The relevance of cut-stone to strategies for low-carbon buildings

A systemic and configurable model for evaluating the global warming potential (GWP) of cut-stone building materials on the French market is developed and then used to benchmark performances against available low-carbon alternatives (cross-laminated timber (CLT) and slag concrete), for which ranges of GWP allocation models (regulatory and research-driven methods) are used to evaluate underlying uncertainties. Cut-stones stand out for their compliance to three key emission profile criteria in which industrial ecology roadmaps should anchor incentives for material selection: (1) a low margin of uncertainty on GWP values, (2) invariability of GWP magnitudes through time and (3) a high comparative performance with available alternatives. Assuming typically implemented load-bearing wall thicknesses (industry averages of 13, 20 and 24 cm for CLT, concretes and cut-stone, respectively) and high-probability scenarios for all materials, cut-stone assemblies are shown to be 1.43 and 2.73 times less impactful (GWP100 ) than CLT and slag concrete, respectively. Potential impacts of industrial applications at the parc scale are studied, showing that implementing cut-stone instead of concrete walls on 30% of new French collective housing projects over the 2025–50 period would result in a 2.77 Mt CO2 e decrease in the embodied emissions of the parc, against 0.43 for slag concrete and 1.18 for CLT (high-probability).