Paris Roof Garden? French Cities Adapt To Climate Change From The Top
PARIS — Finally, after several setbacks, the three young architects who founded Roofscapes have obtained their first construction permit.
The green light is for a rather special building project that required the approval of France’s architectural review board: the construction of a 100m2 vegetated platform on the zinc roof of a historic building belonging to the City of Paris, the former town hall of the 4th arrondissement, which now houses the Climate Academy.
It’s a first not only for Paris but for the whole of France — a market Roofscapes hopes to expand to. The three architects, who finalized their model for a roof terrace on stilts at MIT, advocate a committed approach to urban planning.
“We want to help adapt buildings in city centers, more specifically in Paris, to global warming,” says Roofscapes co-founder Eytan Levi. “Our green platforms allow us to not only recreate a roof that is accessible to residents of Haussmannian buildings, but also to considerably reduce the temperatures on the top floors, under the zinc roofs. In short, they combat heat islands while making city life more pleasant.”
Thousands of flat roofs in Paris
Although the project is ambitious, there’s nothing far-fetched about it. Roofscapes’ approach is part of a more general movement to rediscover the potential of roofs in the heart of cities. At a time of land scarcity and urban overcrowding,
They make city life more pleasant.
this largely untapped space offers an enormous reservoir of untouched surfaces.
In Paris alone, it is estimated at 32 million m2, including 6 million m2 of flat roofs. For all major cities and construction companies, this hypothetical new playground is the ultimate frontier to conquer. The most motivated are already trying to get the general public onboard.
For the past two years, Marseille and Paris have been organizing a unique event called “Rooftop Days.” Over a few days, the general public is invited to access roofs of varying prestige that are often normally inaccessible, from the “Cité Radieuse” in Marseille, a UNESCO World Heritage site, to the Paris Opera House.
With a whole program of activities, gardening workshops, concerts, exhibitions, yoga classes, the events are a way to allow people to realize everything that can be done up there. Not to mention the view!
“Up there, you can reconnect with the city skyline,” says Léon van Geest, founder of Rotterdam Rooftop Days. The Dutch designeris a pioneer of this sort of event, and is a point of reference for his French colleagues. Launched in 2015, his festival became one of local residents’ most eagerly awaited cultural events.
In 2022, he and his partners even linked rooftops together with scaffolded walkways, enabling aerial circulation. Is this a taste of what the city of tomorrow could be?
An ancient practice
We’re not there yet. But the shift has undoubtedly begun, and global warming has only accelerated the process.
In the past few years, all major French cities have progressively modified their local urban planning schemes, introducing climate plans which often include green roofs. The French Climate and Resilience Act, which aims to reduce greenhouse gas emissions, has in part made this process compulsory.
In Marseille, the Euroméditerranée urban renewal project has even said in its guidelines for developers that, from now on, “every roof must have a use.” At the very least, it must retain rainwater or produce solar energy, and in the best case, welcome residents.
This desire to conquer rooftops goes back a long way in history. “There are examples of roof gardens throughout history, from the Villa of the Mysteries in Pompeii to the Piccolomini Palace in Pienza and the Mont-Saint-Michel cloister,” says Pascale Dalix, cofounder of the architectural agency Chartier Dalix.
Venice, for example, has built whole network of “altane” (wooden platform/terraces on four stilts) across the city’s sloping roofs since the 15th century — a principle that helped inspire Roofscapes.
At the end of the 19th century, New York City producers even went so far as to install semi-open auditoriums on the roofs of their establishments.
This was also the beginning of the rooftop café phenomenon.
The movement to conquer the rooftops continued in the second half of the 20th century, but often remained limited to certain emblematic buildings.
Marseille’s Cité Radieuse, which opened in 1952, is undoubtedly one of the most visionary projects. Its first residents were able to enjoy a rooftop gymnasium and running track, among other things. “Long before anyone else, Le Corbusier [architect of the Cité Radieuse] saw the roof as a way to create social ties among neighbors,” says Charles André, head of urban development at Euroméditerranée.
With the development of concrete architecture, cities are covered with flat roofs. But they remained the exclusive domain of technical equipment for ventilation and air conditioning.
“The first extensive greening of roofs took place between 1990 and 2000, mainly for aesthetic optimization,” says Hervé Gatineau, real estate director at developer Eiffage; the aim was to hide unsightly elements from the view of inhabitants in buildings above.
The rise of rooftops
The 2010s marked the turning point, as architects and developers started to take a bold approach. Marseille offers two examples from 2013: the Museum of European and Mediterranean Civilizations, where an aerial walkway links the roof to the nearby Fort Saint-Jean; and the rehabilitation of the Belle de Mai wasteland, which transformed the roof of a former tobacco factory into a 8,000 m2 public square.
