Behavior interventions aiming to reduce energy consumption in the built environment are becoming increasingly common. The application of individual feedback and use of social norms have shown promise in the short-term at improving occupant energy use behavior. Yet, the long-term effects, role of messaging duration, and relative effect of normative elements in feedback messages remain less clear. This paper attempts to address these gaps in the literature by conducting and analyzing two yearlong field experiments that test the effect of normative feedback messages on energy consumption in dormitories. The analysis finds that adding normative elements to feedback messages had no effect on energy consumption in the short-term. When examining behavior change conditional on an occupant's concern for social norms, it was found that individuals with a high concern for social norms positively responded to the normative elements with an estimated treatment effect of -14% (consumed less). Conversely, individuals with a low concern for social norms had the opposite reaction, with an estimated treatment effect of 5%. Further, it was discovered that the duration of messaging positively influenced the long-term durability of behavior change. The long-term effect of behavior change was twice as prevalent in individuals with high concern for social norms. (C) 2016 Elsevier Ltd. All rights reserved.