Patios rather than air conditioning: will the city of tomorrow be Mediterranean?

And to cite as an example the traditional architecture of Mediterranean cities, whose buildings naturally regulate the heat.

Question: To deal with climate change, can we not draw inspiration from the ancestral know-how that presided over the construction of Mediterranean cities?

Reply : In the vernacular architecture of these cities, we protect ourselves from the heat and all its vagaries because we get shade. We must stop building buildings on which the sun shines, hits and amplifies. There are not 36.000 solutions: either we put air conditioning but then we all live in boxes and it is not ideal for the climate. Or we look at what has been done elsewhere in countries that are already warm and know how to build accordingly. Anyway, we have no alternative but to design smarter cities: 80% of us live in them, which is the only place where the carbon footprint can be controlled. The city is about 20 to 30% less carbon footprint compared to a housing estate. Because the myth of the individual house as being the panacea is a climatic catastrophe.

Q: How do these Mediterranean constructions naturally regulate heat?

A: The first thing is to build with matter and inertia. You need materials that are thick or well insulated. Concrete is the worst. Today, we know how to insulate buildings with wood wool or hemp, which have an incredible thermal capacity.

There are also very simple things in the area of ​​natural ventilation, to which we are coming back. When air is brought in from the bottom, it is almost cool and then the hot air must be evacuated from the top. If we manage to find a way to build like that, we would manage to have fairly effective natural ventilation. We know how to do it in Spanish cities for a long time with patios. The principle is to create an island of freshness through the centre. A single tree in a yard is five degrees less under the tree. So we bring in the fresh air through this island and we evacuate it through the facades which are as airtight as possible when they are oriented from east to west in full sun. These are things that we have known how to do for a very long time.

The most paradoxical thing is that where people suffer the most from the heat is not in old buildings. Not so long ago, all the major French avenues were alleys that were completely bordered by trees, and Haussmannian buildings in Paris or classic buildings elsewhere are made of stone, with greater inertia.

Q: What are the obstacles today to the generalization of these construction principles?

A: We would be quite capable of building cities so that people can feel good there, better than in jars, but it's very complicated because it has a financial cost that promoters or social landlords refuse. Concrete is a material that has a catastrophic carbon footprint but there are such lobbies in construction that it is currently impossible to do without. As long as the city will be a financial product, that it will have a market value rather than a social, human and cultural one, we will not get out of it. Building cities so that they are adapted to the world in which we live requires political courage and economic radicalism.