Concrete floors: multi-criteria analysis of conventional and novel solutions

As floors account for a significant share of a building’s embodied carbon, designing low-carbon floors is crucial to mitigating construction’s environmental impact. This research presents a multi-criteria comparison of four concrete floor systems: two widely used conventional systems —flat concrete slabs and timber-concrete composite slabs—and two novel systems —concrete thin shells and systems reusing concrete and steel elements. Six qualitative and quantitative criteria (embodied carbon, total depth, self-weight, waste use, deconstruction ease, supply ease) are used to compare the systems. Additionally, the study examines the sensitivity of key embodied carbon parameters such as material selection and transportation distance. Compared to flat slabs, the novel systems and timber-concrete composite slabs achieve embodied carbon reductions of up to 80 % and 40 %, respectively. While no system outperforms all criteria, the novel solutions surpass flat slabs in all aspects except supply ease and total depth. Since embodied carbon is not yet restricted in Swiss construction, flat slabs remain advantageous and largely prevalent due to their slenderness and ease of construction. To meet carbon reduction targets, the authors call for further supply-chain and business-model investigations and optimisation of the novel systems.