The purpose of this paper is to present a new behavioral indicator, which is still at an experimental stage, and the results of two experiments making use of it. This indicator could be used to complement traditional impact evaluations of energy efficiency programs. In the framework of its Environmental Management System, the State of Geneva planned to save 2 GWh in 2013 due to five projects of energy efficiency optimization, a part of which focused on the promotion of energy-efficient behavior at work. This was done in collaboration with a demand-side management program, éco21, implemented by the local utility. To evaluate its efficiency, a behavioral indicator, the Environmental Awareness Indicator, based on psychological studies, was designed and tested to complement quantitative results in kWh obtained by the instrumentation of several buildings. First, changes in the energy consumption before and after two energy conservation promotional weeks (called « Energy Weeks ») were measured. Consumption was also measured six months after one of the promotional weeks. Our investigations show that a well-organized Energy Week for a fairly large organization (around 400 employees) has a potential of 20% energy savings immediately after the event, decreasing to a value between 3% and 12% after six months. Second, we made use of the above mentioned indicator to analyse the qualitative behavioral evolution of the two populations studied. The indicator shows that after the Energy Week there is a general shift towards behavioral change, at all stages of the change model, with an increase (13% and 19%) of employees moving towards action. The usefulness of such an indicator is therefore twofold: it permits behavioral monitoring and enables to adapt the implementation of change actions to the behavioral stage of the target.