This study investigates social barriers in Norwegian urban energy projects from the planner’s perspective, bridging institutional and reflexive approaches in the field of planning. Compared to technological barriers encountered in the energy transition, social barriers have received relatively little attention. While the former implies a need for hard technological fixes, social barriers cross sectoral dimensions and can potentially be transformed through strategic action during the life of a project. When planning energy transitions under the popular guise of smart and sustainable cities, social barriers arise in the context of urban experimentation, which challenges institutional constructs, participatory planning principles, and knowledge. These aspects are addressed from the planner’s perspective through analysis of planners’ experiences in seven energy pilot and demonstration sites in Norway. The results identify categories of social barriers related to the understanding of a shared vision amongst stakeholders, lowered ambitions over the course of a project, lack of user involvement, and structural constraints to planning. A framework for a deeper understanding of social barriers is proposed, extending to the notion of planners’ transformative agency to support sustainability transitions, which has the potential for future enrichment through the addition of cases and application in other fields of sustainability transitions.