Towards sustainable and climate-resilient cities: mitigating urban heat islands through green infrastructure

Abstract

Rapidly increasing construction and agglomeration in urban areas have made the urban heat island (UHI) problem a turning point for the world, as a result of notably rising earth temperature every year. UHI and its impacts on climate are somewhat linked to weather-related matters, natural disasters and disease outbreaks. Given the challenges posed by urbanisation and industrialisation in achieving sustainability, it is crucial to adopt intelligent and decisive measures to mitigate the adverse outcomes of UHI. Greenery surfaces have long been a significant focus of scientific research and policy development, reflecting their pivotal role in combating urban heat islands and promoting sustainable urban environments. This study critically reviews the potential of green infrastructure, including green roofs, facades, shrubs, and trees, so as to minimise UHI impacts in severe urban contexts. By synthesising findings from a wide range of empirical studies, it highlights key outcomes such as reductions in surface temperatures by up to 2 degrees C and improvements in outdoor thermal comfort indices by over 10 degrees C under specific conditions. Additionally, the paper introduces a comprehensive framework for integrating greenery systems into urban planning, combining passive cooling, air quality enhancement, and energy efficiency strategies. The findings reveal that extensive green roofs, in particular, are highly effective in reducing indoor cooling demands, while strategically placed trees offer significant shading and evapotranspiration benefits. This work provides actionable insights for policymakers and urban planners to boost sustainable and climate-resilient cities whilst addressing gaps in current research related to the long-term performance and cost-effectiveness of green infrastructure solutions.