Home energy efficiency upgrades are easy right?! A systematic review of factors influencing homeowner behaviour across multiple levels

The building sector contributes almost one third of global CO2 emissions. Supporting energy efficiency upgrades in residential homes could provide significant emissions reductions, while also improving thermal comfort and health outcomes for homeowners. Numerous government policies and programs now seek to accelerate the adoption of home energy upgrades. Their success, however, is partially dependent on a range of homeowner behaviours and requires a deep understanding of the factors that influence them. This paper systematically reviews the current evidence base related to energy upgrade behaviours and their influencing factors from a multi-level perspective and organises the different factors at different levels (or contexts). We highlight current skews in the evidence base towards certain upgrade behaviours and propose a new multi-level framework of home energy efficiency upgrade behaviours. This framework explicitly recognises the combined influence and potential interplay of influencing factors at different levels, from which upgrade behaviours emerge. We conclude by suggesting future research directions and policy implications for supporting energy efficiency upgrades in homes.