Embodied GHG emissions of reinforced concrete and timber structures: Relevance, driving factors and target values
Nuno Bernardo Machado, José Dinis Silvestre, Rolf André Bohne
Abstract
In order to deliver on the commitments made in the Paris Agreement and limit global warming to 1.5 °C, greenhouse gas (GHG) emissions must be limited to net zero by 2050. Monitoring and regulating life cycle emissions will be an important step in this direction, especially those considered as embodied. With a sample of 72 cases collected from literature, this study focuses on embodied GHG emissions from the material production of reinforced concrete and timber mid- and high-rise structures and assesses their role in complying with emission limits, investigates the influence of different factors, and establishes reference and target values. The comparison of the cases with benchmarks adapted from the SIA 2040 targets and based on a carbon budget of 1 t CO 2 -eq per capita in 2050 reveals that the production of materials for reinforced concrete structures consumes most of the budget allocated for embodied emissions. Opting for a timber structure can increase the available budget for the other components and life cycle stages of the building and, in some cases, can make the difference between meeting and not meeting the requirements. The results also show that the structural weight of buildings is the driving factor of embodied emissions. Based on the 50th and 5th percentiles of modelled distributions, the reference and target values are, respectively, 3.8 and 1.6 kgCO 2 -eq/m 2 .y for reinforced concrete structures, and 1.3 and 0.4 kgCO 2 -eq/m 2 .y for timber structures.