Karimian Zahra, Mahdizadeh Sara
Department of Horticultural Science and Landscape Architecture, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
School of Civil Engineering, University of Leeds, Leeds, United Kingdom.
PLoS One. 2025 Jun 10;20(6):e0325494. doi: 10.1371/journal.pone.0325494. eCollection 2025.
In hot and arid climates, developing green roofs to improve the microclimate and thermal comfort faces challenges due to water scarcity and harsh climate conditions. To evaluate the effect of green roof types on microclimate parameters and thermal comfort, a simulation was conducted in Yazd, Iran, using the ENVI-met model. Three scenarios-intensive green roofs, extensive green roofs, and roofs without vegetation-were simulated using meteorological data from 7:00 am to 6:00 PM during the hottest period of the year. Desert-adapted plant species were included in two green roof types. The model outputs indicated that, compared to extensive green roofs and roofs without vegetation, intensive green roofs resulted in lower air temperature, mean radiant temperature, and longwave radiation. They also led to higher wind speed and relative humidity, contributing to more desirable thermal comfort. Extensive green roofs and roofs without vegetation generally showed no significant differences in the measured microclimatic parameters or thermal comfort index. As suggested by the findings of this study, intensive green roofs demonstrated superior performance in enhancing thermal comfort compared to extensive green roofs. However, during the hottest period of the year and within the measured hours, all three scenarios were classified as 'very hot' (PMV = 5.03) and 'hot' (PMV = 3.2), experiencing strong to extreme heat stress, respectively. The measured hours and distance from the roofs affected the microclimatic parameters and thermal comfort, with the intensive green roof showing the most favorable thermal comfort condition (PMV = 0.18) during 7:00-9:00 am, perceived as comfortable with no thermal stress. However, the microclimatic improvements and thermal comfort enhancements resulting from the simulated green roofs in the surrounding environment) were not significant. Considering the outcomes alongside the severe climatic conditions prevalent in the city of Yazd, characterized by high temperatures, intense radiation during the summer, and extreme water scarcity, the proposition for the construction and development of green roofs in this region is not advisable. Although green roofs aim to ameliorate the microclimate and improve thermal comfort during hot periods, their effectiveness under such harsh conditions remains limited.
在炎热干旱的气候条件下，由于水资源短缺和恶劣的气候条件，开发绿色屋顶以改善微气候和热舒适度面临挑战。为了评估绿色屋顶类型对微气候参数和热舒适度的影响，在伊朗亚兹德使用ENVI-met模型进行了模拟。利用一年中最热时期上午7:00至下午6:00的气象数据，模拟了三种情景——密集型绿色屋顶、粗放型绿色屋顶和无植被屋顶。两种绿色屋顶类型中都包含了适应沙漠环境的植物物种。模型输出结果表明，与粗放型绿色屋顶和无植被屋顶相比，密集型绿色屋顶导致更低的气温、平均辐射温度和长波辐射。它们还带来了更高的风速和相对湿度，有助于营造更理想的热舒适度。粗放型绿色屋顶和无植被屋顶在测量的微气候参数或热舒适度指数方面通常没有显著差异。正如本研究结果所示，与粗放型绿色屋顶相比，密集型绿色屋顶在提高热舒适度方面表现出更优的性能。然而，在一年中最热的时期以及测量时间段内，所有三种情景都被归类为“非常炎热”（预测平均投票值PMV = 5.03）和“炎热”（PMV = 3.2），分别经历了强烈到极端的热应激。测量时间段和与屋顶的距离影响了微气候参数和热舒适度，密集型绿色屋顶在上午7:00至9:00期间表现出最有利的热舒适条件（PMV = 0.18），被认为舒适且无热应激。然而，模拟的绿色屋顶在周围环境中带来的微气候改善和热舒适度提升并不显著。考虑到这些结果以及亚兹德市普遍存在的恶劣气候条件，其特点是夏季气温高、辐射强烈且极度缺水，在该地区建设和开发绿色屋顶的提议并不明智。尽管绿色屋顶旨在改善微气候并在炎热时期提高热舒适度，但其在如此恶劣条件下的有效性仍然有限。
