Thermographic walk
The city of Paris has promised to make all its buildings energy efficient by 2050. In fact, the pace of renovations will have to be stepped up, going from only a hundred condominiums per year to more than 2,000.
It won't be easy, because in Paris, architectural heritage comes into the equation.
Illustration by a thermographic walk with Nabil Zenasni from the Agence Parisienne du Climat.
He points his thermal camera at buildings: in red or orange on the screen, the heat escaping from the building.
In blue, well-insulated buildings.
"It was from 1974 that a certain insulation was imposed on buildings. The overwhelming majority of buildings in Paris were built before this period and we therefore have a huge majority of buildings that are not insulated in Paris" , notes this energy expert.
The dilemma of renovating Parisian heritage
In Paris, "should we rehabilitate or demolish and rebuild? Systematically we ask ourselves the question," continues Hélène Schwoerer, deputy director of Paris Habitat, a public body which manages Bon Marché housing [the first HLMs in Paris, ndrl] for one in nine Parisians.
For heritage reasons, the challenge is insulation from the inside: there is no question, for example, of modifying the brick facades, characteristic of the red belt of the capital.
In this building in the 5th arrondissement, the choice fell on biobased materials, such as hemp and wood.
"We are on heritage that is truly part of the sustainable city that we can mutate, evolve and I hope that with the work carried out today, we have left for a life cycle of fifty, sixty, even seventy years, "concludes Hélène Schwoerer.
Algae to keep the heat
What if, in 70 years, the city just changed its face?
This is the dream of Anouk Legendre, architect at the XTU agency.
His team has designed "biofacades" made up of micro algae.
"It creates a" buffer "space, which protects against heat and cold. It optimizes the thermal power of the building and halves consumption," explains the architect.
Still for heritage reasons, the technique is only applicable to facades of modern buildings, impossible on Haussmannian buildings.
The district of La Défense in Paris would be an ideal laboratory for this idea, or the 13th arrondissement of Paris, where the team is working on a project, on the edge of the tram, of a residential building with biofacades.
The heat extracted from the algae could be used to heat the hot water balloons.
Anouk Legendre even envisions that these algae be cultivated and harvested by urban farmers to feed the city of tomorrow.
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