Heatwaves are no longer a distant risk: they now hit classrooms regularly. Almost no French school is today adapted to the heat. However, simple and affordable solutions exist, and can save up to 10°C without air conditioning. They need to be deployed now.
In August 2003, France discovered, stunned, what a heatwave could inflict: more than 15,000 deaths, mainly elderly people, and a country taken by surprise. The episode was considered exceptional, unlikely to recur for decades. Twenty-two years later, the narrative has changed. Heat waves are no longer a summer accident: they occur from May to October and return every year.
Since 2003, measures have been taken for nursing homes, but nothing has been done for schools. Back then, heat waves fell during the holidays. They are now almost systematic in June and September, in the middle of class and exam periods. And the phenomenon will increase.
At the heart of the adaptation issue
The early wave that hits the country in May only half surprises us: we were expecting it, just not so soon. According to the Reference Warming Trajectory for Adaptation to Climate Change (Tracc), used by the State to design its policies, such spring episodes were not expected before 2050. Yet we are there.
With 12 million students and 1.2 million staff in 61,000 schools, schools are at the heart of the adaptation issue. However, this park is structurally unsuitable, with buildings not designed for current heat.
According to Snes-FSU, one school in two has neither shutters nor external solar protection. The problem is not limited to buildings from the reconstruction period: schools built in recent years are already overheating, victims of a thermos effect with large unprotected bay windows, insulation designed to preserve heat in winter, and a lack of night ventilation.
Last year, more than 2,200 schools closed at the height of the June heatwave, with a peak measured at 37°C in one classroom in the northern half of the country. Sunstroke, vomiting, discomfort: a large number remained open, in conditions unsuitable for learning and dangerous for the health of children.
Three simple actions
Not surprising, because 70% of these buildings were constructed between 1950 and 1970, when climate change was not yet visibly evident. Staff are not trained in the practices to adopt in the event of a heat peak.
However, adaptation does not require enormous projects, but three simple actions: protect, ventilate, air out at night. Combined, they are likely to gain up to 10°C in a classroom, without air conditioning.
Protect from the sun: prevent radiation from entering at any time, including when not occupied, with shutters or exterior blinds, sunshades or window films. An unprotected window exposed to the sun is like turning on a radiator. This implies agreeing to teach classes, in the middle of the day, in a darker atmosphere and if necessary under artificial light.
Cool: ceiling fans significantly lower the temperature felt, using a hundred times less energy than air conditioning. Physiology confirms this: with an air speed of 0.5 to 1 m/s, i.e. the conditions created under an air mixer, the temperature felt is lowered by 2 to 3°C.
Discharge the heat at night, finally, the most powerful lever: open at night to evacuate the accumulated heat. Almost no school in France exploits this source, while the difference between indoor and outdoor air, in the early morning, sometimes reaches up to 8°C.
This involves protecting the premises against intrusions, installing automatic mechanisms there or organizing temporary occupation there during the night. When the temperature outside becomes cooler than that of the building, the windows are opened and the air is exhausted.
A modest cost
Adapting a school according to this triptych costs between 20,000 and 100,000 euros depending on the size of the establishment. This represents an investment envelope that can be estimated at 3 to 4 billion euros for all schools in France.
A sum to be compared to the cost of air conditioning. Up to five times more expensive in investment, it is also expensive to use, energy-intensive, and rejects hot air outside, contributing to the emergence of heat islands.
If we have to air-condition, which will be essential in certain sectors, let’s do it on a building that is already protected and unloaded: the usage bill will be lower and the electricity network will be less stressed. Adapting first of all means air conditioning less and better.
An economic and health issue
It’s not just about comfort or health. According to Allianz Trade, the days of high heat in 2025 cost France 0.3 points of GDP, the equivalent of the expected growth over one quarter. A school that closes means parents forced to be absent, emergencies clogged with illness. Climate inaction is, as is often the case, more expensive than adaptation.
Summer and winter, it’s the same fight: our schools need to be renovated to consume less in winter (and therefore contribute to mitigating climate change), and to be adapted to the climate that sets in in summer.
The two projects come together and must be engaged together, with the active participation of students and teachers, then be supplemented by a much broader societal and educational project to adapt teaching to the changing climate.
The communities, owners of these schools, must be supported to embark on this project. The climate we expected tomorrow is already that of today, and that of tomorrow will therefore be worse.
Let’s launch now a major plan to adapt our schools to climate change, and let’s make it the lever of a policy that will have to extend to public buildings. We owe it to our children, who will inherit a climate that we continue to degrade a little more every day.
(1) Frédéric Boeuf, vice-president CINOV (National Union of Management Consulting), environment and regenerative models; Frédéric Corset, director of EnvirobatBDM; Magali Cottave, president of CINOV; Amaury Fievez, engineer, doctoral student, pilot of the RACINE project; Alexandre Florentin, climate safety engineer, president of Paris at 50°C; Clément Gaillard, doctor in urban planning, expert on urban heat islands and local climate adaptation; Benjamin Gentils, director of the Fabrique des Communs Pédagogiques; Romain Georges, expert in adaptation to climate change; Jean-Philippe Grand, Envirobat Center director; Stéphanie Jimenez, director of the Burgundy-Franche-Comté Energy Division; Marie-Hélène Lafage, urban planner and author, member of the Adapt association; Valérie Laforest, research director at the École des Mines de Saint-Étienne/CNRS, expert in low-tech; Juliette Lavisse, ecodesign engineer, director of Novabuild; Pascal Lenormand, energy designer engineer, Incub’; Antonin Madeline, Terragilis director; Chloé Maréchal, paleoclimatologist, deputy vice-president Ecological transition and social responsibility – Training, Lyon 1 university; Véronique Pappe, Ekopolis director; Guillaume Perrin, director of ACTEE and FNCCR; Illona Pior, director of Envirobat Occitanie; Antoine Poincaré, director of the Climate School; Philippe Quirion, research director at CNRS, director of Cired; Christophe Rodriguez, director of IFPEB; Jonathan Villot, lecturer at the École des Mines de Saint-Étienne/CNRS; Serge Zaka, agro-climatologist.
About opinions
This text is signed by a guest author. He expresses his opinion and not that of the editorial staff. Our Live section aims to allow the expression of pluralism on religious, social and current affairs subjects, and to encourage dialogue, according to the criteria set by our editorial charter.
Share your opinion in comments or by writing to us at: readers.lacroix@groupebayard.com
