This thesis, grounded in urban studies, analyzes the Green City model associated with neoliberal urbanisation processes in the contexts of Phnom Penh, Cambodia (main field) and Kigali, Rwanda. This urban model is driven in these two cities by top-down planning, promoted inter alia by international and regional organisations and policy makers, not forgetting the central role of Singapore and its influence through specific channels to promote the Green City model. However, this research embarks on a cross-cutting route that brings into play global urban theories, neo-Marxist critiques and the production of the city, with an approach rooted in the local, in the practices of the actors, and in the living to appreciate various alternatives and/or forms of resistance. The qualitative approach adopted is based on multi-site ethnography. It is supported by a multiscalar approach, analysing the Green City from skyscrapers to subsoils, from Southeast Asia to East Africa, thus multiplying the scales of observation and understanding. The economic approaches and dynamics that spread Green City models through urban megaprojects and ‘best practices’ are often very modest elements of the green city. Through iterative work carried out in Phnom Penh, the materialities involved in the creation of so-called green cities are also examined closely with a critical eye, by tracing the sand industry using ethnographic drawing, an alternative form of writing in the social sciences. The grand narratives and their performative solutions associated with the Green City model cannot alone account for the ambitions and results necessary to understand sustainable urban worlds. Complementary narratives, more discreet and yet more audible and comprehensible to the inhabitants, which suggest a heterogeneous collective force, are therefore featured in this work as well. By following the initiatives of the «passeurs du vivant» (bridge-builders for the living), who encourage us to take a greater interest in what connects us, in those who observe, recognise and transmit, in urban environments it is possible to re-establish the notion of the «living green city» beyond the Green City model.