Thermal and energy performance assessment of naturally ventilated roofs with phase change material

Abstract

The effect of incorporating phase change material (PCM) into roofing systems combined with natural ventilation is numerically and experimentally investigated. Four roof configurations, including ventilated and unventilated options with and without an air gap between the PCM and the insulation material, are subjected to experimental research during the winter season in a semi-arid climate using two fully instrumented modules. A sensitivity analysisis conductedthrough annual transient simulations fordifferentair gap dimensions and schedule openings. The experimental campaign demonstrates a decrease in the maximum peak indoor air temperature of between 1.9 and 4.4 %when the PCM is employed. Additionally, an increase in the minimum indoor air temperature between 4.4 and 10.4 % is achieved. Similarly, an improvement in the thermal performance of the PCMis observedwhen natural ventilation occurs, and it positively influences the interiorsurface temperature of the roof.Furthermore, the numerical results show almost zero annual thermal balance in the scenario where natural ventilation is allowed in the combination of 12 and 24 h per day through ducts with a diameter of 15 and 20 cm, respectively. Finally, this demonstrates that PCMroofs enhanced with natural ventilation could be an energy-efficientalternative for semi-arid climates under well-configured ventilation schedules and roof layers.