Study on the Green Space Patterns and Microclimate Simulation in Typical Urban Blocks in Central China

This study attempted to classify blocks in the second ring road of Changsha, a central city of urban agglomeration in central China, according to their green space patterns, and to explore the influence of green spaces in different blocks on the surrounding microclimate. Researchers divided the blocks into five types: green space enclosed by buildings type, green space parallel with buildings type, green space centralized in buildings type, green space interspersed in the block type, and green space dispersed in the block type. Thermal comfort conditions in the different blocks were studied by ENVI-met simulations and using the thermal comfort indicators physiological equivalent temperature (PET), predicted mean vote (PMV), and standard effective temperature (SET). Because the green space was more evenly distributed in the block of green space parallel type and green space interspersed type, the overall fluctuation of the thermal comfort value of all areas of the whole block was small, with more areas having a value close to the median value of the thermal comfort value of the block. In the green enclosed blocks, thermal comfort was better within the green space in the area enclosed in the middle when the surrounding buildings were lower. The green areas in the green space enclosure type significantly improved the thermal comfort around the buildings, and the thermal comfort in the areas decreased rapidly as the distance between the green areas and the buildings increased. The green space dispersion type was found more in older blocks that were not well planned and had poor thermal comfort in the areas. On the premise that the green space area in the different high-rise blocks was equal, if only the thermal comfort of the green space coverage area was considered, in the summer, the green space parallel type was the best (|ΔPET| = 7.96, |ΔPMV| = 1.22). In the winter, the green space centralized type was the best (|ΔPET| = 11.26, |ΔSET| = 10.88). On the premise of equal green space area in the different multilayer blocks, if only the thermal comfort of green space coverage area was considered, in the summer, the green space parallel type was the best (|ΔPET| = 8.89, |ΔPMV| = 1.49). In the winter, the green space centralized type (|ΔPET| = 11.04, |ΔSET| = 10.64) was the best. This shows that different greening patterns have different advantages and disadvantages in different seasons and different situations.