Towards an urban ecosystem sustainability ...

Towards an urban ecosystem sustainability assessment tool Karima Dakhia, Prof. Ewa Berezowska-Azzag Polytechnic School of Architecture and Urban Planning, Algeria e pursuit of sustainability in urban environment requires the implementation of a sustainable urban planning. Urban planners and decision makers need assessment tools to assess the sustainability of cities and monitor their progress toward that goal. is task represents a challenge for urban planners, since cities are studied now as complex organisms. From urban planning to urban ecology, the city is no longer a built and a natural environment to be analysed through their mutual impacts. e city is an urban ecosystem that has a metabolism. Any assessment of sustainability of the city means the assessment of sustainability of both: the urban ecosystem and urban metabolism. In this paper we will use the systemic approach to build a model of a city as a complex system: the urban ecosystem, in order to understand its structure and function, hence understand its metabolism. e urban metabolism is made of a dynamic cycle of flows that nourish the city and reject its wastes. e web of input and output flows woven by cities spreads well beyond urban ecosystem natural hinterlands to neighbouring and remote natural ecosystems. Using the systemic model, we can indicate the state of sustainability of the urban ecosystem and evaluate its metabolism during the given period. e sustainable city is the one that succeeds to control its metabolism to keep it closer to the natural balance value in order to respect the hinterland carrying capacity. us, assessing the sustainability of any urban settlement needs to assess the urban metabolism compared to its state of sustainability with adequate tools integrated in an ongoing planning and monitoring process. Among the available metabolism assessment tools the ecological footprint is already used for urban metabolism assessment, but this tool, developed essentially from an environmental economy point of view, is not suitable for answering the urban planning needs. In fact, it assesses and quantifies the needs to natural environment services. It assesses the overshot in consumption compared to the available natural carrying capacity, but offers no vision on what to do to correct the overshot. Urban decision makers need tools to assess urban ecosystem sustainability compared to a well defined limit value of sustainability and help define the specific actions which need to be done to reach it, and then to monitor the situation progress towards sustainability. In this paper we will propose a tool that will complete the ecological footprint in the assessment of the urban metabolism in order to reach a sustainable urban ecosystem within an urban planning process.

Keywords: assessment tools, complex systems, ecological footprint, sustainability assessment, urban planning

1 Introduction Urban sustainability assessment tools have been developed to assess and monitor the progress towards sustainability of an urban built environment of a scale of a neighbourhood or a city. The city is defined as a socio-economical built environment and so the tools are dedicated to assess the sustainability of the built environment, transport, water and sewage, or economical and social impacts. These tools, such as, Sustainable Renovation of Buildings for Sustainable Neighbourhoods (HQE2R), or Comprehensive Assessment System for Building Environmental Efficiency (CASBEE for urban environment), Cost Benefit Analysis (CBA), Life Cycle Cost Analysis (LCCA), are developed to answer particular sustainability objectives for a given city. These tools lack at addressing the sustainability evaluation of a city as an urban ecosystem. Any sustainability assessment of an urban ecosystem would have to address the sustainability of its urban metabolism. The tools that fulfil this goal are assessment tools borrowed from new disciplines, such as urban ecology, industrial ecology, and environmental economy. The tools: Material flow analysis (MFA), Life Cycle Assessment (LCA), rucksacks and the ecological footprint (EF)... evaluate material consumption and wastes disposal of a given urban metabolism. The Ecological footprint is one of these tools it has been proposed by Wackernagel and Rees in the late 90s to the environmental economy field. It measures the natural services consumed by an urban ecosystem compared to the carrying capacity of the natural environment that sustains it (Wackernagel, Rees, 1998). The tool quantify the input (the demand side) and consequently the output flows and converts the results into the needed natural global land to provide such resources demand compared, to the available natural bio-capacity land and compared also to the land surface of the actual urban ecosystem (Wackernagel, Rees, 1998). Different sectors from the built environment can be considered in this way: housing, industry, services, transport, wastes (Wiedmann et al., 2003). The ecological footprint value is generally converted into lands of carbon absorption, built up land, forest, cropland, grazing land, fishing ground. The ecological footprint is “a framework for sustainability planning in the public private domain” (Wackernagel and Yount, 2000). It can be used at city level (citylimits London), municipality level (Wilson and Anielski, 2004) as well as household scale (Wiedmann et al., 2003). In the case of the new eco-city of Dongtan for example, the ecological footprint has been used as a strategic planning tool in the developing of the city master plan. (Birch, 2007). So far, the ecological footprint is a useful tool to “visualize” any city’s consumption of natural services comparing to the carrying capacity available to be either in a deficit or reserve case. It can also alter urban design options. (Wackernagel, Yount, 2000). This visualization is useful for comparison. In a strong sustainability scenario, it can define the local or global carrying capacity value as a limit to which the urban ecosystem metabolism has to refer to. It allows us to understand where we are in terms of natural services consumption comparing to the available ones. At a nation level a comparison can be made between the ecological footprint of a given city and the ecological footprint of the country. A comparison of all cities ecological footprint would allow classing cities from the least to the most sustainable, in the national or even international scale. Compare different metabolisms and classify them from the highest to the lowest will show also which one needs to be approached first, in order to recover a sustainable value. We can compare here the cities or the districts metabolism, pinpoint the weak city or district responsible of the “bad” metabolism, and make them take proper

