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F. Chiodelli, São Paulo, The Challenge of the Favelas. A cidade informal no século 21. <br/> Heliópolis favelas (São Paulo), Source: Diniz dos Santos e França (2008), p.35

São Paulo, The Challenge of the Favelas.
A cidade informal no século 21

Francesco Chiodelli

The paper analyses and evaluates the exhibition A cidade informal no século 21 in reference to the policies developed in recent decades by the municipality of São Paulo (Brazil) to deal with the situation of slums in the city. As the slum problem is a characteristic feature of the megacities of developing countries in the southern part of the world (of Brazilian cities, too), the most encouraging indications about the possibility of improving the living conditions of the slums’ inhabitants come from São Paulo.


On a day in the last five years (established, according to different research, between 2005 and 2008) [1] something epochal happened without anyone realising or celebrating it: for the first time in the history of mankind the planet’s urban population exceeded the rural one. A sudden increase in the number of urban inhabitants on Earth started mainly in the first half of the 1990s:  within almost half a century mankind changed from 2.5 billion people in 1950 to 6 billion people in 2000 (today it is about 7 billion), with 60 per cent of this growth in the urban areas. [2]
By 2025, 56.6 per cent of the Earth’s inhabitants (4.5 billion out of 8 billion people) will live in a city (United Nations, 2010). This growth has mainly been hosted by the urban areas of emerging countries and countries in the southern part of the world: if the ranking of the most densely-populated cities on the planet has been led for a long time by the conurbations of the most developed countries (Paris, London, Berlin, New York, Tokyo), during recent decades mainly African and Asian conurbations have risen in this chart (Bombay, Lagos, Dhaka, Karachi, Hyderabad). From a long time we see Brazilian cities in this list, and particularly São Paulo with 20 million of people living its metropolitan area (MRSP). [3] In many cases this great urban growth is not at all epic or glorious. This is dramatically true for urban areas in Africa or south-east Asia; nevertheless, in Brazil, a country experiencing rapid economic growth, the rapid urbanisation, has caused enormous problems too, in particular the huge development of slums. [4] A small amount of data is sufficient to give an idea of the magnitude of this problem. In 2001, 924 million people (31.6 per cent of the world’s urban population) lived in one of the 250,000 slums on the planet; if the slums’ growth trend isn’t reversed, half of the urban growth in the next thirty years will be in shanty towns, leading their population to increase by about two billion people, so that in the next decades almost 50 per cent of the planet’s urban population will live in a slum (UN-HABITAT, 2003). A large number of them live in developing countries or in the southern countries of the world (particularly, in Asia and Africa); [5] nevertheless, in Brazil 37 per cent of the urban population still live in a slum. However, in the last decade the most encouraging signal about the possibility of efficiently improving the living conditions of the inhabitants of slums came directly from Brazil.


The São Paulo state is the richest in Brazil and São Paulo city is both the economic and financial heart of the country. Nevertheless, São Paulo is also the city in Latin America with the highest number of people living in slums: the city’s municipal secretary of housing maintains that 30 per cent of the municipality’s inhabitants live in precarious housing conditions, a total of three million people (that is, more than a third of all of the favelados in the country) (França and Barda, 2010). [6]
It was in the 1980s that the precarious and informal housing started to increase in number within the city; the economic crisis which struck São Paulo (which has for decades been the industrial heart of the country) caused a rapid growth of unemployment and poverty, and, as a consequence, a huge increase in informal settlements. In the 1970s the favelas housed only 1 per cent of São Paulo’s population, but at the beginning of the 1990s this figure reached 20 per cent. The expansion of the favelas mainly took place in the suburbs; the city, which until the middle of the twentieth century was both dense and compact, has rapidly extended, with the building of huge and dilapidated informal settlements, far from the centre and characterised by inadequate facilities (which nowadays cover 70 per cent of the metropolitan area).
Nevertheless, the urban configuration is not of a dichotomous nature (rich centre vs. poor suburbs), but it’s extremely more complex and heterogeneous:  a large number of affluent people have their own residences in some areas on the outskirts, while at the same time the city centre continues to house a significant number of poor people in the so called cortiços (UN-HABITAT, 2010). This is significant because it testifies to the fact that the poor suburbs of São Paulo are extremely diversified (and, as a consequence, the way of intervening to face the problem effectively also has to be diversified). Brazilian slums are usually called favelas, but favelas are actually only one of the different types of precarious and informal housing. Generally speaking, we can recognise two main kinds of Brazilian slums (Fix et al., 2003):
cortiços: rented housing units mainly made up of a single room, obtained by the repeated  sub-division of houses, particularly in old buildings in the city centre. They are characterised by overcrowding and problematic sanitary conditions (toilet facilities are common, often one per 20 - 30 people; the rooms are usually small, low, without any windows and with insufficient ventilation; a whole family lives in a single room). In 2000, in the central areas of São Paulo alone (the quarters of Sé and Mooca) 1,648 buildings were registered which could be called cortiços (López et al., 2010)
favelas: irregular settlements built on public or private property (usually in the outskirts) which are illegally occupied by poor families. They are characterised by scant primary and secondary urbanisation. [7]

