Enabling rapid prediction of quantities to accelerate LCA for decision support in the early building design

Buildings are a significant contributor to climate change. This is why life-cycle assessments (LCA) are becoming increasingly popular for documenting environmental impacts during the detailed design stages of building projects, level of development (LOD) 300–400. In that context, wood is gaining recognition as a material that can reduce the embodied impacts of buildings. However, of particular concern is the incapability of research and practice to generate quantities rapidly in the early design stage. It is an underlying key issue for enabling LCA as decision support in these early building designs. Therefore, this study's aim is two-fold: (i) introducing a simplified design tool for wood dwellings and assessing how the predicted early design climate impacts perform compared to detailed design case studies (ii) evaluating the root causes for predicting trustworthy climate impacts in the early design. The LCAbyg tool assessed the impacts of the life-cycle phases A1-A5, B4, B6, and C3–C4. The climate impacts of the simplified designs (LOD 100–200) were analysed against ten detailed design buildings with the impact disaggregated into life-cycle phases, component types and material categories. The simplified design tool shows it is reliable for comparing the various GHG emissions associated with different designs. Still, the total impact is underestimated by an average of 12% compared with the detailed modelling. It primarily arises from the lack of simplified design metals and that a single product in a component can constitute up to 53% of the climate impact. So, the LCA is sensitive to chosen generic processes, EPDs, and quantities estimations. This study points to the critical elements in material quantification and related climate impact between simplified and detailed building designs. The study also adds to the body of scientific literature on wooden building designs by presenting the quantities and GWP results for ten dwellings constructed between 2010 and 2021. Terraced houses with specific design elements, paper wool, and footing foundation show promising carbon reduction abilities here. In addition, the simplified tool has the potential to get small and medium-sized enterprises in the building industry on board with the sustainability agenda and lead to broader adoption of LCA in their practices.