Sustainability and the built environment at and beyond the city scale

Building and Environment 39 (2004) 1223 – 1233

www.elsevier.com/locate/buildenv

Sustainability and the built environment at and beyond the city scale Mark R.C. Doughtya , Geo)rey P. Hammondb;∗ b Department

a Wessex Water, Claverton Down, Bath, BA2 7WW, UK of Mechanical Engineering and the International Centre for the Environment, University of Bath, Claverton Down, Bath BA2 7AY, UK

Received 14 August 2003; accepted 12 March 2004

Abstract Environmental footprint analysis is used to examine the sustainability of cities by placing them in their broader geographic context. The 18th century (Georgian) city of Bath in the South West of England is adopted as a case study to illustrate the urban development process. It is found to exhibit an environmental footprint that is greater than its surrounding bioregion and some 20 times larger than its own land area. Cities only survive because of human, material, and communications networks with their hinterlands or bioregions. It is therefore argued that sustainability assessment can only be realistically applied for the purpose of land-use planning in this wider geophysical perspective. ? 2004 Elsevier Ltd. All rights reserved. Keywords: Cities; Environment; Footprint analysis; Sustainability; Urban and regional planning

1. Introduction 1.1. ‘Sustainable cities’ The concept of sustainability has become a key idea in national and international discussions following the publication of the Brundtland Report [1] and the 1992 Rio ‘Earth Summit’. It was given further prominence in the context of the 2002 World Summit on Sustainable Development held in Johannesburg. Sustainable development is certainly a desirable and, more debatably, an attainable objective in global terms. However, it is less obviously applicable on a smaller scale, where it is sometimes used synonymously with concepts such as urban autonomy, self-reliance, or self-su?ciency. The Latin root of the word ‘civilization’ is cives [2]—citizen—and so cities are clearly at the heart of human development. But it is currently fashionable to Bnd in the literature material on ‘sustainable cities’ (see, for example [3–7]). Indeed, part of the UK Research Councils’ Clean Technology Managed Programme was devoted to this topic (see [8]). However, it has been argued by Day and Hammond [9] that this notion is quite misleading in systems analysis terms. ∗

Corresponding author. Tel.: +44-1225-386168; fax: +44-1225386928. E-mail addresses: [email protected] (M.R.C. Doughty), [email protected] (G.P. Hammond). 0360-1323/$ - see front matter ? 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.buildenv.2004.03.008

It looks back to the 1970s’ idea of autonomy or selfsu?ciency in the built environment, when it became popular to strive for “autarkic” buildings or settlements [9–12]. Such utopian visions of urban habitats stretching from the level of individual buildings to that of whole settlements have developed over recent decades (as outlined recently by Doughty and Hammond [12]), and were precursors for the notion of sustainable cities as popularised in the modern architectural and urban studies literature. Nevertheless, clusters of buildings and an integrated human-scale transport infrastructure can enhance energy conservation and reduce environmental impact. Even what have often been termed ‘compact cities’ are not in themselves sustainable [9–11]. They survive only because they are inextricably linked by human, material, and communications networks to their hinterlands or ‘bioregions’ [10–12]. This outlying support structure extends from the regional to national and even global scale. 1.2. The issues considered The present work attempts to identify the role of cities in terms of contemporary concerns about the need to attain environmental sustainability. It highlights the beneBts of urban communities as well as their dependence on neighbouring bioregions. The technique of environmental footprint

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analysis is used to illustrate the role of cities in a broader sustainability context. Thus, the resource and environmental impact of the city will be analysed in terms of widening geographic areas/regions. The 18th century (Georgian) city of Bath in the South West of England provides the central focus of the study, together with its ever-expanding links with surrounding geographic regions that ultimately stretch out in a globalised economy to encompass resource inputs from around the world. Bath is a small city in numeric terms, but it is shown to display much the same development pattern and modern characteristics as the larger conurbations. It yields a snapshot of sustainability issues, based on the footprint analysis of Doughty and Hammond [10,11]. The uncertainties and deBciencies of using environmental footprints (and related parameters) as sustainability indicators are examined, including problems of urban boundary deBnitions, data gathering, and the basis for weighing the various consumption and associated impacts. 2. Sustainable development versus sustainability Over a period of some 15–20 years, the international community has been grappling with the task of deBning the concept of ‘sustainable development’. It came to particular prominence as a result of the so-called Brundtland Report published in 1987 under the title “Our Common Future” [1]; the outcome of 4 years of study and debate by the World Commission on Environment and Development [1] led by the former Prime Minister of Norway, Gro Harlem Brundtland. This Commission argued that the time had come to couple economy and ecology, so that the wider community would take responsibility for both the causes and the consequences of environmental damage. It envisaged sustainable development as a means by which the global system would satisfy “the needs of the present without compromising the ability of future generations to meet their own needs”. It therefore involves a strong element of intergenerational ethics: what John Gummer, former UK Secretary of State for the Environment (1993–1997), encapsulated in the phrase “don’t cheat on your children” [13]. Many writers and researchers have acknowledged that the concept of ‘sustainable development’ is not one that can readily be grasped by the wider public (see, for example [14–16]). However, no satisfactory alternative has been found. The UK Government has sometimes adopted the layman’s term “quality of life” as a short-hand expression when referring to sustainable development issues applicable to both Britain and the wider world [17]. However, the former UK Round Table on Sustainable Development [18], one of the precursors of the current Sustainable Development Commission, amongst others, argued that the quality of life is only part of what is meant by sustainable development [15]: balancing economic and social development with environmental protection (“people, planet, prosperity”, or the so-called ‘triple bottom line’ [13]). The Round Table contended that it would

