Meta-pragmatic investigation of passive strategies from ‘UHI– climatology’ nexus perspective with digital twin as assessment mechanism

A global phenomenon identified 200 years ago as Urban Heat Island (UHI) effect gained popularity as the sheer contributor to the precipitous temperature gradient between rural and urban interface, instigating excess heat gain and associated ill effects on the urban dwellers. UHI is a function of many interrelated geographical, ecological, and economic parameters that require differential treatment in determining the antecedent impacts. This transdisciplinary review assessed the passive strategies (vegetation, cool roofs, cool pavements, and green roofs) from 83 studies that employed a numerical simulation approach to combat UHI. On average, vegetation and cool/green roofs can reduce ambient temperature by 3–5 ​°C, while cool pavements help to reduce surface temperature by 5 ​°C. All passive strategies also reveal it can reduce buildings' energy demand by 4–10%. However, the current methodological framework for evaluating UHI is quite fragmented, using multiple software and estimates only Surface Urban Heat Island (SUHI), ignoring Canopy Urban Heat Island (CUHI), Boundary Urban Heat Island (BUHI), and the nexus of 'UHI-Climatology,' which is linked to regional and global climate change, failing to model UHI and its complex connection to climate change accurately. The review found that the efficacy of passive strategies is a function of factors ranging from location, cloud cover, and soil type to simulation accuracy; hence, while these passive strategies alleviate outdoor temperature in one place, they can cause counterproductive impacts in another region. Therefore, as a postlude, the paper explores an alternative methodological framework for evaluating the nexus of UHI-Climatology using digital twin technology, thus espousing better mitigation strategies.