22 May 2008
Wastewater (sewage) is a source of energy which can be used for heating and
cooling buildings with heat pumps. The technology is simple and proven. The first installations
were built more than 20 years ago. Over 500 wastewater heat pumps are in operation
world-wide. Thermal ratings range from 10 kW to 20 MW. Studies made in Switzerland and
Germany show that 3% of all buildings could be supplied with heat (or cold) on the basis of
wastewater. On account of the ideal source temperatures available (between 10°C and 25°C
all year round), wastewater heat pumps attain high performance figures. In addition, such installations
have an outstanding environmental performance.
In 1993, the Swiss Federal Office of Energy awarded the SwissEnergy Agency for Infrastructure
Plants the task of developing and propagating the use of wastewater as a source of
heating and cooling for buildings. As a result of the activities of this programme, Switzerland
has actually taken on the role as a pioneer in the international field of wastewater heat recovery.