Slums are a typical phenomenon of the urban panorama of São Paulo and they represent a big problem for the municipality; nevertheless, it is useful to stress that their qualitative state cannot be compared to slums in African or south Asian cities. São Paulo’s favelas and cortiços have basic facilities that are quite unthinkable in the shanty towns of Lagos or Mumbai; 98.4 per cent of the buildings in the metropolitan area of São Paulo are connected to water, 70 per cent of the favelados and the inhabitants of cortiços are legally connected to the electricity distribution network, gas is used by everyone as fuel for cooking, and the collection of waste is guaranteed all over the city. [8] A relevant deficiency in terms of basic services is only related to connection to the sewerage system (which is, nevertheless, guaranteed to 56 per cent of both the favelados and the inhabitants of cortiços). However, São Paulo’s slums are mainly overcrowded, unhealthy, built of inappropriate materials, quite often in areas at environmental risk, illegal, far from central, without public spaces and facilities, and characterised by high levels of violence.
Not only is the less dramatic situation compared to slums in other cities in southern areas of the world quite encouraging, but the improvement trend of living conditions for Brazilian slum dwellers in shanty towns during the last decade is also encouraging (particularly in recent years during the presidency of Luiz Inácio Lula da Silva).  The number of people below the poverty line in Brazil went down from 52 per cent of the population in 1990 to 38 per cent in 2005, with a reduction of 4.2 per cent only from 2006 to 2007. The poverty level in the metropolitan area of São Paulo, which in 1999 reached the peak of 39 per cent (6.4 million people), started to go down drastically in 2003, with a reduction of 20 per cent in five years. All of this is a consequence of both local and national economic and demographic factors, but also of the great public efforts in this direction (UN-HABITAT, 2008).
This decrease in poverty had a positive result on the housing conditions of slums, thanks particularly to requalification programmes started by the municipality of São Paulo (as an integral part of the national strategy of the fight against poverty). By inverting the procedure that, until the 1980s, had characterised the public approach to the problem of the favelas (a mix of clearances and demolition, construction of large concentrations of public housing in the extreme suburbs, and problem avoidance), the municipality has developed several interventions aimed at facing the problem in a radical way. Among them is the Programa de Urbanização de Favelas, based on the pioneering example of the Programa de Recuperação Urbana e Saneamento Ambiental de Bacia Hidrográfica do Guarapiranga (França, 2000), which has benefited  almost 130,000 families living in the city’s favelas. The basic principle of the programme has been to improve the housing conditions of the slums through work on primary infrastructures (sewerage system, rainwater drainage, road paving, connection to running water), accompanied by other interventions to create public spaces and facilities (squares, parks, community and sports centres); the purpose was to diminish the distance (symbolic but also substantial) of these informal neighbourhoods from the formal areas of the city. All of these operations tried to limit the clearing out and have been accompanied by a regularisation process for buildings illegally constructed on public land. [9]

