The renovation of the faculty blocks at Leibnizstraße 4–10 at the Christian-Albrechts-University of Kiel (CAU) demonstrates how existing building stock can be made future-proof. Central to the approach is urban mining: as many building components as possible – from sand-lime bricks to solid wood doors and concrete elements – are carefully dismantled, refurbished, and reused. This not only preserves valuable building fabric but also significantly reduces resource consumption. Sustainability is also prioritized in the selection of new materials, with timber-aluminum windows replacing conventional aluminum units and substantially lowering CO₂ emissions.

C5 supported the project across all aspects of sustainable planning and implementation. This included analyzing the existing structures, identifying and documenting reusable components, advising on material reuse and the selection of new materials, evaluating the CO₂ savings potential, and assisting with the planning and tendering of selective demolition. This holistic approach significantly increased the Urban Mining Indicator: compared to a conventional new build, the renovated faculty blocks already achieve a value of over 57%, highlighting the project’s above-average circularity potential.

The renovation thus demonstrates how resource-efficient, circular construction can be successfully implemented by preserving historical building fabric, optimizing material cycles, and substantially reducing the carbon footprint of the new construction.