Waste water management systems exist in every city and could be exploited to heat buildings. Waste water systems promise major heat recovery potential. The temperature of waste water ranges from 10 to 15°C on average, and can go even up to 20°C during summertime. This guarantees an adequate heat source for the operation of heat pumps throughout the whole year.

According to research conducted within the Stratego project, 5% of the total heat demand in Europe could be covered with excess heat recovered from sewage systems in urban areas with more than 10,000 inhabitants. In the EU this corresponds to an overall waste heat recovery potential from waste water of about 150 TWh/year. Additionally, studies show that for Germany around 20% of all buildings could be heated with this technology.

There are known cases notably in Northern Europe but a large potential remains untapped due to technical and/or financial obstacles. One project has recently been implemented: Cologne has successfully tested and demonstrated three different set-ups of heat recovery methods of waste water systems within the CELSIUS Smart Cities project. ReUseHeat will leverage on this experience and also go beyond the testing phase.

The scheme that will be adopted in Nice, is particularly suitable for replication in Mediterranean areas – but also beyond. It can be easily adapted also to other waste heat sources, such as seawater in proximity of seaside, due to the similarity of waste heat source temperatures and climate conditions.