This study presents accompanying research on the social and behavioural impacts of residents' exposure to newly established energy communities (ECs). Over the past two years, we collaborated with an organization supporting the local founding of ECs in three regions in Upper Austria. To capture the impact of the initiative, inhabitants of these regions participated in a three-wave panel survey (N = 360). The focus was on exposure to ECs, measured through regional presence (binary and membership numbers) as logged by the local organization, self-reported personal contacts, or self-reported direct membership. We measured how exposure shapes both psychological and behavioural outcomes: target variables included collective efficacy and support for climate policies, as well as self-reported energy-saving behaviour and community engagement. Multilevel models with repeated measurements nested within individuals are used to trace changes over time. We discuss the challenges of conducting applied, longitudinal research in partnership with community organizations, comparability between intervention and control regions, and limitations such as uneven exposure across regions, and the constraints of working with ongoing implementation processes.