Passive latent heat thermal energy storage technologies with phase change materials (PCM) provide a potential solution to reduce energy demand and regulate the thermal comfort in occupied buildings. In this study, a numerical investigation is carried out on PCM-enhanced integrated building walls under the semi-arid climate to set the key parameters for the effective utilisation of PCM. A parametric study of PCM-composites walls is performed, including phase-change temperatures range, thicknesses, location, configurations, and mechanical ventilation effect on the performance of PCM integrated building walls. The results showed that the PCM-integrated walls improve indoor comfort and reduce cooling and heating loads and temperature fluctuations. The optimal PCM was RT-28 HC for the semi-arid climate with the highest annual average ATFR of 1.91 °C. In addition, the use of the double layers and triple layers PCM is more efficient compared to the single-layer PCM with energy consumption reduction from 7,30% to 15,21%. Also, the triple-layer system with mechanical ventilation showed the best energy efficiency and load shifting performance in the summer season. Finally, this research reveals that a triple configuration PCM wall comprising the paraffin RT-21+RT-25+RT-28 HC as PCM provides an optimal energy performance for heating in winter and free cooling in summer, as well as an annual energy saving of 102 kWh and 324 kWh in the heating and cooling season respectively, which considerably reduces the annual energy consumption.