District heating distributes heat from a central source through insulated pipes to many buildings, the first commercial system opening in Lockport, New York, in 1877. Twentieth-century networks drew waste heat from power stations in combined heat and power schemes, becoming widespread in Denmark, Sweden, Russia and other cold countries. The technology favours dense development, since pipe networks are economic only where heat demand is concentrated. It is central to many low-carbon city plans using waste heat, biomass or geothermal sources.
District heating ties efficient warmth to urban density and is a key tool for decarbonising the building stock of cold-climate cities.