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The dynamics of societal material stocks such as buildings and infrastructures and their spatial patterns drive surging resource use and emissions. Two main types of data are currently used to map stocks, night-time lights (NTL) from Earth-observing (EO) satellites and cadastral information. We present an alternative approach for broad-scale material stock mapping based on freely available high-resolution EO imagery and OpenStreetMap data. Maps of built-up surface area, building height, and building types were derived from optical Sentinel-2 and radar Sentinel-1 satellite data to map patterns of material stocks for Austria and Germany. Using material intensity factors, we calculated the mass of different types of buildings and infrastructures, distinguishing eight types of materials, at 10 m spatial resolution. The total mass of buildings and infrastructures in 2018 amounted to ∼5 Gt in Austria and ∼38 Gt in Germany (AT: ∼540 t/cap, DE: ∼450 t/cap). Cross-checks with independent data sources at various scales suggested that the method may yield more complete results than other data sources but could not rule out possible overestimations. The method yields thematic differentiations not possible with NTL, avoids the use of costly cadastral data, and is suitable for mapping larger areas and tracing trends over time.

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Most anthropogenic material stocks and flows are associated with the building sector. Several recent studies have developed material composition indicators (MCIs) suitable for calculating material stocks and flows of the building sector using bottom-up approaches, which hold great potential to provide information to support resource efficiency policies. A major limitation is the lack of country-specific MCIs. This study aims to introduce a concept for a better transferability of MCI across different contexts by proposing requirements for defining MCIs and to discuss options and limits of the transferability. We take existing MCIs for residential buildings in Germany and Japan as case studies and make them comparable by applying harmonization methods. Based on that, similarities and differences are systematically identified and discussed, considering their socioeconomic, cultural, technical, and environmental factors. Our results indicate significant limitations to the transferability of MCIs for detached houses, while bigger apartment complexes show greater homogeneity despite the very different environments in which they are constructed. This indicates that while it is possible to assume foreign MCIs as plausible for large constructions, local coefficients need to be estimated for smaller single-family homes. Augiseau and Barles 2016; Moriguchi and Hashimoto 2016; Ortlepp et al. 2016). Bottom-up approaches follow the principle of "multiply[ing] some practical measure of the stock or flow of interest (e.g., m² [of] floor space) by coefficients for characteristic material compositions (MCIs) that describe the relative material content of the considered good" (Ortlepp et al. 2018, 3).Bottom-up approaches offer a high degree of flexibility, paired with the possibility of spatially explicit resolution,

Material flow analysis (MFA) is a helpful tool to understand and develop the circular economy. There exist a number of MFA models to depict inflows and outflows of bulk nonmetallic mineral building materials, which are, in fact, the largest flows in terms of tonnes. However, until now such models have not attempted to directly link inflows and outflows. In order to achieve such closed loops, it is necessary to consider the qualitative aspects of inflows and outflows as well as quantities. The technical possibilities of recycling are, in fact, determined by both the quality and quantity of materials. This requires the integration of knowledge on process engineering, the technology of waste management, and indeed the structure of buildings. The article integrates these aspects within a continuous MFA approach (C-MFA), which is able to analyze and quantify the entire material cycle of bulk nonmetallic mineral building materials by considering the use of recycled aggregates in concrete building elements. This is achieved by methodological expansions that take into account qualitative aspects with regard to outflows and inflows. The approach is applied to questions of high-quality recycling within the German building stock. The continuity of construction and demolition waste output and secondary material input is realized by integrating the process steps required to capture high-quality waste in the course of building demolition, material processing of the material to produce recycled aggregates, and admixing of the aggregates to produce new concrete used in buildings. This can be extended by considering the inflows and outflows of other sectors, for example, the infrastructure sector. The main outcome is an extended C-MFA approach that enables quantification of sectoral as well as, in principle, intersectoral material loops of bulk nonmetallic mineral building materials while uncovering potentials to save natural resources as well to better exploit anthropogenic resources. Keywords: bulk nonmetallic mineral building materials circular economy continuous MFA (C-MFA) industrial ecology material flow analysis (MFA) recycling Supporting information is linked to this article on the JIE website Conflict of Interest Statement: The authors have no conflict to declare.