Enhancing life cycle assessment for circular economy measurement of different case scenarios of modular steel slab

Life cycle assessment (LCA) has emerged as an essential method to evaluate materials' environmental impact. However, using LCA for assessing other dimensions of circular economy (CE), such as the technical, social, system, and functional dimensions, is fraught with several challenges. In this study, the LCA system boundary was extended to cradle-to-cradle and combined with the predictive building systemic circularity indicator to determine the environmental, technical, functional, and system dimensions of different case scenarios of the product system of a modular steel slab of a residential building in China. It was identified that the base scenario of the case slab could lead to about 50.4% of the mass of the slab being recyclable at EoL. In comparison, 0%, 70.8%, and 38.8% of the mass of the slab being recyclable were recorded for case scenarios one to three, respectively. The environmental impact of the scenarios showed that the base scenario would induce 38.64 kg CO2/m2 in global warming potential, while 68.2, 28.2, and 44.95 kg CO2/m2 were noted for case scenarios one to three, respectively. The simple additive weighting method was used to select the optimal scenario for the product system of the case slab. Adopting the optimal scenario for the case slab should lead to positive impacts and high recoverability at EoL. Implementing this iterative integrative method for assessing product systems enables considering the environmental, technical, systems, and functional dimensions of CE in assessments, which should lead to inclusive, sustainable decision-making.