“We can’t wrap up nature in cotton wool, we’ll have to continue building,” acknowledges Jean-Philippe Teilhol, chief representative of France’s National Union of Landscape Companies (UNEP). “Even if we mobilised every vacant home we wouldn’t be able to house everyone.”
The decline in household size, the attraction of the single-family home, the increasing vacancy rate and the construction of second homes, for example, explain why construction is continuing. Moreover, according to Eurostat projections, the French population will continue to grow in the coming years, reaching 78 million in 2080.
However, according to France Stratégie, ZNA will make it possible to limit land artificialisation to 1,200 hectares per year throughout the country, compared with 20,000 to 30,000 hectares in recent years. The main idea will be to “rebuild the city on the city” and make do with what already exists by following the ARO (Avoid, Reduce, Offset) sequence as a guideline, which is already applied in the search for “zero net loss of biodiversity” according to the 2016 Biodiversity Act.
Contrary to popular belief, the densification of buildings can be a good thing for cities, points out Carlos Moreno, associate professor at the IAE in Paris and co-founder of the ETI chair “Entrepreneurship, Territory, Innovation” at the Sorbonne, interviewed by “Usbek et Rica” on 15 June 2021. It is made easier by the ALUR Act of 2014 abolishing the maximum built density per plot in urban planning documents.
“Density is actually a good thing, without it there’s no pooling, and without pooling you can’t set up services for everyone. Density isn’t a dirty word, it can feed into a calming vision of the city and promote a city that feels good,” he adds.
Wood, a material five times lighter than concrete, allows multi-storey eco-constructions to span a traffic lane or raise a building: examples include Woodeum’s project for residences for students and young athletes in the Paris suburbs, and Linkcity’s youth hostel, a five-storey elevation above a supermarket on Place de la Nation. The aim is to move towards denser – but liveable – urban forms that provide comfort while limiting the amount of land used.
In Paris, the Parisian Urban Planning Workshop (APUR) has estimated that 10,000 buildings could be raised. In Lyon, several buildings have already undergone this process in the 3rd and 6th arrondissements.
On the outskirts of cities, David Miet and Benoît Le Foll’s Villes Vivantes agency, which pioneered the “BIMBY” (Build In My Backyard) concept, is convincing residents to restrict urban sprawl by sharing plots of land. It supports them in this type of biodiversity-friendly habitat.
In this context of economical land management, industrial, commercial, railway, military and hospital wastelands, concentrated mainly in the north and east of France, are opportunities, as part of a circular urban planning rationale advocated by Sylvain Grisot (Manifesto for Circular Urban Planning, 2020). A €650 million fund (brownfield fund) has been created by the French Ministry for the Ecological Transition, intended for the conversion of 1,300 hectares of this type of land.
Wasteland is “a space on which activity has halted and is therefore abandoned”, according to France’s laboratory of innovative land and territory initiatives (LIFTI). The BASOL and BASIAS databases list polluted or potentially polluted sites and land (35,000 sites). However, all wasteland in France is currently being inventoried using Cartofriches, a tool developed by the centre for studies on risks, the environment, mobility and urban planning (Cerema).
Most of these abandoned spaces can be reconverted: in Dieppe, the former tobacco hall was renovated in 2020 and converted into a cultural venue, multiplex cinema and restaurants; its surroundings were adapted to increase soil infiltration and spontaneous vegetation has grown there. The Le Foué Paul Prédault ham production plant, which relocated to Goussainville, a 13,000 m² facility, was reclassified as an attractiveness centre for SMEs by Essor Développement in June 2021. During the same month, a former Trois Suisses industrial site, La Maillerie, located between Villeneuve d’Ascq and Croix, and converted into an eco-neighbourhood by Linkcity, opened to its new residents.
However, economic developers and elected officials are worried because wasteland owners are usually more willing to convert it into profitable housing than transform it into a place of business, as is the case with the former Castorama store in Mérignac, which is scheduled for completion in 2022. The Dassault site in Argenteuil, which is moving to a 50,000 m² site in Cergy Pontoise, leaves 9 hectares in the heart of the city. The mayor is refusing to convert it to housing; he wants to revitalise the community by bringing economic activity back to the area where the inhabitants live, based on the quarter-hour city model.
It was noted during the Senate hearings that the number of wasteland sites could increase due to the dual effect of the digitisation of the economy and the economic crisis caused by the Covid pandemic. Some wasteland sites could act as “green lungs” near city centres or on the outskirts, provided they are de-artificialised.
While the bill proposes a definition of “artificialisation”, it doesn’t offer a definition of the opposite. According to the agro-pedologist Xavier Marié, de-artificialised land has regained functions similar or close to those of its original state. “Take the example of deconstructed buildings, the joint development zone Gagarine, in Ivry-sur-Seine: in the decompacted subsoil of the demolished cellars, the developer reconstituted fertile soil to create a nursery,” he says.
The car park of the former bus station in Auchel (Pas-de-Calais) has been cleared of the waterproofing and pollution that made it so dirty, and has once again become a green area returned to nature. On a more ambitious level, the public land development establishment (EPF) Nice Ecovallée, in Alpes Maritime, is planning to remove 250 hectares of urban areas to make room for 125 hectares of agricultural and natural areas along the Var plain. The Loire Atlantique department wants to renaturalise abandoned roads that are still asphalted.
However, renaturisation comes at a cost: around €65 per square metre to deconstruct, €60 to €270 per square metre of land to increase soil infiltration, according to France Stratégie, and between €100 and €400 per square metre to decontaminate.
Daniel Nahon, from Université Paul Cézanne, is pessimistic about the effects of this spending. He believes it isn’t possible to “return to nature the equivalent of the surface area used, as mineralisation is an irreversible process that makes the soil sterile and its clays impermeable.” “Destructive major projects: the bluster of ecological offsetting” stated a headline in “Reporterre” on 6 September 2019.
Avoid (damage and destruction) is also the part of the ARO process to focus on. New forms of construction are emerging, particularly reversible constructions, such as the #Work1 building in Lyon’s Confluence district. This eight-storey office building developed by Linkcity and built by Bouygues Bâtiment Sud Est will be converted into housing in a few years’ time when the A7 motorway, which runs nearby, is downgraded to an urban boulevard; the more qualitative environment will enable this change of use.
Construction on piles, which have a lower ecological impact than construction on slabs, seen in eco-neighbourhoods such as Brazza in Bordeaux, is also part of the models of the future.
The regional elections are an opportunity to examine new housing methods to achieve the ZNA goal, to “put an end” to “poor housing” and “urban ghettos” (a campaign promise made by Valérie Pécresse, the Libres! candidate, as well as Audrey Pulvar, the PS candidate, in the Paris region).
As for companies in the construction industry, they “could pivot from traditional civil engineering to ecological engineering, therefore being able to stand out from the competition via de-artificialisation demonstrators”, according to the Biodiversity Economy Mission, in the Biodiv’2050 report of April 2021.