This chapter uses the notion of 'the energy precariat' to capture the socially and technically fragile underpinnings of energy consumption among transient urban populations in developed countries. It highlights how the articulation of sustainability transitions among transient urban dwellers is contingent upon the wider dynamics of infrastructural embeddedness and everyday life that contribute to this group's increasing vulnerability to energy poverty. The chapter also highlights that sustainability transitions themselves cannot be seen in isolation from other processes of systemic change in society: they need to be understood within the context of related demographic, housing and institutional transformations, while considering the inequities that underpin energy use. It addresses two of the general themes, pertaining to the difference between urban sustainability transitions and other types of sustainability transitions and to the scale-related conflicts and synergies implicated in such processes. The chapter thus commences with a discussion of the multiple transitions that affect young adults across the developed world.