Dealing with uncertainty - integrated sustainability assessment based on Fuzzy Logic

Assessing environmental and social impacts is associated with uncertainties caused by applied assessment tools, the definition of the object of assessment, system boundaries of assessment and data quality. In order to deal with these uncertainties the concept of Integrated Sustainability Assessment on the basis of Fuzzy Logic is presented. Integrated Sustainability Assessment combines ecological, social and economic assessments in one tool and consists of the steps definition of goal and scope, ecological assessment, economic assessment and general assessment. In the first step system boundaries and the object of assessment have to be defined. The ecological assessment evaluates the ecological impacts caused by the assessment object. For the social assessment, specific criteria have to be defined. For the economic assessment common economic concepts can be used. The crucial step of Integrated Sustainability Assessment is the general assessment, where the ecological, social and economic assessments are combined through Fuzzy Logic in order to consider the specific conditions of the decision situation. Preferences of decision makers are modelled with case-specific fuzzy sets. The result of Integrated Sustainability Assessment can be used as a basis for strategic decisions.