UK firm Energy Optimizer has launched a plug-in electricity metre that relies on the wireless ZigBee protocol.

Called the plogg, the device can be used by a business, such as a restaurant chain, to monitor energy usage for refrigerators and air conditioners, with all the data collected at a central server via the internet. If an appliance was left running after hours, the plogg could be used to alert someone or could be set to automatically switch off power.

ZigBee is the name given to the 802.15.4 protocol, which is designed to provide low-power wireless communications for networked monitoring and control products.