As regulated energy consumption in buildings is reduced; the proportional importance of unregulated energy consumption increases. Reducing unregulated energy use in the commercial office requires an understanding of the factors that influence workplace behaviour. To date these factors have been assumed to be similar to those that influence behaviour in the home. However, the social dynamics of the workplace are different to that in the home. This study examined the degree to which theories of behaviour change generated largely in a domestic building setting could be used as the basis for designing interventions to reduce unregulated energy consumption in the workplace. The study examined the unregulated energy consumption of 39 workers engaged in office type activities in two separate locations. Following a 100 day monitoring period, three behaviour change interventions were developed and their impact measured over a 100 day period. Results from the study found, on average, an 18.8% reduction in energy use was achieved. Furthermore, by comparing pre and post intervention responses to an environmental questionnaire it was evident that savings were realised without significant changes to pro-environmental attitude or perceived social norms, which may have implications for energy saving interventions in the commercial sector.