Heating and cooling sytem

Heating system

The main source of heat is drawn from Lake Geneva. The lake water is pumped into the Pierrettes pumping station and conveyed to heat pumps. These pumps extract energy from the water and convert it into heat that can be used to heat buildings through a thermodynamic cycle that requires electricity.

Until 2018, in addition to the two heat pumps, two gas turbines were used during particularly cold periods. These were fuelled by oil.

In order to switch to 100% renewable energy for heating and cooling, the oil-fired turbines will be eliminated and with them the approximately 1800 tons of CO2 produced annually. This will reduce the total CO2 output of the campus from 4300 to 2500 tons per year.

To ensure this transition, the pumping capacity will be doubled. The entire production will now be provided by four heat pumps, each with a capacity of 6 MW, for a total of 24 MW. To accommodate these new installations, the thermal power plant will have to be expanded on the north side, remaining at the edge of the forest and the Sorge River. On the lake side, a second lake pipeline will be built next to the existing one.

Cooling system

Water from Lake Geneva, pumped from the Pierrettes pumping station, is distributed throughout the school to cool the buildings. Cooling is most often achieved by directly using the coolness of the water, which is sufficient to lower the temperature of the premises.

The reuse of energy is a priority for EPFL. Thus, the cold waste from the heat pumps will be reinjected into the cooling network in order to reduce the amount of lake water pumped. As for the thermal waste from the campus cold consumers, it will be reinjected into the heat pumps for heating. In the same spirit of synergy, the data center will be cooled by the cold water discharges from the power plant and will in turn provide heat from the servers, i.e. 4 MW at full load.