Energy consumption behaviours are gradually becoming better-understood. However, there is still a deficit in terms of knowledge of individuals' energy-use behaviours in organisations, despite a variety of available theories. This paper addresses this need in three main stages, based on a survey among mid-level managers at a major infrastructure operator in Great Britain. Firstly, a principal components analysis is performed to identify key determinant constructs driving energy-efficient behaviours in organisations, revealing the importance of perceived benefit to the organisation and flexibility of existing performance goals and targets. Secondly, cluster analysis is undertaken, in an effort to identify differences in behavioural influences between demographic groups. These clusters highlight the heterogeneity of employee populations' energy behaviours, demonstrating that assumptions cannot be made about these based on single responses to cross-industry surveys. Finally, a structural equation model of individuals' energy use intentions and behaviours using the newly-identified constructs is developed, revealing some similarities with existing behavioural frameworks such as the Theory of Planned Behaviour (Ajzen, 1991). Implications for policymakers are then discussed, in terms of encouraging individual employees' curtailment of energy consumption in organisations through tailored engagement programmes.