Studies of energy use at the household level show a large degree of variability in consumption that cannot be entirely explained by infrastructural differences. For example, families living in identically-designed homes use strikingly different amounts of energy. These findings were responsible for highlighting the influential role of the occupant in energy demand some thirty years ago. The extent of this variability also implies that there are no “typical” energy-using households within a society. This paper reviews evidence of the variability in domestic energy consumption and presents data from student apartments in a UK university where both the infrastructure and the number of occupants are comparable. As expected, the variability in consumption is less in this homogeneous sample than previously reported in heterogeneous samples of households. Nonetheless, there is variation, particularly in electricity consumption, that can only be explained by reference to some kind of occupantrelated feature(s). Further qualitative enquiry explores the idea that this difference arises from the practices of the occupants. It is clear that practices do vary between households. This paper develops hypotheses regarding the resulting differences in energy use. To explore these hypotheses, detailed micro-level consumption data is required. But this is difficult data to gather empirically and is not available here, nor widely reported in the literature. However, a framework based on practices could provide a cross-cutting and meaningful structure to relate details of micro-variations to macro-level understanding of the dynamics of energy demand in a society. In this way, analysis based on a practice theory perspective offers much potential to understand and interpret the variation in domestic energy consumption. In particular, it challenges any view that such difference, as it currently exists, is due to idiosyncrasies of individual behaviour.