Modelling Urban Transitions: A Social Practice Theoretic Approach to the Urban Metabolism

Urban growth and the increase of the human environmental imprint has led to a growing interest in urban sustainability, a field mainly addressed by urban ecology and urban metabolism studies. The realisation that the urban material and energy flows are mainly driven by household activities resulted in the acknowledgement that to understand the drivers of urban metabolic trajectories, it is necessary to include social factors into the onceptualisation of the urban system. However, so far no satisfying and operationalisable conceptualisation of the urban system as a nexus of social, technological, geographical and environmental factors exists. The aim of the present research is to develop an approach to overcome this gap. This research starts with the assumption that the household processes driving the urban material and energetic flows are key to understanding urban metabolic regimes and trajectories. It thus attemps to study urban transitions from a social practice theoretic approach. This methodological choice is motivated by the ambition of social practice theory to analyse the formation, reproduction and transformation of practices - nested sets of routinised activities - as parts of a system of things, technologies, skills, social structures, meanings, the environment etc., and in general by its focus on understanding the mechanisms behind social change. However, social practice theory has been struggling with the operationalisation of its concepts, due to the nestedness of practices and the resulting difficulty to delimit the field of analysis, and the lack of a general theory of how the different elements of which social practices consist are related. To overcome these challenges, this research proposes to model urban trajectories and transitions as the emergent behaviour of a socioechnological-environmental system, of which the different components drive the formation, reproduction andtransformation of social practices and thus the urban metabolic flows. For this, a mixed-method approach of agent-based and system dynamics modelling informed by sociological theories and qualitative field work is to be developed. Firstly, urban trajectories and patterns are identified. Secondly, models are used as a tool to test different theory-based explanatios for the emergence of such patterns. More specifically, the aim is to replicate long-term patterns and trajectories of specific practices - such as nutrition or commuting - across different urban contexts based on different theories regarding social change and the formation of social practices. The model hypotheses are to be developed based on theories and qualitative data, and tested with participatory approaches.

A conceptual framework to study the dynamics of routine practice transitions

Franziska Meinherz

Actors from academia, politics, and the civil society increasingly acknowledge that to address our current unsustainable regimes of resource and energy demand, we need to redefine our ways of being and doing. Everyday practices are a key driver of energy and resource demand. Understanding patterns of practice dynamics and their drivers is therefore key on the way to a sustainability transition. This research aims to improve our understanding of how everyday practices, and their underlying conceptions of normality, are formed and transformed in a context of individual, social, infrastructural, institutional, and ecological dynamics. How conceptions of normality are enacted into practices is at the heart of theories of practice. They look at how the interconnectedness of practices in time and space shapes their reproduction or transformation, and have been powerful in providing insights into the often--observed path dependence and stickiness of practices. This focus on the self--reproducing aspects of practices however results in theories of practice remaining vague on how the conditions for practice change come about. And because practices are seen as constantly evolving, it is difficult to clearly delimit practice change. This complicates the analysis of patterns of practice change across cases. To overcome these issues, we propose a framework that looks at practice change as one dynamic process in a tightly interconnected system of dynamic processes on the individual, social, institutional, infrastructural, and ecological level. Practice change is seen as the result of the interplay of these processes. The framework builds on two metaphors from ecology and resilience theory: The adaptive cycle and the panarchy. The adaptive cycle describes the succession of phases of lock--in and innovation, by looking at variations in connectivity, built--up potential, and resilience. The panarchy describes a systems perspective according to which dynamics of self--reproduction and of innovation result from the spatio--temporal nestedness of different processes, each following the pattern of an adaptive cycle. These metaphors are used to operationalise theories of practice for the analysis of practice dynamics. They provide a structured way of describing practice change, and to derive explanations for the observed dynamic patterns. The framework is illustratively applied to the analysis of commuting practices in Hackney, UK. Hackney has observed an important increase in the modal share of cycling in the last years. As it is commonly done in empirical research building on theories of practice, the practice at hand -- commuting -- was operationalised through the materials, meanings, and skills, which are integrated in its enactment. Using the adaptive cycle metaphor to describe the development over time of commuting practices in Hackney allowed to build a timeline of phases in the life of commuting practices which were each characterised by different dynamics. This analysis notably showed the rapid disintegration of the practice of commuting by car, after this practice had for a long time been caught in strong self--reproducing mechanisms. This disintegration was followed by a phase of experimentation with different modes of commuting, which finally resulted in a new phase of stability, with cycling as the new norm. Focusing on the spatio--temporal nestedness of social, infrastructural, and ecosystem processes which played into the enactment of commuting practices, and on their mutual interrelations, further allowed to identify the drivers of the collapse of the practice of commuting by car, and of the emergence of cycling as the new norm. The framework therefore provides insights into how the self--reproducing mechanisms which keep potentially unsustainable practices in place are broken up, and what drives the emergence of new practices. Such knowledge could inspire policies to achieve a transition to more sustainable practices.

