How can researchers and planners best facilitate the transition to low-carbon societies? In particular, can they initiate better dialogue in order to foster stakeholder engagement in planning, building and living in low-carbon settlements? These challenges inform a municipal planning process for a new neighbourhood in Trondheim, Norway: Brøset, as well as for an interdisciplinary research project exploring the role of action research in supporting the transition to low-carbon societies. The processes are described for identifying the central actors and applying the dialogue strategies in the early planning project phase. Researchers and planners collaborated to contribute to new knowledge production and practice to support the transition to low-carbon societies. The utility of the co-produced results is their potential contribution to both standards of rigour as well as the timely dissemination of research and knowledge sharing within and across research communities and to different stakeholders involved in the project. This case study provides interesting lessons about why and how other projects can consider similar action research processes as a viable approach for sustaining the transition to low-carbon economies, particularly in the early planning phase.