate change and planetary constraints, the co-authors of The Sustainable City have proposed several approaches, from biobased buildings to ZAN. Zone d’Artificialization Net), through smart cities. Today’s cities are like our way of life, consuming too much, in this case spaces. This steady growth that bites the soil is not sustainable. After looking at the numbers on urban sprawl, what political and urban levers are there to curb or even stop urban sprawl? Among the proposed avenues, deal with the “already there”, make a “city on a city”, in other words, using vacant apartments, real estate heritage to prevent new construction and encourage population spread over the area, avoiding congestion and known problems in big cities .

All entries in this book include clarifications and definitions that are important to understanding the topic. Definition of urban sprawl, false promises of smart cities, densification, boundaries of ZANs, figures for land reclamation…

What is a “stationary city”?

The term “stationary” was inspired by the economist John Stuart Mill. Philippe Bihouix explains that the stationary city is no longer growing, there is no more urban sprawl and compacted land. However, he continues self-repairing, densifying without harming other areas, with climate adaptation work, water management, urban islands, etc.

How to define urban sprawl?

“An urban sprawl that occurs faster than population growth: the consumption area per population increases, separating population growth and land reclamation.

In France, the artificialization of the soil causes the disappearance of 20-30 thousand hectares of land every year.. And even if the rate slows down, it still equates to a small artificial branch every ten years in our country. A production that is not sustainable in the long term. But over the past decade, we have seen the issue of urban sprawl grow in importance, with the awareness that, among other things, the goal of net-zero emissions by 2050 has been integrated into law. and resilience. So what’s behind this lens? Is it ambitious enough to meet the challenges of sustainability in land use planning?

The origins of the stationary city

We owe the concept of a stationary city to this John Stuart Mill, a 19th-century English economist and philosopher with very modern ideas for the time: he was in favor of women’s suffrage and universal suffrage. He is one of the rare economists who believes that the cessation of growth is a desirable state, and that once we pass a certain level of wealth, we no longer need to continue growing economically and demographically, and can promote human progress, both culturally and economically. arts or sciences. A concept that can also be transferred to an economically stationary city.

Updating the city by optimizing it

The idea of ​​a stationary city is to renew the city by continuing to welcome the population without using the natural land.. Since the 1970s, we have lost 50% of agricultural land and use 20-30,000 hectares of natural land in France every year. For Sophie Jeantet: “The idea is to optimize these surfaces by using other beds in all the square meters we have already built. Use less occupied areas in terms of deposits to allow the city to grow and develop. »

Compensate with natural sinks

Engineer Philippe Bihouix reminds us in this program: The idea is to drastically reduce CO2 emissions by 2050 and then compensate with natural waste such as forests. : “We must offset humanity’s residual emissions to achieve planetary carbon neutrality. The difference with zero artificiality for soils is that natural carbon sinks, especially the oceans, operate over very long periods of time, millions of years. Therefore, renaturization is necessary, which is the opposite of artificialization. After recovering a few quarries, a few industrial wastes, we will have to make artificial, but with zero carbon emissions. »

How to stop growth during construction?

For Philippe Bihouix, there are alternatives to the evolution of our cities: “We can use anything that’s empty or under-occupied, for example. There are approximately 3 million empty homes in France, including 1 million for more than two years. You should know thisToday, 350,000 houses are built in France per year. When we fill them, we empty 50,000. When we have one more resident in France, we need to start two residential buildings. We have increasingly smaller households due to various and sundry aging challenges and socio-demographic changes. » For Sophie Jeantet: “For several years there has been a poor distribution of population where there is housing associated with the strong appeal of metropolises and coasts, which concentrates the population and leads to areas of tension in terms of housing and affordability. . »

The problem of location of data centers and logistics platforms

What occupies the most space with these 20,000-30,000 hectares of artificial land in France every year? According to Sophie Jeantet, housing accounts for 42%, transport, roads, 28% and 30% for activities and commerce: “For retail, these are spaces that often take up a lot of space and you don’t find them in dense environments like city centers. So we intend to expand these activities beyond and therefore. And today there is also the issue of logistics platforms, data centers that are trying to establish themselves near cities and are a source of artificiality. »

We are talking about:

• Philippe Bihouixengineer, worked in construction and currently works at the architecture and engineering agency, AREP (Architecture Recherche Engagement Post-carbone – subsidiary of SNCF) and in particular “L’Âge des low-tech”, “Happiness was for tomorrow” ” and “What is the future of metals?”
• Sophie Jeantet, by training as an architect-urban planner. He has worked in public development companies or communities for more than 20 years.
• Clemens de Selva, an architect works in an agency and responds to orders from government agencies.

Co-author.ices “The Stationary City – How to End Urban Sprawl?” » Area of ​​opportunity in Actes Sud. A book around the sustainable city question.

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