An important element in sustainability concerns the material and energy flows implicated in societal functioning. It is widely recognized that there is now a need to increase as much as possible the level of sobriety in the consumption of energy and natural resources and in the production of waste products and pollution of all forms. The notion of local autonomy at different scales (building, plot, block, neighbourhood, town, agglomeration, urban region…) is often strongly associated with the challenge of sobriety, reflecting an implicit or explicit idea that consumption and waste can be better controlled and reduced through a more or less self-sufficient organization at the local level. Urban services (water, energy, waste) are strongly implicated in this increasing concern for urban sobriety. These services occupy effectively a function of organizing an important part of the urban metabolism. They are also placed within the competence of public authorities, which can make them an instrument of local public policy. These sectors are however undergoing major changes which broadly take two forms: forms of decentralization with the creation of local, more or less autonomous, nets; the development and use of physical and economic relations between services. In this way, there emerges the idea that symbioses between urban services, based on emerging forms of sociotechnical organization of these services which are susceptible to lead to alternative configurations to the inherited large centralized networks of the 20th century, may allow important progress to be made towards a more sober urban metabolism. The project aims to study the action systems guiding the emergence of urban symbioses and the physical (energy, materials) and economic (costs, financing) flows implicated in their functioning. We explore the exchanges and interactions between sectoral systems for water, energy and waste, between these systems and the buildings which are connected to them, and between urban symbioses and their environments at different spatial scales, with a focus on defining as clearly as possible the ‘limiting conditions’ of the systems under investigation. Our perspective combines a functional (physical material and energy flows) and a techno-economic (financial flows) study of urban symbioses and a sociopolitical exploration of action systems and actor relations. The proposed methodology closely articulates a number of in-depth case studies and modeling work leading to the progressive development of a physical and economic model of urban symbioses. This is a basic research project over 48 months, conducted by an interdisciplinary consortium of social science researchers (from two CNRS units: LATTS in Marne la Vallée and PACTE in Grenoble) and engineering and environmental sciences (from Cirsee, the main research centre of the Suez Environnement group, the engineering consulting company Safege and Explicit consultants). The project concerns primarily axe 1 of the call for projects, and sub-axe 1.4 in particular. It will also shed light on axe 2 (sub-axe 2.2 in particular). The project is distinctive in its willingness to analyse together the sociopolitical and physical dimensions of transformations in urban services, which are usually studied separately. Reconciling urban and environmental policies and the challenges of sobriety effectively demands such a detailed understanding of the interdependencies between technical, urban and financial choices and the ‘metabolic’ properties of the systems developed.