be unfortunate if the two expressions became synonymous in the ‘public mind’. Further confusion is added by the large number of formal deBnitions for sustainable development that can be found in the literature, Sara Parkin [13] refers to more than two hundred. The notion of sustainable development is not without its critics. Meredith Thring (1999, private communication) regards the term as an oxymoron, arguing that development per se cannot be sustainable. He would prefer humanity to strive for a creative and stable world with the aid of ‘equilibrium engineering’ [19]. Similar views can be found in developing countries [20], where their debt burden and inequalities in global income distribution are seen as serious obstacles to sustainable development [19]. On a more fundamental level, both Sara Parkin [13] and Jonathan Porritt [21] (environmental campaigners and co-founders of ‘Forum for the Future’) have recently stressed that such development is only a process or journey towards a destination: ‘sustainability’. The end-game cannot easily be deBned from a scientiBc perspective, although Porritt [21] argues that the attainment of sustainability can be measured against a set of four ‘system conditions’. He draws these from ‘The Natural Step’ (TNS), an initiative by the Swedish cancer specialist, Karl-Henrick RobPert: Condition 1: Finite materials (including fossil fuels) should not be extracted at a faster rate than they can be redeposited in the Earth’s crust. Condition 2: ArtiBcial materials (including plastics) should not be produced at a faster rate than they can be broken down by natural processes. Condition 3: The biodiversity of ecosystems should be maintained, whilst renewable resources should only be consumed at a slower rate than they can be naturally replenished. Condition 4: Basic human needs must be met in an equitable and e?cient manner. These sustainability conditions put severe constraints on economic development, which are extremely di?cult to achieve in engineering terms, and they may, therefore, be viewed as being impractical or ‘utopian’ (see, for example, [16]). They certainly imply that the ultimate goal of sustainability is rather a long way o) when compared with the present conditions on the planet. Parkin [13] suggests 2050 –2100 or beyond. 3. The city in the modern age In contemporary society, cities house some 50% of humanity across the globe [6], out of a total population of a little over 6 billion in 2000. This represents a very rapid, virtually ‘exponential’, growth during the 20th century, which opened with only 15% of humans living in urban areas and a total population of about 1.65 billion. There are now 35 cities across the world with over 5 million people, and literally hundreds having more than one million [4]. This

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contrasts with AD 1800 when only London and Peking (renamed Beijing) had urban populations of one million. All cities provide access to community amenities and cultural events, but bring with them a range of social and environmental problems. The disadvantaged and minority groups tend to be concentrated in deprived inner city areas. Modern transportation systems, dependent as they are (to a great extent) on internal combustion engines, result in pollutant emissions and poor air quality, as well as the inevitable trafBc congestion that bedevils major cities. Contemporary cities exhibit a greater diversity, in many ways, than did their ancient and medieval counterparts (see, for example [2,22]). Some urban designers and planners have tried to characterise the di)erent traditions. Barnett [22] divides the evolution of the city into four separate traditions: the monumental city (within which he includes both Bath and London), the garden city or suburb, the modern city (in architectural terms), and futuristic megastructures. Sir Peter Hall, the distinguished British geographer and urban planner, prefers to describe the rich and varied patchwork that constitutes the variety of cities that have developed on all continents throughout human history. He argues [2], in his magnum opus entitled Cities in Civilization, that many have been primary sites for creativity and innovation. A favourite city of Hall’s is Los Angeles, home of the ‘movie’ industry, but the Brst conurbation without a centre and one dominated by the car. Others might see this as more of a technological nightmare than an exemplar of some future idyll. Modern cities require vast amounts of resources, both for their urban inhabitants and for the economic activities concentrated there. They remain dependent on an ever-expanding hinterland to supply these resources every bit as much as did ancient cities of the Old and New Worlds or the medieval cities of Europe. Consequently, they cannot be viewed as sustainable in the limited sense of being self-su?cient, reliant on their own carrying capacity as a resource base. They could not, by themselves, ever meet the sort of ‘sustainability’ system conditions postulated by The Natural Step [21]. Indeed, it could be argued that the Brst three conditions (see Section 2 above) are inevitably broken as a pre-condition of urban living. Those who advocate greater self-su?ciency for cities, fostering (for instance) the development of city farms to provide food, are harking back to ideas for the so-called ‘autonomous’, self-su?cient buildings and settlements that were popular in the 1970s (see, for example [23]). These became fashionable in the aftermath of the oil crisis of 1972– 1973, when the need for greatly improved energy e?ciency was widely acknowledged. An example of this movement cited recently by Doughty and Hammond [12] is the ‘autarkic’ house developed by Alexander Pike (ca. 1975) in Cambridge, East Anglia. This provided the design for a three-bedroom house with a roof-mounted aero-generator, and half the volume dedicated to a tall greenhouse. Ideas and designs of this sort led to an interest in low impact, community living in the spirit of what would now be viewed

