Understanding the synergy between heat waves and the built environment: a three-decade systematic review informing policies for mitigating urban heat island in cities

Abstract The escalating frequencies and intensities of heat waves have become a global concern in the face of climate change. Cities are increasingly vulnerable to overheating due to the amplification of urban heat island (UHI) during heat waves. Factors influencing the synergetic impact of UHI and heat waves on the built environment are complex, mainly including the degree of urbanization, land use patterns, building morphology, thermal properties of construction materials, and variations in moisture fluxes and heat sinks. Researchers worldwide are extensively exploring the characteristics of heat waves, the factors influencing heat waves in urban areas, and the impact of heat waves on built environments, as well as possible mitigation measures. However, the existing literature lacks a holistic and comprehensive understanding of the complexities between heat waves and the built environment that is needed for planning and implementing effective mitigation measures in the future. This study systematically presents a comprehensive overview of the global literature of the past three decades related to heat waves and urban built environments, spanning variations in heat wave definitions, factors influencing heat waves in urban areas, heat wave impacts on buildings, energy, occupant health, and infrastructure, mitigation measures, case studies, best practices, future considerations, and challenges. The objective is to synthesize current knowledge and highlight gaps in understanding, providing a foundation for future research. The review suggests that implementing a combination of strategies across various scales, from individual buildings to entire neighborhoods and cities, can contribute to effectively mitigating heat. This includes prioritizing compact and mid-rise buildings with light-colored exteriors, integrating large parks and green spaces, utilizing cool and super cool materials, ensuring effective insulation, employing passive and mixed-mode cooling and ventilation systems in buildings, and incorporating sustainable technology and innovation. Additionally, community participation and social equity are crucial for addressing vulnerabilities at a local level. It highlights the complexity of the relationship between heat waves and the built environment, emphasizing the need for interdisciplinary approaches for sustainable urban development in the face of heat waves. The outcomes can contribute to the formulation of informed policies to mitigate the adverse impacts of heat waves on built surroundings.