fib Bulletin 121. Sustainability of structures with precast elements

The construction industry needs to adopt sustainable practices to address environmental, economic, and societal challenges. Precast concrete structures offer several benefits, including increased construction speed, improved quality control, and reduced waste. They also have inherent qualities that make them attractive for sustainable construction, such as optimised material use. In this context, multi-criteria decision-making tools can be useful to assess the sustainability performance of buildings and structures. This bulletin proposes a model to assess the sustainability of structures with precast elements based on MIVES. This method involves creating a decision tree, normalising indicators using value functions, assessing alternatives, and aggregating results. In the model developed, the decision-making model includes three requirements: economic, environmental, and social. This model was applied to a case study of a 5-story reinforced concrete commercial building. The model compared the sustainability of two different designs: a prefabricated solution and a cast-in-place solution. The results showed that the prefabricated solution was more sustainable overall, with higher scores in environmental and social sustainability. However, it was slightly less cost-effective than the cast-in-place solution. A sensitivity analysis was conducted to assess the impact of varying the weights of the decision tree requirements on the results. The analysis found that the prefabricated solution remained more sustainable regardless of the weight combination. While MIVES was chosen for its flexibility, alternative methodologies can be considered for similar purposes. This bulletin represents a step towards quantifying sustainability performance, and ongoing research and debates are necessary to refine methodologies.