Optimisation of Embodied Carbon and Construction Cost of Concrete, Steel and Timber Piles  

The construction sector accounts for a considerable share of the carbon emissions globally. While extensive research has examined the embodied carbon and cost optimisation of superstructures, comparatively little attention has been given to optimising deep foundations with respect to these criteria. This study employs a hybrid genetic algorithm to optimise the embodied carbon and construction cost of six pile types across various soil conditions and load capacities. The results indicate that timber piles have the lowest embodied carbon, with reductions of approximately 70 % and 60 % compared to solid concrete piles in clayey and sandy soils, respectively. Hollow concrete piles exhibit lower emissions than solid alternatives, particularly at higher capacities. Steel piles, while structurally efficient, generally have higher embodied carbon than its other counterparts. Conversely, cost optimisation results show that solid and hollow concrete piles are the most economical, whereas timber piles are the most expensive due to their limited load capacity. A case study of a high-rise building in London's undrained clay demonstrated that carbon-optimised pile designs could achieve the same load capacity while reducing embodied carbon by 45 %–69 % and lowering construction costs compared to the as-built design. These findings highlight the potential for significant reductions in the embodied carbon of deep foundations through optimisation, without requiring changes to materials, design methods, or construction practices. The study underscores the call for industry-wide adoption of computational optimisation techniques to support sustainable foundation design.