It’s only 10am but the heat is already radiating off the asphalt at the École Riblette, a primary school on the outskirts of Paris. Sébastien Maire, the city’s chief resilience officer, points to the school’s lower courtyard, a classic heat trap: surrounded by concrete walls that reflect sunlight inside. Last June, the courtyard hit 55C (131F).

“For three days, school activities stopped,” Maire says. “It was not possible for the children to study, nor to go into the schoolyard. We would forbid them because it’s 55 degrees – you can fry an egg on the ground.”

The École Riblette is now a guinea pig for Project Oasis, a plan to convert the concrete schoolyards of Paris into “islands of cool”. The goal is to provide respite in periods of extreme heat, and perhaps even bring down temperatures across a city with a desperate shortage of green space. Just 9.5% of Paris is given over to parks and gardens – the lowest proportion of any European city. (By comparison, London boasts 33% green space and Madrid 35%.)

Maire explains how the courtyards at this school will be transformed: a green wall here, a vegetable planter there, expanded areas of shade and special drainable concrete surfaces that can absorb water when it rains.

Part of the École Riblette’s playground, which reached 55C during last year’s heatwave. Photograph: Magali Delporte/The Guardian

If all goes to plan, all of Paris’s 800 schools will be transformed into green spaces by 2040. The City of Paris plan is also being facilitated by 100 Resilient Cities (100RC), a project of the Rockefeller Foundation, which also supports Guardian Cities.



But if the trees and planters are uncontroversial, the next two steps of the scheme could prove more difficult for the city to sell. Maire first wants to open up these newly built green spaces to vulnerable people during heatwaves, and eventually wants the general public to enjoy them too – albeit outside school hours.

They don’t just address the environmental challenges, but also improve social cohesion Lina Liakou, regional director 100 Resilient Cities

“By 2050, we’ll have 800 cool spots in the city using school infrastructure,” he says, arguing that it is a better alternative than taking vulnerable people to supermarkets and churches.

In Paris, which has the highest population density in Europe, no one lives more than 200 metres from a school, meaning the plan could dramatically increase access to green space for many residents.

Lina Liakou, the regional director for Europe at 100RC, says of the new green spaces: “They don’t just address the environmental challenges, but also improve social cohesion and create a better environment for the people around them.”



That holistic approach stemmed from an 18-month resilience-building process that the city underwent in collaboration with 100RC, attempting to think in a more interconnected way – not just focusing on climate after the Paris Agreement, but also “the social and inclusion issues that have so clearly impacted the city”, says Andrew Brenner, associate director of global communications at 100RC. “The fact that the city is looking at the oases as not climate interventions – tackling a singular challenge, in this case heat – but rather resilience interventions with multiple benefits, and elaborating that from the start, is a huge development.”

The playgrounds will include features such as green walls, vegetable planters, expanded areas of shade as well as trees and special surfaces that can absorb rainwater. Photograph: Handout

Still, opening up Paris’s fortress-like schools to everyone is not an easy pitch in a city that remains on high alert. Terror attacks have killed 150 people since 2015. Heightened security measures make it difficult even for parents to access schools. Liakou says this part of the project has not yet been finalised. “It’s a challenge for the city of Paris, and we want to work with them and pressure them more,” she says.



Maire is undeterred. He says the spaces will be kept safe and clean, and says no one will force a school to open its doors to the public if parents and teachers don’t agree to it.



What is the way? To know your neighbour, to do things with people. Not to be alone in front of your TV scared by terrorism Sébastien Maire, chief resilience officer

He points out that heatwaves have killed many more people in France than terrorism has: 580 people died in a single week of heat last year, and the European heatwave of 2003 killed 14,800.

Maire also argues that bringing people together in school grounds is an essential part of making Paris more resilient to terrorism – setting himself in stark opposition to the French state.

“They have been forbidding people to organise small things together because of terrorism: ‘You shouldn’t convene, you shouldn’t meet together, you’re going to be targets, so stay at home,’” Maire says. “But the resilient vision says, ‘If a crazy guy wants to commit something, we won’t be able to prevent it. Stop lying to the people.’”

Sébastien Maire, Paris chief resilience officer (left), and Stephan Lajous, head of architecture for the 20th arrondissement at École Riblette. Photograph: Magali Delporte/The Guardian

“Our concern is much more how society can face this and bounce back afterwards. What is the way? To know your neighbour, to do things with people. Not to be alone in front of your TV scared by terrorism, but to convene.”

As for whether increasing green cover in schools can actually bring down temperatures across Paris, it’s still unclear. There is some evidence that making Paris greener can cool the city. In 2012, researchers from the French weather service simulated the 2003 heatwave against a number of adaptation scenarios. They found that turning every bit of bare land in the city of Paris into green space, including half of all pavements wider than 15 metres, could bring heatwave temperatures down by three to five degrees during the day.

But that’s only if more than a thousand hectares of land turn green in the next few decades. Together, Paris’s schoolyards comprise just 80 hectares, and they won’t go completely green: École Riblette is keeping two of its yards asphalted so students can play sport.

Greening playgrounds is a step towards increasing the city’s vegetation, but with schoolyards comprising just 80 hectares, this alone is unlikely to have a big impact. Photograph: Handout

“Vegetation in schools is one step towards putting more vegetation in the city, which could have an overall microclimate effect and cool the entire city,” says Vincent Viguié, a research scientist at the International Research Centre on the Environment and Development. But he warns that even the best-case scenario isn’t good enough to take on Paris’s rapidly warming climate. “It’s nice, but it’s not sufficient.”

Virué also points out that drainable concrete surfaces like the one proposed for École Riblette are less effective than grass lawns, which would reflect heat outwards instead of absorbing it. “When there is a heatwave, it doesn’t rain,” he says. “So to have porous bitumen doesn’t have such a big effect to cool the air.”

In another pilot school for the project, heat sensors will be embedded in the ground to measure how the new surfaces respond to heatwaves.

Maire admits that the nature of taking on a project like this in Paris meant compromises had to be made. “We have seven administrative layers at the regional level: it’s a puff pastry” – and says he takes heart from cities that have done something similar in much more difficult circumstances, such as Athens. “They host migrants in the school at weekends, and when we say that to people here … ” He pulls a face. “[Athens] manages despite the fact that they are much poorer than Paris. They can do it, so we can as well.”

But greening every school in Paris will not be cheap. It currently costs €300,000 to renovate a schoolyard, Maire says, and the additional requirements of Project Oasis will add 25-30% to that figure. But he says the “multiple benefits” for the city make it a worthy investment.



Last June’s heatwave was a watershed for Paris, he argues. Never before had an episode of extreme heat occurred during term time. By the end of the century, it is estimated there will be 30 days of extreme heat in the city every year on average. “Can we take the risk [of having] 30 days every year of non-education?” he asks. “Thirty days is huge – it’s complete generations that are going to suffer concretely from climate change.”

Follow Guardian Cities on Twitter, Facebook and Instagram to join the discussion, and explore our archive here