Multiscale thermal optimization of 3D-printed walls: integrating structure, material, and process with fire-thermal synergy

Abstract The rapid development of 3D printing in construction presents new opportunities to enhance building energy efficiency through optimized wall systems. This review systematically analyzes 99 studies from 2018 to 2025 to elucidate the multiscale interactions among structural topology, material composition, and printing processes that govern the thermal performance of 3D-printed walls. Key findings indicate that thermal conductivity exhibits strong anisotropy (X > Y > Z) due to layer-by-layer extrusion, while internal configurations—such as cavities, sandwich composites, and bio-inspired structures—significantly enhance insulation and thermal inertia. Material modifications, including the incorporation of phase change materials, waste glass, ETM, and cork, further improve thermal performance, though potential trade-offs with mechanical strength must be considered. Additionally, synergistic fire–thermal design strategies, leveraging fire-resistant composites and layered functional systems, enable simultaneous optimization of thermal resistance and fire safety. Future research directions include the development of thermally adaptive materials, data-driven multiscale optimization, real-time performance monitoring via digital twins, multi-objective design frameworks, and climate-responsive standardization. This review provides a comprehensive framework for designing high-performance, thermally efficient, and fire-safe 3D-printed building envelopes.