Evolution of natural ventilation potential under urbanization: A method based on Monin-Obukhov similarity theory and surface energy balance model

Natural ventilation (NV) is a crucial means of reducing building energy consumption. However, urbanization has significantly affected the vertical distribution of natural ventilation potential (NVP). To evaluate the evolution of NVP influenced by changes in surface characteristics due to urbanization, this study develops a vertical distribution model of NVP by integrating the Monin-Obukhov Similarity Theory (MOST) with the Surface Energy Balance (SEB) model. The model requires only easily accessible meteorological data and surface characteristic parameters as inputs, enabling the calculation of NVP under various surface conditions. Using the Xiangxue area of Guangzhou as a case study, the vertical distribution of NVP during the cooling seasons in five representative years from 2007 to 2023 were calculated and analyzed. The results indicate that, as urbanization progresses, the increase in building density and the decrease in natural surface coverage result in elevated air temperatures, decreased humidity, and diminished wind speeds. These changes significantly reducing the NVP in the near-surface layer. The interannual differences in NVP are mainly concentrated near the surface, gradually diminishing with increasing height, and eventually converging at higher altitudes. Compared to the early stage of urbanization in 2007, NV_T, NV_TH, and NV_THU at 2 m above the surface in 2023 decreased by 5.6 %, 8.1 %, and 8.1 %, respectively. At 27 m, these values decreased by 5.4 %, 7.3 %, and 7.3 %, respectively. At 100 m, the decreases were 4.7 %, 6.0 %, and 5.5 %, respectively. At approximately 220 m, the NV_THU values for 2007 and 2023 converge. The results of this study provide theoretical support and quantitative evidence for assessing the urban thermal environment and optimizing building ventilation.