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Urban Studies

A bit of fresh air

Climate maps can help urban reorganization

Campinas, third most populous city in the state of São Paulo: between parks and skyscrapers

Eduardo CesarCampinas, third most populous city in the state of São Paulo: between parks and skyscrapersEduardo Cesar

in Campinas, SP

By comparing maps made from satellite images with those from computer simulations, architect and urbanist Alessandra Prata Shimomura discovered that the average annual temperature in the downtown area of Campinas is 3°C higher than it was 10 years ago. Streets like José Paulino, 13 de Maio, Barão de Jaguara and others close by are hot, muggy and crowded, although spacious and clean. Temperature and wind maps, such as those she prepared over a three-year period at the University of Campinas (Unicamp) and presented first to Pesquisa FAPESP, enable a review of urban planning strategies by showing areas that could be made more pleasant if they had more trees to provide shade to pedestrians, as well as those regions that should be off-limits to very tall or closely-spaced buildings, which block air circulation. This lack of air circulation is a climate-related phenomenon that is not often remembered, yet is important for human comfort and health. Demonstrating the value in this approach, a map of wind movements of Hong Kong in 2002 indicated the most vulnerable districts and helped to contain the spread of severe acute respiratory syndrome (SARS) on that Chinese island.

Climate maps are beginning to be used more intensively. In Brazil, one of the products by collective projects, such as the FAPESP Research Program on Global Climate Change, which is financed by the federal government, are maps depicting the vulnerability of large Brazilian cities to the effects of climate change. These maps are offered to mayors and other government administrators (see Pesquisa FAPESP no. 171). Ana Rocha, from the Federal University of Santa Catarina, and Eleonora Assis and Simone Hirashima, from the Federal University of Minas Gerais, took into account ventilation, natural lighting, humidity and temperature while designing a housing project in Governador Valadares, in the state of Minas Gerais. “Given the need for ventilation, a study was made of the land using a scale model and a wind tunnel to simulate the wind,” they noted in an article published in 2012. They also believe it is “essential to promote the formation of multidisciplinary groups and encourage communication between the departments involved in the project process.”

Shimomura prepared the Campinas maps in collaboration with geographer Antonio Manuel Saraiva Lopes, a professor at the University of Lisbon, who has worked in this area since the 1990s. In 2013, in collaboration with Elis Alves, from the University of São Paulo (USP) at São Carlos, Lopes examined the wind patterns and temperature variations that lead to the formation of urban heat islands in the city of Lisbon. According to a survey by Chao Ren and Edward Ng, from the University of Hong Kong, and Lutz Kaztschner, from the University of Kassel, Germany, 15 countries worldwide, mainly from Europe and Asia, with only two from South America (Brazil and Chile), have already adopted this methodology known as urban climate maps, developed in the 1970s as an urban planning resource in Germany.

In a study to be published in the journal Urban Climate, Michael Hebbert, a professor at University College London, goes even further back in time. He dates the origin of climatology applied to urban planning back to the 18th century, with English meteorologist Luke Howard, author of the book The climate of London, deduced from meteorological observations, published in 1833, as well as similar works in France and Germany. At that time, air pollution and ventilation were deemed to be as important as water supply and drainage, although the harmful effects caused by residential chimneys were a harder problem to fix than water quality was.

“Nowadays, we have several different instruments and technologies, such as satellite images, aerial photos, and even drones, which enable us to look at cities from a viewpoint of urban climate and make it easier to recognize areas that are warmed more or less and that have greater or lesser circulation, as well as tools that measure climate variables,” Shimomura says. Her final maps, the result of a combination of other maps and computer processed information, indicated that the winds in Campinas originate along the coast, bringing with them both the ocean breeze and pollution from the city of São Paulo. Still intense, they blow through the cities of Valinhos and Vinhedo before entering central Campinas, losing speed as they cross the city and continue towards Limeira.

Generally speaking, the city of Campinas, the third most populous in the state after São Paulo and Guarulhos, “is satisfactory on a regional scale, but care still needs to be taken,’ she concludes. “Now it is possible to do on-site analyses to adjust the conclusions and measure user satisfaction at each location.” She notes that on a regional or local scale, climate is not just an unchangeable attribute of nature but instead dependent on decisions made by individuals who build houses and put up buildings that block the wind or heat up or cool down quickly.

Urban climate maps show ways to maintain or improve what is known as environmental comfort. It is the presence or absence of this comfort that makes cities, especially their cores, either pleasant or suffocating.  In the case of Campinas, one of the recommendations is to preserve the wind corridors, such as planted areas, wide avenues, highways, and the bottoms of valleys, which help to minimize the effects of temperature at these locations. Another recommendation is to maintain a variety of ways to occupy space in urban areas, by mixing areas covered by buildings together with green, open spaces like the farm on the site of the Agronomic Institute of Campinas (IAC). “Campinas has not yet become another São Paulo,” she notes, reminding us of the vast carpets of asphalted and almost treeless streets and buildings in the latter city’s west zone.

Another era: Intersection of Rua Barão de Jaguara and Rua General Osório, central Campinas, in 1928

COLEÇÃO V8 / Memory Center-Unicamp Another era: Intersection of Rua Barão de Jaguara and Rua General Osório, central Campinas, in 1928COLEÇÃO V8 / Memory Center-Unicamp

Studies like the one by Shimomura suggest the need to pay more attention to simple solutions and time-honored but not always remembered concepts of engineering and architecture. For example, in a study released in September 2014, Fernando Durso Neves Caetano, an architect and urbanist from Unicamp, found that outside walls covered by plants, called “living walls” can reduce the inside temperatures of houses and buildings by as much as 6°C on hot summer days, while inversely retaining heat on cold days.

In a broader sense, there is room for more participation by citizens in their cities. One of the ways Shimomura believes this can be accomplished is through the creation of urban agents, who could accompany and represent the residents of a neighborhood, looking out for public spaces and intermediating requests and complaints directed at municipal government. “Residents want to report or complain about problems on the streets and they generally have a hard time finding someone to talk to,” she says. “For example, requests for tree pruning can take years until they are met!” Before the end of the year Shimomura intends to return to the Campinas Civil Defense Office to present the maps prepared with information on fallen trees, branches, houses and buildings with roof tiles blown off by the wind, which she requested and was given two years ago. “This is feedback I must give,” she says. This will be her first meeting with potential users of her maps.

Urban dynamics and territorial planning: urban climate map and its use in master planning) (nº 10/19447-7); Grant Mechanism Young Investigator; Principal investigator Alessandra Rodrigues Prata Shimomura (Unicamp); Investment R$ 63,349.26 (FAPESP).

Scientific articles
HEBBERT, M. Climatology for city planning in historical perspective. Urban Climate. 2014. on-line.
ROCHA, A. P. de A. et al. Conjunto para habitação social com princípios bioclimáticos para o município de Governador Valadares, MG. Revista de Arquitetura Imed. v. 1, n. 2, p. 122-32, 2012.