Household-targeted energy efficiency policies based on Demand Side Management (DSM) combine two complementary facets: frugality (reduced consumption of energy services) and efficiency (less energy used for the same service). They have adopted a broad discourse on individual responsibility in saving energy and tend to focus on economic motivation, for which they have developed instruments and incentives. Yet, the actual energy usages of urban households do not meet their set objectives, partly because DSM campaigns have a poor understanding of households’ energy usage and of their related capacity of aligning them with “good practices”. This paper argues that this capacity is highly constrained by class-based cultures of consumption and by place-based conditions of living. It is based on the results of a socio-anthropological survey on lower-middle-class energy usages in Cape Town (South Africa) and the way they respond to DSM measures promoted by the national company ESKOM and the municipality. It emphasises that in the absence of more finely targeted awareness campaigns, the promise of savings and moralising language are not enough to establish an effective balance between normative recommendations and the inertias inherent in the living patterns of an urban population under stress.