The paper presented a non-equilibrium heat, air, and moisture transfer model in bio-based building materials. The macroscopic approach was used to model the porous building material. The three phases, i.e., the solid matrix, bound water, and humid air, were considered. Four transport equations were formulated, i.e., the bound water, dry air, vapor continuity equations, and the energy equation. The interaction between bound water and vapor was modeled using a non-equilibrium sorption-desorption source term to accurately represent the coupling mechanisms. The non-equilibrium approach implies that the sorption-desorption process occurs at a finite rate. The model was implemented in ANSYS Fluent software using advanced customization interfaces such as User-Defined Function (UDF), User-Defined Scalar (UDS), and User-Defined Memory (UDM). A custom experimental setup was designed and developed to validate the proposed model. The setup was placed in the climatic chamber, enabling control of the test conditions. Measurements were conducted on a hemp concrete sample. During the experiments, the temperature was kept at a constant level, while the relative humidity varied. These changes in ambient conditions forced heat and moisture transfer between the sample and its surroundings, which was carefully monitored. The experimental data obtained were then used to validate the model. The simulation results were found to be in good agreement with the experimental data during the sorption process, but the desorption process was modeled with too slow kinetics.