In this paper, we present Power Agent - a pervasive game designed to encourage teenagers and their families to reduce energy consumption in the home. The idea behind this mobile phone-based game was twofold; to transform the home environment and its devices into a learning arena for hands on experience with electricity usage and to promote engagement by means of a team competition scheme. We report on its evaluation with six teenagers and families that were playing the game for ten days in two cities in Sweden. Data collection consisted of home energy measurements before, during and after game play in addition to interviews with participants after the game session. The results suggest that the game concept was highly efficient in motivating and engaging the players and their families to change their daily energy consumption patterns during the game sessions. The study indicates that pervasive games for behavior change and learning may also be appropriate to approach related domains su...