Sustained behavior changes are required to reduce the impact of human society on the environment. Much research on how HCI may help to do so focuses on changing behaviour by providing information directed at an individual or a microstructure (e.g. household). We propose societal macrostructures (e.g. municipalities) and their interaction with microstructures as a focus for HCI aimed at designing behavior change. We present two ongoing case studies involving municipalities in Denmark and discuss how and why macrostructures may be used in the design of HCI for behavior based environmental suatainability.