Where cultural heritage meets climate ambitions-Insights from a circular transformation case study

Abstract

Kristian Augusts gate 23 (KA23) in Oslo is Norway’s first listed building to be transformed in line with circular construction principles, serving as a pioneering example of how cultural heritage and climate ambitions can be aligned. This paper analyses how circular strategies were implemented in a complex transformation process and what lessons can be drawn for future projects. Using a qualitative case study approach, the analysis combines FutureBuilt’s circular criteria, case material, and theoretical frameworks, such as the circular economy, the 9R model, Design for Disassembly, Design for Adaptability, and heritage-based transformation strategies. KA23 achieved a substantial reduction in environmental impact by preserving approximately 80% of the original structure, resulting in 85% less material consumption and a 66% lower greenhouse gas footprint compared to a new-build alternative. The project employed multiple R-strategies across material, product, and building levels, demonstrating the value of selective deconstruction, high-value reuse, and adaptive transformation. However, the study highlights key challenges, including regulatory barriers, documentation requirements, limited market maturity for reused materials, and reduced design flexibility resulting from shifting from collaborative procurement to a total contract. Overall, KA23 shows that circular transformation is both feasible and climate-effective, offering valuable insights for scaling circularity within heritage contexts and the broader construction industry.