Encapsulation box of tetradeconic acid was heated and naturally cooled under a simulated hot wall condition by a thermostat oven. Thermocouples were embedded into different positions of encapsulation box for monitoring the evolution of temperatures. Based on the test results, the effects of encapsulation material type and thickness on exothermic and endothermic process of the encapsulation box were analyzed. The results show that the encapsulation box of tetradeconic acid absorbs and reserves a great deal of heat during the heating period, and a continuous heat release stage is found during the cooling period. Therefore, the encapsulation box of tetradeconic acid can be used to adjust temperature in the hot wall heated building. With increasing thickness of box, the heat storage and supply capacity for the surrounding space are increased. With the same box thickness, a 10%20% reduced complete phase time of tetradeconic acid is found for the aluminum encapsulation box when being compared with the boxes of copper or iron.