Construction 3D printing material selection: Minimizing cost and carbon footprint of residential wall assemblies

With the increasing prevalence of construction 3D printing (C3DP), a variety of applicable materials have been developed with sufficient strength for low-rise residential wall construction. However, the economic and environmental impact of these materials is not well understood in comparison to more common housing construction methods today. This research examines the upfront cost and carbon footprint of materials that have been previously employed in C3DP, including cements, geopolymers, clay- and earth-based materials, and polymers, per unit of strength applicable to common C3DP wall assemblies. A case study is then presented that evaluates the cradle-to-gate, cost, carbon footprint, and embodied energy of wall assemblies using a selection of these materials, in comparison to a functionally equivalent wood-framed wall assembly. The results show that up to 47 % of cost, 72 % of carbon footprint, and 61 % of embodied energy of a 3D-printed wall assembly can be eliminated through the partial replacement of Portland cement with supplementary cementitious materials. Regardless, the cost and carbon footprint of the best cementitious 3D printing materials evaluated do not rival wood-framed construction, which costs up to 55 % less and has 88–99 % lower carbon footprint (depending on the inclusion of carbon sequestration). Consequently, while C3DP can help to address the housing crisis in the U.S. through partial automation of the construction process, more sustainable materials must be developed for its use to avoid further escalation to the environmental impacts of building construction.