Reconciling Moisture and Dimensional Stability in Wood Through Cell Wall Reconstruction for Sustainable Buildings

ABSTRACT Reducing building energy consumption requires passive materials that buffer environmental fluctuations and lessen reliance on energy‐intensive heating, ventilation, and air‐conditioning systems. Wood is attractive for humidity regulation because its hydrophilic cell walls enable reversible moisture sorption; however, absorbed water also induces swelling, anisotropic deformation, and mechanical relaxation, imposing a long‐standing trade‐off between moisture‐buffering capacity and dimensional stability. Here, we report a cell wall reconstruction strategy in which D‐sorbitol forms a flexible multivalent hydrogen‐bond network with cellulose, while reconfigured lignin features strengthened covalent connectivity and enhanced interfacial coupling with cellulose, thereby modifying cell wall interactions associated with moisture uptake and deformation. The resulting wood combines a moisture buffer value of 3.9 g m − 2 %RH − 1 with a reduction in volumetric swelling from 13.6% to 2.5%. It exceeds native wood in modulus of rupture and impact toughness by 32% and 33%, respectively. Building energy simulations show that replacing gypsum board with reconstructed wood reduces office‐building energy demand, achieving a nationwide weighted energy‐saving rate of 12.9%. By coordinating cellulose, D‐sorbitol, and lignin interactions, this work establishes a molecular design principle for adaptive biomass‐based building materials that convert moisture into a functional resource for passive environmental regulation.