Comprehensive analysis on the thermal comfort of various greening forms: a study in hot-humid areas

Abstract

The potential impact of greening on improving thermal environments is widely recognized. However, few studies have comprehensively evaluated the influence of different forms of greening, such as various tree crown widths, green facades, green roofs, and their combinations, on both outdoor and indoor environments. In this study, we conducted an extensive investigation within a residential precinct at Guangzhou University by combining on-site measurements and numerical simulations with the ENVI-met model. Physiologically Equivalent Temperature (PET) and Temperature Humidity Index (THI) were used to assess outdoor thermal comfort. The results indicated that planting trees had a greater impact on improving the outdoor thermal environment than green facades and green roofs, and this effect increased with the crown width of the trees, with a maximum potential reduction of 4.8 °C (0.2 °C) in PET (THI). Green facades can bring a change of up to 101.9 W m−2 in sensible heat flux, resulting in a reduction of up to 1.8 °C in indoor Ta (air temperature). Conversely, green roofs composed of grass exhibit minimal effects in both outdoor and indoor environments. Finally, we provide recommendations for the construction and renovation of projects in residential areas, with a focus on hot-humid areas.