The Compact City
Theory and Reality

Abstract

Taking into account contradictory opinions of theoreticians and planners about Compact City it is crucial to understand the meaning, pros and cons of this model. This paper gives a critical opinion on the theoretical statements of the compact model. Due to the complexity of the subject it was chosen to analyse the parameters according to the importance of the energy resources conservation and decreasing the pollution. Since the analytical tools are required on a complex level, including computer software simulations, the paper deals with empirical analysis towards sustainable solution for contemporary cities. Can this solution be found? While analysing a heterogeneous structure like a city, it is evident that the reality and theory create a matrix of connections and relations more appropriate, rather than a linear analysis process. Therefore assumptions can be driven from research undertaken by professionals and positive examples of the implementation of sustainable urban strategies.

Keywords: compact city model, theory and practice, opposite points of view

1. The Compact Model

While entering the 21st century humankind is facing major urban changes - massive migrations of population into cities and on the other hand - the growth of cities onto the natural green-land. Due to extended distances and social demands, cities, together with transportation modes within and between them, have tremendous impact on natural environment of the planet - they are the main consumers of energy and producers of pollution. While discussing the state of contemporary cities Hall and Pfeiffer [1] have divided world cities into three basic kinds representing three typical constellations according to the 'demographic-socio-economic evolution':

1. The City Coping with Informal Hypergrowth [India, sub-Saharan Africa, Moslem Middle East and Latin America]

2. The City Coping with Dynamic Growth [most cities in East Asia, Latin America, Caribbean, Middle East]

3. The Weakening Mature City Coping with Ageing [North America, Europe, Japan, Australasia and parts of East Asia]

Globally, the most damaging fact for the natural environment is the enormous exploitation of fossil fuels, which the whole civilisation is still depending on. While considering environmental impact of Mature Cities [1] the strategies should concentrate on decreasing the consumption of fossil fuels and on the transition to “a world of recycling and renewable energies”. In the third type of cities, apart from the lower rates of urban migrations, the "out of town" movement can be observed. "But the suburb now dominates. It's where most people live and work" - Marshall [2] speaks from American point of view where cities grow enormously, both vertically and horizontally. In Europe the situation is quite similar in many cities but not on such a scale as in North America. Burton and Matson notice that every day 300 people move out from the cities in UK. "But we cannot all move out!" [3, p.298].

In 'Weakening Mature Cities Coping with Ageing' these two contradictionary tendencies - urban migration and urban sprawl exist together - but in a different scale within different locations. This means more people in cities, more traffic, more poverty, and more chaos, especially if city centres become partially empty and city structure becomes dispersed while the distinction between town and country is blurred. On the other hand, large amount of land is being turned into low dense suburbia with square metres of land surface covered with concrete - shopping centres, highways and parking places. That is why, it is important to be aware of the consequences of this development and take actions within planning while it is still possible, before the cities will be overwhelmed and exhausted in terms of space and infrastructure.

The number of people living on the Planet is one of the factors that have major impact on the natural environment. Other ones are the average consumption per person [energy and resources] and the technology used to produce each unit of consumption [embodied energy]. While the natural supplies are getting short, urban growth continues. An accelerated intensity of industrial activities during last centuries together with vast population growth contributed to the unconscious consumption of Earth's precious resources and energy use based mainly on fossil fuels.

In the last 20 years energy production has grown by 52%. Of all global energy production, 90% comes from fossil fuels [oil, coal, and gas], that pay a major role in the devastation of the environment. Over the past 200 years emissions from combustion of fossils and deforestation have increased levels of CO2 by almost 30%. Cities cause biggest environmental damages to our planet. They occupy 2% of the Earth land and use 75% of resources [4]. It is proven that 40% of energy consumption in Europe is from built environment [5]. Rogers observes that 75% of pollution is from urban environments, whereas 45% of pollution comes from buildings and 30% from transport [6]. If mainly the cities are the sources of those problems, then, the question is can they contribute to rectifying the situation?

Searching for the solution how to improve global situation the model of the Compact City was brought to the arena of international debate. It is not a new idea; it has strong roots in the tradition of European urban form. In the past, when there were no cars, no highways, no high dense skyscrapers, cities had compact form. That was the result of natural approach to city development and capacity allowing the surrounding green areas to provide necessary food and other resources. The questions are - is the Compact City a solution today? Can it decrease energy consumption and the use of private transportation?

