SPR was commissioned by the NSW Department of Climate Change, Energy, the Environment and Water to analyse how the state’s existing housing stock is represented in the Australian Energy Market Operator’s 2024 Integrated System Plan scenarios. The work quantified projected energy efficiency improvements for dwellings built before 2022 under each scenario, drawing on both policy-driven and market-led change. The analysis examined the influence of current and possible future policies, such as minimum performance standards and disclosure requirements. The findings provide the Department with a clearer understanding of the implied efficiency trajectories for existing homes to 2050, supporting long-term planning.