Occupancy interventions, which are typically used to diffuse energy conservation practices among commercial building occupants, are showing promising but un-sustained energy savings. One possible explanation to the observed results is the presence of extreme energy users in the buildings who can have an important influence on their moderate peers and revoke the benefits of occupancy interventions. While this 'extremism' in human behavior phenomenon has been extensively studied in various social science fields, it has yet to be applied on the study of energy conservation from occupancy interventions in commercial buildings. Using agent-based modeling and data from actual commercial buildings, this paper evaluates the influence of extreme energy users (1) on their peers and on the energy performance of commercial buildings and (2) on the effectiveness of commonly implemented occupancy interventions. Parametric variations and statistical analyses indicate that extremism can highly affect the effectiveness of traditional occupancy interventions. In parallel, a combination of methods has shown to empower moderate energy users, helping diffuse and maintain energy conservation practices even in the presence of extreme energy users. The demonstrated capability to test and optimize occupancy interventions is expected to support and boost their adoption in large-scale energy conservation initiatives. (C) 2015 Elsevier B.V. All rights reserved.