Green roof energy performance in different climate zones: a simulation study

Green roofs are widely used as a passive building design technique to decrease the cooling demand in buildings. The vegetation uses the energy of the surroundings during the evapotranspiration process, leading to a temperature decrease in air. This paper investigates the effectiveness of green roofs in 45 cities in different climate zones. The simulation of the energy performance of buildings is performed using DesignBuilder software, which integrates the EnergyPlus engine. The results show that green roofs effectively reduce the cooling load but increase heating energy consumption. The highest performance in total energy savings was in the arid zone with savings ranging from 3.2% to 9.1%, despite having a high heating demand. Tropic and temperate zones show relatively lower results, which vary from 1.4% to 4.1% and -0.2% to 4.2%. The cold zone shows the worst result, ranging by around 1%. Thus, green roofs show better performance in cities with high-temperature ranges, direct radiation, and humidity level.