Fuzzy Logic Approach for Sustainability Assessment Based on the Integrative Sustainability Triangle

The energy revolution's goal is to transform the current energy system into a sustainable system based on renewable energy technologies (RET). Even though RET are generally acknowledged as low-emission technologies with positive connotations, there are also negative impacts on ecological, economic and social environments throughout their life cycle. In order to support decision makers in building a sustainable energy system, comprehensive and easily understandable sustainability assessment-tools are required. Current approaches based on methods like Life Cycle Assessment or Multi-Criteria-Decision-Analysis have weaknesses in terms of comprehensiveness, processing of uncertainty and subjectivity, and visualization of results. In this paper, the holistic Fuzzy Logic Approach for Sustainability Assessment Based on the Integrative Sustainability Triangle (Fuzzy-IST) is proposed in order to resolve these weaknesses. Quantitative and qualitative Basic Sustainability Indicators of all sustainability dimensions and life cycle stages are hierarchically processed in a multi-stage fuzzy system. This results in seven crisp Sustainability Dimension Indices and a General Sustainability Index. The crisp values are then visualized in a color-coded Integrative Sustainability Triangle to provide an easy and intuitive interpretation of the results. This allows for the identification of deficits in all dimensions and the deduction of fields of action to improve the overall sustainability of RET.