Public displays have been used as a persuasive technology in many prior works. In this paper, we describe a persuasive pervasive system aimed at influencing users' behavior for reducing energy consumption in buildings. This system exploits a pervasive display that visualizes the energy consumption in different levels (rooms, floors, and buildings), exploiting social comparison techniques. Moreover, our system may be extended by means of a mobile application that sends persuasive personalized messages to the users regarding their energy consumption. We then present our evaluation study design, aimed at comparing the effectiveness of three possible implementation of our system: one based only on the use of displays, a second one that relies only on mobile notifications, and a third solution that combines both these approaches.