The challenge of the project CESAR is first to unravel the complex relationships between the spatial configuration of land uses and infrastructures, meteorological processes and behavioural decisions concerning mobility patterns, residential locations and car ownership. Second, CESAR will integrate this knowledge in the improved interactive planning support system Urban Strategy to balance climate demands on space with other interests of the Randstad. For that purpose (1) knowledge transfer mechanisms will be designed and tested and (2) a "climate proof" Urban Strategy model will be developed and assessed in participatory workshops.