actions. By comparing the urban metabolism value to the sustainability value of the carrying capacity limits we evaluate the gap to be bridged. We can also set scenarios on the long run and monitor progress toward that value. From an urban planning perspective, any sustainability assessment is done in order to plan urban actions that will correct the lack of progress towards sustainability. Thus the ecological footprint tool appear to be not sufficient because urban planning discipline needs tools that helps not just analyzing or measuring the metabolism, but also planning and controlling it by proposing planning scenarios, adopting programs with local urban actions In this study we will propose a new tool to be added to the ecological footprint in order to constitute a complete decision making tool for urban metabolism sustainability assessment, management and control. We would adopt a systemic approach to develop a complex system model for the urban ecosystem. This abstract model would help us understand the mechanism of the urban metabolism.

2 Planning approach method by building an abstract complex model of the urban ecosystem and its metabolism It is important to define the urban ecosystem and define its limits. As an ecological concept, the ecosystem is a natural habitat biologically independent from its environment that rests in state of equilibrium thanks to the interactions of all its inhabitants divided into consumers and producers of natural services. According to Rees the term of ecosystem appears to be inappropriate for the city because in ecosystems “…producers and consumers organisms (particularly microconsumers) coexist in a mutually interdependent obligatory relationship which ensures a cascade of energy and the continuous recycling of essential chemical nutrients through the ecosystem.” (Rees,2003). In the city though, the majority of organisms who participate in sustaining city life are beyond the limits of the urban built environment space. The urban ecosystem is certainly not just the city but something wider enough to encompass “…the total natural capital and flows on which a city depends to meet the long-term needs of its inhabitant” which is called by Alberti “the urban ecological space” (Alberti, 1996). Second, the metaphor of urban metabolism drawn from biology was first quoted by Wolman in 1965 “The metabolic requirements of a city can be defined as all the materials and commodities needed to sustain the city’s inhabitants at home, at work and at play.” (Wolman, 1965). The city is compared to a living being which has a metabolism consuming resources and transforming them into rejected wastes in a continual production process. To outline the abstract model of the urban ecosystem with its metabolism we draw on the systemic theory of Joel de Rosnay (Rosnay, 1975). From a systemic view, the urban ecosystem is a complex open dynamic system composed of a structure and a function of dynamic of flows. The system, in its functional dynamic, pursue the stationary balance between stocks and sinks level. In other words, the urban ecosystem searches for a balance between the capacity of the natural environment to answer the urban ecosystem needs and its demand for natural services. The structure of the urban ecosystem represents its organization on space. It is composed of limits, elements, stocks, and communication network. The function is composed of flows, valves, feedback, and delay. The urban ecosystem through its flows is in continual motion from the stocks to the sinks that are both located in the

hinterland or natural environment. The system is in a stationary balance if the stocks and sinks level keep balanced despite the flow dynamic. The balance is preserved thanks to the action of the valves that control the flows motion. The valves reduce or increase the flows according to the feedback action as the following scheme shows (Figure 1).

