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From the direction of my studies insofar, I tried to focus on the following question: how could we design better high density environments, and especially collective housing environments?

The research from the previous post has led me to a set of general conditions for designing built environments that could improve the perception of density.

It appears that built environment, both in terms of public space as well as building, if configured in a correct way can improve the perception of density, while if configured incorrectly may lead to a negative perception of density. In this regard it is useful to attempt to establish the general conditions which could support a positive perception of high density while alleviating the effects of high density. These conditions or requirements are formulated according to the needs identified in the perception and social behavior of residents of high-density environments. They do not represent predetermined spatial configurations, but are topics that can be traced by design in order to be translated into spatial configurations. Pursuing these requirements through design can lead to well balanced future living environments, to an improvement of housing and environment quality as well as an increase of residential satisfaction in high density conditions.

The conditions that support a positive perception of high density built environments could be formulated as:

  • achieving a fair balance between the need for privacy offered by housing and the need of interaction and expression in the wider community.
  • reducing unwanted social interactions, while supporting positive interactions that reinforce a sense of community.
  • maintaining satisfactory group sizes at satisfactory residential rates, depending on the conditions of the project, since contact with too many people in the common areas of residential buildings will discourage close social interactions and the sense of community.
  • presenting in the immediate vicinity of residential buildings qualitative outdoor areas, appropriate for social interaction and group control, that community members can use frequently.
  • providing availability and quality in relation to various functions and services. Also, providing easy and diversified access to those facilities is important, as well as the possibility of walking to most of the facilities needed for the daily routine.
  • providing availability and quality of transport, and also diversity for transport, such as bicycle lanes and good public transport links.
  • offering visual relationships and accessibility with qualitative green areas and support in various ways contact with nature. The green public areas in high density settings should be large, coherent, well-landscaped and well-maintained.
  • presenting a high-degree of safety and discouraging vandalism through the configuration of open, public space and also intermediary, semi-public space.
  • presenting sustainable and ecological features in the design of the housing buildings.

DSC_0729

Image: Project OASE 22 :: studio uek, ARGE Köb & Pollak / Schmoeger, goya: (Wien, Austria)

Excerpt from the paper:

Contemporary High-Density Housing. Social and Architectural Implications

written and presented at the QUESTIONS workshop held in Cluj-Napoca, Romania, 14-16 july 2013; in process of printing at Acta Technica Napocensis: Civil Engineering & Architecture

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Dense environments have always carried dual connotations – on one side they are considered positive due to the sustainable use of resources and the intense social links they generate, but on the other side they are recognized to generate negative effects on humans, such as stress. Starting with the industrial revolution, a strong debate arose regarding the benefits and downsides of density, especially regarding the relation between existing crowded urban environments and the programmatic development of new healthy environments. The debate remained unsolved for a long time, until recent studies have determined an important element that actually shifts the balance between good or bad density, namely the quality of an environment.

I’m currently reading cities full of space, qualities of density by Rudy Uytenhaak. He argues that the built density is the source of a loss of (natural) quality, and the role of urban and architectural design is that of neutralizing this effect by eliminating oppressive spatial configurations and by generating diversity through the design of “intelligent puzzles”.

rudy uytehhaak-desaturatedRudy Uytenhaak Architectenbureau

The quality of density is the most significant feature of the urban built context, and as Uytehnhaak R. points out, “without sufficient quality, density does not work – it even becomes dangerous”. This idea balances the previous interdisciplinary discussions about the justifications underlying positive or negative high-density architecture models of the architectural culture, determining the defining criterion for models with a correct functioning. Spatial quality, as he states, should be sought for in the architectural design of new buildings as a way of compensating for density and its potential negative effects.

Dietmar Eberle (Baumschlager Eberle), in a lecture held at TU Graz on Density, talks about density as determining the urban atmosphere, and that this atmosphere is mostly dependent on the character of the empty public space. The empty open space is what makes us relate to a place. After studying 4 different cities and 40 different locations within those cities, he concludes that the quality of density isn’t good or bad, but it simply has automatic fixed determinations upon quality, atmosphere, people  fluctuation etc. Also, the categories of density represent the current values of time and society. Currently, the quality of a neighborhood is proportionally related to the quantity of public owned open space – 30%…40% for qualitative neighborhoods. So, open space must be increased in order to obtain quality in dense environments. Buildings and open space remain un-ordered in built densities under 1,5, meaning that the position of buildings remains insignificant to other buildings and their organization is based on other characteristics of the interstitial spaces. With densities higher than 1,5, the open space and buildings start to become ordered in relation to the other buildings. higher density attracts also an increase in visual richness (important in relation to quality),in the careful care of public space, the walk-ability and the mixed-use quality of a neighborhood.

