To address energy transition through a net-zero built environment, significant citizen activation and participation is crucial. The chapter aims to identify the challenges, outline best practices in citizen co-creation based on the results of selected EU H2020 projects, and provide future research directions. Best practices are analysed in three phases. (1) Recruitment Phase: The first phase of engagement encompasses all the moments in which potential users are exposed to information that is relevant to participating in a specific project or programme until the moment in which they sign up. Core success factors for the set-up of a promising recruitment phase will be outlined. (2) Consumer Response Phase: In the second consumer response phase, strategies are directed at initiating and consolidating responses to innovative net-zero projects. This phase starts with the user’s own acts of planning and reflecting on how best to integrate existing into changing and rearranging urban and domestic living perceptions. (3) Persistence Phase: In the third phase (i.e., persistence), engagement strategies seek to maintain interest and continuous involvement in programmes. By prolonging interest and interaction over time, the goal of this phase is to ensure that participation remains sufficiently interesting and comfortable for users, transferring them to ambassadors and multipliers for innovative solutions. The chapter provides a co-creation framework with project insight-based best practice recommendations and proposes a clustering of stakeholders according to a quintuple helix approach and a stepwise phase approach towards the set-up of net-zero built environment projects.