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Efficient use of solar energy by thermal energy storage composites and utilizing environmentally friendly cementitious materials are important trends for sustainable building composite materials. In this study, a paraffin/low density polyethylene (LDPE) composite shape-stabilized phase change material (SSPCM) was prepared and incorporated into a sulphoaluminate cement (SAC) mortar to prepare thermal energy storage mortar. The thermal and mechanical properties of SSPCM and a SAC-based thermal energy storage material (SCTESM) were investigated. The result of differential scanning calorimeter (DSC) analysis indicates that the latent heat of SCTESM is as high as 99.99 J/g. Thermogravimetric analysis demonstrates that the SCTESM does not show significant decomposition below 145 °C. The volume stability test shows the volume shrinkage percentage of the SCTESM is less than that of pure SAC mortar and far less than that of ordinary Portland cement mortar. The SCTESM has high early strength so that the compressive strength at 1-, 3-, and 7-day curing age is up to that at 28-day curing age of 67.5%, 78.3%, and 86.7%, respectively. Furthermore, a mathematical prediction model of the SCTESM compressive strength was proposed. The investigation of latent heat storage characteristics and the thermoregulating performance reveals that SCTESMs have the excellent capacity of heat storage and thermoregulating.

To analyze the effect of summer ventilation on the thermal performance and energy efficiency of buildings utilizing phase change materials (PCMs), this paper simulated the indoor temperature variation and energy saving performance of buildings constructed with PCM under different ventilation conditions from June to September. With EnergyPlus and degree-day method, 48 ventilation schemes, including eight ventilation periods (3 h per period) and six ventilation quantities (0.5 ac/h to 3 ac/h), were modeled and simulated in five cities located in different climate regions in China. According to the results, it is believed that the simultaneous use of PCM and ventilation can significantly improve the indoor thermal comfort and offer a good energy saving performance in summer. Considering the economic benefits, different optimal ventilation schemes (including ventilation periods and ventilation quantities) were suggested for different climate regions.