This paper investigates the determinants of smart energy tracking app usage by citizens residing in French cities. Our framework is inspired by the extant strands of literature on smart cities and smart home technology adoption, but also contributing to them as smart energy applications reveal specificities that need to be incorporated; the latter include, for instance, the distinction between adoption and frequency of use, or the consideration of additional determinants such as privacy or environmental concerns. For our study, we build an original survey and rely upon citizen-level data, testing a Zero-Inflated Ordered Probit (ZIOP) model which allows to differentiate between adoption of the smart energy app and its frequency of utilisation. Our empirical findings reveal how the drivers related to smart city characteristics mainly affect the decision of adoption of energy tracking apps. Conversely, the more individual characteristics related to the perceived benefits of using energy tracking apps, dwelling type, and privacy concerns, primarily affect the frequency of utilisation. Our results bear policy implications on the issue of privacy, premising additional research on energy challenges in the utilization of energy apps in smart versus non-smart environments.