This paper explores how the design of domestic appliances influences people's energy use during everyday activities. Drawing on findings from an interview study with 81 informants, a variety of design characteristics were uncovered, which set preconditions for use that in different ways impede or support energy conservation. The identified characteristics concerned not only appliances' operative functions but also their interactive and communicative functions as well as people's underlying motives for using specific appliances. Addressing the full range of characteristics during the development of new appliances will highlight a variety of design opportunities and increase the possibilities for developing appliances that support people to go about their everyday activities in less energy-reliant ways.