The Compact City model, according to today's standards, can be described by "The theory [is] to an extent premised on urban containment, to provide a concentration of socially sustainable mixed uses, that will concentrate development and reduce the need to travel, thus reducing vehicle emissions" [7]. This is one of the many definitions, which vary in approach and details.

According to the issues of global warming [greenhouse emissions], pollution, shortage of resources and overpopulation in urban areas Compact City offers:

• mixed use functions - creation of liveable areas [versus mono function zoning] where people live and work

• intensification of density

• more efficient infrastructure and functionally flexible buildings

• more sustainable transportation system - the use of public transport, cycling and walking and reduction of private transport

• encourage of using renewable energies in buildings

• concentrated water management and energy recycling

However, these parameters are to contribute in limiting the environmental impact of the compact urban model, the relation between a 'Sustainable City' and 'Compact City' is to be defined. 'Sustainable development' issues were brought to improve the situation in cities and to decrease their impact onto the environment. Compact City is not the main principle but it is one of the strategies suitable for Mature Cities, according to the World Commission Urban 21 [1].

In the theoretical debate on the sustainable city there are opposite points of view - a dispute between centralists and decentralists. In today's discussion there are more centrists who claim that sustainable development can be achieved by compact and centralised cities and who propose high-density in cities to protect land and reduce car use therefore reduce greenhouse gases emissions. Instead of developing new areas into the settlements it is better to infill the existing urban structure. That contributes to the Brownfield debate, which proposes to regenerate post -industrial and empty areas in cities. Centralists, who declare 100% devotion to the Compact City model, like Hillman [8] or Rogers [9] argue that mixed-use areas and higher densities will reduce travel distances, what might change also the lifestyles in the city but for the benefit of citizens. They conclude that reduced fossil fuels consumption will bring not only less pollution but also lower transport expenditure. On the other side of the barricade there are those, who think that compactness is not the best solution and it will not work, that the compact city is "unsuccessful, undesirable and unworkable" [10, p.12]. Thomas and Cousins [10] argue that the problem is that the Compact City demands on planners to concentrate on dense centres of cities, forgetting the existence of decentralisation and any good aspects it has. They also claim that the political and economical reality, social expectances are not helping compactness to prove its beneficial qualities. As Breheny [11] simplifies those who are for decentralism can be divided into two groups:

• the "free-marketeers" - who are against top down planning and claim that market is the force that will drive urban development

• the "good-lifers" who believe in "rural values" of life and geographical and institutional decentralisation

Breheny [11] holds a "compromise" attitude towards the compact city model. He argues that compact model can be good for certain issues but it cannot cover all the problems of the cities of today. There are simply too many points of view or interest and too many different lifestyles. While considering Compact City model it is clear that it is not a perfect solution. Even though in the past European cities usually had compact form, today after "sprawled" expansion of cities the situation is different. There are compact cities but there are also spread ones and both kinds can be sustainable with 'good governance'. Many contemporary cities need "guidance" and proper management to meet the energy efficiency and comfort standards. If the compact model is revised theoretically in purpose of that, it has to be also concluded that it is a matter with multiple issues. Possible advantages [after 10, p.56] can result in:

• less car dependency - lowers emissions of greenhouse gases and pollution

• reduced energy consumption and energy- saving opportunities for new technologies, such as CHP [Combined Heat and Power systems] [11]

• better public transportation services increased overall accessibility

• the reuse of infrastructure and previously developed land

• the rejuvenation of existing urban areas and urban vitality

• a high quality of life

• the preservation of greenfields due to the use of urban brownfields

• the milieu for enhanced business and trading activities

And possible disadvantages:

• increased local air pollution due to concentrated traffic congestion

• noise

• decreased green urban areas

• crime - unknown neighbourhoods

• loss of privacy and NIMBY attitude

• overcrowding and loss of urban quality

As it can be seen, the theory of the Compact City is not clearly 'black or white'. Obviously, theoreticians, planners and urban residents have various opinions about these issues. Complex reality brings considerable parameters, which vary for different cities due to climatic conditions, urban form, culture, social aspects and policies.

