This chapter presents Sustainability Solution Spaces for Decision-Making (SSP) as an integrative method for assessing sustainability. The SSP represents the room to manoeuvre in the system at hand so that it can develop sustainably. The approach fulfils (1) systemic criteria; (2) normative criteria; and (3) procedural criteria. It provides a consistent set of targets and considers the systemic relations among the indicators representing the city-region. This gives the decision-makers concise guidelines for sustainable decisions and makes them aware of the associated trade-offs. SSP can be pursued following a participatory and an expert approach. Whereas the expert approach requires high quality of data, preferably either over time or over a large number of cities, the participatory approach is more flexible and can deal with qualitative data. That is, the expert approach is appropriate for comparing large sets of cities with each other, clustering and providing benchmarks for specific city types, and delivering general indications where policy development is required. The participatory approach might be particularly useful for assessing the impact of a specific project or analysing a specific sector, such as mobility or housing, in depth.

The Integrative Concept of Sustainable Development (ICoS) was developed through an intensive process in order to operationalise the guiding rules of sustainable development in an interdisciplinary team. Through its three general sustainability goals and 25 sustainability rules, ICoS establishes that indicators are part of a step-wise, systematic, and consistent construction that links theoretical abstraction to deliberative action: the political and societal practice of sustainable development (Barton & Kopfmüller, 2012, p. 84). The application of the concept is presented through two examples: a completed project in Santiago de Chile, and a project currently being developed, which will enable the calculation of regional sustainable energy balances.

This chapter presents a comparative analysis of four Participatory Multi-Criteria Approaches (PMCAs) usually applied in sustainability assessments (SMCE, MCM, 3-SPM, and INTEGRAAL). Such approaches are presented in detail and subsequently compared to each other according to three elementary yet crucial questions: who assesses?; what is assessed?; and how is it assessed? The results outline potential synergies and theoretical incompatibilities between the four approaches. The analysis also supports future PMCA applications when choosing one particular approach according to: key meta-principles (i.e., epistemological stance, methodological emphasis); logistical constraints (e.g., time, budget); local idiosyncrasies (e.g., pertinent geographical scales, power asymmetries); and organisational factors.