Should we build higher and higher to fight against land artificialisation?
The fight against urban sprawl and land artificialisation is a national priority that is pushing those in the building sector to look for solutions to make cities denser. One of these solutions is to build ever taller buildings. A controversial issue.
The French Climate and Resilience Law of 22 August 2021 includes numerous provisions aimed at adapting town planning rules to combat urban sprawl and protect ecosystems. In particular, it sets out the objective of halving the rate of land artificialisation over the next 10 years in order to achieve Zero Net Land Artificialisation by 2050. This is no mean feat, as it is currently estimated that the consumption of agricultural, natural and forest areas by urban sprawl is between 20,000 and 30,000 hectares each year. In total, this represents the equivalent of one department every fifteen years.
To address this, the Climate and Resilience Law has therefore highlighted the need to better control urban sprawl, in particular through “urban renewal and optimising the density of urbanised areas”. On this point, the Law intends particularly to act on the height of buildings in the local urbanisation plan (PLU) therefore allowing public authorities “to authorise constructions that demonstrate environmental exemplarity to go against the rules of local town planning schemes relating to height, in order to avoid introducing a limitation on the number of floors compared to another type of construction”.
In other words, the future of the city should now be written vertically in order to reconcile population growth with that of urban areas while respecting environmental constraints. However, this reasoning may not be sufficient in itself and needs to be carried out in consultation with the inhabitants.
High-rise construction: one tool among others
High-rise construction provides an answer to the issue of urban sprawl in order to counter what could be considered as a kind of “French passion”: the stand-alone house with garden. In France, since the 1970s, this has been the main model for urban development and one of the main reasons for urban sprawl. As such, all over the country, private housing areas and developments of small stand-alone houses with gardens have been built in recent years. Between 2000 and 2007, for example, 61% of the housing built was stand-alone houses, compared to 50% at the end of the 1990s.
But this urban model, particularly that of housing developments, is no longer viable because of the ecological emergency. And since it is now necessary to protect both biodiversity and agricultural land, regions are obliged to reinvent their urban development around a key concept: densification.
However, densification doesn’t necessarily mean building higher and higher, even if the subject is obviously part of the consideration. Regions have several tools available to them to combat land artificialisation: renovating industrial and commercial wastelands; integrating a logic of circular town planning that promotes modular construction and the pooling of uses; or optimising regions through practices such as BIMBY (Beauty in my backyard) which involves dividing up gardens which are deemed too large by their owners in order to build new housing.
“France has 19 million stand-alone houses. If every year one owner in 100 decided to divide their land to use it as land to build on, some 200,000 plots could be created without causing any urban sprawl” explains town planner David Miet, who is campaigning for the democratisation of this subject. Increasing city density makes it possible to recover space without necessarily needing to build higher, simply by anticipating changes in use: it means being able to transform a canteen into a co-working space; it means being able to add a floor to a building or knowing that when we build offices or car parks, we will do so in such a way as to be able to transform them into housing a few years later if need be.
Alongside these tools, putting collective housing back at the heart of urban policies also appears to be a priority approach in order to respond to 2 challenges: that of ecology and also social diversity. And to do this, it is obviously through the construction of high-rise buildings that this will happen. The problem is: how high can we build?
Vertical construction still lacks social acceptability
While it is certain that increasing city density will be achieved through the use of increasingly taller buildings in order to accommodate more people, to promote social diversity and to lower property prices, the subject must also face a real obstacle: social acceptability.
A recent survey published by Harris Interactive shows that 51% of French people think that more construction is needed in France “to bring down housing prices ” and “to accommodate more people”. On the other hand, only 32% agree that this should be done in their area. “What I see, […] is that when you go from a construction with one floor to one with a second, you already have petitions. Acceptability of constructions of upper floors is very complicated, it is even close to zero” explained Yannick Moreau, mayor of Sables d’Olonnes in the Vendée, recently to the Ouest France newspaper, to illustrate this problem.
All over France, vertical construction of cities is met with reluctance and skyscraper projects attract the wrath of local residents and environmental protection associations. This was recently the case in Paris with the much-publicised case of the Triangle Tower. But opposition to vertical construction of cities isn’t new. Already in the 1970s, the construction of the Montparnasse tower in Paris, the Brittany tower in Nantes and the Part-Dieu tower in Lyon were controversial, mainly due to issues of fitting in.
Today, the same applies to the creation of collective housing in urban areas which, for some, will only succeed if we rethink the construction of cities in a global way, with more proximity, with more green spaces. “Increasing city density does not mean putting concrete everywhere or building towers everywhere. We have phenomenal potential for green development in 48% of the space allocated to cars” explains Sylvain Grisot, a town planner from Nantes, who specialises in frugal cities and circular town planning.
This is an important clarification in order not to forget the city of tomorrow, beyond its vertical construction, it will have to be rethought in depth in order to be more desirable for all, and for all ages.