Linking Blue-Green Infrastructure to Microclimate and Human Thermal Comfort for Urban Cooling: A Review

In cities, urban heat island (UHI) effect is one of the most distinct climate issues where it is characterized by warmer conditions in city centres than the surrounding rural areas. This may influence the urban residents, especially on the health hazard issues such as thermal stress. Blue-Green Infrastructure is a nature-based solution that can improve the microclimate conditions of urban environments and improve human thermal comfort. However, the nature, imbalances and gaps of research on Blue-Green Infrastructure should be reviewed to see the extent of research on how its utilization can be linked to microclimate and human thermal comfort. Therefore, this review addresses this issue based on the previous literature. From 2018 to 2021, there was a gradual increase in the Blue-Green Infrastructure research. More research focused on Green Infrastructure followed by the combination of Blue-Green Infrastructure; however, limited studies were on Blue Infrastructure. Most studies used biophysical modelling followed by fieldwork, and only 36% studied human thermal comfort at micro level. This suggests that more studies should be done in the field to link the contribution of Blue-Green Infrastructure to urban microclimate and consequently its effect on thermal stress of urban residents. The review is concluded by highlighting aspects of Blue-Green Infrastructure research that can be further studied to improve future urban planning efforts for urban cooling.