2. Mixed-use

One of the main topics in the Compact City discourse is mixed-use planning. According to Dutch VINEX location system [12] means 70% of housing and 30% public buildings. After the period of 'zoning' in urban planning there is a major need to return to the mixed-use areas to encourage community life and to provide more efficient infrastructure. Large scale 'zoning' approach has been very popular especially in United States, although in European cities 'residential only' or 'office only' areas can be found as well. Rogers [9] and Breheny [11] call for infilling existing urban structure, providing mixed-use functions. Beatley [12] admits, that living above retail is a perfect solution in many European cities in terms of creating a liveable space and possibility of retail incomes for residents and owners. Another advantage, in terms of energy, is that an efficient heat exchange strategy could be implemented between residential and office spaces - excess heat from offices can be used to heat apartments. In terms of solar radiation lower floors in mixed-use buildings [offices or working places with high internal heat gains] can be overshadowed thus avoid energy consumption for cooling. Within mixed-use spaces, if spatial planning and transportation systems are designed accurately, transportation by car can be reduced, and more facilities can be provided in the area. As Rogers [13] claims "we must encourage higher densities and a greater mix of uses. We should not allow low-density, residential developments on greenfield land to go ahead, if there is available inner city land nearby".

Density is the number of people per ha and can be measured and controlled through "plot ratio" - the ratio between the gross floor area [GFA] of the building and the area of the building site. "Plot ratio controls govern the amount of GFA in buildings but affect population density only indirectly due to the interplay of other factors like, flat size and person per flat ratio." [14]. Densities differ in cities due to the social and spatial development, for instance in Europe cities are relatively more dense than in North America [12]. In Europe density also varies along the latitude - southern cities are relatively denser than cities in Northern Hemisphere; this is a result of historical settlement patterns, social processes and climatic conditions. It is accepted [15] that in Europe sustainable net residential density is 300 persons per ha. Although in cities density can vary according to the development of different areas or boroughs as results of influences of many divergent factors like land prices, tax systems, land use and developing strategies, accessibility and infrastructure, existing structures and neighbourhoods or sometimes simply fashion. Today the living patterns have changed and family model is different in many Western cities - there are more single people or couples without children [9]. Sociological changes had brought new family models, especially in cities among high-educated people in comparison with the people living in the countryside, suburbs, traditional ethnic minorities or people with lower incomes, who still have large families. Therefore, planning compact settlements requires consideration - for one or two persons' households - more floor space comparing with traditional family mode [3-5 persons], whether the latter requires more efficient infrastructure to maintain the needs and consumption.

3. Form

Breheny and Rookwool state that "it is clear that a major strategic factor determining sustainability is urban form; that is, the shape of settlement patterns in cities, towns and villages" [in 16, p.151]. If the city or an area has few very dense centres and vast empty space around [wasteland, parking lots, less developed areas without proper access] then, as Breheny suggests it is more difficult and expensive to maintain the infrastructure, deal with overcrowding, accessibility and increased traffic. Therefore, a more supportable solution would bring dispersed centres with less intense use and encouraged accessibility - decentralised concentration, in existing cities achieved by urban infill and regeneration and in new developments through careful planning strategy. The components influencing sustainable development in the Compact City are based on land use policies, but first of all in the compact model the land available is limited, therefore the third dimension of the city can be explored and intensified. As city follows external weather conditions, at the same time built environment creates its own microclimate. In large cities, a phenomenon called 'heat island effect' [Manley, 1958] can be observed, meaning the temperature difference between the city and the surrounding areas. This is due to nocturnal long-wave heat radiation cumulated in building stock during the day to the streets. There are different factors, which 'heat island effect' depends on. In some cities this effect can be bigger depending on the number of the population. [17] Hui [14] notes that "urban density is the major fact that determines the urban ventilation conditions, as well as the urban temperature." Other factors are built urban stock with large surfaces absorbing solar radiation, high thermal storage and high surface albedo. The total amounts of solar radiation differ with the latitude and orientation. The radiation actually reaching urban surfaces depends on the urban structure. The disadvantageous character of increased temperatures in the city demands more ventilation within the buildings and hence increasing the electricity use for ventilation and air-conditioning systems. To minimise the impact of 'heat island effect' proper geometry of urban canyons is relevant to allow wind and trees to cool the outside space. Numerous research and measurements were undertaken [Santamouris 2000, Oke 1973, Shashua-Bar and Hoffman 2000 etc.] to optimise urban geometry and the use of green areas in cities in order to minimise the 'heat island effects'. In dense cities like New York, Hong Kong, Bombay or Athens the impact of 'heat island effect' is large and the use of air-conditioning systems is necessary. Therefore, it is crucial to improve the thermal performance of buildings [insulation levels] and adopt urban cooling strategies, such as consideration of wind flows and arrangement of green areas. Whether the situation can be changed in existing cities it largely depends on the market, planners, and financial status of building owners, their lifestyles and awareness of urban conditions. Obviously it is difficult to change urban form of existing cities but as cities grow due to urban migrations the improvement of existing structures and urban landscape has to take place.