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as sustainability. Some despaired of urban living, and advocated instead a return to rural, often communal, living. Nevertheless, even at that time, this vision of an ideal, rural existence (freed from the unwanted ‘side-e)ects’ of modern living [15]) was not without its critics even amongst the radical or alternative technologists. ‘Autonomy’ was viewed as utopian in the 1970s and ‘sustainable cities’, its counterpart at the dawn of the 21st century, can be similarly criticised as impractical now [9–12]. Notwithstanding the above criticisms of ‘autonomy’, cities can be regarded as forming part of a broader sustainable community; stretching beyond the city boundary and drawing resources from its rural hinterland or ‘bioregion’. This bioregional thinking attempts to emphasise the interdependence of cities and their natural surroundings. Berg [24] argued that in order for cities to become more sustainable, they should secure a reciprocal dependence between their urban settlement and the surrounding bioregion. However, at current rates of consumption, the footprint of cities far exceeds their natural catchment [10,24]. The least restrictive interpretation of a sustainable community would be one that is both resource e?cient and relied only on products of sustainable production. A ‘compact city’ [25] could have a major role in ensuring the most e?cient use of resources within a given urban land area. It might be developed in such a way as to enhance the energy e?ciency of the building stock, promote the use of public transport and alternatives, such as walking and cycling, and improve the feasibility of waste recycling and reuse at common locations. But it would still depend, in large measure, on resources from beyond its physical boundary. 4. The historic development of the city of Bath 4.1. The early settlement Bath is situated in the South West of England, between the Mendip Hills and the Cotswolds. The evolution of the city, and its architectural heritage, have recently been placed in the context of the broad sweep of human and urban history by Doughty and Hammond [12]. Its origins lay in its development as a Roman spa. A quarter of a million gallons of hot spring water erupts from the ground in Bath, and was utilised by the Romans both for bathing and for the central heating of their dwellings. The eRux of the springs emerges from a clay ridge in a bend in the Avon river valley at a temperature of some 40◦ C [26]. The Brst hot baths were built in the AD 1st century, around the religious centre of Aquae Sulis [27]. However, there is archaeological evidence of earlier settlement at this crossing over the River Avon at a point where the meander creates a peninsula of land on roughly a North–South axis [26]. It eventually became an intersection in the network of Roman roads that connected larger settlements, including the nearby port of Bristol to the West, Cirencester to the North East, and Ilchester to the

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Fig. 1. The medieval city of Bath ca. 1676 (Source: Bath Historic Buildings Record; courtesy of Professor A.K. Day, Department of Architecture and Civil Engineering, University of Bath).

South West beyond the Somerset coalBeld. This enabled the community to perform a regional market function. Indeed Davies and Bonsall [26] noted that “the economy of Bath was closely associated with the rural hinterland”. In the aftermath of the Romano-British era, Bath became successively a Saxon monastic town and then a Norman cathedral city. Its economy was stimulated by the abundance of three natural resources: the hot springs, the Oolitic limestone from which much of settlement was constructed, and the associated mineral deposit of Fuller’s earth clay [26]. The latter was used to remove grease from woollen cloth, and stimulated the development of a regional textile industry based on wool from sheep reared on the nearby Cotswold and Mendip Hills. 4.2. The medieval city The local economy continued to depend on the wool trade until the end of the 15th century [26]. The hot baths were largely disused after the withdrawal of the Romans in the 5th century, until their supposed medicinal properties became more widely recognised in the 16th century as a cure for illnesses, such as leprosy, smallpox, and infertility. Inevitably this led to the growth of the city in medieval times, as depicted in the contemporary (AD 1676) map shown in Fig. 1. This mirrors a rather more famous map by the Bristol mathematician, Joseph Gilmore, in 1694 (see [27]). In both illustrations a mixture of baths, churches, and houses, many

