Studying the Effect of Blue-Green Infrastructure on Microclimate and Human Thermal Comfort in Melbourne’s Central Business District

Abstract

Blue-green infrastructure (BGI) is defined as a strategically planned network of natural and semi-natural areas with other environmental features designed and managed to deliver a wide range of ecosystem services, which include microclimate regulation and enhanced human thermal comfort. While green infrastructure is widely known to be capable of mitigating the adverse effects of urban heat island, the effect of blue infrastructure to regulate thermal comfort is still poorly understood. This study investigates several blue-green-infrastructure (BGI) scenarios in the central business district (CBD) of Melbourne, Australia to assess their effects on microclimate and human thermal comfort. Three-dimensional microclimatic modelling software, ENVI-met, was used to simulate the microclimate and human thermal comfort. Physiological equivalent temperature (PET) was used to quantify the level of thermal comfort in selected research areas. Ten different scenarios were simulated, which included those based on green roofs, green walls, trees, ponds and fountains. The simulations suggest that green roofs and green walls in the high-rise building environment have a small temperature reduction in its surrounding area by up to 0.47 °C and 0.27 °C, respectively, and there is no noticeable improvement in the level of thermal perception. The tree-based scenarios decrease temperature by up to 0.93 °C and improve the thermal perception from hot to warm. Scenarios based on water bodies and fountains decrease the temperature by up to 0.51 °C and 1.48 °C, respectively, yet they cannot improve the thermal perception of the area. A deeper water body has a better microclimate improvement as compared to a shallow one. The temperature reduction in the fountain scenario tends to be local and the effect could only be felt within a certain radius from the fountain.

Examining the Microclimate Pattern and Related Spatial Perception of the Urban Stormwater Management Landscape: The Case of Rain Gardens

“…The implementation of multilayer planting design can increase the areas with higher relative humidity and moderate temperature. Existing studies have found advantages of increasing green coverage in regulating regional temperature and humidity [15,16]; this study focuses on intra-scale GSI [17] and the findings align with other regional-scale research. Meanwhile, including trees and shrubs can significantly improve the public perception of a rain garden from the perspectives of visual comfort, the landscape's visual beauty, and the overall favorite.…”

“…The microclimate of an area is decided by a combination of various environmental factors, such as temperature, solar radiation, humidity, wind, and air [15]. The microclimate is significantly shaped by the presence of specific elements in the site, such as buildings, vegetation, and construction materials [16]. Microclimate regulation is not solely affected by the regional green infrastructure system, intra-scale GSI design, such as green streets, vegetative swales, and rain gardens, can also control the microclimate and influence related spatial perceptions [17].…”

“…Various microclimate impacts have the potential to affect daily human activities and the quality of the urban living environment [15]. Among them, the potential air temperature, relative humidity, and wind speed/direction are typical and fundamental components [15][16][17]. Regarding the relationship between these microclimate impacts and the studied variables, existing research has shown that the land scale, topography, and vegetation can either significantly or subtly affect the pattern of the potential temperature and relative humidity [19][20][21].…”

Simulation study of summer microclimate in street space of historic conservation areas in China: A case study in Changsha

“…By analyzing the measured and simulated temperature and humidity data at a fixed location on Taiping Street during the hours of 10:00-20:00 on 12 July 2022, researchers found that the coefficient of determination (R 2 ) between the two sets of data was 0.91, the root mean square error (RMSE) was 1.68, and the index of agreement (d) was 0.75 for temperature, while the R 2 was 0.92, the RMSE was 3.2, and the d was 0.86 for humidity. Typically, an R 2 greater than 0.5 is considered reasonable (Santhi et al, 2001;Balany et al, 2022). The RMSE values for air temperature and relative humidity are within the range reported in many related studies (RMSE of relative humidity ranging from 2.04% to 11.12% and air temperature ranging from 0.52 °C to 4.30 °C) (Tsoka et al, 2018).…”

Simulation of the Energy Performance of a Building with Green Roofs and Green Walls in a Tropical Climate

“…The efficiency of different green infrastructures in attracting and promoting biodiversity is still restricted. With its ability to host and sustain urban wildlife, thus enhancing previously depauperate regions, green roofs, along with other urban green spaces, may have significant ecological value [54,55]. There is evidence that green roofs may boost cities' biological diversity if implemented widely [56,57].…”