In relation to dense residential environments, I am also interested in the study of collective housing typologies.

Collective or mass housing is defined primarily by quantity and it acquires its spatial quality through grouping. This type of dwelling houses large numbers of people with varying degrees of housing quality. Within it the housing units are closely grouped, according to rules of horizontal or vertical assemblage, generating spaces with public, semi-public or private character in which certain social practices of housing unfold. Collective housing draws its name origin from the way in which the building is accessed, namely by a common path serving all the units [1].
In an attempted typological classification of contemporary collective housing models of high-density, I turned towards a non-exhaustive generic formal classification, based on the studies of Mozas J and Per AF from the “Density Series” books [2]. Each of the typologies uses as starting point the individual housing unit, the apartment, which is consequently multiplied in an identical or variable pattern of configuration. The typological categories vary according to composition principles based on the housing unit, on size and by the way in which the building relates to the urban tissue.

Houses

Starting from the singular and abstract typological unit represented by the individual house, the first category is driven by multiplying, joining or overlapping multiple units. The configurations generated by those operations are either classical attached or row houses, either contemporary types of folded row or stacked houses.
The individual unit is usually related to the terrain, benefiting of a court or a terrace and of direct individual or paired access from the ground level. This category makes the transition from individual housing to collective housing of a higher degree of density.

1 HOUSES

Blocks

The second typology represents a quantitative increase in size, in number of individual units and scale compared to the “house” typology. The block height is moderate, usually ranging between 3 and 5 levels; this height is traditionally justified by the number of levels convenient for walking. Its relative low configuration, its flexible footprint on the ground and its scale allow the object to enroll organically within the context.
The block can be freestanding on the plot, it can have free sides or it can continue an existing building by cleaving onto a party wall.

2 BLOCKS

City Blocks

The city block  is an urban building flanked on all sides by streets in relation to the urban fabric. Its scale is directly related to the scale of the city. The city block generally involves a large spatial diversity and a relatively high privacy degree. It can have the same height as the block typology or higher, depending on the context. Buildings ranging between 4 to 7 levels are ideal in terms of energy footprint, which is lower than that of taller buildings.

3 CITY BLOCKS

High-Rise Buildings

The high-rise type, also known as tower block, is represented by tall buildings with multiple levels. There is no universal definition for the number of levels that determines a building to gain this status; this height is variable according to different geographic areas.
This typology is justified by economic considerations, not only in relation to construction costs, but also in relation to urban infrastructure and land resources. Their impact on the neighboring urban tissue is high and the main disadvantages are excessive shading and energy consumption.
The stacked units block is the most interesting type from my point of view, being able to generate spatial quality and diversity. It derives from additive processes of small scale units or overlapped uneven floors.

4_2 HIGH RISE

Mixed Solutions

The mixed solution typology involves combinations of the above, justified by context and project brief. There are no precise formal categories for this typology.

References:

[1]   Zahariade AM. Arhitectură Locuire Oraș, ALO 2009-10. Second year’s course, second semester. Department of Hystory & Theory of Architecture, Faculty of Architecture, UAUIM, Bucharest.

[2]   Mozas J, Per AF. Density: New Collective Housing. A+t ediciones, Vitoria-Gasteiz; pp. 14-17, 2004.

Population density is a phenomenon related to the way in which the population is distributed on the land surface. The population is unevenly distributed across the land, reaching high concentrations in large urban areas while large areas of land remain uninhabited, because people naturally tend to concentrate in areas with desirable conditions, like those of urban areas. The differences in population distribution are high both across countries and between regions of the same country [1], and thus the concept of density of the built environment has relative connotations when trying to compare indices of different areas.

Starting from this fact, it becomes clear that the exact definition of the term high-density architecture can be difficult. The term “density” is itself a complex concept, involving some diversity in terms, and defining it is important before beginning a discussion on density in relation to architecture.

