European industry, including the building sector, is aiming to shift to a “Bioeconomy”, relying on forest products to decrease their climate impacts while boosting economic growth. Life Cycle Assessment (LCA) is a tool used to analyze the environmental impacts of design alternatives of buildings, where biobased alternatives are often favored when a comparison with non-biobased alternatives is made. LCA of biobased products has methodological complexities that are not addressed traditionally in LCA studies such as biogenic carbon dioxide sequestration, storage and emission, timing of emission and impact characterization factors, storage in longlived products, changes in forest carbon stocks, and land-use baseline in the forest. The aim of this work is to discuss these complexities, and how they affect LCA of biobased materials and comparative studies. Case studies of different constructions are analyzed using the Dynamic LCA method under different methodological setups to study the effects of assumptions where these complexities are accounted for. Results show that these methodological complexities have a significant influence in the outcome of an LCA, and therefore should not be overlooked. Different methodological setups can influence the outcome of an analysis, being the choice of time horizon and end-of-life scenario the most influential assumptions. Despite the difference made by these assumptions, results still favor biobased building materials in a significant majority of the studied setups, but the gap between biobased and non-biobased increases, especially in those where the time of biogenic carbon is storage in products is maximized. Recommendations based on the results are also given.
Keywords: life cycle assessment, forest products, timber buildings, timber bridges, climate impact assessment
Authors
Peñaloza D.
Department of Civil and Architectural Engineering, KTH Royal Institute of Technology
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