Enhancing energy efficiency in hot climate buildings through integrated photovoltaic panels and green roofs: An experimental study

Numerous research has included passive cooling techniques and renewable energy-generating technologies to enhance the near-zero energy community. This study aims to evaluate the impact of various Green Roof (GR) parameters on photovoltaic performance, indoor thermal comfort, cooling energy savings, and CO2 emissions. The study focuses on the effect of parameters such as soil type, soil depth, irrigation, vegetation layer, PV height, and PV coverage ratio on the performance of a green roof compared to a traditional bare roof in a hot steppe arid region in Egypt. Two calibrated small-scale rooms were built and tested with eleven different scenarios to determine the improvement in indoor air temperature, relative humidity, and photovoltaic electricity output. The results showed that GRs made with clay, sandy soil, and vegetation reduced maximum indoor air temperature during the daytime by up to 10.75 %, 7.80 % and 9.09 %, respectively. Increasing soil depth and PV coverage ratio further improved maximum indoor air temperature reduction up to 11.85 % and 9.6 %, respectively. The photovoltaic electricity output was increased by up to 2.27 % compared to the traditional bare roof. The study also found that green roofs with photovoltaic systems reduced cooling energy consumption and CO2 emissions by 19.12 % and 59.56 kg/m2 annually, respectively.