The Sustainable Development Goals (SDGs) affect societal development within multiple sectors, both strategically and at street level. For instance, SDG 6 and SDG 11 have contributed to a shift in urban stormwater management that has traditionally been pipe-based, including only control of runoff volumes, to a more multi-functional nature-based blue-green infrastructure (BGI), where"blue" areas are characterized by (temporarily or permanent) open water and "green" areas by vegetative systems. As an alternative drainage approach, the use of BGI was developed and primarily evaluated in regions with temperate climates where a recent focus has been the role of BGI as providers of multiple ecosystem services within an urban context.

However, as the use of BGI expands into non-temperate zones, there is a clear need to address the fact that these nature-based systems are not only blue and green. For example, in northern climates BGI systems e.g., street-scale bioretention systems include white aspects (i.e. snow) for varying time periods. Whilst the design options for bioretention are varied and complex, (e.g., differing combinations of construction styles, filter materials and plants) research into the impact of alternative design options has focused on technical evaluations, i.e., the impact on pollution treatment and/or hydraulic control of stormwater. Knowledge of how these different bioretention designs affect other sustainability criteria, such as economic, social, and environmental aspects, needs to be fully developed.

The purpose of this licentiate thesis was to characterise and compare different street-scale bioretention designs to gain a better understanding of the relative sustainability of different bioretention systems and how the use of BGI can contribute to SDG delivery. In addition, the aim was to lay the theoretical foundation for an extended BGI concept by including white urban environments within the concept of blue-green-white infrastructure (BGWI). The overall goal was to contribute with new, relevant knowledge about the relative sustainability of alternative design aspects for bioretention systems in particular and the implications for BGI in general. A review of the literature informed the identification and approaches to benchmarking a series of social, economic, and technical-environmental criteria. In a life cycle assessment and a multi-criteria analysis, 12 different designs of bioretentions were evaluated. The results showed that, although design features had a large impact on the performance of bioretentions, no single design configuration scored highest across all sustainability criteria. The best performance in relation to social criteria was associated with the use of trees and smaller volumes of pumice in the filter material mixture. In the economic criteria, costs increased when using concrete constructions and a complex mixture of filter materials. Bioretention systems with a water-saturated submerged zone and a variety of plant species outperformed the other systems in the technical-environmental criteria.

The foundation of and justification for the concept of BGWI was developed in a perspective essay, including the development of a theoretical framework to support the systematic expansion of BGI to BGWI and to inform and align future studies. The framework identifies the potential for the delivery of a wider range of ecosystem services via BGWI in comparison to BGI. However, while the technical functionality of BGI in temperate climates has an established evidence base, its performance in cold climates (as BGWI) is less well evaluated with the extension of the BGI concept to BGWI identified as an opportunity to address these knowledge gaps in a way that is sensitive to seasonal variations in ecosystem service delivery (both positive and negative).

The results from this licentiate thesis can be directly used in both the strategic and practical planning of sustainable urban stormwater management strategies. Specifically in the early planning stage of BGI, design considerations should be made that recognise the differing role of BGI across seasons as an opportunity to aid multifunctional urban drainage implementation and thereby, the sustainable development of cities.