Development of a rating system for the embodied carbon of 2D building elements based on their structural performance

Abstract

Climate change and how to prevent it is most likely one of our generation's most discussed topics. It varies from person to person how much action they take towards reducing their own carbon emissions. Popular choices might include flying less, biking to work, or not buying redundant consumer goods, just to name a few. In general, the efforts that are beneficial to the environment can be gathered in the 9R categorization: Refuse, Reduce, Reuse, Repair, Refurbish, Remanufacture, Repurpose, Recycle, and Recover. A problem that arises when planners are trying to reduce their projects' embodied carbon emissions is that the results of LCA calculations rarely offer information on local saving potentials. Without this information, implementing any changes that improve the carbon footprint of a project is difficult and requires a lot of experience and estimation.The scope of this thesis is to research if it is possible to rate the carbon efficiency of a load-bearing element accoding to it's load-bearing capacity. A new rating system with this logic will be introduced to aid structural engineers in finding carbon saving potentials in their projects' structural elements. The approach to achieve this, is to rate single span beams and pinned columns by their ratio of embodied carbon to their load bearing capacity in kgCOe/kN and establish benchmark values to estimate the quality of the result.The method to achieve this is to create a large variety of structural beams and columns with different geometries, materials and loadings. They will be verified according to the respective Eurocodes and then analyzed for their embodied carbon.It was found, that the median of the embodied carbon to load bearing capacity ratio of a beam is 7.22 kgCOe/kN and that of a column 0.228 kgCOe/kN. The established benchmark values for beams are smaller than 1.86 kgCOe/kN for an A++ rating and larger than 68.45 kgCOe/kN for a G rating. For columns, the benchmark values are smaller than 0.074 kgCOe/kN for an A++ rating and larger than 1.809 kgCOe/kN for a G rating.The established rating system will require further development to include more complex elements. However, it is already provides a key figure for structural engineers to identify carbon saving potentials of their projects' structural elements and therefore contribute to a more sustainable built environment.