Figure 1: Urban ecosystem and metabolism model The functional dynamic of our urban ecosystem model with its input flows and its transformation in output flows, represent in fact the so-called urban metabolism. Hence, a sustainable urban ecosystem is the one that keeps a balanced dynamic of flows between stocks and sinks, in other words a metabolism within the limits of the natural environment carrying capacity. Of course, in order to control the urban metabolism we need to measure it with the Ecological Footprint tool, used already in several regions around the world. Adopting the ecological footprint tool to our urban ecosystem model will convert the source and sink of the natural environment into the ecological footprint of the city with its different lands (carbon absorption, built up land, forest, cropland, grazing land, fishing ground). All complex living systems are in fact intelligent systems that integrate in their structure a controlling mechanism which helps the system to regulate its metabolism to meet a balance with its surrounding environment. This mechanism represented by the valves and feedback is the intelligent regulatory centre of the system. Likewise the urban ecosystem is an intelligent system, it must have an intelligent regulatory centre we call the “metabolism control centre”. If the urban metabolism values of a studied urban ecosystem fail at reaching the target balance, it means that the “metabolism control centre” is deficient. If we want to change, alter or correct the urban metabolism, we have to control the dynamic of flows through the “metabolism control centre” where decision is taken. And thus to plan urban ecosystem towards sustainability we need to analyze, simultaneously, the dynamic of flows of the metabolism and the capacities of the “metabolism control centre”.

In many cases, from municipality scale (Anielski, 2004) to home scale (SEI, 2003), the use of the ecological footprint is not yet integrated beyond the diagnosis stage of urban planning. Nevertheless, it tells where is the problem and what we should stop doing. But, the EF gives no information on the metabolism control: why is it deficient, and what to do to make it efficient in controlling the metabolism balance. So, we need to integrate a second tool to measure the “metabolism control centre” capacities, as the following figure shows (Figure 2).

Figure 2: urban ecosystem model with EF and metabolism control centre

3 Missing tool of a metabolism control as a result of urban ecosystem functions analysis In order to assess the sustainability of an urban ecosystem, we need to assess at the same time the urban metabolism dynamic of flows with the metabolism control centre. The tool we propose is the one that will help decision makers to visualise at the same time the ecological deficit of the urban metabolism with the mechanism of the metabolism control centre. To fulfil this mission, we propose a second tool, additional to the ecological footprint, we call the “the Institutional Ecological Footprint” (IEF) and which represents the ecological institutional profile of the urban ecosystem. This tool will indicate for each sector measured by the ecological footprint, its institutional capacity profile. The IEF will focus on institutions, instruments, laws and programs (or project) addressing the control of the given sector, as well as on the public/private participation process. It will indicate first whether they exist or not, and second, if existing, the tool will evaluate their actions on the metabolism control for each sector to be persuasive, incentive or regulatory.

For participation the evaluation would be on the level of public/private participation from none to effective participation in decision making. To build the IEF a matrix is set from the sectors concerned by the EF analysis and the elements of the institutional frame of the metabolism control centre as in the chart (Table 1). The EF analysis sectors are: Energy, Water, Wastes, Matter, Transport, Built land. The IEF analysis points are : • • • • • •

Institutions: all public or independent organisms that are in charge of the control of the flows for a given sector responsible of a high EF. Laws: all legal texts that have for objective to control or reduce the flow of a sector responsible of a high EF. Instruments: all legal instruments that are used by institutions to control and reduce the flow of a given sector responsible of a high EF. Standards: sustainability or limit values for a given sector or flow. Programs: all programs or projects that are initiated in order to reduce the flow of a given sector responsible of a high EF. Public participation: all forms of public/private participation in the decision making process for the above institutional elements.

