Heat wave: how to lower the temperature in the city?

Benjamin Peter edited by Wassila Belhacine 06:19, June 18, 2022

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"What we wanted was to adapt the urban architecture to the Mediterranean climate", summarizes Pierre Tourre, the urban architect who designed the Rive Gauche eco-district on the banks of the Lez, in Montpellier.

Studies began in 2007 and the first stone was laid in 2012 to allow 1,200 housing units to come out of the ground.

Housing designed not to use air conditioning, with an eye to ecology while allowing the accommodation to be pleasant in summer and winter alike.

The first thing was to rethink the layout and shape of the buildings.

"Studies have shown that neighborhoods that were strictly orthonormal are warmer than neighborhoods where urban settlement is more random," says Pierre Tourre, showing the overall map of Rive Gauche.

"The closed island is the worst way to create urban heat islands. We break that. We must avoid air concentrations as much as possible. We have broken lines that promote air circulation" , he explains at the microphone of Europe 1.

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It relies in particular on the "Venturi effect" which causes the air to pick up speed on contact with tall buildings.

"In this district we have the Lez", adds the architect.

"We will take advantage of the evapotranspiration of the Lez which will refresh the district thanks to the circulation of the air".

Shutters and terraces caps

He designed two of the twenty buildings in the district.

The man established specifications that his colleagues had to respect.

"There was a basis, it was that there was never a ray of sunlight on a glazed part", he explains.

"If you have that, behind you have a dramatic overheating and it's difficult to regulate the temperature. So I recommended the creation of shutters to protect the openings from the light. We also have adjustable sunscreens with which we can modulate the opening especially at night to circulate fresh air".

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Many dwellings have been designed to be through.

In addition, on several buildings, "capped terraces", balconies deep enough to shade the accommodation also prevent the sun from penetrating directly into the apartments.

Isolated and vegetated

For the inhabitants, the contract is fulfilled.

Danièle has lived here for three years in a through apartment: "It allows us to create air currents which make the temperature quite acceptable even at the moment", she specifies.

"The apartments are recent so very well insulated and you can really feel it."

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In addition, the district has been designed to be massively vegetated.

500 trees have been planted throughout the area and the vegetation has had time to develop, which has created islands of freshness that counterbalance the heat of the bitumen, stone or concrete.

"We have an interior garden which refreshes our whole building. We have a lot of greenery. The terraces have a lot of plants", enthuses Marie-Christine who chose Montpellier a few years ago for its proximity to the sea. "I am very sensitive to environmental problems so I refuse to have air conditioning. I close all day, I open at night and we make a draft to ventilate our accommodation", details t -she.

Ten degrees less

Studies have been carried out on the whole neighborhood and in the dwellings.

The inhabitants note an average drop of ten degrees in the temperature in the district thanks to these developments.

"If we manage to lower the temperature by seven to ten degrees in places, it's already considerable", explains Pierre Tourre.

"Especially in a passive way. None of these devices need electricity. It's low tech. Once it's built, it works", concludes the architect.