A numerical simulation, employing a local-volume-averaging formulation, was validated for each flow direction (exfiltration/infiltration), based on the experimental temperature and moisture accumulation results obtained in Part I of this study. The predicted results compare well with the measured temperature profiles throughout the insulation slab for both air exfiltration and infiltration. The comparison for the moisture accumulation profiles is generally reasonable, except for locations near the boundaries. Discussion is presented for the model evaluation. The simulation results indicated that air exfiltration and air infiltration through fiberglass insulation can increase the combined heat flux at the cold surface by factors of more than 13 and 6, respectively, compared to dry, no-flow conditions