Are present microclimate assessments valid in future changing climates? A case study from Hong Kong

This study investigated how climate change affects the outcomes of two microclimate assessments, an Air Ventilation Assessment (AVA) and an outdoor thermal comfort assessment, at an urban site in Hong Kong using computational fluid dynamics (CFD) simulations. The current and future climate data were prepared using historic meteorological observations from 1981 to 2020 and climate projections from 2025 to 2100 under three Shared Socioeconomic Pathways (SSPs), SSP126, SSP245, and SSP585, which represent the most sustainable, business-as-usual, and the most unfavorable climate change scenarios, respectively, using 44 General Circulation Models. The simulations revealed an increase in both the magnitude and frequency of wind in the dominant wind direction in the future. As a result, areas with the acceptable wind speeds (>1.5 m/s) recommended in AVA and satisfactory wind speeds (1 m/s–1.5 m/s) will slightly increase in the future, improving long-term air ventilation at the site compared to the current condition. However, the enhanced long-term air ventilation may not be sufficient to alleviate worsening outdoor thermal comfort in summer, primarily due to a greater impact of rising air temperature from global warming. Climate change will increase air temperature by 1 °C to 1.4 °C in the near future (2025–2062) and 1.5 °C to 3.6 °C in the far future (2063–2100). The Universal Thermal Climate Index (UTCI) shows a substantial increase in thermal stress from night to early morning in the future, in particular, under the most severe climate scenario of SSP585, causing outdoor thermal discomfort for extended periods at the site. © 2025 Elsevier Ltd.