Managing demand for energy is becoming increasingly important for efforts to shift toward more sustainable lifestyles. Managing demand for energy involves changes in human behaviour, and can be achieved through more efficient uses of technology, and through conservation. Feedback is often cited as a critical tool to promote energy conservation and efficiency, but recent studies in behavioural science suggest that feedback alone may not be enough to promote lasting changes in behaviour. As an alternative, recent studies have shown the effectiveness of providing residents with normative feedback, rather than simple personal feedback. The current study analyses the impact of real-time feedback on residential electricity consumption over a two-year period. Results showed that when framed as a social comparison, feedback resulted in long-term reductions in household electricity consumption. Importantly, greater reductions were observed for households that identified more strongly with the normative referent group. Theoretical implications of the findings for behavioural science and the corresponding practical implications for fostering long-term sustainable behaviours are discussed.