In this work, thermal performance of a conventional brick incorporating phase change material (PCM) is studied. The influence of brick containing PCM on heating and cooling loads is examined considering different fusion temperatures, locations and quantities of PCM. Seasonal and annual thermal performance analysis of brick filled with PCM is evaluated and quantified for climatic conditions of Marmara region, Turkey, by an established and verified numerical model. The obtained results are compared with those of conventional brick and brick filled with phase stabilized material to identify the contribution of latent heat to energy saving. The results showed that filling the gaps of brick near the indoor ambient provides a higher energy conservation. The optimum fusion temperature of PCM varied from season to season in the range of 18-26 degrees C. An adverse effect of the latent heat activation was observed in summer season, causing higher cooling energy demand by an inappropriate selection of phase transition temperature. Then, an annual analysis was performed to determine the optimum melting temperature which was found to be 18 degrees C. By incorporating PCM to the brick, the annual thermal load decreased by 17.6%, 13.2% of which was attained due to the utilization of latent heat. The outcomes of this study suggest that the integration of PCM with optimum fusion temperature into the brick can reduce heating and cooling loads considerably in every season of the year and provide thermal comfort for the occupants.