Benchmarking embodied carbon in structural materials

ABSTRACT To inspire structural engineers to contribute towards the vision of zero carbon buildings by 2050, this paper discusses the Structural Engineers 2050 Commitment. To participate, structural engineers are encouraged to share their progress with data on material quantities and embodied carbon in their structures within the database of embodied Quantity outputs (deQo). The literature reviews the variations in carbon emissions (Embodied Carbon Coefficients expressed in kg of CO₂ equivalent or CO₂e per kg of material) for common structural materials. These variations illustrate why it is necessary to collect data on material quantities in buildings rather than the end result in terms of carbon emissions of building structures: once the ECCs of materials become more accurate, the collected material quantities can be used to update the Global Warming Potential (expressed in kg of CO₂e per m² of floor area or another functional unit) of the building structure. This is needed to create benchmarks of embodied carbon in building structures. To align methodologies for evaluating embodied carbon in industry practice and in deQo, an LCA specification guide is being published by the Carbon Leadership Forum. From the presented benchmarking efforts, strategies to lower embodied carbon are derived: structural optimization and low-carbon material choices. Compared to conventional practices in concrete, steel and timber structures, these strategies are applied to project case studies provided by Magnusson Klemencic Associates. In particular, new lower carbon construction materials under development are explored to illustrate the potential reductions toward the goal of zero carbon buildings by 2050.