constructed by local entrepreneurs to meet the needs of visitors, are clearly seen as being enclosed within traditional battlement walls. Bishop Oliver King instigated the building of the Abbey Church on the original site of the Norman cathedral, starting in 1499 and taking some 40 years to complete [26]. The Gilmore map gives a slightly better feel for the surrounding farmland from which the agricultural requirements of the city were met. British cities, including Bath and London, displayed several di)erences from their European counterparts in this period. They spread out beyond their early fortiBcations, relying for defence on Britain’s naval power (England had not been successfully invaded by a foreign rival since the Normans led by William the Conqueror in 1066), and tended not to have a central market square on the European model. Instead they adopted the ‘main street’ [22], which performed much the same function as a market square in the UK context: the Milsom Street/Union Street/Stall Street ‘ribbon’ in Bath and Cheapside in London. Such thoroughfares were typically intersected by other streets to provide a network of shops and markets. The urban layout depicted in Fig. 1 closely matches the development of European cities in the period around 1200 –1600 [12], except for the absence of an inner citadel and a market square. Medieval Bath was constructed on a bend in the River Avon, with battlement walls and an Abbey, on an otherwise similar model to its continental counterparts. By the late 1300s the population of the city was estimated to be about 1000–1100 [26].

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Fig. 2. The Georgian City of Bath ca. 1825 (Source: Simms’ Improved Bath Guide of 1825; courtesy of the Archive Collection in the University of Bath Library).

4.3. The Georgian city The architecture of Bath city centre is predominantly of the Palladian style (named after the Italian architect, Andria Palladio), built mainly in the period 1714–1830 when a succession of Georges (I–IV) reigned over the United Kingdom, and the era is consequently known as ‘Georgian’. Building in Bath really took o) from 1726 when the river between Bath and Bristol was made navigable, and building materials could be imported into the city by water from Bristol. The characteristic soft, mellow (Oolitic) limestone was extracted from quarries owned by Ralph Allen (1693– 1764) on nearby Combe Down. The city expanded dramatically from the original medieval core (depicted in Fig. 1 above) to meet the needs of visitors, with new public spaces linked by terraced houses in the Palladian style. The old battlement walls were dismantled, and the farmland immediately surrounding the core was built upon, whilst most of the grander houses depicted by Gilmore (and in Fig. 1) were demolished. Much of Bath’s present architectural elegance is associated with John Wood the Elder (1704–1754) and his son, John Wood the Younger, both architects and developers, who planned the internationally famous Queen Square, the King’s Circus, and the Royal Crescent. These were formally laid out in the old Manor of Walcot, a patchwork of small Belds to the north and west of the medieval city walls [27]. Simms’ contemporary map (ca. 1825), showing

the development of the city just after this period of expansion, is illustrated in Fig. 2. The medieval core is clearly evident towards the bend in the river and marked with a black dotted line. Inevitably some of the planned buildings and squares, illustrated by Bne simple lines, were not subsequently constructed quite as shown here. Nevertheless, ‘Georgian Bath’ remains the focus of the city’s heritage and its world renown. Its fundamental layout is still much as that indicated in Simms’ map (Fig. 2). The supposed ‘healing powers’ of Bath’s spa waters were identiBed well before Roman times and have been used through the centuries (see Section 4.2 above and [27]). However, one of the main reasons for the city developing rapidly in the 18th century was the visit to the city by Queen Anne in 1702, followed by the aristocracy of the country. People came to Bath for a variety of reasons (both commercial and recreational) during that period, only one of which was to take advantage of the healing powers of the spa waters. 4.4. The modern city The Victorian period saw signiBcant development in the industrial and commercial sectors of Bath, resulting in a reputation for cabinet making, printing, and engineering [26]. Much of this took place to the South West of the Georgian city (see Fig. 2) and of the River Avon: in an area

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that stretched out to the industrial village of Twerton. The construction of a canal network (including the Kennett and Avon (1810) that traversed the city), and then the Great Western Railway (1840) linking the city directly with Bristol and London, facilitated trade with the capital and other parts of the UK. Local government reorganisation in 1994 meant that the city became part of the unitary local authority of Bath and North East Somerset: the B&NES Council. This brought together the City of Bath and the former rural district of Wansdyke. The architectural heritage of the city was o?cially recognised by UNESCO in 1987, when it became one of some 10 ‘World Heritage Sites’ in Britain. Bath now has a population of about 84,200, and the residents have an income that is generally higher than the UK average. Nevertheless, there are areas of relative disadvantage, such as Foxhill and former industrial village of Twerton. Tourism remains a major industry, and a large proportion of the city’s income and employment comes from this sector. The amount of available space for transport within the city centre is extremely restricted. Tra?c congestion has become so severe in recent years that several feasibility studies have been undertaken to investigate the potential for pedestrianising core areas. Major redevelopments are planned for the Southgate area (a commercial and residential scheme incorporating a major transport gateway for buses and trains) and the Western Riverside in order to revitalise an acknowledged poor quality part of the city. 5. Environmental footprint analysis

