Household energy use data may contain sensitive inferences into family life, yet its potential for surveillance is imperfectly understood. To explore this space, we developed Household Wattch, a speculative eco-feedback ‘provotype’ that profiles households according to their energy use data. Evaluated by 16 participants from Australian households engaged in an 18-month energy use monitoring trial, Household Wattch elicited users’ perceptions and expectations about a near future where energy use data is a useful yet potentially sensitive commodity when analysed. We highlight challenges and opportunities for energy use data across three scales: (1) Within the household, (2) Beyond the household (e.g., sharing energy data with third parties) and (3) Post-household (e.g., what happens to energy data when a household re-configures or disbands). Findings suggest users may require support in understanding the sensitivities of their energy use data, particularly when deciding whether to share it with third parties. Opportunities exist for accidental or deliberate surveillance via energy use data, and these need to be identified and managed. Provotypes represent a useful tool for navigating this space, and we provide considerations for how they can support users in speculating over possible energy futures.