Phase change materials is one of the innovative technologies to reduce the heating and cooling demand of buildings. In this research, the thermal performance and energy efficiency of PCM-incorporated residential house located in Sharjah and Al-Ain cities using DesignBuilder software have been evaluated. According to the simulation results, for both cities PCM 32 was found to be the most effective with energy consumption reduction around 19%. The optimum PCM decreased the maximum temperature by up to 1.09oC and was able to reduce temperature fluctuations. For constant volume, the influence of different thicknesses and surface area on energy savings was evaluated and it was found that energy savings increased with the increase in surface area and decrease in thickness of PCM layer. Finally, from correlation analysis, it was found that relationship between energy savings and meteorological factors like wind speed, temperature, relative humidity and solar radiation exist.