The paper shows the semantic linkage between the energy efficiency concept and comfort focusing on the step from the normative and technical domain to the daily housing practices. From the case study the CasaClima energy certificate emerges as a criterion of differentiation within the housing system. Nevertheless, it needs of a cultural affirmation aimed to a territorial expansion. These dynamics provide an interpretation of the energy efficiency as socially built phenomenon.
Keywords: Energy efficiency, CasaClima, comfort, cultural affirmation, systemic approach, housing innovation