Performance evaluation of a PCM-embedded wall integrated with a nocturnal sky radiator

Abstract In recent years, building energy saving technologies are attracting more and more attention worldwide. A PCM-embedded wall coupled with a nocturnal sky radiator is proposed for active heat defense with the outer dynamic thermal environment. This new system can improve the building energy performance and utilization efficiency of PCM with diurnal building insulation through co-work of the PCM, nocturnal sky radiator, and active heat removal mechanism of circulating water. This paper investigates the thermal and energy performance of a typical room with the new wall system in cooling season. The system energy efficiency is analyzed by comparing with a common PCM wall and a common wall without PCM. Main influential factors on system energy efficiency are analyzed and results show that, comparing with a common wall, the average temperature of internal surface of the new system is reduced by 1.6 °C. The reduction of the cooling demand and energy-saving ratio are respectively 37.8%–57.8% and 15.7%–24.1% comparing with the reference system. Besides, the impacts of pump operation hours, area of the nocturnal sky radiator, the wall orientations and phase change temperature are discussed in depth, which can provide a useful guide for its further developments and applications.