This book on the metabolism of the Brussels-Capital Region presents, on the basis of foreign experience, a report on material and energy flows at the level of the Brussels-Capital Region for the year 2011 as well as concrete improvements on certain value chains in a circular economy perspective. It also opens perspectives for the development of the regional program in circular economy initiated by the Brussels government in terms of operational, regulatory, economic and socio-economic plans. In more practical terms, the content includes: · a bibliographic analysis which makes it possible to situate the construction of Brussels' circular economy policy in relation to other neighboring and non-neighboring territories; · A regional metabolic assessment offering a new way of approaching materials, energy and water on the territory, linking the incoming, stored and outgoing flows of the territory. The assessment also constitutes a tool base for monitoring the effectiveness of resource use in the territory; · An assessment and the definition of actions for the improvement of flows selected by Brussels Envionnement and their value chains for new projects or studies to be driven by Brussels actors; · The rendering of the participatory dynamic that has allowed to start a reflection and definition of intentions regarding the development of the circular economy on a Brussels scale. The present study thus constitutes a new starting point in the work of optimizing flows of materials, water and energy in the Brussels regional territory in a circular economy perspective based on a theoretical basis related to concrete applications. who want to be as realistic as they are practical.