Catalyzing sustainability through prefabrication: Integrating BIM-LCA for assessing embodied carbon in timber formwork waste

Prefabrication is effective in reducing construction waste, as well as mitigating the associated carbon emissions. Timber formwork, as a crucial source of construction waste, has a substantial influence on the environmental performance of construction projects. Since no previous studies have investigated the effectiveness of prefabrication for reducing embodied carbon from timber formwork waste, this study develops a building information modeling (BIM) model of a case study building for quantifying timber formwork waste reduced under different prefabrication rates. The embodied carbon from cradle-to-cradle and during the materialization phase of timber formwork is calculated by employing life cycle assessment (LCA), while Monte Carlo simulation is conducted for uncertainty analysis by varying the parameters of consumption rates related to timber formwork waste. The results show that the manufacturing phase of timber formwork accounts for the largest proportion of embodied carbon: 83% during materialization and 78% throughout the cradle-to-cradle life cycle. The study also concludes that at a prefabrication rate of 88.47%, 30.38 kg/m² of timber formwork can be saved, resulting in reductions of 11.43 kg/m² and 10.80 kg/m² of associated embodied carbon during the cradle-to-cradle life cycle and during materialization, respectively; conversely, at a prefabrication rate of only 30.08%, the reduction in embodied carbon during both phases decreases to 4.57 kg/m² and 4.32 kg/m², respectively.