The promotion of the nature is one of the tools used to improve the urban environment, reduce pollution, mitigate climate changes and contribute to the maintenance of biodiversity. But works in urban ecology have focused essentially on parks, gardens and vegetated roofs. Only few researches involve the greening of walls and streets that could play a social, ecological and physical role, base of an urban sustainability. This research is essential for a global approach to the urban planning and set up of green networks in dense city. We propose a consortium of research laboratories, SMEs and associations involved in urban approach, able to make a first assessment of the ecological services provided by these greenings, to study their ecological and biochemical functions, technical implementations and citizen appreciations, but also to experiment with innovative prototypes. Our program can be divided into two main areas: - What is and how does it work today? This work will involve national and international literature review (Phase A on the state of the art and synthesis of knowledge on ecological vegetation walls , courtyards and streets in town: expected technical services, implementations, observed social involvement...) but also active research on the ecological functions (Phase B on the evaluation of biotic and abiotic functions of current vegetation techniques: what biodiversity, what relationship with substrates, conditions and physicochemical constraints...) and social (Phase C on assessment of societal functioning of the vegetation: what economy, what governance, what regulations, what perception and opinions... ) - What innovative proposals can be made? This involves experimental work at building and street scale (Phase D testing of innovative proposals for vegetation: reasoning on the development of prototypes, architectural experiments on coatings, substrates, methods of irrigation...), but also studies on the potential and functioning at a global scale (Phase E on the evaluation of urban potential and functionning expected in an urban project: area available, types of spaces and owners, relationship with greenways, possible regulations...). The work is set to three years and analyses will be conducted at different scales island / district / city on the city of Nantes and the Grand Paris.