Zero-Watt Networked Standby: Development and Evaluation of a Home A/V Network System

Energy conservation is an important global issue. Home is the third largest energy consumer, and 10% of the home energy is standby power of home appliances. The proliferation of home networks increases the standby power. The conventional technologies for low networked standby power such as WoL require continuous AC power, as much as 0.5 watts, to monitor wake-up signals. The large portion of the consumed power is due to the power loss in an AC-DC converter. Moreover, the technologies are applicable only to the specific network types such as Ethernet and IEEE802.11. We propose a solution to reduce the networked standby power down to zero virtually, regardless of the network type. For monitoring wake-up signals, the solution utilizes the precharged power in an ultra capacitor without using AC power supply almost all the time. In order to realize this idea, the solution also utilizes unique and simple protocol dedicated only to the networked standby /wake-up functionality. This protocolenables the monitoring circuit to consume very small power enough for the capacitor to supply. The networked standby/wake-up functionality is easily combined with any conventional network application protocol by protocol address mapping. As one realization example of our solution, we implemented an experimental system which is integrated with an ultra low power wireless signal receiver and extended UPnP protocol. The system evaluation showed that our solution achieves the zero-watt networked standby while keeping network functionalities. Moreover, the analysis of the results shows that the practical networked standby power is one seventeenth of the conventional technologies in usual usage. This corresponds to 1.11 kg-CO2 emission reduction per year per product.