CADOUEST SA

DISTRICT HEATING

FROM YESTERDAY TO TODAY

District heating in the Lausanne metropolitan area developed from the Pierre-de-Plan plant. Initially dedicated to the production of town gas for public lighting, it was converted in 1934 into a single boiler room for the buildings of the neighboring hospital, which became the CHUV.

Throughout its history, the network has benefited from technological innovations and its production facilities have evolved.In addition to a gas turbine, boilers were installed to meet the needs of the heating network. Coal-fired boilers were replaced in 1965 to produce directly at the distribution temperature, which was then 180ºC. Supplementary electric boilers were also abandoned in favor of gas or oil-fired boilers.

Since the winter of 2006, the Tridel plant has replaced the old household waste incineration plant, producing 220 GWh of heat compared to 80 GWh previously. This transformation has ushered CAD into an era where fossil fuels are no longer the main source of supply. Various production stations have also been added to the network, including a sewage sludge combustion station at the Vidy wastewater treatment plant.

After decades of expansion, the CAD in the Lausanne metropolitan area now has more than 1,300 connected buildings and a network of over 100 km.

In order to promote development in the western part of the agglomeration, CADouest SA was created in 2011 with the mission of promoting district heating and overseeing the expansion of the network.

HOW DISTRICT HEATING WORKS

Heat is produced by several industrial-scale production units serving a network of consumers. The heat is distributed throughout the city via an underground network of high-temperature pipes, supplying the connected buildings. The superheated water circulating in the pipes heats the secondary network inside each connected building via a heat exchanger. The water, cooled by the heat transfer, returns to the plant to be reheated.