Biogenic carbon dioxide storage and mineral carbonation uptake in EU buildings

Storing atmospheric carbon dioxide (CO₂) in products is identified as one of the key measures for carbon dioxide removal. The building sector and its potential use as a carbon sink is quickly becoming a consideration for active policies in Europe. However, while this remains a key element of informed decision-making, robust data on CO₂ storage and uptake potentials vis-à-vis current greenhouse gas (GHG) emissions in the buildings sector is still lacking. Here, we quantify the carbon dioxide storage and uptake potentials for EU buildings in 2020 on three hierarchical levels: the material, building, and building stock level. We assess the potential of bio-based materials and mineral carbonation and compare the results to the baseline GHG emissions of the EU building stock. At the building level, bio-based materials show the largest storage effects. Carbonation during the use stage of buildings is smaller than in the end-of-life stage, yet both yield non-negligible effects that should be considered in life cycle assessments of buildings. However, when calcination emissions in the production stage are considered, the carbonation uptake of mineral materials does not lead to net removal of CO₂ at the building level. At the building stock level, net biogenic carbon storage effects result in net storage equivalent to 1.27% of embodied GHG emissions, while mineral CO₂ fluxes, including carbonation, result in net emissions equivalent to 10.16% of embodied GHG emissions in the EU-27 building stock in 2020. The results at the material, building, and building stock levels can be used as a comparative baseline for future net-zero GHG research in the European context.