Investigating thermal performance of 3D-printed cubic lattices integrated in bio-based nonwoven assemblies under wind exposure

Cold-weather protective clothing must retain high thermal resistance in windy environments. 3D-printed lattice structures present a novel approach to enhancing the thermal resistance of textile assemblies; however, their potential for wind protection and airflow management remains largely unexplored. This study experimentally investigates the heat transfer behavior of a hybrid insulating composite consisting of a bio-based nonwoven textile integrated with a 3D-printed cubic lattice structure. Five lattice opening ratios (0 −100%) were integrated with the nonwoven in two configurations with the lattice positioned either above the nonwoven or beneath it. These configurations were evaluated to quantify how geometric arrangement influences airflow and thermal resistance. Standardized ISO 11092 tests were performed under controlled horizontal wind (1 m·s⁻¹) and under vertical wind (4 m·s⁻¹) to examine the role of forced convection. Under horizontal wind, all assemblies improved thermal resistance by ∼40%, with no significant differences among opening ratios or positions. Under vertical wind, the nonwoven alone lost more than 80% of its insulation, while above-positioned lattices restored and surpassed baseline performance. The lattice with a 25% opening ratio delivered a notable improvement, increasing thermal resistance by over 350% while generating high airflow resistance. Pressure-drop results showed that lower opening ratios impose higher airflow resistance, directly correlating with insulation gains. Statistical analysis confirmed the strong effects of opening ratio and orientation on thermal performance. The findings demonstrate that lattice geometry provides a tunable structural lever for controlling convective heat loss in porous materials, offering fundamental insight into geometry-dependent thermal transport relevant to advanced insulating systems.