Above certain houses in Parque Arará, in the North Zone of Rio de Janeiro, the sheet metal soaks up the sun and then spits it into the rooms for hours. In these popular settlements, often built hastily and as needed, the heat accumulates between concrete, asphalt and metal roofs. In some urban areas of Rio the heat island can be up to about 20 degrees higher than in nearby vegetated areas, and when the air remains still the toll hits the body: dehydration, heat stroke, breathlessness, poor sleep, half-lived days.
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Luis Cassiano starts from there, from the most concrete possible version of the word necessity. He lives in Parque Arará, he has known that heat for years and at a certain point he stops treating it as a neighborhood condemnation. Thus was born Teto Verde Favela, the project with which it teaches residents to transform roofs into light gardens, robust enough to withstand the Rio sun and economical enough to enter places where air conditioning often remains a luxury or an expense that weighs too much.
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In Parque Arará the sun hits the sheet metal, slips into the rooms and stays there for hours
The system works precisely because it avoids the ecological brochure fantasy. First the structure is checked: Cassiano repeats that every intervention must be seen by an engineer or an architect. Then comes a waterproof vinyl shield.
Instead of earth, which would be a gamble on those roofs, comes bidim, a light geotextile also obtained from recycled bottles and used in hydroponic form, so the weight remains low. Above are placed plants that can get by with little, often recovered or donated, however carefully chosen: succulents, Spanish mosses, kalanchoe, tradescantia, species accustomed to resisting the heat and essential maintenance.
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Here the difference is measured without poetry. In a comparison made at Parque Arará, the project recorded up to 15 degrees less in the internal temperature of a room compared to the neighboring house without a green roof; in other surveys the roof of Cassiano remained around 30 degrees while the one next door rose up to 50, with a difference of close to 20 degrees on the roof itself. Translated into normal language: more habitable houses, less ferocious days, fans that run less, rainwater retained better when a storm arrives.
Houses, shelters, nurseries and even food trucks
The strength of the project lies in the fact that it does not stop at the founder’s house. Over time, green roofs have appeared on homes, kindergartens, bus shelters and food trucks in the neighborhood. Residents, school children, university students and volunteers move around the works. Cassiano accompanies those who start from scratch, from the procurement of materials to the installation, and in the middle he inserts something that in urban policies almost always arrives late: the education to stay close to plants, to understand them, to keep them alive with one’s own hands. When these roofs multiply, the benefit goes beyond the single room and extends to the street, the block, the neighborhood.
Even the accounts, for once, speak clearly. With bidim and vinyl sheet it goes down to around 5 reais, i.e. 1 dollar, per square foot; a conventional green roof can cost up to 53 reais, about 11 dollars, for the same surface area. It’s the kind of distance that separates a good idea from a solution that actually fits into a working-class neighborhood. And in fact the profound meaning of Teto Verde Favela lies here: to bring urban greenery where grey, noise and still air usually arrive first, in a city where heat and green spaces are distributed with the same elegance with which income is distributed.
Cassiano talks about cooler houses, birds and butterflies returning, air flowing better. The experts who work on these issues add the rest: less runoff, less noise, more well-being, even a mental relief linked to just the sight of greenery. It seems like little only to those who already have greenery under their homes. In a favela, the way of being in the world within four walls often changes.
In some places, climate justice passes through conferences, strategic plans and promises that make a resume. In Parque Arará she climbed a ladder, with a scroll under her arm and her hands dirty with light earth. The rest, in those parts, grows on the roof.
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