22 May 2008


The city of Zurich is known for its leading role in the energy friendly use of energy.
Further has the city of Zurich a politically binding mandate. The buildings in the city councils
portfolio shall be technically and economically exemplary in the use of natural ressources.
The city of Zurich can support technologies with the use of pilot-projects that are state of the
art in the forseeable future. These projects must use energy ecologically and stand a chance
of becoming economically feasilbe.
The heat pump in the Limmat-school uses sewage as its energy source. The sewage has a
yearly average temperature of 12 °C. This is a higher average temperature than that of the
lake of Zurich. A further advantage of sewage is that the temperature in winter almost never
sinks below 10 °C, even after a fortnight of really cold temperatures. In sommer times on the
other hand the temperature will not rise above 18 °C. This makes sewage a perfect energy
source for a heat pump.
The heat pump installed produces 85 % of the yearly heat, the remaining 15 % heat is
produced conventionally with a gaz boiler.
The heat-pump is also producing the hot water for the three sporting halls which mean that
for the hot water production the condensation temperature is close to 65 °C in a single stage