2018

Méthodologie de gestion durable des ressources du sous-sol urbain

Pascal Blunier

The world is becoming more and more urban. During the last fifty years, the population in Swiss cities has grown from 45% to 70% of the total population. This change is characterised by urban sprawl and by an increase in the consumption of resources, particularly those coming from rural areas. This evolution is not compatible with the principles of sustainable development. To solve this problem, new urban policies are being developed. They favour development within the urbanised areas and reduced use of exogenous resources. The urban underground contains resources – space, geomaterials, groundwater and geothermal energy – which can efficiently support such policies. This project analyses how these resources have been exploited until now and how they could be used with sustainability in mind. The use of underground resources was analysed in five cities : Mexico, Paris, Helsinki, Tokyo and Montreal. It appears that, although resources participate in the urban metabolism, there is an important lack of planning and coordination in their use. Developments follow a sectional approach where the resources are considered independently, and only at the scale of a given construction project. As a consequence, conflicts occur between uses and resources are wasted. An understanding of the urban underground as a system was developed with the aim of preventing conflicts and promoting synergies. To this effect, the way in which resources interact was considered attentively. Situations in which interactions occur were described and analysed and compatibility conditions were suggested. A methodology was elaborated to evaluate the resource potential of an urban underground. It aims at considering the resources and the interactions between their uses from the beginning of the process of urban planning. The methodology is based on the use of Geographical Information Systems and 3-D modelling of geological and hydrogeological conditions. It aims at reversing the current paradigm, that proceeds from the needs to the resources, into an approach based on resources to satisfy the needs. Spatial information was exploited to determine indicators and maps of potentiality and of restrictions. The derived results will help support decision making by planners and policy makers who seek to better exploit the resources from the urban underground. The methodology was tested and applied on a case study : Geneva. The developed approach allows more efficiency in the use of urban underground resources, it can help prevent conflicts between uses and develop synergies. When integrated in the urban planning process, it highlights new opportunities and helps to develop projects that take into account the physical conditions of the underground.

EPFL2009

Conception et évaluation d'un prototype de simulation de la morphogenèse urbaine par agents vecteurs multi-échelles

Vitor Silva

The research work of this PhD thesis was carried out in the context of an interdisciplinary project related to the study of urban morphogenesis. A team composed of architects and engineers specialized in GIS technologies have worked together in this project during three years, sharing their knowledge in order to understand and simulate the evolution of the urban environment of cities. The fundamental hypothesis that conducted this research is that the city can be seen as a self-organizing system governed by a set of morphogenesis rules, which can for example, determine the location of new architectural programs and induce the city's organization, from local to global scales. Architectural programs themselves are supposed to determine city's development. In this PhD thesis a simulation prototype of the urban growth based on the use of multi-agents systems was carried out. This prototype is a computer tool that allows the analysis and representation of the growth of the built environment. Nowadays, the ability to understand and simulate urban evolution proves to be essential in order to control the evolution of a city in a sustainable development view. Furthermore, this tool should facilitate the understanding and decision-making of those concerned with problems related to urban development. The urban system has been modeled as a set of space objects, such as buildings and networks, which interact between themselves. These interactions are carried out at different levels, from local to global scales, being controlled by behavioral rules or laws of growth. The result of their interaction can be figures or emergent phenomena represented at several scales. The approach using multi-agents vector systems was chosen in order to model a geographical complex system like a city, which integrates a vectorial modeling of space. Hence, each spatial agent does not possess a limit of form and size. The interest of using multi-agents vector systems also lies in their ability to manage various models of individuals, from simple entities to more complex ones. Thus, various levels of representation, such as individuals and groups of individuals, can be managed, which is not easily feasible, for example, with cellular agents. The development platform used is GeOxygene (Java computer programming language), which is an open-source platform developed at IGN (Institut Géographique National, France), by COGIT laboratory. This platform provides several GIS functions, allowing the development and implementation of the prototype here presented. An interaction model between agents was defined and the type of scenarios of each of these interactions was detailed. A set of methods and associated classes was developed. Agent's architecture was conceived in order to allow manipulation (sending, receiving and treatment) of exchanged messages. In order to show the relevance of the multi-agent multi-scale methodology, examples of buildings creation in a case study zone were carried out. Using the multi-scale vector simulation prototype here presented, the development of cities can be computed in a very innovative way. However, the developed prototype still lacks some accuracy, mostly due to the fact that the specified laws adopted for simulation do not reflect the whole reality, which is obviously much more complex to traduce. We have not yet validated the model for other cities – nevertheless, the model could already be used as a decision support tool, particularly as a planning support instrument for architects and urban planners. With regards to future work this prototype shall be integrated in a global approach of urban simulation, allowing the analysis of environmental risks, demographic and economic growth and transports simulation at different scales of analysis and 2D/3D visualization output, such as district and city.

EPFL2010