Exploring the interplay between technological decline and deinstitutionalisation in sustainability transitions

•advances understanding on institutional conditions for technological phase-out.•complements the existing focus on full decline of unsustainable technologies.•examines multiple dissipation mechanisms and their effects on technological decline.•highlights the role of institutional remnants in shaping technological decline. The decline side of transitions is an emerging study, which advances thinking on regime destabilisation, technology decline and phase-out policies. Previous research has predominantly focused on the complete phase out of specific unsustainable technologies as desirable or possible, but it has given less attention to how these technological aspects interweave with institutional elements in ways that may constrain or enable system transformations. Our research develops a framework that clarifies the nuanced relationships between technological decline and the dissipation of institutional elements as distinct but interrelated processes. Through a longitudinal case study, we used the framework to examine the decline of unsustainable drainage technologies in Melbourne, Australia. These technologies are embedded within existing institutional elements, i.e. routines, rules, roles, and meanings that govern how stormwater should be managed. The near-full decline of one type of the drainage technologies is enabled by mixing old and new institutional elements. We found that the dissipation of multiple elements using combined mechanisms is important to achieve this partial decline outcome, and more attention needs to be paid to the effects of institutional remnants in constraining systems transformations.