The exhibition A cicade informal no século 21 (The informal city in the 21st century) (curator, architect Marisa Barda) presents, through maquettes, pictures and videos, 18 projects related to seven favelas in São Paulo (with great attention to the Paraisópolis favela, the second largest in the city with almost 56,000 inhabitants and 21,000 buildings).[10] The different projects come from three distinct experiences: a PhD course (Infraestrutura Alternativa para a Cidade Informal) in architecture and planning organised by Christian Werthmann at Harvard University Graduate School of Design;[11] a Sustainable Urban Living Model course, which took place at Columbia University Graduate School of Architecture Planning and Preservation (co-ordinated by Alfredo Brillembourg and Hubert Klumpner) [12]; a selection of the work of six teams of architects [13], presented in 2009 during the International Architecture Biennial Exhibition of Rotterdam. The different works are organised according to four themed sections: connections (projects which try to reconstruct both connection and continuity between the informal areas and the formal city); transitions (projects that explore the relations between public and private spaces within the favelas); fruitions (projects which suggest alternative solutions to the traditional systems of water drainage, use and recycling, towards greater environmental sustainability for these neighbourhoods); transformations (projects for the transformation of particular areas of the favelas, with the purpose of creating parks, housing and public spaces).
However, all of this information on its own doesn’t help us to understand the real value of the exhibition; in fact, is the exhibition discloses all its value only if it is considered within the context of the conditions in the informal settlements in São Paulo and, moreover, within the context of the municipal policies for the requalification of the favelas. Without this context it would have been little more than an exercise similar to many other exercises of this genre, certainly interesting, but still a little bit more than rhetorical (the projects by the six teams of architects) or simply didactic (the courses at Harvard University and Columbia University); and this, in fact, is the impression that an absent-minded observer or an observer with only a superficial knowledge of the context of São Paulo could have. Placing it within the described situation gave the exhibition quite a different meaning, establishing both its value and its interest. The conditions in the favelas in São Paulo and, above all, the municipal policies for São Paulo’s slums, constitute both the background and the horizon of the proposals presented in the exhibition. They constitute the background because all of the different projects (even if they have a distinct quality) deal with the key themes through which the requalification programmes of the favelas have actually been developed (the attention to the connection between the formal and informal city, the interstitial intervention for the creation of a mosaic of public places in the little space available, the attention to environmental and infrastructural matters, the attempt to limit the negative effects of public policies in the existing social context). They are the horizon because the planning proposals can be seen as an incentive and a suggestion for the innovation of public policies ‒ in this direction the Pindaric component that characterises some projects acquires the significance of a motivation for the innovation of the municipal policies towards possible new paths.
If this is the intrinsic value of the exhibition, it also acquires an extrinsic meaning related to the School of Architecture and the Society of the Polytechnic of Milan which are hosting it. What the exhibition suggests to our school is the opening towards new reference horizons, both of geographic and thematic nature. In a world where the economic barycentre is quickly moving towards developing countries (not only China, but also Brazil and India, for example), the suggestion that can be taken up by the exposition is to start to turn the attention of future Italian architects and planners on these areas as well, and on the new themes that these new areas bring with them. Among all of these new themes, informal housing acquires a privileged position: in Western countries is mainly a residual phenomenon, but in many urban areas in southern countries of the world it is one of the main ways of living. It seems to be useful to train architects and planners who are able to work with consciousness within the context of the informal city for at least two reasons: firstly, because as the developing and emerging countries (and among them Brazil) become more and more a possible professional destination (it is sufficient to think of the FIFA World Cup in 2014 and the Olympics in 2016 which will take place in Brazil), this can be useful for stimulating actions that are different from the acontextual quality of many architecture projects that are realised in these areas; secondly, and more simply, because it is not possible to continue to ignore, at least for quantitative reasons, some billion people living in.


Brillembourg A., França E., Zacarias E.S.F., Klupner H.,  (Eds) (2010), São Paulo. Projetos de Urbanização de Favelas, Superintendencia de Habitação Popular, São Paulo.
Davis M. (2006), The Planet of Slums, Verso, Londra.
Diniz dos Santos M.T., França E. (2008), Urbanização de Favelas. A Experiência de São Paulo, Marcos Boldarini, São Paulo.
Fix M., Arantes P., Tanaka G. (2003), Understanding slums : Case studies for the Global Report on Human Settlements. UN-HABITAT, São Paulo [].
França E. (Ed), (2000), Guarapiranga: urban and environment rehabilitation in the City of São Paulo, Marcos Carrilho Arquitetos, São Paulo.
França E., Barda M. (2010), A cidade informal no século 21, Tinta Pura, São Paulo.
Herling T., França E. (Eds) (2009), Social Housing in São Paulo: Challenges and New Management Tools, The Cities Alliance, Washington.
López A., França E., K. Prado Costa (2010), Cortiços: A Experiência de São Paulo, Prefeitura da Cidade de São Paulo, São Paulo.
United Nations (2004), World Urbanization Prospects. The 2003 Revision, United Nations Editions, New York.
United Nations (2010), World Urbanization Prospects. The 2009 Revision, United Nations Editions, New York.
UN-HABITAT (2003), The Challenge of Slums. Global report on human settlements 2003, Earthscan, London.
UN-HABITAT (2008), State of the World Cities 2010/2011. Bridging the urban divide, Earthscan, London.
UN-HABITAT (2010), São Paulo: A Tale of Two Cities, United Nation Human Settlements Programme, Nairobi [].
Werthmann C. (Ed) (2009), Operações táticas na cidade informal, Secretaria Municipal de Habitação, São Paulo.


