Air conditioning systems transfer heat from indoors to the outdoors during hot summers, exaggerating the urban heat island (UHI) phenomenon and the risks of relevant climatic disasters. Urban form renewal strategies are urgently required to improve the diffusion of building heat emissions (BHEs). In this study, the impacts of BHEs on the outdoor airflow and air temperature fields of 42 typical urban blocks in Xi’an were simulated using scSTREAM program. BHEs increased the near-surface UHI intensities by 1.0 °C and 1.4 °C in residential and mixed-use blocks, respectively. The diffusion conditions of the BHEs were better for blocks with lower building densities. However, the UHI increase caused by the BHEs was positively correlated with the floor area ratio only in the mixed-use blocks. Regression formulas describing the relationships between the UHI increase caused by the BHEs and block-form indicators were then proposed. In a district renewal project for urban climate optimization, these formulas were used as the fitness functions of genetic algorithm to determine the form indicators for all blocks therein. The district UHI intensity caused by BHEs could be reduced by 0.3 °C with the maintaining of the district development intensity.

中文翻译：

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促进建筑热排放扩散的多尺度城市形态更新策略——以习安为例


在炎热的夏季，空调系统将热量从室内传递到室外，夸大了城市热岛 （UHI） 现象和相关气候灾害的风险。迫切需要城市形态更新战略来改善建筑热排放 （BHE） 的扩散。本研究使用 scSTREAM 程序模拟了 BHEs 对习安 42 个典型城市街区室外气流和空气温度场的影响。BHE 将住宅和混合用途街区的近地表热岛强度分别提高了 1.0 °C 和 1.4 °C。BHEs 的扩散条件对于建筑密度较低的街区更好。然而，仅在混合用途街区中，由 BHE 引起的 UHI 增加与容积率呈正相关。然后提出了描述 BHE 引起的 UHI 增加与块状指标之间关系的回归公式。在城市气候优化的地区更新项目中，这些公式被用作遗传算法的适应函数，以确定其中所有区块的形式指标。在保持区域开发强度的情况下，BHEs 引起的区域 UHI 强度可降低 0.3 °C。