One of the largest single uses of energy, and in most countries therefore oil and gas, is the heating and cooling of buildings. Much of the built environment we need to decarbonise by 2050 is already built. Adapting this infrastructure is going to be disruptive and expensive, and take time we arguably do not have. The main current approach to limiting this consumption is to try to tightly control the indoor conditions to a given setpoint temperature. But, is there another approach? We have conducted a year-long study of the actual thermal performance of a large non-domestic building. We find that there are three significant socio-technical gaps between the buildings systems’ perception of how the building performs and the temperatures experienced by building users which affect peoples’ comfort and waste energy. In contrast with traditional approaches, we argue for more flexibility and adaptivity in both the policy and and how the building is controlled to address this. We believe that mitigating these gaps and avoiding the wasted energy and associated indirect emissions is a significant opportunity for future ICT for sustainability systems.