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Heat and cold production currently accounts for 50% of energy demand in Europe and is the source of significant greenhouse gas emissions. The greening of this production is based on the development of heat from renewables (biomass, solar, geothermal) and, to a lesser extent, on recovered energy. The article shows how waste heat, a singular source of energy, is constructed as a territorial resource through a framing process at multiple levels (European, national, regional, metropolitan). The case studies of Dunkirk, Lille and Lyon, which each uses recovered heat from industry and urban services in its own way, illustrates urban authority interest in this local resource as well as the diversity of the trajectories of territorial transition pursued through this energy source.