[en] This publication by a think tank specialised in social and solidarity economy first outlines that energy transition means a transition from the present energy model to a new model based on three pillars: a drastic reduction of energy consumption through sobriety (energy saving, struggle against wastage), an improvement of energy efficiency, and an energy mix based on renewable and sustainable resources. A first part proposes a discussion of what 'citizen' energy transition can be: general framework of energy transition, pioneering examples in Europe, citizen empowerment, importance of a decentralised model which is anchored in territories, general interest as a priority. Each of these issues and aspects is illustrated by examples. Then, as this evolution towards a citizen-based model requires a change of scale, the authors discuss how to involve public authorities and to adapt regulation, how to develop financing tools, how to support the emergence and development of projects, and how to be part of international dynamics. The author then discuss what their think tank can do to accelerate energy transition. Proposals made in the different chapters are then summarized