This paper develops a numerical model for simulating heal and moisture transfer through a porous insulation, with impermeable, adiabatic Vertical boundaries, and with one horizontal boundary facing a warm humid ambient and the other facing a cold impermeable surface. The problem is modeled as one-dimensional, transient, multi phase flow with variable physical properties. The analysis has identified four phases of energy and moisture transport processes, and they are formulated by a system of transient intercoupled equations and several thermodynamic relations using the local volume averaging technique. The numerical model is validated by comparing with experimental data for different operating conditions and for times up to 600 h. The model predicts the temperature distribution, the heat transfer and the total moisture gain successfully. The predicted liquid distribution agrees with measured data for a period of up to 70 h. The interesting effects of pertinent parameters on the energy and moisture transfer in the porous insulation are investigated.