The institutions, laws, instruments and programs will be evaluated according to their strength of application in the urban metabolism control. The evaluation level is expressed by values from 0 to 3 according to the following criteria: • •

•

•

0 : Missing: when there is no existing action 1: Persuasive : When the action aims only at showing the negative points due to the high level of EF for each sector and explain the possible dangerous consequences for the urban development. Leaflets and documentaries are edited or conferences organised to raise awareness among public opinion and concerned actors. 2: Incentive: When the action aims at inciting people, enterprises and investors to compel to the recommendation of flow reduction by the implementation of measures such as fiscal and financial instruments or pollution fees. 3: Regulatory: when the action is to strongly reduce the flow responsible of high EF by implementing regulatory measures such as fiscal, legal instrument and permits, land use control, urban planning control, emission standards...

For the public participation the evaluation level is expressed from 0 to 3 for different criteria: • • •

•

0 : Missing: no public participation 1 : Public information: at this level all institutional process is not directly accountable to the public opinion which have only the right to be informed. 2 : Public consultation: the public is informed and is given the right to give his opinion for different issues but there is no obligation by the authorities to adopt their opinion. 3 : Public participation: the public is consulted but also participate in the decision making process.

Transport

Energy

Wastes

Matter

Water

Instruments: 0. 1. 2. 3.

Missing Persuasive Incentive Regulatory

Institution: 0. 1. 2. 3.


Laws: 0. 1. 2. 3.


Standards: 0. 4. 5. 6.


Program – project 0. 1. 2. 3.


Public participation 0. 1. 2. 3.

Missing Public Information Public Consultation Public participation in decision making Table 1:The IEF matrix The information collected will be translated from the matrix (Table 1) to the AMOEBA graph. The assessment is than visualised and we are perfectly able to judge which actions are needed to improve the metabolism balance, like in the scheme below (Figure 3).

Built land

Ins$tu$onal Ecological Footprint Energy

Wastes

Built land

Transport

Water

MaAer

Ins)tu)on

3

Par)cipa)on

Program

2

2

1 1 1 0 0 0 1 1

1 1

2 Instrument

2 Law

Standards

Figure 3: IEF AMOEBA

4 Institutional Ecological Footprint capacities discussion The ecological footprint associated to “the Institutional Ecological Footprint” will form the “Urban Institutional and Ecological Footprint” tool which is a strategic controlling and planning tool for the urban ecosystem. This tool will give a diagnosis of the urban metabolism compared to the limit of the carrying capacity of the natural environment. Through the EF, it helps visualize the gap towards balance and through the IEF gives a diagnosis of the “metabolism control centre” that will help us to understand where, the deficiencies of this structure in controlling the metabolism, lies and how they can be corrected. This tool answers the fundamental questions for urban ecosystem sustainability: How far is the urban metabolism from sustainability state? And what flows are responsible of the unsustainable state? Why is the “metabolism control centre” unable to control the metabolism? and what has to be done, at both levels: urban metabolism and metabolism control centre, to achieve sustainability?

