Cooling the cities: A comprehensive review of urban heat island mitigation strategies in Southeast Asia

Abstract

This systematic review synthesizes 27 peer-reviewed studies (2020–2023) on urban heat island (UHI) mitigation in Southeast Asia, focusing on cooling effectiveness and implementation feasibility. In dense cities like Singapore and Kuala Lumpur, green infrastructure—urban forests, green roofs, and street-tree networks—proves most effective, reducing air temperatures by up to 2.6°C and surface temperatures by 11°C. Engineered solutions, such as high-albedo coatings and permeable pavements, offer 4–9 K of surface cooling and added benefits like stormwater control, though tropical humidity, glare, and maintenance pose challenges. Informal settlements demonstrate the value of low-cost, community-led cooling efforts using shade structures and vegetation. Despite these benefits, barriers persist: high costs, limited urban land, and fragmented governance systems hamper the scalability of hybrid green-grey solutions. Evaporation-based strategies are further constrained by complex urban geometries and monsoonal climates. Fewer than 20% of Southeast Asian cities incorporate UHI mitigation into formal planning frameworks, limiting systemic uptake. To advance climate-resilient urbanism, interdisciplinary collaboration is needed. Future priorities should include long-term monitoring in tropical climates, integrated trials of hybrid interventions, and cost–benefit models that capture health, energy, and flood resilience co-benefits. Embedding these approaches into planning systems, as seen in Bangkok’s zoning reforms and Singapore’s Green Mark, is key to sustainable adaptation. • The systematic review on urban heat islands (UHIs) mitigation has been conducted. • Green infrastructure most effectively reduces urban heat and cost-effective solution. • UHI mitigation emphasizing interdisciplinary, international, sustainable approaches. • Emphasized important strategies for mitigating UHI effects. • High costs and weak policy hinder UHI mitigation efforts.