Thermal evaluation of non-deform laminated composite phase change material (PCM) gypsum board has been carried out. The theoretical studies covered the analysis of different thicknesses of PCM layers and their corresponding heat transfer rates during energy storage and discharge processes. For the purpose of experimental validation, a laminated gypsum board consisting of a 4 mm PCM layer was evaluated and achieved a maximum heat flux and energy storage capacity of 15.6 W/m2 and 363.7 kJ/m2 respectively. A model room built with the laminated PCM gypsum board was also evaluated and obtained a maximum temperature reduction of 5 °C as compared with 1.8 °C for the model room with ordinary gypsum board. Even though about 25% of the energy stored could not be released within the targeted period, the overall thermal performance of the PCM gypsum board was found to be quite remarkable.