Cool Islands: 4 Solutions to Cool Overheated Cities

The mercury is rising in French cities, forcing them to adapt their infrastructure. Faced with climate change, islands of freshness are settling in cities. These places, such as urban forests, seem to be the right place to keep urban areas habitable.

In the midst of a heat wave, three little words resonate like a promise of well-being: “islands of freshness”. They bloom all over France. Liberating for some, comforting for others, these devices find their audience and establish themselves in the urban landscape.

An island of freshness can be the greening of a concrete square, the banks of a river or even the opening to the public of cooled spaces, such as museums or swimming pools. “During heat waves, these are occasional refuges to improve residents’ comfort”defines Erwan Cordeau, responsible for climate, air and energy studies at the Institute for Development and Urbanism.

Essential infrastructure in the face of rising temperatures. Between 1950 and 2020, the average temperature in Île-de-France rose by two degrees. “Global warming is already here”warns Erwan Cordeau.


One of the solutions for cooling cities is to (re)place plants there. A concept included in the “Climate and Resilience” law of August 22, 2021. To facilitate its implementation, the government announced on June 14 support of 500 million euros for urban and urban renewal programs.

Plants release water into the atmosphere through their leaves, a phenomenon called evaporation. “A tree can shed up to 450 liters per day, the equivalent of five air conditioners running at full blast”, analyzes Anthony Bru, horticultural engineer for the company Fredon, specialized in greening cities. Another example, less expensive, growing lawns can lower the temperature on the ground.

hand over rivers

When trees are praised, they are not the only ones that bring a breath of fresh air to cities. The presence of water is essential. In contact with heat, the water evaporates, humidifying the atmosphere and thus cooling it.

If the city of Paris counts on the Seine to lower the temperature by a few degrees, a second river, the Bièvre, should help it in this task. According to the “Bièvre Eau, Climat, Trame Verte et Bleue-2020-2024” project led by the Paris City Hall, this tributary of the Seine is to be redeveloped by 2026.

Repaint the walls

Changing the color of the walls is another easy method, especially in concrete and densely populated metropolises. “This is a lever for action inspired by Mediterranean cities”, explains Anthony Bru. This limits the amount of stored heat.

Its purpose is to reflect solar radiation back into the atmosphere. They can be measured using the albedo, a unit of measurement, numbered between 0 and 100. The closer a material’s albedo is to 100, the more it reflects the rays and therefore cools the city.

Improve thermal insulation

Insulation, an essential resource for the urban population, is one of the greatest challenges of global warming. The increase in mercury points to inequalities. “On the one hand, there are those who keep it cool, those who can afford to leave and on the other hand, those who live in a ‘thermal sieve'”, laments Laurent Delcayrou, Regional Resilience Project Manager for the ThinkThank The Shift project. He believes a focus on this point would save lives and help cities adapt to climate change.

(Photo credits: Leonid Sorokin/Getty Images)

(ETX Daily Up)

Leave a Comment