Evaluating the microclimate impact of extensive green roofs on school buildings in mediterranean environments: A case study in Athens, Greece

This study explores the microclimatic effects of an extensive green roof system on a typical school building in Athens, Greece. Simulations were conducted using ENVI-met over a 24-hour period on 21 July 2024, incorporating meteorological data from the Hellinikon EPW weather file. A digital model was developed to evaluate the impact of the green roof on air temperature and thermal comfort across three vertical levels: pedestrian (1.5 m), mid-building (6.5 m), and rooftop (12.5 m). Thermal comfort was assessed using the Universal Thermal Climate Index (UTCI), calculated at all three levels for an 8-year-old child profile. At a selected reference point near the building (85, 56), air temperature reductions of 0.53 °C, 0.57 °C, and 0.79 °C were recorded at pedestrian, mid-building, and rooftop levels respectively. Corresponding UTCI improvements ranged from 0.53 °C to 0.86 °C during peak afternoon hours. These findings support the use of extensive green roofs as a passive strategy to mitigate urban heat in educational buildings in Mediterranean climates.