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To face the climate change and carbon neutrality, reductions of energy-uses and carbon emissions are imminent. Pipe-encapsulated phase change material (PenPCM) wall is a novel envelope system with renewable energy utilizations in buildings. It combines the PCMs, nocturnal radiant cooler and gravity heat-pipe with the wall to achieve the automatic heat insulation and removal without the mechanical energy. Parameters may have influences on system performances and the parametric analysis is understudied. In this study, the influences of parameters including phase-change temperature, PCM thickness, pipe-spacings, cooler areas and orientations are investigated. The system applicability for different climate regions is also studied. Results show that, when the phase-change temperature is 27–29 °C, the ratio of the cooling load reduction to the cooling load of the conventional wall reaches largest with 17.4%. Appropriately increasing the PCM quantity can improve the thermal-storage capacity and decrease the wall temperature fluctuation. Enlarging the cooler area can increase the energy-saving effect of the PenPCM wall system. For different climate regions, the PenPCM wall system is applicable. Compared with conventional wall, the ratio of the cooling load reduction from June to September can reach 11.7%, 16.1%, 21.1%, 28.6%, 44.2% respectively for Hong Kong, Wuhan, Beijing, Harbin and Kunming. [ABSTRACT FROM AUTHOR]

Roof is a weak part of the building envelope due to the high intensity of solar radiation in summer. Improving thermal performance of roof is crucial to reduce energy consumption. In this study, the thermal performance of a new ventilation roof with shape-stabilized phase change material (SPCM) is investigated. The dynamic heat transfer model for this roof is established by coupling the number of transfer units (NTU) heat exchange model with the resistance-capacity dynamic heat network model and used to analyse the heat transfer. The accuracy of the model is validated by experiment. The indoor air temperature, internal surface temperature of the roof, and cumulative cooling load in summer are simulated and analysed in Wuhan. The results show that PCM and night ventilation have great energy saving potential. When the 30 mm PCM is applied, the peak indoor air temperature and peak internal surface temperature decreased by 2.9 °C and 5.5 °C, respectively, and the cumulative cooling load of the building decreases by 19.2%. When night ventilation is applied (v = 3 m/s), the average latent heat utilization rate of the PCM layer increases, and the cumulative cooling load decreases by 22.9% and 37.5% compared with the PCM roof and the reference roof, respectively. [ABSTRACT FROM AUTHOR]