Interview with Michel Reynaud

There is a link between the housing climate and the social climate, shows us Michel Reynaud, architect, who will give a lecture entitled "La kaz courant d'air", Thursday, in Saint-Leu. "We must rediscover the know-how of our elders and live with the climate, not against it," he explains. When architecture meets urban planning.

- Michel Reynaud, next Thursday you will present a conference entitled "La Kaz courant d'air". What is it about?

This is of course a reference to the buses of yesteryear. I am going to present the different aspects of the bioclimatic habitat to the general public, evoke the lost know-how, give a few recipes...

- What is bioclimatic habitat?

- The simplest example is the palaver tree. A tree for shading and a place underneath where air can circulate freely. In a warm climate it is a particularly comfortable place, which is why it is also frequently found in countries with equatorial or tropical climates. This principle must be reproduced in the construction if we want to make comfortable houses.

- You're talking about lost expertise...

- The typical Creole hut evokes softness, today we build hard. We lived then with the climate and not against it. The stakes are high because, from one mode of construction to another, the average temperature of the cities is increased by four or five degrees. And up to ten degrees at the end of the afternoon. That is what happens in cities like Saint-Denis or Saint-Pierre. Neighbourhoods like Ravine-des-Cabris, for example, and there are so many others, have become unliveable. Everything is closed, concrete, and you can only drive around in them. These neighbourhoods have become hard, noisy, mechanical, violent... Pedestrians no longer exist, they are barely tolerated. Social life is also being lost. The harshness is general, people close themselves off. It's the bunker culture.

What's that due to?

- We copied the Western model. In practice, there is no more air circulation and we built with unsuitable materials. It's the ransom of a certain modernity. Trees have been cut down, courtyards have been concreted or planted with grass, gardens have been enclosed by high, airtight walls, and streets are covered with asphalt. All these materials capture, concentrate and store solar energy. Then they release the heat by infrared radiation, which is the principle of operation of the radiator panels of the radiators.

- In terms of housing, is it the same problem?

- Yes, we build ovens. The best example is the Satec house. It stores energy and then releases it for about eight hours. That's what makes these buildings so hot at night. They are ovens, literally. The only solution is to add buttons. Air conditioning. It's a leaky one because to produce one calorie of cold, you need ten calories of heat.

- What then are the recipes to make your home enjoyable?

- The feeling of warmth is a combination of temperature, humidity and air circulation. A comfortable living space is one where the air circulates. It takes a draught of one metre per second. To force the air to circulate because it is lazy. A depression must be created: the leeward side of the house must have an opening at least equal to that of the windward side. For the same reason, waterproof fences should also be banned. Materials that do not radiate, such as wood, should also be used. Pergola walls can also be lined, as can the roof, because 80% of the energy comes from the sky. All these techniques were used by the ancients.

- You also attach great importance to the vegetation...

- In fact, trees are also needed in the yard: for shade and for evapotranspiration; the water that turns into steam absorbs energy, bringing that feeling of freshness that plants give. The best adapted trees are the endemic ones, which plunge their roots vertically and therefore do not threaten the walls. For freshness, the type of vegetation, such as at the front of the lontan courtyards, is important. Grass does not fulfil this function. I remember this anecdote: Guy Roux, the football coach, had measured the temperature of the stadium's lawn during a heat wave by dipping a thermometer into it. He read 60°C. The grass was literally burning. And then, in the past, the Creole garden was an offering to its neighbours, a gift; it also helps to improve the climate in every sense of the word.

Propos recueillis par Philippe NANPON

Source : Le Quotidien de la Réunion

Date de parution 22 Avril 2014

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