In the UK, the domestic sector is a major contributor of national carbon emissions. In a country with a low turnover of housing, improving the energy efficiency of the existing stock, particularly the oldest and least efficient homes, is of utmost importance if ambitious carbon reduction targets are to be met. Analysing the rich, narrative data of households living in old, hard-to-treat homes, this paper produces novel insights into the ways in which domestic thermal comfort practices are shaped by meaningful relationships, intimately bound to identificatory positions, that are deeply connected to these valued domestic environments. Findings concern how households renegotiate widely accepted understandings of thermal comfort to better fit with the materiality of their old homes by constructing for themselves meaningful 'moral' identities that focus on living sufficiently well. This relational understanding of domestic energy consumption highlights how materiality, practices and moral narratives are produced and reproduced dynamically over time, challenging static notions of utility maximisation and technical interpretations of efficiency that dominate contemporary energy policy.