The Definition of Density

High density refers either to physical density, namely the density of a large number of people or the built density related to the land surface, either to subjectively perceived density in relation to the environment and to other participants into a certain space. Physical density is a numeric measure of the concentration of individuals or of physical structures in a certain geographic unit, being a spatial objective indicator, quantitative and neutral. In practice, it only makes sense when linked with a specific reference scale. On the other hand, perceived density represents the individual perception of an estimated number of people present in a given area, of the vacant space and its organization. The character of space itself is important for the perception of density, but the interaction between individuals and environment as a whole is more important. Also the individual cognitive attributes and socio-cultural norms are factors that contribute to this interaction. Perceived density doesn’t only refer to the relative relations between individual and space, but also to the relations between individuals located in the same space.

The definition of density in relation to built environment can have different meanings or different quantification according to the method of analysis and spatial indices taken into account. There is no universal standard formula, only some of the formulas are being used more as opposed to others. Usually, in architecture and town planning, two categories of measurement are used for physical density: population density (Fig. 1) and building density (Fig. 2). Population density is defined as the number of individuals or households per given area, and the building density is defined as the ratio of building structures related to plot surface. All those measures are used in urban planning policies.

population density
Figure 1. Population density

built density
Figure 2. Building density

Building density has a complex relation to urban morphology, playing an important role in determining the urban form. Different combinations between the plot ratio and site coverage will manifest into a variety of different built forms, and urban development of the same density can take very different urban forms [2].

The differences between the surface distribution of population density and that of building density are visible when comparing data of almost every urban tissue. The following example illustrates the difference between the two densities in the case of Timișoara, by graphically expressing the data for the year 2011.

Z:1_PROIECTE63_pug4_work1_urbanism1_ETAPA ANALIZA2_PRED

Figure 3. The difference between the distribution of densities of people and buildings in Timișoara.

Source: illustration from the board Development Analysis I 13_Densities, General Urban Plan (PUG) of Timișoara, drawn by Vitamin Architects based on data provided by the City Hall of Timișoara and used with the consent of Vitamin Architects [3].

In reality, especially when the geographic reference unit is one at large scale, the distribution pattern of people or buildings can vary significantly. To solve the spatial variation of density, different measures have been introduced, such as density gradient or density profile. The density gradient is a composite measure of density and is defined as the rate in which density decreases in relation to the distance towards a reference location, usually calculated according to concentric circles (Fig. 4). By comparing the patterns of density over a period of time, the process of spatial evolution of the city can be depicted, showing either decentralization with a drop of population density in the center and increased density towards the outskirts, either centralization with a growth in population density in both center and outskirts, and the expansion of the borders (Fig. 5) [2].

gradient densitate ENG

Figure 4. Population density gradient for an abstract case.
Figure 5. Density gradients over time: (a) progressive decentralization; (b) centralization.
Source: Illustrations adapted and redrawn after Vicky Cheng (2009, p. 8).

From the perspective of rapid urbanization, the relationship between urban density and built form has always been an important focus of research, determining massive mathematical and geometrical investigation upon the spatial benefits of buildings with multiple levels. The presented definitions and measurements of density are the most relevant ones in relation with the subject of density from an architectural point of view, but they are not the only ones.

References:

[1]   Freedman, JL. Crowding and Behavior. San Francisco: W. H. Freeman and Company, 1975.

[2]   Cheng V. Understanding Density and High Density. In: Ng, Edward (Ed.). Designing High-Density Cities For Social & Environmental Sustainability. London: Routledge; pp. 3-17, 2009.

[3]   Public document downloaded from the City Hall of Timisoara web-site: http://www.primariatm.ro/uploads/files/PUG/URBANISM/parte%20desenata/03_ANALIZA%20DEZVOLTARE/13_ad_DENSITATI.pdf.

I started this blog quite abruptly, and missed out on a proper introduction, but not unintentionally. I  focused more on the concept of density and its meaning, and I’m still pondering things. So, this would be a kind of delayed introduction…

what about density 2

The continuous growth of population in relation to a constant earth surface and to the limited or hardly renewable resources is one of the global concerns. The year 2006 represented a key moment in the evolution of the phenomenon, because from this point on the inhabitants of the cities exceeded half of the world’s global population. It is estimated that in the near future the population, and particularly urban population, will continue to grow, at such a rate that two out of three people born in the following thirty years will live in cities [1]. The population growth requires a physical and spatial support and directly attracts the demand for housing. In this context high-density architectural forms and dense urban environments represent the most viable models for the future in general and for housing in particular.