5.1.2. Methodology Footprint calculations involve several steps. Initially, the per capita land area appropriated for each major category of consumption (aai ) is determined ci annual consumption of an item ; ∼ aai = pi average annual yield
 kg=capita : (1) kg=ha In the version of footprint analysis employed by Wackernagel and Rees [30], and adopted here, four consumption categories are identiBed: energy use, the built environment (the land area covered by a settlement and its connection infrastructure), food, and forestry products. This is a restricted subset of all goods and services consumed, which was determined by the practical requirements of data gathering and inXuenced by the development of the technique in a Canadian setting. Nevertheless, unconnected work by Friends of the Earth Europe [31], using the related ‘Environmental Space’ concept, adopted a similar set of categories. In order to calculate the per capita footprint (ef) for the present work, the appropriated land area for each consumption category is then summed to yield ef =

i=n 

aai :

(2)

i=1

The calculation leads to a matrix of consumption categories and land-use requirements, which is ideally suited to a spreadsheet implementation. In order to determine the total footprint for a given community, the per capita Bgure is simply multiplied by the relevant population size (N ), viz.

5.1. Ecological or environmental footprints

EF = ef (N ):

5.1.1. Early roots of the approach The use of environmental footprint analysis has grown in popularity over recent years, both in Europe and North America. It provides a simple, but often graphic, measure of the environmental impact of human activity: whether or not in the foreseeable future humanity will be able to “tread softly on the Earth” [15]. Resources used and wastes produced by a deBned population are converted to a common basis: the area of productive land and aquatic ecosystems sequestered (in hectares) from whatever source in global terms. Its roots lie in earlier ideas, such as ‘Ghost Acres’ and similar concepts developed by Borgstrom [28] and Ehrlich [29] in the late 1960s. Rees used footprint analysis in its basic form to teach planning students for some 20 years (see [30]). The terms ‘environmental’ and ‘ecological’ footprints are used interchangeably here, although the former is preferred. Ecology is that branch of biology dealing with the introduction of organisms and their natural surroundings. ‘Human ecology’, sometimes used for the study of humans and their environment, is closer to the usage implied by footprint analysis.

However, this is generally a less useful parameter for comparative purposes in the authors’ experience.

(3)

5.1.3. Critical assessment The environmental footprint provides a quantitative basis for evaluating the environmental impact of a population and a means of raising awareness of the consequences of human activity. It is a valuable technique in a toolkit of measures that can aid the assessment of sustainable development [14,15]. Satterthwaite [32] has devised a wider set of criteria for urban sustainability, including health and sanitation, recreational facilities, and numerous other aspects of social provision. Clearly, environmental footprint analysis would need to be supplemented by the use of other measures to account for these broader aspects of human welfare. Footprint analysis implies judgements about the relative weighting of the various consumption categories and their environmental impact. It reduces all such impacts to a common basis in terms of hectares per capita, which may not prove to be a unit that can be readily assimilated by ordinary people. The International Institute for Environment and Development [33] described the process of analysis, whereby

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all environmental impacts are aggregated into a simple index as “resource reductionism”. They likened it to traditional measures of economic welfare, such as the gross domestic product (GDP); see [15]. Nevertheless, it provides a useful basis for contrasting the footprint of human activity with the available land area. The consequences of human consumption can be graphically viewed against the ‘carrying capacity’ of a nation, region, or the planet as a whole. 5.2. Footprint analysis The city of Bath is used here as a focus for an examination of the sustainability of cities in their wider context. A data set was compiled for the present study in an analogous manner to that devised by Wackernagel and Rees [30] for their footprint studies, principally in a Canadian setting. The version used here was based on the spreadsheet program developed by Mathis Wackernagel [34] for his footprint analysis of Santiago de Chile (and for which the authors are very grateful to have been given early access [10,11]). It was adapted to reXect the novel features, as well as the particular resource and waste streams, of Bath and its neighbouring bioregion (see also [10,11]). The duration of the present study was a little longer than that for Santiago de Chile, but this does not imply any greater accuracy in the data or analysis. Like Wackernagel’s study [34], the aim here has been to make a rough estimate of the per capita footprint for didactic purposes in a relatively short period of time and at moderate cost. The environmental space available on a city scale is roughly equivalent to the area of the watershed in which the city is located. In the case of Bath, the watershed of the former County of Avon has been divided here between its population, and then the appropriate amount allocated to the population of Bath city itself. This method avoids the problem of attempting to assign a natural bioregion to a city that shares its watershed with other populations, such as Bristol and Bradford on Avon. The available areas at the county, regional, and other scales were deBned by their geopolitical boundaries, and are illustrated in Fig. 3 [11]. The per capita land-use matrix for Bath is presented in Table 1 (adapted from [10]). It is evident that the largest contribution to the overall environment impact is due to ‘fossil energy’, followed by ‘pasture’ and then ‘forest’. The other components are signiBcantly smaller, although the uncertainties in some of the components must be borne in mind. These are reXected in the question marks inserted into Table 1 and the ‘error bar’ in Fig. 4 (which displays Bath’s environmental footprint as well as that for surrounding bioregions). Doughty and Hammond [10] argued that the point at which the environmental footprint curve intersects the available ‘ecospace’ (see Fig. 4) indicates when enough land area is just available to support a population sustainably. In the case of Bath and wider geographic areas, the footprint line does not cross the available area line, suggesting that even

