Improving City Vitality through Urban Heat Reduction with Green Infrastructure and Design Solutions: A Systematic Literature Review

Cities are prone to excess heat, manifesting as urban heat islands (UHIs). UHIs impose a heat penalty upon urban inhabitants that jeopardizes human health and amplifies the escalating effects of background temperature rises and heatwaves, presenting barriers to participation in city life that diminish interaction and activity. This review paper investigates how green infrastructure, passive design and urban planning strategies-herein termed as green infrastructure and design solutions (GIDS)-can be used to cool the urban environment and improve city vitality. A systematic literature review has been undertaken connecting UHIs, city vitality and GIDS to find evidence of how qualities and conditions fundamental to the vitality of the city are diminished by heat, and ways in which these qualities and conditions may be improved through GIDS. This review reveals that comfortable thermal conditions underpin public health and foster activity-a prerequisite for a vital city-and that reducing environmental barriers to participation in urban life enhances physical and mental health as well as activity. This review finds that GIDS manage urban energy flows to reduce the development of excess urban heat and thus improve the environmental quality of urban spaces. Furthermore, it finds that the most equitable approach to urban cooling is one that reduces the intensity of the meso-scale UHI that affects all urban inhabitants. Subsequently, a cooler urban fabric based on GIDS is proposed. A cohesive approach to the widespread adoption of GIDS shows potential to produce a cooler urban fabric that is human-centered in its function and aesthetic to enhance participation in public life and stimulate life on the streets. Four spatial scales are presented in which a combination of GIDS may be collectively implemented to reduce the meso-scale UHI, including the urban, intra-urban, building and body scales. This approach considers the interacting nature of GIDS applied within contrasting urban landscapes, and aims to produce cooler urban conditions, better walking environments, and ecosystem co-benefits to stimulate participation in physical activity and public life to underpin public health, productivity and livelihoods, thereby inducing city vitality.