This paper investigates the effects of information feedback mechanisms on electricity and heating usage at a student hall of residence in London. In a randomised control trial, we formulate different treatments such as feedback information and norms, as well as prize competition among subjects. We show that information and norms lead to a sharp - more than 20% - reduction in overall energy consumption. Because participants do not pay for their energy consumption this response cannot be driven by cost saving incentives. Interestingly, when combining feedback and norms with a prize competition for achieving low energy consumption, the reduction effect - while present initially - disappears in the long run. This could suggest that external rewards reduce and even destroy intrinsic motivation to change behaviour. (C) 2016 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.