After Phases I and II of the EU commissioned project concluded with a methodology for the evaluation of external costs and its implementation for selected EU member states, Phase III took to the further development and application of the framework. The ZEW was contributed to the following packages:

• The integration of indicators for sustainable development into the ExternE project´s model framework (specifically, the application of a unified concept of weak and strong sustainability derived from previous project work to the areas of climate change, acidification, eutrophication, radioactivity and fishery).
• Assessment of social costs and benefits of climate change (methodological improvements of the assessment strategy concerning the isuue of inter- and intragenerational equity in particular).
• Assessment of non-environmental externalities (integration of nuclear proliferation under consideration of associated problems).
• Assessment of social costs and benefits of rational energy consumption (use of case studies for the approximation of external costs (savings) due to the use of various ´smart energy´ strategies).