A three-year field experiment was conducted with 185 prosperous households to assess whether behavioural interventions by a community environmental group during and after thermal upgrades (cavity wall and/or loft insulation) can achieve reductions in households' energy use, including reductions in direct and indirect rebound. The engineering interventions on the thermal efficiency of dwellings appear effective in reducing energy use in both treatment and control groups: a direct rebound effect is estimated to be at most 40 per cent from the engineering interventions. However, across a range of measures of energy use, we observe no significant effect of the community behavioural intervention across the total lifetime of the project. Qualitative data collected on similar community groups suggests substantial constraints on their capacity to realise reductions in energy use amongst households.