4. Transport

The nature of compactness involves high density; concentration and availability of mixed functions as main factors, and it is desired to encourage public transport more than private transport, due to reduction of gas emissions. Compact cities, as they may contribute in decreasing global pollutants levels, they can be generators of local pollution, caused by traffic and exhaustion gases. Thus while increasing density in the city it is important to apply a strategy limiting the car use, also. Williams [16] suggests that there is no relation between higher density areas in the city and car use reduction. This is based on research in three London Boroughs that have been intensified for last 10 years and there is no sign of decreased number of car journeys. Increased densities, Williams argues, can cause either benefits like "increased neighbourliness" and "improved social cohesion" or negative perception as "overcrowded" city with parking, traffic and noise problems [16, p.172]. On the other hand as research in developing countries shows [14, p.630] that "as population density increases, transportation options multiply and dependence on private cars lessens."

5. Energy

Following the research by Owens [1986], Newman and Kenworthy [1989], Lowe [1991], and Gilbert [1992]; Alberti [in 18] assumes that compact settlements are more energy efficient, than the dispersed ones. Rogers [9] admits, that Compact City with higher densities can bring major ecological benefits in this matter. Through mixed-use areas, compaction and integrated planning energy efficiency can be increased while resource consumption and pollution can be limited. Waste management and intense infrastructure can also be implied more efficiently. Santamouris [19, p. 82] gives arguments, that intensification of density even by 1% can increase energy consumption by 2,2%. He also argues that energy consumption per capita in inner parts of cities is considerably higher than in the outer parts. Either on the country or local scale there are methods to balance energy consumption: 1. Upgrading efficiency of energy sources [power plants etc]. 2. Cleaning up fuels or switching to more "clean" energy sources, 3. Energy conservation and reduction of energy demands.

In Europe there are many cities, especially in Scandinavia, Germany or Netherlands, where energy consumption can meet sustainable levels, due to the implementation of efficient energy production systems like PV panels or CHP systems [which achieve about 80-90% efficiency, whereas traditional power plants have about 40% efficiency]. According to Santamouris [19, p.83] constructing new generating plants is less environmental = more expensive, than energy saving strategies.

The main issue in energy related discussion is the threat of increased electricity use. Electricity used for heating is of the worst source - 'high quality' energy [electricity] transformed into 'low quality' energy [used for heating] with a large amount of CO2 released into the atmosphere. What is most crucial, though, is the change of energy generation systems into renewable energy sources; otherwise the strategy can be categorised as 'shallow ecology' proposal. Even very efficient CHP systems based on fossil fuels are suitable in short term perspective, but the real benefits can be raised if the renewable sources are to be implied.

Compact urban form can bring advantages such as intensification of density and urban stock, therefore more efficient infrastructure [shorter piping network] can be applied. Compact form is not the necessity for sufficient results; the main concern lies in spatial planning of infrastructure for a certain number of population and economical demands. A city or an area can become not only a consumer, but also a producer of energy ["Feed-in-Law" programs in Germany, 2000].

Another consequential issue is the heating strategy in buildings. Energy consumption of the building depends on heat losses and burning efficiency. Therefore energy saving strategies should include: 1. Proper thermal insulation; 2. Passive solar heating, natural cooling and lighting [depends mainly on orientation and overshadowing]; 3. Application of efficient heating systems and electrical equipment.

Heat balance in buildings is largely influenced by their form, thermal performance and surrounding urban structure. "The effect of building form on heat loss is largely a function of the degree of envelope exposure to outdoor temperature and wind conditions." [20] Heating is one of the major energy-consuming factors thus positive results can be brought by improving thermal performance of buildings - u-values of external walls and especially glazing, with the window to wall ratio optimisation according to the orientation, latitude [solar gains] and application of adequate ventilation strategies. Compact form of buildings encourages more efficient insulation strategies, due to decreased insulation cover area. But on the other hand, lower u-values for external walls and glazing can compensate less compact forms. The stronger the insulation is in a building, the lower is the impact of the form.

