An anergy network for Estavayer-le-Lac

Could the lake of Neuchâtel become a source of clean energy? This vision is set to become a reality thanks to a partnership between Groupe E and the municipality of Estavayer-le-lac. When it launches in autumn 2020, the innovative Estav’ALAC project, the first of its kind in the canton of Fribourg, will make it possible to heat and cool Estavayer’s regional hospital, the Hôpital Intercantonale de la Broye or HIB, using water from the lake. With this new anergic system, the hospital’s oil-based heating infrastructure, which dates from 1978, will finally be replaced.

The Thermal and Energy Laboratory (LTE) is assisting the project by determining the network’s temperature distribution as well as the amount of energy that can be recovered by the hospital’s heat pumps or through the use of fish farms.


As a sign of its commitment to the UN’s sustainable development goals (SDG 7: “Access to affordable, reliable, sustainable energy”), the municipality of Estavayer-le-lac authorized the project to make use of a decommissioned, 1700-meter-long underwater pipe, formerly employed to pump lake water up to the town. To complete the project’s infrastructure, a pumping substation, an underground pipe network and a water return channel will be built. In addition, two heat pumps will be installed in the building that currently houses the hospital’s massive oil tank.


The Thermal and Energy Laboratory has been charged with determining the temperature distribution of the network as a function of seasonal variations in lake water temperature. Our objectives are to estimate temperature fluctuations at the heat pump inlet as well as the total power recoverable from fish farms according to season.


  • Heat production: 1.5 to 2 GWh per year
  • Cooling power production: 0.1 GWh per year
  • Investment: 2.2 million Swiss francs
  • Liters of heating oil saved: 200’000 liters annually
  • Reduction in CO2 emissions: more than 500 tons annually