The building sector consumes large quantities of resources and generates high levels of construction and demolition (C&D) waste. From an ‘urban mining’ perspective, the building stock can be seen as a repository of natural resources. In order to manage this repository, evidence is needed on its quantity and dynamics. Although data exist for domestic buildings, little evidence exists for non-domestic buildings. A new method is presented to quantify the material stock of non-domestic buildings – based on the German building stock. The quantification process involves three steps: (1) material composition indicators (MCIs) are calculated with respect to various building types; (2) the country's total floor space is estimated and disaggregated; and (3) the total material stock is calculated. The main results are MCIs and the floor space for both domestic and non-domestic stocks, as well as the material mass in total. In Germany the total material mass of non-domestic buildings is approximately 6.8 billion tonnes, accounting for 44% of the entire building stock. The method can be adapted and validated for use in other countries. These results will assist both policy-makers and the construction industry to understand the potential for moving toward a more circular economy.

Building stocks are the dominant consumers of resources within national economies. Correspondingly, there is high demand for improved knowledge of material stocks and flows in the built environment. Material flow analysis is well suited to meet this demand. Although numerous studies have been conducted on this topic over recent years, these frequently lack applicability and transferability due to insufficient documentation or treatment of uncertainties. A new approach is presented here to calculate material stocks and flows for domestic buildings using the example of multi-family housing (MFH) in Germany. The approach is critically examined to determine its validity. The calculation process involves four steps: (1) building types are classified according to building age; (2) highly specific material composition indicators (MCIs) are calculated for the respective building types; (3) the total material stock as well as inflows and outflows are derived from the total floor space of Germany’s MFH; and (4) validity tests are performed to quantify uncertainties. The main results are age-based MCIs for MFH, the total material mass as well as quantitative information on parameter- and model-related uncertainties. Conclusions are drawn on the validity of results, the scalability and applicability of the model and its implementation, along with potential model refinements.