Scaling impact of urban green infrastructure on urban climate and energy: A critical review

The accelerated accumulation of greenhouse gases in the Earth’s atmosphere is leading to rapid changes in global temperature trends and climate patterns. In urban areas, this issue is further exacerbated by the phenomenon of the urban heat island effect. This problem is compounded as urban populations expand and energy consumption rates increase, intensifying the adverse impacts on local climates. Urban green infrastructure, which includes parks, green roofs, and tree-lined streets, is widely recognized as a key tool for mitigating the urban heat island effect and helping cities adapt to climate change.In recent years, a growing body of research has investigated the cooling effects of urban green infrastructure, with a particular emphasis on how these effects vary with the scale of greening.

This paper reviews recent studies on the cooling effects of urban green infrastructure, with a specific focus on the impact of green infrastructure of different scales on urban climates. The studies reviewed are categorized into two groups based on their evaluation methodologies.The first group includes research examining how urban green infrastructure of varying scales—from urban parks to extensive green belts—affects urban climates. These studies generally find a positive correlation between the increase in green space area and improvements in urban climates, such as reductions in local temperatures. However, this relationship is not linear; beyond a certain threshold, the marginal benefits of increasing green space diminish.The second group of studies focuses on the impact of urban green spaces on building energy consumption. These studies demonstrate that green infrastructure can reduce the demand for cooling energy, thereby lowering overall energy consumption in urban areas. This effect is particularly important in densely populated cities where energy demands are high.

It is important to note that the effectiveness of urban green infrastructure is not solely dependent on scale. The natural elements that constitute these green spaces, such as plant species, vegetation density, and the presence of water features, play a significant role in determining their cooling effectiveness. Therefore, the planning and management of green infrastructure at different scales are crucial for optimizing its climate benefits, especially in rapidly developing urban environments. These infrastructures not only contribute to improving urban climates but also effectively reduce the energy consumption of urban buildings.