How to plan urban green space in cold regions of China to achieve the best cooling efficiency

Jianxin Zhang,Li Yang,Jingyuan Zhao,Bo Pang

doi:10.1007/s11252-022-01202-1

Abstract

With the acceleration of urbanization, the urban heat island (UHI) effect has intensified. Urban green space can retard the UHI effect. However, most existing studies have only focused on hot regions, while little attention has been given to cold regions that also have summer heat protection requirements. Furthermore, existing researc has not classified urban green spaces according to the presence or absence of water, which can lead to inaccurate results. This paper takes four cities in cold regions of China as examples and studies the cooling effects of two different types of urban green space. The results indicate that in cold regions of China, green spaces containing water bodies have a stronger cooling effect than those without water. For green spaces without water, the cooling intensity is related to the background temperature and green space areas, while for green spaces containing water bodies, the area of the internal water body is the key influencing factor. Specifically, there is a threshold value of efficiency (TVoE) for the green space areas without water in cold region cities of China, which is approximately 0.52 ha, while there is no TVoE for the green space areas containing water bodies. Additionally, there is a TVoE for the water/land ratio of the green spaces containing water bodies of approximately 0.5. The methods and results of this study can provide a reference for future research and for urban planners and managers designing urban green spaces.

Highlights

The Department of Economic and Social Affairs of the United Nations Secretariat (UN DESA) Population Division’s “World Urbanization Prospects (2018 Revision)” [1] reported that more people live in urban areas than rural areas globally; the urban population accounted for 55% of the world population in 2018
By analyzing and calculating the threshold value of efficiency (TVoE) of the cooling effect of two different kinds of green space in each city, this study aimed to find the optimal green space areas in cold regions and to explore the relationship between the urban cold islands (UCIs) effect of urban green space and landscape indicators and background temperature
It was found that the proportion of water bodies of green spaces in the four cities is weakly negatively correlated with the spaces’ internal temperature and is positive correlated with the UCI intensity, which shows that the water bodies inside of the green spaces have a certain impact on the Background temperature (BGT) and the cooling effect of the patch

Summary

Introduction

Rapid urbanization has brought significant changes in land use, and with the loss of green spaces, coupled with the substantial increase in the amount of heat released artificially, the urban climate has deteriorated significantly and the urban environment has deteriorated seriously [3-6]. UHIs are urban areas that are warmer than surrounding non-urban areas [7-10]. Their presence can increase water consumption and energy use, aggravate environmental pollution, and cause harm to human health [11-16]. A considerable number of studies have demonstrated the significant cooling effect of urban green spaces, which can form urban cold islands (UCIs), improve people's outdoor thermal comfort, and significantly reduce the environmental pressure generated by urban heat islands [17-20]

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Discussion

Conclusion