[1] United Nations (2004) establishes the date as 2005; Davis (2006) talks about a date between 2007 and 2008; UN-HABITAT (2008) refers to 2008.
[2] If in 1950 there were only 86 cities with more than one million inhabitants, today the millionaire conurbations are more than 400.
[3] The population within the municipal area of São Paulo (MSP) it is made up of about of 11 million people (UN-HABITAT, 2010).
[4] The term slum usually refers to “a heavily populated urban area also characterized by substandard housing and squalor” (UN-HABITAT, 2003: 8). The United Nations identify five parameters whose non-satisfaction reveals the presence of a slum: access to water, access to sanitation, sufficient housing space (absence of overcrowding), structural quality of housing, security of tenure. The terms used by different languages referring to slums are diverse; each of them indicates a particular declination of the problem (in Brazil they talk about  favelas, cortiços and loteamentos irregulares).
[5] The urban population who live in slums is considerably different according to the areas of the planet: for example, in the countries of sub-Saharan Africa it is 71.9 per cent; in northern Africa, 28.2 per cent; in central and southern Asia it is 58 per cent, and  in Latin America and the Caribbean, 31.9 per cent (UN-HABITAT, 2003).
[6] UN-HABITAT (2010) maintains that it is 20 per cent of the population of São Paulo (almost two million people) who live in the favelas, while 57 per cent of the city inhabitants live in the suburbs’ precarious quarters.
[7] In addition to these two main types there are also the so-called loteamentos irregulars, residential areas built on land belonging to residents, but outside any established rules of land use (they are usually rural areas, built in violation of any planning rules). These areas have the same problems as the favelas in terms of the facilities and basic infrastructures; nevertheless, unlike the favelas, they are not places which are illegally occupied: the legal property has made easier the regularisation process of a large number of these settlements.
[8] For instance, in Sub-Saharan Africa only 19.1 per cent of houses are connected to water, 7.4 per cent to sewerage, and 20.3 per cent to electricity (UN-HABITAT, 2003).
[9] For example, in the Strategic Master Plan of São Paulo of 2002 (Plano Diretor Estratégico do Município de São Paulo) the regularisation of illegal settlements was defined as one of the main strategies for the city’s development; the Programa de Regularização Urbanística e Fundiária de Supetintendência de Habitação Popular aims precisely to regularise public areas occupied for housing purposes by low-income families (see Diniz dos Santos and França, 2008; Herling and França, 2009). For municipal policy concerning the cortiços, see Lopez et al., 2010.
[10] The other informal settlements are Bamburral, Córrego de Mina, Parque Novo Santo Amaro V, Cantinho do Céu, Vargem Grande and Cidade Júlia.
[11] The results of this experience are presented in depth  in Werthmann (2009).
[12] For a close examination of the work of SLUM Lab (Sustainable Living Urban Model Lab) co-ordinated by Alfredo Brillembourg and Hubert Klumpner, see Brillembourg et al. (2010).
[13] Urban Think Tank (Venezuela), Elemental (Chile), Christian Kerez (Switzerland), Ciro Pirondi, Marcos Boldarini and MMBB (Brazil).

Francesco Chiodelli
DiAP Dipartimento di Architettura e Pianificazione
Politecnico di Milano 

F. Chiodelli, São Paulo, The Challenge of the Favelas. A cidade informal no século 21. <br/> A dwelling unit in a cortiço <br/> Source: López, França e Prado Costa (2010), p.53 F. Chiodelli, São Paulo, The Challenge of the Favelas. A cidade informal no século 21. <br/> Favelas rehabilitation project (Vila Nilo and Santa Inês – N.Senhora Aparecida) <br/> Source: Diniz dos Santos e França (2008), p.53-58 F. Chiodelli, São Paulo, The Challenge of the Favelas. A cidade informal no século 21. <br/> Two projects on display (on the left, Limpando a Água project, at Cantinho do Céu, by Dorothy Tang, Harvard University; on the right, Parque Novo Santo Amaro V pr