Temporally‑differentiated biogenic carbon accounting of wood building product life cycles

摘要

Although standards have identified temporary carbon storage as an important element to consider in wood productLCAs, there has been no consensus on a methodology for its accounting. This work aims to improve the accounting of carbonstorage and fluxes in long-life wood products in LCA. Biogenic carbon from harvested roundwood logs were trackedusing the Carbon Budget Model Framework for Harvested Wood Products (CBMF-HWP). Carbon flows through woodproduct manufacturing, building life and end-of-life phases, and carbon stocks and fluxes from harvest to the atmospherewere estimated. To cover the products commonly used in the Canadian building industry, a range of softwood productstypes, provinces and territories and building lifetimes were considered. In addition, policy scenarios were consideredin order to model the effects of dynamic parameters through time as a policy target is reached. Most wood productshave similar emissions profiles, though cross-laminated timber has higher sawmill emissions and oriented-strand boardhas higher initial post-demolition emissions. The region of construction is also predictive of the initial post-demolitionemissions. Higher recycling rates shift materials from landfills into subsequent product systems, thus avoiding landfillemissions. Landfill decay rates are affected by climate and results in a large range of landfill emissions. The degree ofpostponement of end-of-life emissions is highly dependent upon the wood product type, region and building lifespanparameters. This work develops biogenic carbon profiles that allows for modelling dynamic cradle-to-grave LCAs ofCanadian wood products.