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The hollow block ventilated wall is a new kind of ventilated wall, the exhaust air of HVAC system is used as the supply air to flow through the cavity of this wall in this paper. The heat or cool storage in the wall is reduced by using the heat recovery technology; the temperature of internal surface is lowered in summer and increased in winter, and the human thermal comfort is enhanced. A semi-dynamic heat transfer model of the ventilated wall is presented for thermal performance prediction. The dynamic optimized resistance-capacitance (ORC) model and the number of transfer units (NTU) model are joined together to develop the semi-dynamic heat transfer model of this ventilated wall. The experimental study is carried out for validating the semi-dynamic heat transfer model. The maximum relative error is 4.3% for mean internal and external surface temperatures, and it is 2.6% for the outlet air temperature of the cavity. The heat transfer model established for hollow block ventilated wall is fairly reasonable and possesses high accuracy. This model can be used to predict the surface temperature of the hollow block ventilated wall and the heat flux removed by the airflow in the cavity for performance evaluation. [ABSTRACT FROM AUTHOR]

Pipe-encapsulated PCM wall system with self-activated heat removal by nocturnal sky radiation cooler is a feasible means for building insulation and heat removal by using natural energy. In this paper, a system simulation platform including the simplified pipe-encapsulated PCM wall model, heat pipe heat-transfer model and nocturnal radiation model are established to investigate the thermal performance of the pipe-encapsulated PCM wall system with self-activated heat removal by a nocturnal sky radiation cooler. The temperature and heat flow of this system used in light-weight, medium-weight and heavy-weight walls under a dynamic boundary condition are respectively simulated on this platform. Results show that about 55.6%–82.8% of heat from the outdoor can be resisted by the pipe-encapsulated PCM wall, and 54.7%∼81.0% of that can be removed by the nocturnal radiation cooler at night. Comparing with the common wall, the proposed system can reduce by 32.4%∼55.5% of the accumulated heat entering into indoor environment. Good energy-saving potential can be achieved by this pipe-encapsulated PCM wall system. Besides, the result further reveals that the reduction of the accumulated internal surface heat transfer of this system used in medium-weight and heavy-weight walls is obvious larger than that of this system used in light-weight wall. • System platform of a pipe-encapsulated PCM wall system with heat removal. • Thermal performance of three walls (light, medium, heavy) with the PCM wall system. • 55.6%–82.8% of heat from the outdoor can be resisted by the PCM wall system. • Reduction of heat into the indoor is lager for the heavy wall with the PCM system. [ABSTRACT FROM AUTHOR]

Highlights: [•] Sensitivity analysis of energy performance is performed for residential envelope. [•] EETP method is introduced to calculate cooling and heating energy use. [•] Shading coefficient and window to wall ratio are the most vital factors in summer. [•] Wall heat transfer coefficient and shape coefficient have crucial effect in winter. [•] Wall heat transfer coefficient and window to wall ratio weight the most in a year. [ABSTRACT FROM AUTHOR]