Fig. 3. Widening of the system boundaries for environmental footprint analysis (Bath, Avon, the South West Region, and the United Kingdom) (Source: Doughty and Hammond [11]).

at the continental scale the sustainable carrying capacity has already been exceeded. This supports previous research conducted by Friends of the Earth [31] and Wackernagel and Rees [30], which found that most western lifestyles, such as those in Europe and North America, have consumption patterns that result in footprints which are far greater than the amount of geographically available land. In the case of cities, this ‘overshoot factor’ [35] amounts to some 20 times the urban area for Bath [10], 125 times for London [4], 16 times for Santiago de Chile [34], and more than 200 for Vancouver [35]. These factors, which Rees and Wackernagel [35] suggest are representative of a ‘sustainability gap’, do not correlate directly with urban population size or geographic land area, but depend largely on economic wealth per capita and building density. Much clearly needs to be done in terms of signiBcantly reducing the environmental footprints of cities as part of the overall sustainability agenda. 6. Sustainability and cities An extensive literature on ‘sustainable cities’ developed in the 1990s. One of the leading thinkers and advocates

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Table 1 Land-use matrix and environmental footprint for Bath (ha/capita) Fossil energy Food Vegetarian Animal products Water

0.02 ? ?

Housing and furniture Transport Road Rail Air Coastal and waterways

0.70 0.39 0.30 0.01 0.06 0.01

Goods Paper production Clothes Tobacco Others

0.70 0.06

Total

1.81

Built-up area

Arable land

Pasture

Forest

Sea

Total

0.21 0.20

0.70

0.01

?

0.94 0.20 0.70

0.70

0.03 0.02

0.01

0.22

0.01

0.22

0.64

? 0.25 0.04

0.98 0.45 0.30 0.01 0.06 0.01

0.18 0.18

1.11 0.24 0.23 0.00 0.84

0.20 0.05

0.22

0.92

0.48

?

3.48

Fig. 4. Geographic representation of environmental footprints (Source: Doughty and Hammond [10]).

has been the so-called ‘cultural ecologist’, Herbert Girardet [3,4]. Although he did not initially use the term, The Gaia Atlas of Cities [3] was one of the earliest texts to stimulate an interest in the role of cities as a major source of environmental damage: “the city as parasite”. There he posed the question as to whether or not cities are sustainable, but did not really answer it. Instead, he identiBed the many disbeneBts of modern cities and argued for a change in the way that they are planned and organised. Girardet noted that the inputs and outputs of urban living are unsustainable: Bnite energy resources and other material inputs together with waste outputs. This he termed the ‘linear metabolism’ of cities, which is depicted schematically in Fig. 5(a). A more desirable system would be one that he called ‘circular metabolism’ [3,4], in which the inputs are e?ciently harnessed and the waste products are reduced, reused, or recycled. Such an arrangement is also illustrated in Fig. 5(b).

Fig. 5. The ‘metabolism’ of cities: towards sustainability (adapted from Girardet [3,4] and Rogers [6]).

The notion of cyclic resource usage comes from the study of natural ecosystems (see, for example [36]), but complete recycling is not feasible in an urban context. Perhaps, the best that might be achieved is an urban system in which the recycling of process scrap or waste is e)ectively represented by a feedback loop. In this way, the waste streams could be minimised and the resource productivity of the city optimised.

