Over the past decade, circular strategies have been introduced into the construction sector to reduce resource consumption, waste generation and environmental impacts. This transition is requiring not only changes in project phases but also transformations in the constellation of actors involved. Previous research has mapped actors in circular construction and emphasised early involvement, but has not captured how these roles evolve over time. This study adopts a longitudinal perspective to examine how the roles and responsibilities of actors in circular construction projects changed over the last five years.
The study combines a literature review with a longitudinal qualitative design. Between 2021and 2022, 32 practitioners representing different roles in the construction process were interviewed about their involvement in projects with circular strategies. In 2025, a questionnaire was sent out to the same practitioners, allowing for a direct comparison of roles and responsibilities across two points in time. The analysis focuses on identifying new actors entering the process, shifts in the responsibilities of traditional actors, and the drivers behind these changes.
Preliminary findings reveal the emergence of new actors, such as material brokers and digital platform providers, alongside a reconfiguration of responsibilities among traditional actors like architects, contractors, and clients. Furthermore, actor involvement across project phases (initiation, design, procurement, construction, operation, end-of-life) has changed significantly.
This longitudinal study demonstrates that the transition to circular construction is not only about adding new actors or titles, but also about existing actors adapting to new roles and responsibilities over time. The results provide practical insights for practitioners navigating collaboration in circular projects and contribute to research on actor dynamics in the shift toward a more circular and sustainable construction sector.