But it is the development of urban agriculture has been the main driver of this change. “At first, we were looking to bring the city closer to the countryside,” says Frédéric Madre, founder of Topager, an urban farming pioneer created in 2013. “We weren’t yet concerned with global warming or socialization.”
In fact, Topager’s first roof installations were mainly designed to supply vegetables to prestigious restaurants, such as the Pullman Tour Eiffel hotel or the Maison de la Mutualité. Other landmarks followed suit, such as the Parisian department store Bon Marché or the Opéra Bastille, and, more recently, the headquarters of major French companies.
The aim is to get employees and local residents more involved, in particular by selling vegetables. In 10 years, Topager has installed more than five hectares of roof gardens. Supported in the French capital by the Parisculteurs program, rooftop cultivation is gradually spreading to multi-family residential buildings.
In 2017, Topager began work on a housing complex in the Paris suburb of Ivry, called Madiba. Two rooftops are dedicated to container gardening and to allowing residents to socialize. A third has been planted to provide a refuge for biodiversity. The company often delegates a facilitator for one or two years to help the gardening program “take root.”
“Generally speaking, only 10% of residents get involved. But that’s enough to encourage all the others to take ownership of the area,” says Célia Etard, in charge of activities at
Topager. Over the past few years, this type of shared development has been gaining popularity throughout France.
In Marseille, the Smartseille ecodistrict set new standards with its 1,000 m2 of green roofs and shared vegetable gardens. “Currently under development, Smartseille II will go even further, with the planned installation of a small urban farm,” says Gatineau of Eiffage, which is lead contractor for the project.
Professional buildings have not been left behind. Vitry-sur-Seine, a town southeast of Paris, has just inaugurated its Les Ardoines logistics hotel, on whose rooftops a hectarelong farm will be set up to sell its produce on site. “In this way, the building becomes a resource,” says Dalix of the Chartier Dalix agency, who designed the project.
But the most successful and inspiring achievements are undoubtedly taking place in schools. As early as 2012, the Aimé Césaire school in Nantes, boasted an entirely green roof where pupils can stroll. It’s as if the structure is set in a small meadow. There’s a similar feeling on the rooftop of the School of Science and Biodiversity in Boulogne-Billancourt, west of Paris, where a small grove of lime trees, maples and cherry trees grows.
“We’ve imagined it as an extruded landscape,” says Dalix. “We wanted to restore the green space that the
We wanted to restore the green space that the building robbed from the ground.
building robbed from the ground.” These projects have set an example. Today, in many new projects, roofs often disappear in favor of vegetalized school yards — for example, at the Marceau schools in Paris and the Fabriques district in Marseille, which are due for completion this autumn.
Rooftops of the future
Despite this effervescence, “every year, only 5% of new buildings are vegetalized,” says Topager’s Madre. And the majority are planted with extensive cover crops — plants intended to cover the soil rather than to be harvested.
“We are at the very beginning of this phenomenon,” Gatineau says. “But we can clearly feel rising expectations of local communities and developers.” There are also a number of obstacles to overcome. One is the additional cost for developers, who earn their income from the sale of habitable square meters.
“We will need to motivate them more by allowing them, if need be, to play around with the maximum authorized heights, so that they don’t lose a floor of living space if they create a collective roof,” says André of Euroméditerranée. Beyond new construction, existing buildings have great potential. Yet even today, most buildings do not have roof access. Events such as Rooftop Days are a way to inspire their development.
“At the last festival, we made a radio program with neighborhood associations and managers of the local shopping mall, who due to necessary waterproofing work were studying the possibility of using the 9,000 m2 of the roof,” says Colombe Pigearias, head of social and environmental projects at Marseille Solution and co-organizer of the event. Marseille has a total of 9 km2 of roofs, 12% of which belong to public institutions and 8% to social landlords.
Roofscapes is positioned precisely in this vast roof rehabilitation market, with a focus on building platforms on stilts to adapt to sloping roofs, costing between 1,500 and 2,500 euros per square meter.
“Lots of condominiums have expressed an interest in our project since our creation,” Levi says. “The obstacles don’t come from potential customers, but from France’s architectural review board, to whom any project within 500m of a historic building —94% of Paris’ surface area — must be submitted.”
And this review board often tends to consider that rooftop developments detract from building’s character.
“If we want to adapt the heart of our cities to climate change, we’re going to have to give ourselves more room to maneuver,” says Isabelle Debricon, in charge of renewable energy development at the City of Paris’ Department of Ecological Transition and Climate.
In fact, it’s hard to see how we can both make a city more dense to limit urban sprawl, while making it greener to combat heat islands and to make it more livable, without exploiting on the potential of rooftops.