The implications of high-density architectural models in the current moment overpass the realm of the architectural object and acquire social, ecological and urban meanings. The connotations of contemporary density and the relations they have with the city are important for understanding the way in which high-density architectural forms return to the international culture after a period in which they have been perceived and discussed as a negative phenomenon [2].

The forms of dense architecture have dual connotations, both positive and negative, and the balance between the two is a fine one, based in part on scientific evidence and partly on subjective perceptions. On the one hand, design that uses principles of high-density is more compact and manages to conserve important land resources, reduces required distances for transportation and therefore the energy use, and represents a more economically efficient model. There is also the assumption that areas containing high numbers of people are themselves sources of variation, of intensity and diversity, and that densely populated areas provide a communication experience with multiple possibilities and therefore a very rich exchange of ideas [3]. On the other hand there are potential negative implications directly linked to increased noise or lack of intimacy, or more subtle implications, supported by a number of sociological and behavioral studies that identify crowding as a source of stress and as a factor that can cause behavioral changes in people, in conjunction with the architectural environment [4]. Recent researches in neuroscience come to support sociological speculations about the implications of crowding on stress, recently discovering that people born in large cities and involved in a larger social network have an increased amygdala compared to other people (amygdala being a region of the brain associated with memory and emotional intelligence) [5].

what about density 1

I will try to focus my future study on dense architectural forms in relation to housing, because housing is one of the most inciting themes of architecture, by its universal character and its relation to one of the most basic human needs, that of dwelling. Additionally, the forms of housing are the result of multiple overlapping contexts, namely political, social, cultural, geographical and beyond. High-density collective housing is being reconsidered as a viable design solution in the current context, but although life planning, social rituals and economic conditions are constantly changing the architectural support remains yet stable. Currently, collective housing is an architecture program in which innovation is not actually perceived, compared to the museum program for example, and the principles of spatial and planimetric configuration remain the traditional ones. The rooms and the functional relations between them remain those intended for a traditional family in relation to a society in which the classical family tends to disappear, being replaced by other dynamic social structures defined by complex relationships [6]. The justification of that is partly linked to the commercial interests of the construction industry seeking maximal results with minimal risks and investment, and partly to the conservative mentality of the population in relation to housing.

Taking into consideration the implications of the recent economic crisis, most of the major current crisis are based on real estate crisis. A large number of families have recently lost their homes which they bought by credits that they couldn’t really afford, aiming for an ideal home and ignoring their real possibilities of purchase. The number of those that can afford an individual home on a plot with a garden is continually decreasing, and the environmental implications of individual houses are negative, respectively a high consumption of energy for transportation, an increase in the number of private cars and pollution generated by burning fossil fuels. However, this dream seems to have been the only available alternative until now for a family in relation to the available housing typologies [7].

It is obvious that traditional design methods are no longer viable under current conditions, and finding new ways to design high-density built environments is a necessity. These new concepts should achieve a balance between the dream of a rural house and the reality and necessity of living in dense urban areas, combined with the real economic possibilities.

what about density 3

References

[1]   By the Editors. Street-Savvy: Meeting the biggest challenges starts with the city. Scientific American, Volume 305; pp. 38-41, 2011.

[2]   Clemente MC. High-Density Collective Housing and Urban Space. In: Segatini MA. Contemporary Housing. Milano, Skira editore, pp. 17-23, 2008.

[3]   Schumacher P. My kind of town, http://www.architecturetoday.co.uk/?p=22997. Accessed in 21.05.2012.

[4]   Baum A, Vallins S. Architecture and Social Behavior: Psychological studies of social density. New York: John Wiley & Sons Inc, 1978.

[5]   Katsnelson A. The Stress of Crowds. Scientifica American, Volume 305; pp. 38-41, 2011.

[6]   Schittich C. The Challenge of High-Density Housing. In: Schittich, Christian (Ed). High-Density Housing: Concepts Planning Construction, In Detail. Műnchen, Birkhäuser Architecture, pp. 8-11, 2000.

[7]   Maak N. Japanische Architektur als Vorbild Der Fluch des Eigenheims. Frankfurter Allgemeine, Feuilleton, 04.01.2012.

