Research on sustainable practices has attracted increasing interest as a way to understand energy demand and transitions towards sustainability. In this paper we elaborate on how practice theories can inform the discussion of experimentation. Practice theory suggests that the everyday life of people appears recalcitrant. Practices are robust, resilient and have multiple, historically formed constituents and are thereby difficult to destabilize and change quickly. The making and breaking of links inside and between practices is highlighted, as is the need for enduring, multi-sited change efforts. Practice theory further helps us to better understand the constitution of new, levelled forms of expertise, the distributed nature of experimentation and the enrolment of citizens as active participants in sustainability transitions. We have operationalized and examined these suggestions in a Finnish research project related to climate change mitigation and energy use in detached houses. We report specific modes of experimentation and innovation, including user innovations, and the shared resources of situated expertise, the collective and shared processes of empowerment and the ways in which normality is challenged by ruptures in everyday life. Based on the results, we derive suggestions for effective policy interventions. We also bring forward a set of generic suggestions for more sensitive, appreciative and effective public policies on sustainability transitions and cast experimentation in a particular and partial role in such policies.