Better understanding of the factors influencing how people use energy in public buildings can help deliver more effective CO2 reduction strategies. This paper describes the institutional, social and individual behavioural effects of communication campaigns in over 500 public buildings in 11 European cities. These campaigns involved engaging with staff to reduce energy use through feedback services based on information from sub hourly meter readings. A summative evaluation was conducted to understand impacts of different information provision in these cities. Qualitative data were gathered through a set of interviews with 40 building professionals at the central or building level. These interviews identified differences in how the energy efficiency communication-based campaigns were implemented at each site and elicited factors to explain how users' perceptions and understanding changed as a result of the interventions. The evaluation framework helped to identify not only improvements in the delivery of communication-based campaigns, but also the communication factors that impacted on individual behaviour change. The research highlighted the influence of institutional and social effects on individual beliefs and norms. To achieve more effective change in attitudes to reduce use, energy feedback needs to be supported with engagement activities, such as energy coaches, campaigns, and interactive online fora.