I used to think that a city is made up of buildings, people, utilities, social and political relationships, communication networks, green areas and so on, and that its limits are visible and recognizable. Later on, it became clear that a city has an extended area of influence, derived from complex territorial relationships, administrative borders, long distance transportation routes… But only recently I read a study on Hong Kong from the perspective of food consumption in relation to the city [1]. Seen from the perspective of the surface needed to grow food for its inhabitants, a city’s surface grows beyond visible and administrative territories, expanding widely…

The calculations state that for a city of 1.000.000 people, with a density of 300 persons/hectare, that determine a occupied surface of 3333 hectares, a surface of 1.500.000 hectares is acctually needed to grow food. This is a diagram made to envision the difference between built territory and the surface needed to grow food, for HK…

HK area necessary for food

… and it made me think about growing a roof garden. I also tried to calculate my carbon footprint for the first time, and it seems that all the bicycling I did this summer doesn’t compensate for the heating system I’m currently using.

[1] – Brenda Vale, Rober Vale. Is the High-Density City the Only Option?, Designing High-Density Cities for Social and Environmental Sustainability, by Edward Ng

The growth of population is currently one of the general global issues, its severity being increased in relation to resource depletion. From the perspective of the continuous growth of population, generating built environments capable of housing the entire population and adapted properly to the context is a major challenge of contemporary architecture. Proper relationship to a dynamic context in which the social, political, environmental and economic components are constantly changing is even a greater challenge.

However, density as unique criterion for generating built environment and urban quality has limitations. General attitudes towards high density architectures so far are dual. The positive arguments take into account the rational use of urban land resources, in relation to maintaining a compact urban and infrastructure development, with minimal impact upon the surrounding rural and natural areas, with efficient use of urban transportation systems and fuel resources. Also, areas including major population become themselves sources of variation and intensity, providing a very rich exchange of ideas, as Patrick Schumacher1 notices. On the other hand, negative implications arise in relation to the same urban components, identified by the congestion of urban landscapes, reduction of urban green areas and the occurrence of heat islands, deterioration of urban networks and traffic infrastructure by overloading, and not least an increase of psychological stress for the inhabitants.

Architecture is cyclically rewriting its formal and morphological language, generally as a counteraction to previous negative experiences in relation to context changes. In the past 30 years, constructions of large scale developments were accompanied by homogenization of the built product, resulting in maximizing the economic value of the project at the expense of social value2. Today, we are witnessing a new transition in the writing style of architecture, where the expansion of the built environment based solely on making a profit and speculative investments becomes abandoned by the manifestation of the recent economic crisis. Urban societies undergo a subtle transition in parallel, due to jobs migration from the perspective of the same crises and recent changes in family structure. The mononuclear monogamous family as it existed in the last century is no longer exclusively the norm. In relation to this background, new rules are needed for composing the built environment.

Architectural experience so far has shown that large-scale urban projects are generally incapable of long-term adaptation, generating urban and social conflicts and eventually being blamed in the end by being left empty. A design that vertically multiplies the same plan scheme or over determines constructions while looking for the perfect match of form and function is no longer viable in light of current changes. The main theme of contemporary design is relating to a constantly changing context. The process of urban development itself is a complex process constantly evolving, and the nature of contemporary urban life is very different from that of the traditional town, being more complex, heterogeneous, interrelated and dynamic3. For the contemporary city, consisting of a dense and varied overlapping of layers, information, populations, activities and relationships, a complex design strategy is required, able to incorporate all these components.

50 years ago Jane Jacobs, in her book The Death and Life of Great American Cities4, identified a series of principles that support a dense and vital city. The same principles remain valid until now, namely supporting the density of the built environment through diversity, of constructions as well as of activities, through multiple functions, small building components forming larger units, a mix of buildings of different conditions and a high concentration of population, all for the purpose of supporting diverse actions and interactions. Density of the built environment itself cannot generate quality and direct benefits by exclusively applying principles of quantity, for density must be related to other factors such as building shape, mixed use or organisation of activities, in order to generate environments of rich activities. The principle of sustainability is also important in relation to the qualitative aspect of future developments. Architectures must relate in a sensitive manner to the existing urban character, to incorporate local influences while promoting diversity and being adapted to climatic, cultural and social local character.

