Cooling strategies for thermal comfort in cities: a review of key methods in landscape design.

Under the climate change scenario, the negative impacts of urban heat island (UHI) will exacerbate due to unsustainable urban planning and human activities. Thermal comfort has close relationships with UHI in urban areas. This paper is based on the studies of urban heat island, thermal comfort, microclimate, and urban planning in cities in the recent decade, combined with a method of research into design. The key topics include vegetation and water conditions, the albedo of materials, and urban morphology. By the comparative case studies in landscape projects, the results further reveal that the density of tree canopies, the natural structure and density of ground cover, the form of water features, the color and texture of materials, and the scale of shading structures have different cooling effect and performance in outdoor thermal comfort improvement with specific features in the landscape design. It is also found that there are some external conditions that can influence design determinations in real practices. The purpose of this study is to provide theoretical research methods and evaluation of thermal comfort landscape design elements and to provide guidance for future sustainable city research and landscape design.