There is evidence that occupants' energy use holds a large fraction of the total energy consumed at the office. Our work, motivated by a relevant study investigating the effect of individual feedback on energy use at the workdesk, exploits earlier findings to design a six-month field trial that monitors occupants' energy use and provides individual feedback to 18 office employees in a university setting. This paper presents the research design and methods used, employing data analysis to assess how office workers responded to the feedback provided, and to examine their impact on the energy consumption of their desktop computers. The main findings were: the behavior of occupants affected the energy consumption of their computers in a large extent; emails were considered better communication channels than posters and leaflets; a combination of feedback messages was more useful, with personal advice, self monitoring and education being the most powerful; finally and most importantly energy reduction and proper use of equipment continued for 13 weeks after the feedback was removed. (C) 2015 Elsevier B.V. All rights reserved.