There is a great need for a sustainable heat supply. With the expansion of ewz's thermal networks, the "CoolCity" energy network is taking a major step towards its climate protection target of net zero by 2040. By expanding the Fraumünster lake water network, Lake Zurich is to be used to supply energy for heating and cooling to surrounding properties and buildings. As a renowned hydraulic engineering company, Willy Stäubli Ing. AG was commissioned by ewz to implement and install a new pump platform in the Zurich lake basin. This was put into operation by the existing Fraumünster lake water network.

A large volume of water is required to cool or heat the connected buildings. The capacities of pumps on land would not have been sufficient to provide the required suction capacity. With an innovative pump platform that "pushes" the water from Lake Zurich to the energy centers, we have realized a Europe-wide novelty. The platform was lowered into Lake Zurich by our experienced professional divers at a water depth of approx. 12.5 meters with the utmost precision, fitted between the pipe systems and flanged to the power supply.

Thanks to the new submersible pumps, the previous output of the Fraumünster lake water network has doubled. The heat pumps can produce a heating output of 8,800 kW from the lake water. This ensures the hot water and heating supply for over 2,000 apartments. In addition, 8,400 kW of cooling capacity will be achieved in future.