The increasing potential for dramatic climatic changes, the need to protect the future of our energy supply and rising fuel prices, mean that there is an urgent need to reduce energy consumption. This Special Issue of Indoor and Built Environment on ‘People and energy use in the indoor and built environment’ recognises that while buildings account for 32% of total global final energy use, the role of people in buildings’ energy use is often overlooked, despite the fact that ‘buildings don’t use energy: people do.’ The papers in this Special Issue demonstrate a broadening of the social science contribution to understanding energy use in the indoor and built environment. As well as focusing on ‘routine actions’ (or behaviours) using technologies and buildings, many papers presented here focus on ‘one-off actions’ to change technologies or buildings. Several papers go beyond a focus on individual building occupants, to include chains of actors or intermediaries (e.g. landlords) that influence the choice and/or use of technologies or buildings. These papers often also address the processes or chains of actions entailed in introducing new technology or buildings – such as service design or the communication process. Many papers explore the social, economic or technical context for actors and their actions. Most papers explore motivations for actions. Indeed, for many authors in this Special Issue, context is motivation and, combined with existing technologies and buildings, it creates the conditions that virtually require the routine actions that are observed. A few papers report on experiments with relatively ‘deep’ interdisciplinarity; approaches that might help the social and technical sciences learn from each other and so improve our understanding of people and energy use in the indoor and built environment. Three papers focus on the use of technology. Moore et al. note that the installation of heat pumps into homes has traditionally been seen as a purely technical matter, but if heat pumps are not used effectively, they won’t save energy. Examining the installation of domestic heat pumps in UK social housing, they focus on the design of the service to support the user experience of this new technology. Landlords and installers thought heat pumps were too complicated for users and more complicated than necessary. Tenants felt they were given insufficient information on how to use their heat pump, and many lacked confidence using heat pump controls, resulting in feelings of frustration and dependence. However, the authors’ prototype leaflet on using the heat pump controls was not favourably evaluated by users and tenants wanted a personal follow-up visit from the landlord or installer to answer any questions. Belatedly trying to explain how to use a too-complicated technology seems a less-promising approach than developing a technology and its control interface to suit its users. Dimitrokali et al. also examine the use of technology – smart home heating controls. Participants were customers of a UK utility company who volunteered to take part; nearly all were men who felt they had a good understanding of the purpose of smart home heating controls. Participants felt the trial positively changed their heating behaviour but wanted better capacity to control schedules when away from home and personalised tips on how to control their heating. The use of technology is also explored by Watson, focusing on a recently built UK ‘passive design’ office development, featuring a range of natural ventilation technologies and newly inhabited by a tenant organisation. The building was using significantly more energy than predicted, even after a post-occupancy evaluation helped fine-tune the technologies. The author uses social practice theory to understand this ‘performance gap’. Although the material element (technologies) of social practice theory was eventually functioning correctly, this was not the case for the three other elements of the practices framework: embodied habits, engagement (developing shared meaning) and institutionalised knowledge. The habits of building users were deeply