This study analyzes the performance of phase change materials (PCMs) to control and optimize energy in buildings. The utilization of PCMs could decrease energy consumption and enhance indoor thermal comfort of occupants in buildings. For this purpose, a computational model-based optimization is developed to estimate the thermal behavior of a multilayer wall of the building envelope in hot climate locations. The finite element model is coupled with design exploration tools based on design of experiments methodology to investigate the thermal behavior of PCMs under various parameters such as PCM thickness and location as well as melting temperature and melting zone is implemented in the computational model for a simulation period of 10 days. Optimization analysis is conducted using ANSYS software to obtain a set of PCM thermophysical and geometrical parameters which minimize the heat flow into the building. The simulation was carried out for 10 days and the findings of this study showed a reduction by 80% in the heat entering the building when using PCMs. The analysis shows the possible application of PCMs as a mechanism to improve the thermal performance of the building envelope and decrease energy consumption in hot climate regions.