For well-insulated buildings the solar orientation is less important in terms of solar heat gains and heat losses through the envelope [21]. Santamouris [19, p.88] argues that while comparing an old building downtown in an American city with poor thermal conditions to a well-insulated building outside the city "the global energy consumption was almost the same". Following his arguments the conclusion can be driven, that the urban structure is less important for energy consumption than proper design of a building. As Hui [14, p.629] implies "it is believed that 'super-efficient' buildings, which have significantly lower energy consumption can be achieved through good design practices and effective use of energy efficient technologies. In ideal case, buildings can even act as producers rather than consumers of energy."

There is a direct relation between energy required for heating and obstruction angle in the urban space. In existing compact cities this situation is often unavoidable but for new developments adequate spatial planning can profit in decreased amount of energy consumed for heating. Compact urban environment can be advantageous, if the heat balance strategies are accomplished. Compact settlements can encourage positive solutions. In reality, energy consumption, apart from individual patterns of energy use, depends on policies, financial status and approval of environmental strategies within the city. Each city is a different case, and on the way towards compactness, they can meet various parameters for optimisation. Reaching increased density and compact urban form in a city, both positive and negative effects have to be considered within specific context of a case study. Energy consumption studies in cities require complex computer simulation and analysis, according to Baker [in 19, p.77] and today's technology allows measuring more detailed parameters. What is still beyond the reach, is the individual use patterns. Regarding energy flows in cities [either compact or not] it is assumed as crucial to reduce energy consumption based on fossil fuels, thus decreasing resources depletion and pollution. Methods to achieve this goal are most complex and depend not only on urban form, but mainly on socio-political factors.

The potential of change in cities depends largely on lifestyles. There are areas in cities, offering possibilities for sustainable living, where people live in dense urban structure with mixed-use functions, urban gardens and proper public transportation [Copenhagen or Amsterdam]. But there are also people who drive their cars to buy food in supermarkets without conscience where is the food coming from. Both situations can occur in low dense settlements as well. People choose their lifestyles, but good guidance and proposition from the City [municipalities and planners] and can have a large potential to change its impact on the environment. Examples of urban best practices show that implementation of these policies can be successful.

6. Conclusion

While discussing urban model ['Compact City'] it is crucial is the understanding of the dual feature of its nature. First division is between the advantages and disadvantages of the model, second discord is between theory and practice. The reality shows that there are compact cities, and weather they are successful depends on the implementation of certain policies and co-operation between different sectors. Thus not every city has a potential to be compact or to obtain benefits from compaction. Each city is a separate case. Therefore, it is substantial to search for and learn from 'good urban practices', that have implemented sustainable strategies in their policies and in real city life. Worldwide there are numerous guides and directories for 'best urban practices' based on urban indicators towards sustainability. All cities are different and it is impossible to apply a single solution to all of them. And maybe there is no such solution called the ‘Compact City’. It is one of the possible models for a complex and contradictionary reality of cities. Compactness with its strong European urban tradition is highly recommended for Mature Cities [World Commission Urban21, 2000], while it brings advantages of space savings and limitation of distances thus private car use. However, if and how can it be implemented depends on the type of city, climatic conditions, context of the site, lifestyles of citizens and culture. Only then, the parameters for sustainable development [decrease of energy consumption and pollution] can be analysed, evaluated and revised by planners through detailed research and simulations. Creation of a successful city requires more than a consideration of the urban form. It is just one of the factors within sustainable development strategies.

As Jenks admits, “the claims about the sustainability of the Compact City have not been proved” [1996]. The question is do people accept and want to live in a Compact City? How can the preferences be evaluated? The tools for the successful implementation of the Compact City strategy are still required. That definitely needs a co-operation of the national, local governments, business managers and citizens, which should be aware of advantages and also disadvantages of the Compact City. This is a crucial point in the debate upon Compact City model. There are also the Global and National Markets - major engines of all the development and civilisation progress. It is not easy to “join forces” and set common goals based on sustaining the natural and human-built environment. Still, the social acceptability is questionable due to lack of proper information and research. The knowledge achieved from theory and successful examples - urban best practices can be implemented into governments’ policies and media can widespread information within the society.

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