The key to sustainable future high density architectures lies in generating built environments capable of adapting to changes. These models will be flexible, renewable, adaptable and capable of transformation and self-redefinition in relation to context changes. The adaptability of the built environment in a future scenario can result either from the compositional pattern of designing the whole, either through over-engineering and bio-mechanization of building materials and technologies. I am interested in the first approach, that of context adaptation through the composition of the whole made out of small-scale units, various and vaguely defined, basically a large-scale object constructed ​​of many small sub-units. The granulation of the whole is what generates spatial quality as well as quality of use, enabling the adaptation to context. A possible future scenario includes large-scale spatial organizations made up of multiple parts that can interact in complex ways and generate simultaneous responses to the challenges of context. Their adaptation can be achieved either by changing the inhabitants and the use, either by physical regeneration done by removing or grafting new subunits according to needs.

Monolithic spatial growth / fine-grained spatial growth

Img 1 – Monolithic spatial growth / fine-grained spatial growth

From a functional perspective, projects being build, managed and adapted incrementally can accommodate a wide range of functions and users. In relation to function, it is important to avoid both formal and functional over-determination in the design process, the primary objective being that of generating various support spaces with vague definition that can accommodate manifestations and activities as varied as possible. Those spaces are capable of physical and moral sustainability in the long term, compared to rigidly modeled spaces correlated with a unique function, whose chance of survival is small if the function vanishes. The solution is to produce spatial ambiguous models, whose ambiguities can support functional changes or ongoing uses and may lead to changes in the urban tissue in relation to changes in context. Viability of an architectural model is ultimately verified by its user’s satisfaction and the built environment must be able to negotiate almost in real-time with the needs of each actor involved in urban life.

Decomposition of a solid into micro-units / model of adaptive growth consisting of micro-units

Img 2 – Decomposition of a solid into micro-units / model of adaptive growth consisting of micro-units

Adaptable spatial growths, fine-grained and composed of agglutinated micro-units already exist as architectures of the limit, of vernacular architecture, in slums and in the areas illegally occupied by the poor communities. Spontaneous architecture is an incremental process, and its developments are able to constantly adjust to the situation of the physical and social immediate context, being more adaptable to changes and thus more resistant. To imprint these qualities to a large scale high density architecture can generate an architecture that’s sustainable and responsive towards its context, and the product acquires regenerative qualities. There are a series of contemporary projects of exploratory type in this regard, much of them being generated by architectural competitions. Projects using principles of spontaneous growth have emerged in studies, exploratory researches or competition projects, suggesting possible models of adaptive architectures. One such project is Scrap Skyscraper belonging to the group Projeto Colectivo, which uses a fix vertical circulation core and a solid base for generating a housing complex with augmentative growth, consisting of residential units that add up over time, with an additional exoskeleton-like supporting structure that enhances and extends in relation to the growth of the built body. The master thesis project Favela Cloud developed by Johan Kure, Kemo Usto and Thiru Manickam proposes a fluid incremental growth model composed of micro-units with different functions consisting of a mix of housing and cultural functions, related to knowledge and learning processes. The composition of units is the result of a computational process that follows the growth principles of the favelas and the generation of a compact “cloud” hovering above ground, placed on stilts.  Similar principles have begun to migrate towards constructed projects such as 56 Leonard Street by Herzog & de Meuron, a residential skyscraper  in New York, which proposes a series of 145 residential units with unique character, although diversity here appears to be more a commercial asset.

An important challenge in generating adaptable architectures is related to the design process, which involves the integration of diversity as a constructive force, as opposed to the multiplicative process so far. Either it is sought to design a generic framework that functions as skeleton, onto which basic modules are inserted, while other modules will appear or disappear over time, driven by the change context, either a finite object resulted by running all possible future scenarios. The process of growth and adaptation in the first case is not necessarily programmed by design, the original framework acting as a directing skeleton onto which growth can occur spontaneously.

One of the main challenges of the future is adaptation – to the decrease of resources, to the sociopolitical and economical context, to climate changes. Architecture will have to find its own way to adapt.

  1. Patrick Schumacher, My kind of town, http://www.architecturetoday.co.uk/?p=22997, accesed in 10.09.2012
  2. Nic Clear, A Near Future, in: Castle, H., Clear, N. (eds.), “The Near Futures”, Architectural Design Vol. 79, No. 5, September/October, Wiley, London, 2009, p. 6-11
  3. Chye Kiang Heng, Lai Choo Malone-Lee, Density and Urban Sustainability: An Exploration of Critical Issues, in: Designing High-Density Cities for Social and Environmental Sustainability, Edward Ng (ed.), Earthscan, London, 2010, p. 41-52
  4. Jane Jacobs, The Death and Life of Great American Cities, Random House Inc, New York, 1961