Phase change material (PCM) applied in multilayer glazing facades can reduce energy consumption and increase thermal comfort by improving their thermal energy storage capacity. In present work, a simplified calculation method is developed to analyze its thermal performance, which considers the convective heat transfer of air layer and the radiative heat transfer of PCM layer. The model was validated by the experimental results collected in a facade test facility. A fairly good agreement between the measurements and predictions is obtained. The effect of PCM thickness on the thermal performance of the facade system was also investigated by the developed model. Numerical results showed that by increasing the PCM thickness, time lag increases and the interior surface temperature rises approaching the room temperature, i.e. smooth indoor temperature. PCM thickness has a significant impact on the trade-off between thermal and solar transmittance performance of facade system. It was concluded that the heat loss through the multilayer glazing facade can be reduced significantly by utilizing PCM even with a thickness smaller than 20 mm.