This is the final version of the article. Available from UKERC via the link in this record.This is working paper 1/3 from the Heat, Incumbency and Transformations (HIT) project.Incumbency is frequently considered as a barrier to the transformation of unsustainable socio-technical systems such as energy systems. However, despite wide use of the term, ‘incumbency’ has never been fully or adequately defined within the sustainable transitions literature. This working paper considers the use and meaning of the term incumbency in relation to sustainable transformations, specifically in relation to the UK’s heat system. It takes ideas of incumbency from other disciplines including economics, politics and innovation. Synthesising these literatures, the paper proposes a number of characteristics of incumbency. Finally we propose a definition of incumbency in relation to sustainability transformations, which suggests that incumbents are actors already present in a specific socio-technical system, who are likely to be involved with unsustainable practices, and who possess the capacity to affect system change.UKERC is funded by The Research Councils UK Energy Programme
