Technological solutions to domestic energy reduction are insufficient without the cooperation of inhabitants. It does not matter how much energy hypothetically could be saved by efficient technologies if no one wants to live in the properties, install or use efficient lighting and heating. Therefore, to improve the uptake and effectiveness of household energy-efficiency interventions, it is necessary to understand 'why people react to particular energy-efficiency interventions in the ways they do?' An analysis is presented of in-depth interviews with 50 inhabitants who participated in one of four domestic energy-efficiency interventions. The findings indicate that issues such as aesthetic tastes and effects on lifestyle are central to why people reject economically viable, simple and well-understood domestic energy-efficiency interventions.