This paper presents findings from a study carried out to contribute to the growing knowledge base within the Design for Sustainable Behaviour research field. Coffee makers, electric kettles and toasters were evaluated to explore if and why particular appliances may mediate less energy-intensive use to a greater extent than others. Eighteen participants used three appliances of the same type for two weeks each, during which the participants’ use of the appliances and the resulting energy use were monitored. In addition, semi-structured interviews and online surveys were conducted to explore how the appliances’ functions and overall design influenced energy use. The findings show that both specific functions and the design as a whole form the design characteristics that set preconditions for energy use. The study thus suggests that if appliances are not designed to support energy conservation holistically, there is a risk that aspects that have not been addressed will lead to more energy-intensive use. This makes it essential for designers to consider the full variety of characteristics influencing energy use. Based on the findings, design opportunities were identified and design guidelines formulated. The insights gained highlight new opportunities for design practice that can aid designers in designing for less energy-intensive use.