Assessing Plastic Material Options for Large-Scale Robotic 3D-Printed Facades

Large-scale robotic 3D printing (LSR3DP) has emerged as a promising technology for the production of customized architectural façade components, enabling geometric freedom without the need for dedicated molds or tooling. To date, most experimental façade applications have relied on PETG due to its favorable printability, despite the fact that this material was originally developed for packaging applications rather than building envelopes. This study investigates the suitability of transparent polymer materials for LSR3DP façade systems through a comparative assessment of PETG, polycarbonate (PC), polymethyl methacrylate (PMMA), and the bio-based polymer Durabio. The materials are evaluated according to both façade-performance and manufacturing-related criteria, including heat resistance, impact resistance, resistance to photo-oxidation, reaction to fire, and production ease. The methodology combines literature review, numerical thermal simulations, accelerated weathering experiments, and reaction-to-fire testing adapted from EN ISO 11925-2. Thermal simulations were conducted for different climatic contexts and façade configurations, while artificial weathering experiments assessed optical degradation through Yellowing Index measurements. Fire behavior was evaluated using small-scale flame exposure tests on 3D-printed specimens. The results demonstrate significant differences among the investigated materials. PETG exhibits the best printability but limited thermal resistance and poor resistance to photo-oxidative aging without stabilization treatments. PC provides superior heat and impact resistance together with favorable fire behavior, although its high thermal shrinkage complicates large-scale printing. PMMA and Durabio show excellent optical stability and long-term durability, as well as moderate printability, but both display less favorable fire behavior. The study highlights that no single material optimizes all performance criteria simultaneously, emphasizing the need for application-specific material selection in robotic 3D-printed façade systems. More broadly, the research contributes a comparative framework for evaluating transparent polymers in architectural Additive Manufacturing (AM) and identifies key challenges for the industrial adoption of digitally fabricated façade technologies.