Urban green space cooling effect in cities

Soran Mansournia,Ester Higueras García,Ebrahim Solgi,Farshid Aram

doi:10.1016/j.heliyon.2019.e01339

Soran Mansournia, Ester Higueras García + Show 2 more

Open Access

https://doi.org/10.1016/j.heliyon.2019.e01339

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Abstract

Urban green spaces are considered an appropriate way to reduce urban heat island effects and provide comfort to the nearby occupants. In addition to cooling the actual space, urban green spaces are also able to influence the surrounding area, and this phenomenon is called the urban green space cooling effect. The most important issues with regard to the cooling effects of urban green spaces are the intensity and density of the cooling, which can play a major role for urban designers and planners in dealing with urban heat island. This article reviews the latest studies that have examined the cooling effects of urban green spaces in recent years. Based on the method of evaluation of their samples, the studies are divided into three groups. The first category consists of research into a set of urban green spaces in one part of or in an entire city, mainly conducted through remote sensing and satellite maps. The second category investigates city parks or several urban parks with recognizable shapes and locations. In this section, information was mainly gathered by virtue of field observations. The third category relates to studies in which a part of urban space according to different scenarios of green space placement was modeled by simulation. The results of the present study illustrate that the highest cooling effect distance and cooling effect intensity are for large urban parks with an area of more than 10 ha; however, in addition to the area, the natural elements and qualities of the urban green spaces, as well as climate characteristics, highly inform the urban green space cooling effect.

Highlights

The intensified accumulation of greenhouse gases in the Earth’s atmosphere has led to rapid changes in global temperature trends and climate (IPCC, 2017; Ng and Ren, 2017)
The present study aims to review and categorize the recent studies carried out regarding the relation of characteristics of urban green spaces (UGSs) to their cooling effect, in order to facilitate the study of data collection and analysis methods commonly used in this area, and assist future planning and development attempts to use urban parks and urban gardens for creating the cooling effect and countering the Urban Heat Island (UHI) effect
With steadily growing impacts of global warming, cities are increasingly struggling with new problems such as intensified UHI effect

Summary

Introduction

The intensified accumulation of greenhouse gases in the Earth’s atmosphere has led to rapid changes in global temperature trends and climate (IPCC, 2017; Ng and Ren, 2017). The UHI effect has several causes, including the increased absorption of sunlight by dark-colored surfaces of buildings, the physical properties of the materials commonly used in urban areas, the imposition of heat in the urban space due to the urban morphology which affects shading and air movement, the urban compactness which stems from density, plot ratio, land-use and travel proximity, and the deficiency in urban green spaces (Giridharan and Emmanuel, 2018; O’Malley et al, 2015; Kaloustian and Diab, 2015; Xi et al, 2012; Priyadarsini et al, 2008) This phenomenon is exacerbated by the growing size of the city dwelling human population and the increasing rate of energy consumption (Mirzaei, 2015; Battista et al, 2016). Since it has been estimated that the ratio of world urban population to total population is set to increase from 54% in 2016 to 60% in 2030 (UN, 2016), UHI can be expected to become a major challenge in the future urban life

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