Edinburgh Napier University

  This paper presents Wattom, a highly interactive ambient eco-feedback smart plug that aims to support a more sustainable use of electricity by being tightly coupled to users' energy-related activities. We describe three use cases of the system: using Wattom to power connected appliances and understand the environmental impact of their use in real time; scheduling these power events; and presenting users with personal consumption data desegregated by device. We conclude with a user study in which the effectiveness of the plug's novel interactive capabilities is assessed (mid-air, hand-based motion matching). The study explores the effectiveness of Wattom and motion matching input in a realistic setup, where the user is not always directly ahead of the interface, and not always willing to point straight at the device (e.g., when the plug is at an uncomfortable angle). Despite not using a graphical display, our results demonstrate that our motion matching implementation was effective in line with previous work, and that participants' pointing angle did not significantly affect their performance. On the other hand, participants were more effective while pointing straight at Wattom, but reported not to finding this significantly more strenuating then when pointing to a comfortable position of their choice.