It is now fully acknowledged that one of the priorities to deal with energetic and environmental challenges and to reach an important decrease on energy consumption is to improve energy management in the building (residential and service) sector. To reduce energy consumption in the built environment, and besides for optimizing the building envelope and improving the overall management of building equipments and systems, the building energy consumption by users and the impact of use and occupancy are critical aspects. This article focuses on approaches to make people aware of the importance of saving energy, and introduces to the "EcOffices" energy challenge, a competition for saving energy in office buildings by change of behavior, based on a comprehensive use of ICT and including an advanced usage analysis on the acquisition of eco-friendly behaviors generated by this type of challenge.