Complex interventions like retrofitting have wide-ranging impacts, which can be illustrated through systems maps – a method increasingly used in public sector strategies. These maps visualise system interactions, including elements such as health, environment, inequality, finance, and regulation, and outcomes: feedback loops, tipping points, and unintended consequences. However, we do not yet have a systems understanding of the real-world impacts of retrofits. Building upon successful applications, including for transport decarbonisation, we will employ the PSM approach to co-develop systems maps for housing decarbonisation. Our PSM approach enhances stakeholder understanding, by highlighting critical interdependencies and feedback loops, informing more effective interventions