A Danish model of building macro-components to promote circularity

A better understanding of the material composition of the existing building stock is important for the development of circular economy strategies in the building sector. This paper presents a recently developed model to map the types and amounts of various materials in existing buildings in Denmark, with a high level of detail at the level of components rather than just material types. The model is meant to enable a detailed description of the building stock and a consideration of how components could be reused. Building properties are imported from the Danish national building registry (BBR) and processed into a relational database. Properties are combined with information on past construction techniques from architecture handbooks to estimate the most likely macro-components (types of wall, roof, etc) used in each building, and dimension these components. Material amount estimates from the model are compared with previous estimates as well as with material inventories from case study buildings. While the open-source model currently lacks accuracy, it is intended to be easily modifiable, and can support continuous improvements of the estimates based e.g. on new information from material passports, waste treatment facilities or remote sensing data. The paper discusses future opportunities to improve the model's accuracy and use it to help develop circularity strategies and complement on-site inspections to overcome barriers to circularity.