CaCl2 center dot 6H(2)O/expanded graphite (EG) composite phase change material (PCM) with melting and freezing points of 27.11 degrees C and 21.67 degrees C and corresponding latent heat values of 118.7 J/g and 115.7 J/g was employed to fabricate the PCM panels for building application. The thermal performance of the test room equipped with the PCM panels at each position was evaluated by placing the room in an artificial climatic chamber. Compared with the reference one without the PCM panels, the test room equipped with the PCM panels exhibited much lower maximum temperature, higher minimum temperature, and reduced temperature amplitude, revealing the function of the PCM panels for reducing indoor temperature fluctuation. Furthermore, the investigation on the effect of the position of the PCM panels indicated that, the more inside position the PCM panels were placed at, the better thermal performance the obtained test room had. Moreover, numerical modeling was carried out to study the thermal performance of the PCM panels containing the CaCl2 center dot 6H(2)O/EG composite. It was found that the results from the numerical modeling agreed well with those from the experimental investigations. Base on the numerical modeling, it was found that the optimum thickness of the PCM panel was about 8-10 mm, and the thermal performance of the CaCl2 center dot 6H(2)O/EG panels was better than that of the RT27/EG. It is revealed that the CaCl2 center dot 6H(2)O/expanded graphite composite PCM shows great promise in building energy saving. (C) 2017 Elsevier Ltd. All rights reserved.