Urban heat resilience at the time of global warming: evaluating the impact of the urban parks on outdoor thermal comfort

Farshid Aram,Amir Mosavi,Ebrahim Solgi,Ester Higueras Garcia

doi:10.1186/s12302-020-00393-8

Abstract

BackgroundIn densely populated urban centers, increased air temperature due to urban heat island (UHI) effect can undermine the thermal comfort and health of citizens. Research has shown that large urban parks can mitigate the effect of UHIs and improve thermal comfort, especially in the warmer months of the year when temperature changes are more noticeable. This study investigated the cooling effect intensity (CEI) of the Retiro Park in the center of Madrid at three different distances from its southern edge and the impact of this cooling effect on thermal comfort from physiological and psychological perspectives. This investigation was performed by measuring microclimate data and conducting a survey simultaneously during the summer days.ResultsThe results showed that the CEI of the park varies with distance from its edge. Because of this effect, air temperature within the 130 m and 280 m distance of the park was, respectively, 1.6 °C and 0.9 °C lower than the temperature at the 520 m distance (the nearest heat island). After examining the effect of the park in terms of physiological equivalent temperature (PET), it was found that the PET at the 130 m and 280 m distance of the park was 9.3% and 5.4% less than the PET in the heat island domain. More than 81% of the respondents (in all three areas) had a mental image of the park as the place where they would experience the highest level of outdoor thermal comfort, and this rate was higher in the areas closer to the park. The analysis of citizens’ responses about perceived thermal comfort (PTC) showed that citizens in areas with higher CEI had perceived a higher degree of thermal comfort from the psychological perspective.ConclusionThis study demonstrates the significant role of large urban parks located in the core of the populated cities in providing thermal comfort for citizens from both physiological and psychological perspectives. Additionally, the results of this study demonstrated that among the environmental (natural and artificial) factors around the park (topography, urban structure, etc.), the aspect ratio has the greatest impact on thermal comfort.

Highlights

In densely populated urban centers, increased air temperature due to urban heat island (UHI) effect can undermine the thermal comfort and health of citizens
It was found that the cooling effect of the Retiro Park on the neighborhoods to its south has led to a 0.9 °C reduction in air temperature within the 280 m distance and a 1.6 °C reduction in air temperature within the 130 m distance of this park, which is in areas closer to the park
In the present study, it was found that the cooling effect of the Retiro Park on the neighborhoods to its south varies with the distance from the park and diminishes at the distance of 520 m, which falls in the domain of a heat island

Summary

Introduction

In densely populated urban centers, increased air temperature due to urban heat island (UHI) effect can undermine the thermal comfort and health of citizens. Research has shown that urban areas are typically warmer than their rural counterparts; a difference that can be attributed to the phenomenon known as urban heat island effect (UHI) [67, 83, 90]. This effect is strong enough to cause major physical and mental health problems for citizens [16, 52, 55, 85]. This effect can be felt in the park itself and within a radius around the park, leading to improved thermal comfort in the neighborhood [31, 92, 95]

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Results

Discussion

Conclusion