Comparative Life Cycle Assessment of Manual and Robotic Fabrication of an Unstabilized Rammed Earth Wall

Current rammed earth in situ practices face economic challenges that outweigh its ecological advantages, rendering it a niche product in the construction sector. This is mainly due to the inefficient and labor-intensive character of the manual construction processes involved, especially those related to formwork. The introduction of automated and robotic fabrication presents an opportunity to reduce the existing imbalance through digitalization, by shortening the building time and reducing labor input. In this paper, the associated potential environmental impacts of manual and robotic in situ manufacture of unstabilized rammed earth walls are compared and quantified in a life cycle assessment. The results show that robotic in situ manufacture is the more environmentally favorable option within the construction phase, with the highest optimization potential in the building phase. The standard robotic scenario demonstrates significant reductions across a range of environmental impact indicators of approx. 9–97% compared to the standard manual scenario due to a reduction of waste and formwork. Specifically, the GWP100-total is reduced by 28% and EE by 68%. Further key factor optimizations—including minimizing transport distances, using locally sourced loam, reducing packaging materials, and utilizing renewable energy—show even greater benefits. In the robotic procedure, this result in reductions in GWP100-total of 76% and EE of 70% compared to its robotic standard scenario, and to reductions of 83% and 90%, respectively, compared to the standard manual procedure.