Due to global warming and rapid urbanization, the frequency and intensity of extreme heat events in the United States have increased. Particularly for pedestrians, excessive heat has been reported as a critical barrier to walking activity, which, in turn, can deteriorate walkability and urban vitality. By using a multilevel spatial approach, this study investigates the combined effects of microclimatic urban design features on daytime pedestrian thermal comfort. For this purpose, it uses on-site field measurements taken in July 2019 and estimates how different scales of street- and block-scale design factor impact the physiological thermal comfort of pedestrians on the High Line in New York City. Based on the findings, the High Line experiences high thermal stress conditions, with clusters of hot spots particularly in its upper section. In addition, the urban design features at both the street and block scales are highly correlated with estimated pedestrian thermal comfort. Specifically, at the block-scale level, the mean energy budget value largely depends on block density and volume, while at the street-scale level, the height-to-width ratio, tree view factors, and tree canopy cover ratio have a negative linear relationship with absorbed solar radiation. Moreover, the findings indicate that the combination of urban design factors at the street- and block-scale levels significantly impact pedestrian thermal comfort. This study offers practical knowledge and a deeper understanding about climate-sensitive urban designs that are highly resistant to extreme heat events.

For the full text of this article, please view it on ScienceDirect.

Source: Kim, Y. J., & Brown, R. D. (2021). A multilevel approach for assessing the effects of microclimatic urban design on pedestrian thermal comfort: The High Line in New York. Building and Environment, 205, 108244. https://doi.org/10.1016/j.buildenv.2021.108244