How much better does a concrete building have to perform energy-wise to have the same CO2-impact as a timber building? : A Life Cycle Assessment study

Abstract: This thesis aims to calculate the life cycle emission of a timber building and compare it to a concrete alternative. Furthermore, to investigate whether there is a chance that the total impact of the concrete model can be off-set completely by certain design strategies. The case study under investigation was called “Cederhusen – Bologna” which is located in Hagaesplanaden in Stockholm. The methods that have been used in this project are energy simulations and life cycle assessment. First the energy simulation was conducted for the timber model then an LCA. Same was done for the concrete twin model in the light of a reference project. Later, the emissions of the two models were compared and hotspots were found. Using the findings from the hotspot analysis, alternative improvement scenarios for the concrete model were created. The results showed that all life cycle stages included, the original timber building yielded 32% less emissions than its concrete twin. The hotspot analysis revealed that for the timber building the order of largest percentage impact by material was insulation, timber, gypsum boards and for the concrete one: ready-mix concrete, reinforcement steel, insulation. By choosing the best of materials and installing PV panels, it was possible to shrink the whole life emissions by 22% for the same concrete design. The author sees a great opportunity of future research to improve the accuracy of this study and potentially, to reveal more unknown facts. This can be achieved mainly by obtaining more information on the excluded parts of the building for LCA, trying out multiple climate scenarios during the sensitivity analysis, employing Eurocode 5 for a better and more realistic structural load bearing aspect of the case study.