The sustainability challenges facing society today require approaches that look beyond single product-user interactions. Focusing on socially shared practices—e.g. cooking, laundering—has been identified as a promising direction. Building on a growing body of research in sustainable HCI that takes practices as unit of analysis, this article explores what it means to take practices as a unit of design. Drawing on theories of practice, it proposes that practice-oriented design approaches should: involve bodily performance, create crises of routine and generate a variety of performances. These guidelines were integrated into a Generative Improv Performances (GIP) approach, entailing a series of performances by improvisation actors with low-fidelity prototypes in a lab environment. The approach was implemented in an empirical study on bathing. Although the empirical example does not deal with common types of interactive technologies, the guidelines and GIP approach offer sustainable HCI a way to think beyond immediate interactions and to conceptualize change on a practice level.