Building Change Together
Hardly possible to miss, the award-winning Rockywood building complex rises above Offenbach’s harbour basin. Visible from afar, its contemporary timber-hybrid construction signals a new era of circular building. Along the waterfront promenade, the L-shaped “Wood” and the cuboid “Rocky” form a harmonious ensemble. A visit to the Circle, which is based here, makes clear that the construction industry is entering a new chapter. Both the architecture and the interior design of the building impressively reflect the ethos that is radically embraced by the people working inside. It quickly becomes clear: this is a place where the most pressing problem facing our built environment – the enormous flow of waste – is tackled fearlessly and without compromise. “Something” means the circular economy.
Materials must remain in circulation, and construction projects must be economically viable as well as sustainable. To achieve this, more than 90 companies from Germany’s construction and circular economy sectors – ranging from major corporations and associations to architecture practices and tech start-ups – have joined forces within Circle. As a collaborative network, Circle aims to increase recycling rates for construction waste, shorten lorry transport routes for construction waste and increase the use of alternative modes of transport such as inland waterways. Under one roof, it brings together not only people, but also knowledge and technologies from across the entire value chain.
Circle Hub & Circle Cube
As the heart of the organisation, Rockywood showcases what is already possible today – and what is currently being developed. Behind its generous glass façade, several floors demonstrate how recycled products and new technologies for circular building are not only presented, but also jointly developed and explored further.
The Circle Hub is located on the third floor of the “Wood” building. The network’s open-plan coworking space provides partner companies with up to 80 workstations, as well as space for innovative ideas and new approaches to problem-solving. As soon as you enter the space, one thing becomes clear: this is where the principles of Design for Disassembly are at the heart of the work. Exposed ceilings, visible structural elements and minimalist glass walls in a loft-style setting define its authentic industrial character. Alongside fixed desks and dynamic co-creation spaces, the space also features “Think Tanks” and “Phone Boxes” – dedicated areas for undisturbed work.
The Circle Cube extends from the ground floor to the first floor of the “Rocky” building, serving partner companies as a showroom and event venue. The network’s extensive, carefully curated exhibition features market-ready recycled products, technologies and material streams. Here, circularity becomes tangible and accessible to visitors. Companies use the event space for workshops, networking meetings, presentations and strategy days.
Building Bridges
The construction sector alone generates more than 200 million tonnes of waste in Germany every year. According to the German Environment Agency, this accounts for 61% of the country’s total waste generation, placing the sector among the most resource-intensive areas of the economy. This is a tension within the transition towards a more sustainable construction industry that Circle founder Daniel Imhäuser no longer wanted to ignore. As a waste management and recycling specialist, the CEO of Urban Mining Group felt a strong urge to do more: “The real challenge of the circular economy lies not in the material itself, but in collaboration. Technically, we could already reuse and high-quality recycle significantly more construction materials than actually make it onto the market. What is often missing is networking across the entire value chain.” However, if planners, deconstruction specialists, building material manufacturers, construction companies, researchers and policymakers operate solely within their own silos, closed loops cannot be created. And so, in 2024, Imhäuser – in his role as a bridge builder – initiated a special place with Circle. “My task is to bring together stakeholders who would not normally work together on a daily basis, initiate new collaborations and create the conditions needed to turn good ideas into concrete projects.” Although he laid the foundation for the initiative, the idea was supported from an early stage by committed partners such as CDM Smith, Glöckle, Optocycle and Holcim.
But how did he manage to bring established construction companies, tech start-ups, architects and even policymakers to the same table? “Surprisingly, the willingness was greater than many might have expected. The challenges facing the industry have become so obvious that many companies have realised: no one will be able to achieve this transformation alone.” Circle member Helena Fischer, Managing Director of the Northern Hesse regional group of the Construction Industry Association of Hesse-Thuringia, sees it the same way: “Joining Circle is not an engagement ‘alongside’ the association’s work. It is an opportunity to fulfil our core role as an association with a focus on the future: we do not want to merely represent the interests of construction companies within existing regulatory frameworks, but also help shape those frameworks so that our companies can remain competitive and build in a circular way in the future.” As trust grew and the focus shifted from simply discussing problems to working concretely on solutions, enormous momentum developed. Today, Circle is home to numerous companies of different sizes and specialisms. What unites them all is a shared conviction: the circular economy is a collective effort.
Built on Respect
“Here are companies that are doing more,” is how Imhäuser describes Circle. They are all connected across the entire value chain, making the organisation its own ecosystem – bringing together people from different fields and with varying levels of professional experience. But when established construction giants meet agile founders, does that not lead to a struggle over expertise? Imhäuser does not see it that way: “Start-ups often bring speed, a willingness to experiment and new ways of thinking. They question established processes and develop solutions from a different perspective.” Established companies, on the other hand, have greater market knowledge, production capacities, experience and access to real-world projects. At best, the result is a symbiosis. The start-up ReWorth, which has developed ReBlock, the first fully circular lightweight building block, is particularly fascinating to him at the moment. An enthusiasm that is mutual, as CEO Esther Heyse reveals: “The network, the atmosphere and the space for opportunities that the team has created are truly unique – and have come together remarkably quick. From my perspective, this also shows the urgency of the issue of circular building.”
“Our greatest strength is our ability to bring together knowledge, decisions in favour of the circular economy and speed of implementation,” is Imhäuser’s answer when asked about Circle’s true superpower. However, he says, the network cannot limit itself to exchange within the industry. “When we encounter regulatory or legal hurdles during implementation, we deliberately bring policymakers to the table. Circle sees itself as a bridge between practice, business and politics.” The organisation consciously seeks dialogue with the relevant stakeholders. Just this spring, former Federal Minister for Transport Patrick Schnieder and Federal Minister for the Environment Carsten Schneider were guests at the site. Ultimately, Circle also sees itself as a kind of knowledge platform, regularly welcoming representatives from local authorities, building and planning departments, as well as public-sector clients.
Destination: Normality
Where good ideas are on solid footing, they should not remain alone for long. Circle is not the only project of its kind in Germany. The Construction Hub at Circular Valley near Krefeld and the CRCLR House in Berlin also share similar ambitions and visions. “If we are serious about transforming the construction industry, we need many more places like these. The challenges are too great to be solved from a single location,” says Imhäuser, once again emphasising collaboration as the guiding principle. Each network can set its own priorities, address local material flows and bring together relevant stakeholders. The hubs should not compete with one another, he argues, but work as part of a wider network. The more real-world labs there are, the sooner the circular economy will become the norm.
