Recent focus on sustainability has made consumers more aware of our joint responsibility for conserving energy resources such as electricity. However, reducing electricity use can be difficult with only a meter and a monthly or annual electricity bill. With the emergence of new power meters units, information on electricity consumption is now available digitally and wirelessly. This enables the design and deployment of a new class of persuasive systems giving consumers insight into their use of energy resources and means for reducing it. In this paper, we explore the design and use of one such system, Power Advisor, promoting electricity conservation through tailored information on a mobile phone or tablet.