5

ECOLOGICAL FOOTPRINT

4.5

EF limit value

4

Transport

3.5

Energy

3

Wastes

2.5

MaAer

2

Water

1.5

Built land

1 0.5 0

Energy

Water

Mater

Wastes

Transport

Built land

Ins)tu)on 3

Par)cipa)on

2 1

Laws

0

Program

Standards Instrument

Figure 4: Example of the UEIF represented by the two footprints the EF and the IEF The UIEF tool clearly pinpoint the problem and the possible solutions, who will do it (which are the stakeholders to be involved) and in which way. It gives the ecological footprint an institutional basis to its application at local level that will help in decision making and action taking because it gives information, simultaneously, on the metabolism overshoot for a city or district and the institutional structure in charge of the control of the urban metabolism. This strategic tool allows also the comparison between sustainability level of two or more cities by comparing their EF and their IEF. The comparison will make it easier to visualise the reasons of ecological deficits for one and healthy metabolism for other. The urban ecological and institutional footprint UIEF tool introduces the urban metabolism approach in the urban planning process and in the city institutional framework. The sustainability assessment of the urban ecosystem would be done through the assessment of the metabolism by the EF and through the assessment of the metabolism control centre by the IEF. After assessment, scenarios and programs would be drawn for integrated actions to reduce EF and control the metabolism. Actions on the metabolism control centre and on the flows will follow, located in space and time with ongoing monitoring and feedback (Figure 4).

• Metabolism assessment (EF) • Metabolism control center assessment (IEF)

Analysis

Program • Integrated program of ac)ons to reduce EF • Ins)tu)onal empowerment to control metabolism

• Ac)ons specified in place and )me • ongoing monitoring

Ac)on

Figure 5: Integration of the EF and IEF in the urban planning process The implementation of the UIEF tool requires its integration in an urban ecosystem planning process by a multidisciplinary team work. This assessment tool is dedicated to urban metabolism and so requires changes in: paradigm through an integrated multidisciplinary approach, and in institutional framework through the empowerment of the control metabolism centre.

5 Conclusion The existing urban assessment tools address the city as a sum of different parts. The city considered as an urban ecosystem requires a holistic tools to assess the urban metabolism and help the decision making for controlling it. The available tools to measure the urban metabolism, such as the ecological footprint, lack at giving information on the urban metabolism control level. The ecological footprint measures the natural services needed by the city from the natural environment and convert it into lands. The urban planning discipline is about applying strategies and taking actions to achieve it. By analysing only the dynamic part of the ecosystem (flows), the ecological footprint fails understanding the laws that drives the urban metabolism and so fails at giving hints towards actions to be taken in order to keep it in a balance state. The present study aimed at bridging this gap by proposing a new tool the IEF that will allow the understanding of the institutional process responsible of the metabolism control. Associated to the EF this tool will form the UIEF which is a strategic assessment tool to be integrated in the urban planning process.

6 References Alberti, M, & Lawrence Susskind. (1996). Managing urban sustainability: an introduction to the special issue. Environ impact assess rev, 16, 213-221. Alberti, M, et al. (2003). Integrating Humans into Ecology: Opportunities and Challenges for Studying Urban Ecosystems. BioScience, 53(12), 1169-1179. Alberti, M. (1997). Measuring urban sustainability. Elsevier Science Inc, ENVIRON Impact Assess Rev., 16, 381-424.

