We examined the role of the built and social environment in changing occupants' energy consumption in an office building. We argued that understanding occupants' behavior is the key factor to achieve energy efficiency. We collected contemporary scientific articles from the fields of psychology, energy efficiency, and sustainable architecture that discuss the encouragement of sustainable behavior. We found two main factors that emerge as the key to shaping energy-saving behavior: knowledge input and environmental feedbacks. After that, we conducted qualitative research to observe occupants' behavior in the Ministry of Public Work and Public Housing Main Office-a platinum-certified green building-to see whether there was indeed a correlation between environment and sustainable energy behavior through field observation and questioners. Our research showed that occupants who worked in a green environment have good sustainable energy behavior. We argued that a balanced perceptive-a consideration of how building and occupants simultaneously and mutually affect each other-is crucial in efforts to encourage behavior change that will lead to building energy efficiency.