Impact of Plant Layout on Microclimate of Summer Courtyard Space Based on Orthogonal Experimental Design

With the rapid development of urbanization and industrialization, many green spaces have been replaced by urban buildings, resulting in decreased green spaces in courtyard space. Nonetheless, as an enclosed green space integrated with the natural environment, courtyard space plays a vital role in regulating environmental microclimate, so it is necessary to study its microclimate through vegetation greening. Therefore, this study took courtyard spaces in humid and hot areas as an example, and with the help of ENVI-met 5.5.1 software, introduced an orthogonal experimental design to simulate various plant layout models, including tree layout (TL), shrub layout (SL), grass layout (GL), and the interaction of their combined layout, and analyzed the simulation results of temperature, humidity, and wind speed. The results show that first of all, plant layout plays a crucial role in cooling and wind control, and the more uniform the plant layout, the better it is for cooling and ventilation. Secondly, plant layout showed a changing pattern of cooling and wetting in the morning, noon, and afternoon periods. Furthermore, TL had the best cooling and humidifying effect in the morning and midday, and the combined interaction of TL, SL, and GL and of SL and GL significantly affected the wind speed in the courtyard space. During the afternoon, the combined interaction of TL with SL and SL with GL outperformed the single-plant-element type of layout regarding cooling and humidification efficiency. Finally, scattered-form tree layout, single-form shrub layout, and 20% grass layout were the best combinations of plant layout for cooling, humidity reduction, and ventilation. The results provide reference data and an empirical case for the microclimate optimization of summer courtyard spaces.