Alberti, M. (1999). Modeling the urban ecosystem. A conceptual framework. Environment and Planning B , 26(04), 605-630. Alberti, M. (2000) An Integrated Urban Development and Ecological Simulation Model, Integrated Assessment, Vol 1, No 3, 215-227. Barrett, John, et al. (2001). A Material Flow Analysis and Ecological Footprint of York. . SEI Stockholm Environment Institute. Birch, Rachel. (2007). From Masterplans to Local Strategies - High and Low level Applications of the Ecological Footprint. In International Ecological Footprint Conference Stepping Up the Pace: New Developments in Ecological Footprint Methodology, Policy and Practice, 8-10 May 2007, Cardiff, UK, BRASS. Brugmann, Jeb. (1996). Planning for sustainability at the local government level. Environ impact assess rev, 16, 363-379. Collins, James P., et al. A New Urban Ecology Modeling human communities as integral parts of ecosystems poses special problems for the development and testing of ecological theory. American Scientist 88: 416-425. Collins, Richard. (2007). Energy Footprints of Cork City Council’s ‘Sustainable City Campus’. In International Ecological Footprint Conference Stepping Up the Pace: New Developments in Ecological Footprint Methodology, Policy and Practice, 8-10 May 2007, Cardiff, UK, BRASS. Dakhia, Karima, & Ewa Berezowska. (2005). Systemic model for a sustainable city . In (procs) "Environmental Sustainability: The Challenge of Awareness in Developing Societies", PLEA 2005, Beirut, Lebanon. De Rosnay, Joel. (1975). Le macroscope. Paris: Seuil. Girardet (1999), Creating sustainable cities, Schumacher society Habert, H., Erb, K., & Krausmann, F. (2001). How to calculate and interpret ecological for long periods of time: the case of Austria 1926-1995. Ecological Economics, 38(1), 25-45. Holden, Erling. (2004). Ecological footprints and sustainable urban form. Journal of Housing and the Built Environment, 19, 91–109. Hurley, Joe, Ralph Horne, & Tim Grant. (2007). Ecological Footprint as an Assessment Tool for Urban Development. Paper presented at the Sate of Australian Cities conference, University of South Australia, 29th November 2007, retrieved from http://www.cfd.rmit.edu.au/content/download/590/5142/file/Hurley2007_footprint_paper.pdf. Kitzes, Justin, et al. (2007). A "Constant Global Hectare" Method for Representing Ecological Footprint Time Trends. In International Ecological Footprint Conference Stepping Up the Pace: New Developments in Ecological Footprint Methodology, Policy and Practice, 8-10 May 2007, Cardiff, UK, BRASS. Newman Peter, (2006). The environmental impact of cities. SAGE Publications, 18(2), 275–295. Pickett et al. (2001). Urban Ecological Systems: Linking Terrestrial Ecological, Physical, and Socioeconomic Components of Metropolitan Areas. , Vol. 32, 127-157. Piracha Awais L & Marcotullio Peter J, 2003. Urban Ecosystem Analysis, Identifying Tools and Methods, United Nations University Institute of Advanced Studies. Rees, William E.. (1992). Ecological footprints and appropriated carrying capacity: what urban economics leaves out, Environment and Urbanization 1992; 4; 121-130 Rees, William E.. (1996). Urban ecological footprints: why cities cannot be sustainable and why they are a key to sustainability. In Environ Impact Assess Rev, Vol 6; Issue.6, 223-248 Rees, William E.. (2003). understanding urban ecosystems: An ecological economics perspective. In Understanding Urban ecosystems (NewYork Springer-Verlag.). Sheng Zhaoa, Zizhen Lib, & Wenlong Lia. (2005). A modified method of ecological footprint calculation and its application. Ecological Modelling , 185, 65-75. UNU/IAS, 2003. Urban Ecosystem Analysis, Identifying Tools and Methods. retrieved from http://www.ias.unu.edu/binaries/UNUIAS_UrbanReport2.pdf Wackernagel, M., & Rees W. (1999). Notre empreinte écologique, comment réduire les conséquences de l'activité humaine sur la terre" (écosociété.). Montréal. Wackernagel, M., & Yount, J. D. (2000). Footprints For Sustainability: The Next Steps. Springer Netherlands., 2(1), 21-42.

Wackernagel, M. et al. (2006). The Ecological Footprint of cities and regions: comparing resource availability with resource demand, Environment & Urbanization, Vol 18(1): 103–112 Wiedmann, Tommy, John Barret, & Nia Cherret. (2003). Sustainability rating for homes - The ecological footprint component (p. 44). SEI Stockholm Environment institute. Wilson, Jeffrey, & Mark Anielski.(2005). Ecological Footprints of Canadian Municipalities and Regions (p. 59). Canada: The Canadian Federation of Canadian Municipalities. Wolman, Abel. (1965). "The metabolism of cities". Scientific American, V213(3), 179-190. WWF, Living planet Report 2006, ZSL, Global Footprint Network.