Solar energy is clean and renewable energy; phase change material (PCM), used in buildings, can store the surplus heat and release when needed to save energy in winter. This paper establishes a new model of PCM floor coupled with solar water heating system (PFCSS). A module of PFCSS building was established in TRNSYS. The module was validated by a full-scale experiment. Two experiment buildings, a reference building and a PFCSS building, were set in Ninghe County of Tianjin, China. The experiment lasted for 15 days in February. Two mathematical methods, MRE (mean relative error) and Bland-Altman consistency analysis, are used to evaluate the accuracy of the model. In the comparison of the experiment data and simulation data of PFCSS building, MRE is 0.6% and the result of Bland-Altman consistency analysis is 95.1% (95% confidence interval -1.94-1.46). A model of the control building with ordinary radiant floor was set up to compare the differences in its temperature performance in relation to that of the PFCSS building. PFCSS building's temperature fluctuation is smaller and the heating process is longer than control building. If the indoor temperature is maintained at 20 degrees C, the PFCSS building can save 5.87% on the energy consumption, when compared with the control building. Based on these two existing models, the influences of PCM's thermal physical parameters on the indoor air temperature were analyzed by simulation. (C) 2017 Elsevier B.V. All rights reserved.