Material intensity and embodied CO2 benchmark for reinforced concrete structures in Brazil

Cement and steel production significantly contribute to global CO2 emissions, with reinforced concrete structures accounting for a substantial portion. Therefore, optimizing the structural design helps reduce material and carbon intensity. However, industry-based benchmarks for material and carbon intensity of structures are scarce and lack transparency. This study fills this gap by analyzing detailed industry data derived from construction designs of 53 reinforced concrete structures for multifamily residential buildings in Brazil and assessing their cradle-to-gate material intensity and embodied CO2 emissions. The findings revealed significant variations in the usage of steel (70-159 kg/m3) and concrete (0.17-0.29 m3/m2). The quantity of structural materials ranged from 418 to 731 kg/m2, and the embodied CO2 ranged from 35 to 140 kg CO2/m2, including the variability in CO2 emissions during material production. Building height is the primary geometric parameter that determined material intensity and embodied CO2, particularly for columns. However, structural materials quantity varies considerably among buildings with the same number of stories, suggesting the presence of additional design parameters influencing material intensity. The results emphasize the role of designers in promoting decarbonization through dematerialization. Also, selecting the right material supplier is important as, on average, differences between manufacturers corresponds to a difference of 38 kg CO2/ m2 in structural embodied CO2. Selecting low-carbon material suppliers and employing structural design benchmarking practices can efficiently reduce the embodied carbon of reinforced concrete structures.