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Lord (Richard) Rogers of Riverside, the eminent modernist architect, has been inXuenced by Giradet’s ideas about sustainable cities. In the book based on his 1995 Reith Lectures [6] (cowritten with Philip Gumuchdjian, an Associate Director in his Partnership) he uses the notion of ‘sustainable cities’ as well as Girardet’s concept of ‘circular metabolism’. But the former was given a broad deBnition (which might better be denoted by the expression ‘convivial cities’) that could encompass the views of many, disparate protagonists: • A Beautiful City, where art, architecture, and landscape spark the imagination and move the spirit; • A City of Easy Contact and Mobility, where information is exchanged both face-to-face and electronically; • A Compact and Polycentric City, which protects the countryside, focuses, and integrates communities within neighbourhoods and maximises proximity; • A Creative City, where open mindedness and experimentation mobilise the full potential of its human resources and allows a fast response to change; • A Diverse City, where a broad range of overlapping activities create animation, inspiration and foster a vital public life; • An Ecological City, which minimises its ecological impact, where landscape and the built form are balanced and where buildings and infrastructures are safe and resource e?cient; • A Just City, where justice, food, shelter, education, health, and hope are fairly distributed and where all people participate in government. Richard Rogers also advocates ‘sustainable urban planning’, which he contends should involve citizens in decision-making at every level. (Something that should perhaps have been taken by the local authorities and planners to be a pre-requisite, given the Latin root of ‘civilization’ alluded to in the opening Section 1.1 above.) However, by the time Rogers chaired the UK Government’s Urban Task Force [7] the idea of sustainable cities had formally disappeared, although component parts of the broader concept of sustainable development remain centre stage. The Task Force was given the remit of determining an appropriate strategy for providing 4 million additional homes in England over the next 25 years. They recommended greater re-use of ‘brown Beld’ sites to develop new compact, cohesive settlements. Ironically Girardet’s support for the notion of ‘sustainable cities’ seemed to be solidifying [4], although he now uses Rogers’ broad and inclusive deBnition reproduced above. This contains many desirable elements of a modern urban community, but they do not amount to a veriBcation of the concept. In order to secure sustainability in the wider context, the greater hurdle is arguably the urban–rural divide. It is this interface or system boundary over which most of the input resources for cities must pass.

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7. Concluding remarks 7.1. Cities and sustainability Three-quarters of the world’s population may live in cities by the year 2025 (according to Rogers [6]). They consequently form a very important element of the human condition. It has been argued here that the notion of ‘sustainable cities’ is simply based on a misconceived idea of the full implications of sustainability, as well as the way that cities have developed historically. Satterswaite [32] notes that (nearly interchangeable) expressions like ‘sustainable cities’, ‘sustainable human settlements’, and ‘sustainable urban development’ were much in evidence at the second UN Conference on Human Settlements (Habitat II) held in Istanbul, June 1996. But even here, they were poorly deBned or understood [32]. The technique of environmental footprint analysis has been employed in the present work to examine the sustainability of cities by placing them in their broader geographic context. The ‘Georgian’ city of Bath was adopted in the present work as a case study following the early research of Doughty and Hammond [10,11]. Its per capita footprint was found to be greater than that of the surrounding bioregion and indeed of the wider geographic areas. The environmental footprint of the city is nearly 20 times larger than that of the corresponding land area. This lends support to the authors’ critique of the idea of sustainable cities popularised in contemporary literature. Cities only survive because they are inextricably linked by human, material, and communications networks to their hinterland or bioregions [9–11]. Such views were novel at the time they were Brst made (by Day and Hammond [9], and then Doughty and Hammond [10]), but the criticisms have subsequently been echoed by other authors [32,35,37,38]. Notwithstanding the above critique of the idea of ‘sustainable cities’, urban design of compact and convivial cities can obviously contribute to a more sustainable way of life, particularly in industrialised societies. This can be done by encouraging the development over time of integrated mixed-use urban communities in much the same way that has been advocated by a diverse range of architectural critics and urban planners. Such cohesive and convivial human settlements could provide diverse, yet socially balanced, communities in an attractive setting [7]. This requires a conscious e)ort to reverse the trends in urban planning evident during most of the 20th Century. Sustainability assessment techniques need to be employed across the urban–rural interface in an extended process. Environmental footprint analysis could form an important part of that assessment as an integral part of ‘systems thinking’ more generally. A key element in this type of development is to focus on greatly improving the e?ciency of resource use within cities, and thereby reducing their environmental footprint. This will clearly enhance ‘sustainability’, although it is impractical to achieve the very strict system conditions laid down under ‘The Natural Step’ [16].

