Key words: Phase Change Materials (PCM), Suspensions of micro-encapsulated Phase Change Materials (mPCM), Heat transfer, Convection, Physical characterization of mPCM and of the systems, Fluid mechanics, Energetics, urban environment, process optimization. Methodologies: Multi-scale and Multiphysics approaches via experiments and computations. Providing urban thermal comfort and maintaining human mobility in case of icing, snow or heat waves in densely populated areas is of crucial importance in our increasingly urbanized world. The goal of the project Convinces is to investigate reversible systems, cooling during heat waves / heating during icing at strategic urban places via the flow of a microencapsulated Phase Change Materials (mPCM) suspension in the draining layer. In the present project, fundamental and applied research will be carried out to understand physical mechanisms at play in the flow of mPCM suspensions subject to a vertical temperature gradient. Thus, studying buoyancy driven flows in detail is crucial in order to optimize heat transfer. While natural convection involves heat transfer rate enhancement up to 40% during phase transitions, the convective flows of mPCM slurries can involve still better heat transfer. However, in most experimental studies, global temperature measurements have only been obtained by means of thermocouples or IR thermography, since most of the systems are opaque. For similar reasons, local velocity fields are difficult to obtain within the fluid which leads to macroscopic measurements of heat transfer. However, local measurements are required to gain insight regarding the coupling between dynamics and heat transfer as well as to understand physical mechanisms involved. The Convinces project aims at dealing with the mixed convection of mPCM suspensions in porous media considering any relevant scales (from the micron caps to the meter mock-up), facing also with the multi-physics aspects. To achieve this, a wide range of advanced experimental techniques (SThM, laser-based photothermal methods, Digital Holographic Microscopy, IR Thermometry, MRI Velocimetry and Thermometry...) will be implemented to characterize the systems and describe the flows locally. Numerical modeling of these systems is of crucial importance to the success of this project. Sophisticated numerical methods will be implemented. Determining heat transfer in the system (porous layer and surface layer) is also an essential key and a final objective to tend to applicative engineering systems. More particularly, we intend to focus on urban applications (downtown squares, schoolyard, pedestrian area, sidewalks, café terraces, touristic places). Optimizing energy systems places Convinces at the heart of a general thinking on reducing energy consumption supported by “Stratégie Nationale de Recherche sur l'Énergie” (SNRE).