[en] Whereas heat networks have evolved to become now installations with a major role in the reduction of the environmental print of territories, thus becoming major actors of the integration of renewable and recovery (RnE and R) energies into the energy mix, this publication first describes their development: brief indication of the main development phases since 1950, an always higher efficiency (from and energy and environmental point of view). It also comments their role in the French law related to energy efficiency for a green growth. Then, the benefits of heat networks are outlined, notably improved energy efficiency and low CO₂ content. The evolution of the share of renewable and recovery energies in the energy mix is addressed with a focus on the development of biomass-energy and of incineration, and on the still under-exploited potential of geothermal energy. A brief overview of market actors is proposed, and the evolution towards always smarter networks is discussed