When Green Roofs Make Cities More Beautiful and Peaceful ~ The green roof is undoubtedly the most talked about theme when we talk about sustainable architecture and has been attracting a lot of people in recent times when environmental awareness becomes more and more common. This concept, which causes in many the sense of novelty, was long thought of, more precisely in ancient Egypt , but defined as an architectural concept only in 1920 by the French architect Le Corbusier . The modernist architect Charles-Edouard Jeanneret-Gris, better known as Le Corbusier , was the one who developed the idea of garden terraces with the intention of compensating for the environmental footprint caused by the constructionon the ground and provide a higher quality of life to people through green recreation areas.
The concept was so important that it came to be considered one of the 5 fundamental points of the new architecture and with its great diffusion, the garden terrace served as influence for several other architects. In Brazil, it was used by Lucio Costa in the Gustavo Capanema Palace project in Rio de Janeiro, the current headquarters of the MEC (Ministry of Education).
For Le Corbusier , the modern cities were suffocated, without enough green areas, not contributing to a good quality of life of the citizens . So he proposed that all buildings have their own garden terrace . With almost a century of existence, the concept of green roof developed by Le Corbusier is more current than ever. In times of environmental crisis , everyone can do their part by collaborating with their community and the planet.
Recently , France , the Danish city of Copenhagen and Canadian Toronto have passed laws that make green roofs mandatory. Here in Brazil, the ecotourism becomes mandatory for residential buildings with more than 4 floors in Recife (the bill also provides for the construction of reservoirs to capture rainwater in new residential and commercial properties, with above ground area of 500 m² and that have 25% of the ground waterproofed).
Researcher compared two buildings in São Paulo:
The use of the green roof can be an important instrument to reduce the impacts of specially formed heat islands in large urban centers, according to a study by the University of São Paulo (USP). When comparing two buildings in the state capital, one with green area and the other with concrete slab, geographer Humberto Catuzzo found that the temperature at the top of the garden building was up to 5.3 degrees Celsius (° C) lower . There was also a gain of 15.7% relative to the relative air humidity .
“If we imagine that it is doing 25 ° C in the green roofed building, and in concrete, 30 ° C, that makes a big difference within that microclimate,” said the researcher and author of the doctoral thesis on this topic. Catuzzo pointed out that it is not possible to define exactly what impact the initiative would have if it were expanded, but noted that the differences in temperature and humidity found in the experiment were very significant . “It could improve the climatic or environmental issue of that central region,” he said.
The buildings analyzed were Conde Matarazzo , head office of the city of São Paulo, Viaduto do Chá, and Mercantil / Finasa , in Rua Líbero Badaró, whose slab is concrete. The two buildings, located on the right bank of the Anhangabaú Valley, were chosen because they were subject to similar atmospheric conditions and insolation . At the top of the buildings sensors were installed 1.5 meters from the floor (international standard), which, for a year and 11 days, measured the temperature and the relative humidity of the air in the area of the two roofs.
According to Catuzzo, the heat island in the center of São Paulo raises the temperature in the region by up to 10 ° C during the summer. “The concrete, the pavement, the large circulation of vehicles make this area have a greater warmth compared to others,” he said. The use of ecological roofs would also solve the problem of the lack of spaces in the center that could house green areas.
In the study, Catuzzo compared the data of the building of the city hall with information from the National Institute of Meteorology (Inmet). In this case, the green roof, even being in the central area, presented lower heating and higher relative humidity of the air . The most significant variation was 3.2 ° C cooler and 21.7% wetter.
According to the researcher, these areas absorb about 30% of the light radiated by the sun . “Part [of energy] is retained by plants, even by the issue of photosynthesis, and a smaller amount of heat is emitted back into the atmosphere,” Catuzzo told Agência Brasil. Without the vegetation, the concrete receives the solar energy, gets heated and emits heat again , meaning it is heating even more.
In addition to the climatic gains, the green roof can contribute to reducing energy use. “It increases the thermal comfort inside the buildings and, consequently, reduces the use of the air-conditioning”, exemplified Catuzzo. It also improves rainfall , which is especially important for a city that suffers from flooding. “Rainwater seeps more slowly into the galleries.”
For the geographer, the expansion of the use of this type of roof can help in the formation of ecological corridors in the big cities, interconnecting several covers to the preserved areas, like squares and parks. “On the 14th floor of a building, there is life. They are birds, as you well know. There is a whole ecosystem, even if reduced, working perfectly. Seeing the greener city would mean gaining environmental quality for the community as a whole. “
Why use eco-friendly roofs?
Why do they replace a heavy infrastructure with one that is not only more efficient but also more beautiful and useful;
Ecological coverages serve as a haven for people who work in offices, and are places to plant gardens or people who live in buildings can relax;
Even where they are not accessible, they create beautiful aerial views for surrounding neighbors and are isolated and safe places for wildlife;
Reduce energy costs with natural insulation ;
They absorb rain water, reducing the need for complex and expensive drainage systems ;
They increase air quality (on a higher scale) and help reduce the effect of the Urban Heat Island (a phenomenon in which the growth of cities and suburbs causes heat to be absorbed and stored);
These roofs last longer than conventional roofs .