The Effects of Surface Temperature on Wind and Thermal Environments in Step-up/down Building Canyons

This study analyzed the effects of building height and surface temperature on wind and thermal environments in step-up/down building canyons using a computational fluid dynamics (CFD) model. The effects of building height variations were evaluated in low-rise canyons, step-up-to-down, and step-down-to-up canyon configurations, with comparisons made based on the surface heating conditions of windward and leeward building walls. The results showed that wind speed distribution significantly changed with building height, especially in step-up-to-down canyons, where airflow was directed into the canyon, leading to increased wind speed. Additionally, changes in surface heating conditions affected vertical wind components, causing flow reversals in some cases. Air temperature distribution was strongly influenced by building height and arrangement. In other words, low-rise canyons had weaker airflow, leading to higher air temperatures, while step-up-to-down canyons had stronger inflows and lower air temperature distributions. This study demonstrates that building height has a more significant effect than surface heating on wind and air temperature changes in urban canyons. These findings provide valuable data for urban planning as well as important insights into urban regeneration that wind and thermal effects should be considered to ensure better environmental outcomes.