CityLoops: How cities can learn circularity from each other

The careful use of natural resources is an imperative of our time. A paradigm shift is needed, away from a linear and towards a circular economic system. Cities have particularly great potential for circularity and resource conservation, and it is already the declared aim of many municipalities to realise this potential. In the CityLoops project, seven European cities - Apeldoorn (the Netherlands), Bodø (Norway), Høje-Taastrup (Denmark), Mikkeli (Finland), Porto (Portugal), Roskilde (Denmark) and Seville (Spain) - have carried out pilot projects to use digital tools to close the cycle of biowaste as well as construction and demolition waste, thus reusing valuable materials instead of disposing of them.

To this end, these seven so-called "demonstrator cities" developed tools and processes that were then analysed for their transferability in so-called "replicator cities". In May 2021, Vienna was selected as a replicator city for Bodø, Norway, in order to test the tools and processes developed there with regard to their applicability for the construction industry in Vienna.

Klaus Kodydek from the Coordination Unit for Resource Conservation and Sustainability in the Construction Sector (SRN), Executive Group for Construction and Technology, describes the benefits of this approach: "Cities benefit immensely from international networks. A key point for achieving the climate targets is that not all cities are constantly trying to reinvent the wheel. We need to look at which cities are already developing practicable tools and solutions and then evaluate how these solutions can be applied to our own city. The city of Vienna is already an international role model in many areas, but there are always new tools and processes that we can replicate in the Viennese context."

Vienna in dialogue with Bodø: focus on digital tools

In contrast to Vienna, Bodø is a small city with around 50,000 inhabitants, but the municipality of Bodø is nevertheless confronted with similar issues relating to the finite nature of resources. The exchange within the framework of the project was therefore very enriching for both sides. In spring 2023, two SRN employees travelled to Bodø and presented current projects, programmes and studies from Vienna dealing with circular planning and construction and material flows in the construction industry to their colleagues from Bodø Municipality.

In return, Vienna invited its Norwegian partners to a two-day workshop in June 2023, which was also attended by the relevant municipal departments. The digital tools and solutions developed by Bodø were presented to the experts from Vienna and the significance of these tools for the implementation of the circular economy in the construction industry in Vienna was jointly evaluated. Of the many topics covered by the CityLoops project, three areas were of particular interest to the City of Vienna in connection with circular construction: The digital twin, material flow analyses and stakeholder activation.

Concrete benefits of digital tools for urban development projects

Depending on the use case, various data sets can be integrated into a digital twin. The city of Bodø has linked its digital twin with data for circular construction. For example, predictive modelling and simulations could be created, particularly with regard to soil conditions, to determine how and whether excavated soil can be reused directly on site in an urban development project. At neighbourhood level, the linking of material data could facilitate forward-looking (urban) planning and scenario planning for complex construction projects. The exchange between the Norwegian project partners and the relevant departments of the City of Vienna on the numerous different possible applications will be continued.

The City of Bodø utilised the "Urban Living Lab" method for stakeholder activation. This is an applied research method in which various stakeholders (public administration, companies, academic institutions, civil society, etc.) work together on complex problems in a real environment. On this basis, a physical and virtual platform, a "CityLab", was created in Bodø for the joint exchange and development of research questions in the field of 3D visualisations and circular economy in the construction industry.

The successful submission of a project application to the City of Vienna's Innovation Management (Municipal Department 23, Call 5) has enabled the Executive Group for Construction and Technology to realise the "Urban Living Lab Circular Construction Nordwestbahnhof" project. The Urban Living Lab is currently being conceptualised and the team is benefiting from the exchange with Bodø and the shared experiences.

The CityLoops project, funded by the EU's Horizon 2020 research framework programme, has been successfully completed. The knowledge gained will become an essential part of Vienna's path towards circular construction.