Small test rooms (100 mm 100 mm 100mm) were set up using 6 pieces of the boards with the dimensions of 100 mm 100 mm 10 mm, in which five boards were made of the ordinary cement mortar, and the four boards with the percentages of the n-octadecane/EG composite PCMof 0, 0.5,1.2 and 2.5%were used as the top board, respectively