Especially metropolitan areas, but also smaller cities are focusing on sustainable growth and resource recovery. Within this process, the potential of wastewater heat is widely neglected. Especially highly populated cities such as Berlin can benefit from capturing the heat from the wastewater in the sewer system and using it as a circular source for heating properties in the neighbourhood. 

Contributing to Berlin’s aim of reducing 70% of its Co2 emission by 2030, the Berliner Wasserbetriebe (BWB), as the largest water supply and wastewater drainage company in Germany, developed in collaboration with further partners, a web application. The app allows users to obtain and manage data relevant for matching the supply and demand of wastewater heat (WWH). The wastewater heat radar is especially interesting for cities, real estate developers, and industrial companies in need of production of wastewater heat. The solution focuses on the increasing interest among European cities to reduce their energy consumption and to implement more sustainable and circular energy sources, which waste water heat is counted as. As data acquisition and visualisation is the first step to achieve this transition and very few cities have developed such maps, simply offering this work to municipalities is in demand. The agency can also offer an integrated solution to realise the city’s WWH potential in line with its carbon and sustainability targets. In addition to developing the map, this would include setting up a team of technical partners, identify potential demand and accompany these in the full process to capture WWH. City planners together with climate and energy departments will be the specific customers of such a solution. 

The key functions of the application allow the user to either search for a specific address or apply a filter on the estimated heat usage of a property. Through both options, the app checks for a potential match between supply and demand. The user can then see how much potential heat capacity is available at the particular location. The app portrays the overall wastewater heat potential of the building as well as the estimated heat demand of the property and shows how much of this demand could be covered by the wastewater heat potential. Users can show their interest in the building and the more users show their interest in one building, the more likely it is that a heat pump is installed, to facilitate the wastewater heat recovery. The wastewater heat radar functions as a tool to enable heating district networks. 

The development of the wastewater heat radar demonstrates the need for deep, data-driven insights into the potential of wastewater heat as an urban resource. Thereby data security concerning critical infrastructure is important. During the project, several approaches to data anonymization had been developed and will be further tested. The radar can function as a tool to drive the circular transition and industrial symbiosis, functioning as a role model for other European players.

REFLOW was an EU Horizon 2020 innovation action project running from 2019 to 2022, with the aim to increase circularity in European cities. Through REFLOW, the 28 project partners developed a range of solutions to make the material flows more circular within the six pilot cities of Amsterdam, Berlin, Milan, Cluj-Napoca, Paris, and Vejle. The cities' social, environmental, and economic impact was assessed, and a range of solutions enabling the circular transition were developed through active citizen involvement. The project combined the expertise of the project partners spanning municipalities, scientific and research institutions, technology providers, design and grassroot organisations, and small- and medium-sized enterprises.