Handling changes through diagrams. Scale and Grain in the Visual Representation of Complex System

To change towards a more sustainable development could means to make decisions not only with a systemic approach, but also to be able to decide in the right time: the density. It seems that, when the discipline of Design integrate a systemic approach with the competences of designers in visualization, it can cope with dense situations, providing effective artefacts – diagrams - to improve the decision process and making profit from the richness of complexity. The prior findings of the Complexity Science are here assumed as a theoretical framework to have an interpretative model on how the knowledge about systems could be organized and depicted. Three tools to produce effective diagrams, framing, graining and scaling are here discussed though six case studies.