ABSTRACT In hot‐arid climates with extreme diurnal temperature swings, achieving thermal stability through passive means remains a critical challenge in building design. This study introduces a novel 3D concrete printed (3DCP) honeycomb wall system incorporating a 30% phase change material (PCM)‐sand composite as infill. Unlike conventional strategies, this work solves the “PCM‐printability paradox” by decoupling thermal and structural functions, using sand‐stabilized PCM infill to preserve mechanical integrity while achieving unprecedented thermal performance. The cellular honeycomb geometry, enabled by additive manufacturing, maximizes internal surface area and optimizes heat exchange between infill and environment. Finite element simulations under sinusoidal thermal loading and reflective of Middle Eastern desert conditions, demonstrate an ultra‐low decrement factor ranging from 0.00170 (linear model) to 0.00440 (Gaussian model), along with a 14‐h thermal time lag. These results significantly outperform both traditional wall assemblies and previously studied PCM‐integrated systems. Beyond attenuating indoor thermal fluctuations, the PCM‐sand infill contributes valuable thermal mass to the envelope, enhancing inertia and energy efficiency. This research presents a design‐integrated path toward thermally responsive, structurally sound, and highly adaptable building envelopes, advancing the pursuit of net‐zero energy‐efficient 3DCP buildings.
Mansouri et al. (Sun,) studied this question.