Grön-blå infrastruktur : en utvärdering av temperatursänkande och mikroklimatreglerande åtgärder i två utvecklingsområden i Stockholm, Sverige

The global rise in temperature caused by climate change, in combination with an increasing urbanization have made urban heat islands (UHI) a common phenomenon. This puts pressure on microclimates in urban areas. Additionally, the densification of cities has led to a reduction of green and blue surfaces, which triggers further UHI effects. To combat heat phenomena, such as UHI, temperature can be regulated through carefully planned integration of green and blue infrastructure (GBI). GBI, such as street trees, green roofs, parks, dams and wetlands, provide temperature cooling effects by absorbing heat and evaporating water. In Nordic cities, GBI has mainly been adapted in urban planning to manage stormwater and prevent flooding. However, as the UHI is becoming a recurring phenomenon in densifying cities globally, there is an increasing demand for GBI integration in temperature regulatory purposes in Nordic cities. The objective of this thesis is to examine how and where GBI can be integrated into two development areas in the municipality of Sundbyberg to provide heat mitigating effects. This is evaluated by using a literature review of the characteristics and usage of GBI for temperature cooling. Additionally, a multi-criteriaanalysis proposes the most suitable areas for integration of GBI. Finally, a heat mitigation analysis is executed in InVEST, which also identifies capabilities of albedo and evapotranspiration based on current and planned GBI in the study areas. The results show that the most suitable areas for GBI integration are concentrated in the more densely built-up areas, where surface temperatures are highest and vegetation is sparse. In contrast, less suitable areas already contained significant vegetation and naturally lower temperatures. The Urban cooling model in InVEST demonstrated that vegetation and water sources have a strong cooling effect through evapotranspiration albedo and shading. However, areas with limited vegetation and highly impervious surfaces exhibited lower cooling capacity. These findings are consistent with previous research highlighting the temperature cooling benefits of GBI. The thesis concludes that GBI should be prioritized in high-density areas lacking vegetation, preferably characterized by flat terrain and high maximum temperatures during summertime. Trees are the recommended choice of GBI integration from a temperature cooling perspective due to their capacity to provide both shade, transpiration and are costeffective to implement. Future research should consider the long-term maintenance, economic feasibility, and social equity of GBI implementation.