The CAD-SIG district heating network (DHN) is located in the canton of Geneva. It expanded during the ’60s with high supply/return temperatures of around 110 °C/70 °C. It supplies 214 substations, mostly multifamily buildings from the 20th century. The heat sources are mainly gas boilers (160 MW) and waste heat from Geneva’s waste incineration plant (60 MW). The total heat supply was 359 GWh in 2021, 71% coming from fossil fuels.
To facilitate the future integration of renewable heat, its working temperature needs to be lowered, with the target to reach a supply/return temperature of 90 °C/55 °C in a few years. However, this raises questions on how to proceed, from detecting substations that poorly perform in terms of temperatures, to the choice and implementation of solutions, especially on old district heating substations.