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Communities like Bath and North East Somerset can play a useful role as potential exemplars of the type of holistic (or systems) thinking that is a prerequisite for sustainability assessment and planning. Its unitary local authority has responsibility for both the historic city of Bath, employed here for the purposes of footprint analysis, as well as a rural hinterland encompassing number of small towns. Planners and administrators within B&NES are consequently ideally placed to account for the impacts of resource and waste Xows across the urban/rural boundary. Some steps towards holistic thinking have already been undertaken in the consideration of transport and waste strategies. Indeed, the Council is already viewed as being advanced in relation to its waste management and recycling activities [4] in UK terms. However, the environmental footprint analysis reported here suggests that sustainability assessment and planning will need to extend out to the regional level (although perhaps ‘regions’ that di)er from those designated for local government purposes) or beyond. This case has been argued from a Canadian perspective by Rees and Wackernagel [35] and from a European one by Renn et al. [38]. The latter suggest, taking the German industrialised region or ‘Lander’ of Baden-WZurttemberg as their example, that cities have too many input resources (products and services) crossing their boundaries to be considered sustainable. This applied even to the regional capital of Stuttgart. (It is interesting to note that Renn et al. [38] reached this conclusion using a set of sustainability principles that were similar to those incorporated into the Natural Step system conditions [21,36].) Likewise Rees and Wackernagel [35] advocate regional self-reliance by way of ‘rehabilitating’ natural capital stocks, including the promotion of local Bsheries, forests, and agricultural land. This approach to reducing ‘ecological deBcits’ with the rest of the globalised World might appear rather more feasible in a Canadian setting than that of the UK, although even B&NES has been in the forefront of developing a local farmers’ market (in their case for Bath), a modest beginning that subsequently led to a network of some 400 such markets nationwide. Land-use planning and sustainability assessment could therefore usefully be employed on a regional scale with the aim of reducing environmental footprints by encouraging greater self-reliance and low-impact development, whilst protecting indigenous ecosystems (much along the lines recently suggested by Rees [37]). 7.2. Towards a sustainability research agenda in an urban context The UK Government is currently in the midst of the second phase of its (Technology) Foresight Programme aimed at generating ‘visions for the future’ that might assist decision-making in both the public and private sectors of the economy. The Foresight panels most closely associated with the present work are those covering ‘Built Environment and Transport’ (BET) and ‘Energy and Natural

Environment’ (ENE). The latter panel identiBed the rapid growth of cities (particularly in South East Asia and Latin America) as a major challenge for sustainability [39]. They recommended R&D activities in the areas of less resource intensive city construction and infrastructure (the so-called ‘Factor 10’ improvements in productivity; see also [13,15]), distributed utility systems, and integrated transport. The development of low carbon technologies is an underlying theme in each of these areas. In addition, the Panel [39] advocated ‘closed-loop’ production and consumption, with less hazardous materials and reduced waste, health, and biodiversity damage. This is essentially the Girardet’s ‘circular metabolism’ concept [4] (see Fig. 5), whose implementation and e)ectiveness can be assessed using environmental footprint analysis. It was noted in Section 6 above that a fully cyclic system is not feasible, although much can be achieved in terms of improving urban resource productivity. The BET Foresight Panel’s Construction Associate Programme [40] have proposed the promotion of ‘smart’ buildings and infrastructure to create new business opportunities, improve living/working environments, and enable information feedback to improve construction quality. They recommend accelerating the introduction of new technologies, ‘intelligent’ products, standardised preassembled components, and advanced materials into every level of the built environment. This ‘high-tech’ approach has also been advocated in Girardet’s more recent work [4]. Traditionally, the construction industry has been perceived as being rather ‘conservative’. The BET Panel [40] therefore suggests that it should be encouraged to “embrace sustainability” by adopting sustainable construction methods and whole life principles. They contend that by shifting the industry’s culture towards sustainable thinking at every level, it “can save energy, reduce waste and pollution, and cut the lifetime costs of property ownership” [40]. In Section 7.1 above it was suggested that a regional framework might be the most appropriate scale for assessing and monitoring such steps towards sustainability. Acknowledgements The Brst author (MRCD) is grateful for the support of Wessex Water plc., but the views expressed in this paper are those of the authors’ alone and not necessarily of the company. The second author’s research (GPH) on the built environment and sustainability has been supported by research grants from the UK Engineering and Physical Sciences Research Council, jointly awarded with colleagues at Bath. These formed part of two EPSRC managed programmes: its “Sustainable Cities” Programme (GR/J92910; project entitled ‘Monitoring the City’, and awarded jointly with Professor A.K. Day of the Department of Architecture and Civil Engineering and Professor A. Lewis of the Department of Psychology) and more recently the “Construction as a Manufacturing Process” Programme (GR/L02227; project entitled ‘Agile Construction of Civil Engineering Projects’,

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and awarded jointly with Professors A.P. Graves and C.R. Tomkins of the School of Management). The ideas set out were initially presented to an interdisciplinary audience at two seminars held under the auspices of the International Centre for the Environment (ICE) at the University of Bath. Both the authors are grateful for the care with which Sarah Fuge prepared the typescript and Gill Green prepared the Bgures. The authors’ names appear alphabetically.

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