This article examines the discourse that the idea of efficiency is built upon according to different actors trying to influence households' energy behaviour in Sweden. The focus is on information from authorities as well as from interest organisations and energy companies. Information directed to households often contains a strong idea that the individual has to take responsibility for his/her own choices, and that it is through consumer choices the energy system will become more sustainable. The reasons given for changing one's behaviour are motivated both by lower energy costs and a reduced impact on the environment. Common advice for energy reduction is to change to a more energy-efficient apparatus. In this sense efficiency is a way of not changing lifestyle but instead changing technical equipment and user routines. Only the LA21 project questions the need for all the apparatus as well as the possibility to improve existing artifacts, pointing to a need to change our lifestyle. The strong belief in science and technology results in a definition of the problem as a lack of knowledge, where the only solution is to fill this gap. (C) 2009 Elsevier Ltd. All rights reserved.