Extreme heat events such as heatwaves or urban heat island effect are
some of the noticeable outcomes of climate change within cities that can
affect citizens' quality of life significantly. Effects range from
slight thermal discomfort to extreme heat stress and even heat-related
mortalities. Although there is a need for an immediate response to the
problem of extreme heat in cities, there is still uncertainty in
developing effective and place-based heat mitigation strategies.
Previous studies, mainly by doing parametric analysis and changing one
factor at a time, tried to evaluate a single point in the parameters
space in just a one-time slice, resulting in narrow conclusions with
limited applicability. However, in this study, by employing a
three-dimensional model and conducting sensitivity analysis, we tried to
assess the relative impacts of morphological and vegetation parameters
in reducing thermal stress during an extreme heat event and evaluate how
the magnitude of their effects might change in various contexts and
different hours a day. We implemented the weather-related data of the
Chicago heatwave in July 1995 for our simulations, in which 514
heat-related deaths, mostly among racial and ethnic minorities, had
happened. Our findings demonstrate physical parameters such as urban
morphology and surface material have the highest cooling impact during
the hottest hours of the day, while vegetation parameters exhibit almost
constant effects during a day. However, when analyzing specific time
steps, the results revealed that the effect of vegetation parameters on
modifying thermal stress largely depends on the other physical and
morphological parameters. This study hopes its findings by better
understanding the impacts of influential parameters under a variety of
contexts help planners craft place-based and effective heat mitigation
strategies. Providing safe and equitable urban environments for all
citizens and reducing heat-related casualties are the overreaching goals
of this study.