The cooling intensity of green infrastructure in local climate zones: A comparative study in China's cold region

Abstract

We compared the effect of green cover on common urban green infrastructure (UGI, roof greening, vertical greening, and ground trees) to determine the relationship between the cooling efficiency and local climate zones (LCZs) in Xi'an, China using numerical simulations. We found that: 1) The temporal variation of pedestrian cooling intensity (PCI) among LCZs, varied; the maximum PCI of green roofs occurred at 11:00 in low-rise buildings and 13:00 in mid-rise and high-rise buildings. The maximum PCI of green walls occurred at 19:00. 2) The spatial pattern of PCI was dominated by the wind direction, with its maximum occurring downwind of the block. 3) The cooling intensity (CI) of green roofs and green walls was more greatly influenced by building geometry than green cover, with greater CI in compact blocks. This was the opposite for ground trees. 4) The maximum PCI per unit of green area occurred in open low-rise buildings with low-cover green roofs (0.30 °C/ha), compact low-rise with low-cover green walls (0.21 °C/ha), and compact mid-rise with high trees cover (0.56 °C/ha). Our results provide theoretical guidance for urban designers to implement UGI design by considering the spatial and temporal variation patterns of CI under different LCZs.