Understanding the up-scaling mechanisms of urban energy transitions: An application of a capital-based framework to a comparative case study of two solar communities in Hong Kong

Urban community energy can play a critical role in enabling urban energy transitions. Engaging households (residential electricity end-users) is an essential bottom-up approach to scaling up these efforts. A key question to address is how to scale up individual household impacts to achieve meaningful contribution. Building on previous sustainability research on community capitals and scaling mechanisms, this study aims to fill this gap by developing a model of capital-based up-scaling mechanisms for community-driven urban energy transitions, which is deployed to understand and examine up-scaling mechanisms of community solar in cities. By adopting a mixed-method approach, this comparative study of two prospective solar communities in Hong Kong collected qualitative data from 78 semi-structured household interviews, 21 in-depth stakeholder interviews, and qualitative, transcription from two community workshops that engaging 57 householders, conducted between 2018 and 2019. Our results show that local residents assume multiple user roles and have access to a diverse range of community capitals, interacting in a complex mechanism that involves five critical up-scaling processes: envisioning, leadership, experimentation and social learning, network building, and institutionalisation, creating a complex mix of enabling and disenabling conditions for up-scaling. We found that major disabling conditions include a lack of shared visions, an absence of leadership to inspire and mobilise action, insufficient trial-and-error processes, a lack of replication of best practices, a failure to establish linkages, disembedding, and inadequate electricity market liberalisation. We further conceptualise the limits of the community energy approach by specifying three types of user-oriented relationships with the state and market at community-level, organisational level, and institutional level. This highlights that users alone cannot create sufficient enabling conditions; rather, broad external social relationships have to be developed with critical stakeholders, including residential management offices, utilities, and government, to overcome disenabling conditions. We conclude by suggesting possible directions for further research on capability building to empower transformation. © 2025 The Authors.