Climate change and surplus energy consumption are significant problems in the global scenario. The demand for effective thermal management technologies is expected to grow, and one such technology is the usage of phase change materials (PCMs). PCMs facilitate passive cooling in buildings, which is crucial in managing thermal environments and improving energy efficiency. Incorporating PCM into the building envelope increases its thermal mass by reducing overall heat transfer. While research into the thermal storage capacity of PCMs for various applications is extensive, their utilization remains restricted due to high initial costs. Additionally, there are limited studies examining the influence of PCMs on the thermal environment in tropical climates. This study delves into the effect of PCMs on the thermal environment within an office in Tiruchirappalli, a warm and humid climate. Through an extensive literature review, two PCMs suitable for tropical climates have been identified. The research aims to comprehend PCM's effects by analyzing surface temperature fluctuations throughout the day and night and how they impact the thermal environment of the space. Design builder software with the finite difference algorithm focuses on critical parameters such as air temperature, relative humidity, and surface temperature. To comprehensively assess PCM performance, the study examines its impact during the hottest and coldest days of the year. A series of iterations are conducted with the selected PCMs, involving placement on various wall orientations and varying thicknesses. This thorough investigation aims to capture the nuanced effects of PCM integration within the office environment. The findings indicate that PCMs outperform conventional building materials, showcasing their potential to significantly improve thermal environment and energy efficiency in warm and humid climates like Tiruchirappalli.