ZigBee-based meter aids energy efficiency


Boston, MA, U.S.A. and Cambridge, England — (METERING.COM) — March 19, 2008 – Energy Optimizers Limited (EOL), a U.K. company, has developed a ZigBee-based plug-in electricity meter that can help companies and households shave hundreds to thousands of dollars off their electricity bills. The device, called the plogg, allows home  and building owners to monitor how much electricity is being used by individual appliances and electronic devices so that energy efficiency can be improved. Recent studies by the British government and the Carbon Trust show that people can save five to 15 percent of the electricity they use by using smart meters to manage energy demands.

The plogg is a combined smart meter plug and data logger, based on Ember’s ZigBee wireless technology running on a Telegesis module. It can be attached to any electrical appliance or device that uses a standard U.K. 13 Amp or European 16 Amp plug. A plogg for the North American market is currently under evaluation.

The plogg stores the measured electricity data and wirelessly communicates this information to a PC, mobile phone or building management system anywhere in the world through an Internet-linked Ethernet gateway. For instance, a restaurant chain could use ploggs to monitor energy use by refrigeration and air conditioning units, with all the information collected at a central point via the Internet. Upon discovering that some air conditioners were left on after business hours, the plogg would allow them to switch off air conditioning units by remote activation, or alert a manager that a unit needs servicing. The plogg meters can support a range of other wireless-based energy saving devices as well, such as temperature and light level sensors.

Using Ember’s EM250 ZigBee system-on-chip transceiver and EmberZNet PRO wireless mesh networking software running on a Telegesis module, a network of ploggs can self-organize to provide robust coverage of the home or building. The plogg can act as an end device, a router or ZigBee coordinator. It is available as a stand-alone end user device, or part of an energy reporting network, or as an embeddable device for OEM products.

In addition to measuring power consumption, a real time clock function allows time-of-use metering information for multi-rate applications. Data logging can be set from one minute to one month. The meter samples voltage and current signals 50 times per AC cycle, at a sampling rate of 2520 Hz.

"Telegesis embedded devices provided us with a straightforward, cost effective and importantly, a quick route to market," said Shaun Merrick, general manager at EOL. "With the release from Ember of EmberZNet PRO 3.1, we now have the means to deliver micro building management systems, incorporating compatible energy controls such as light, presence and temperature sensors."

The EM250 is an 802.15.4/ZigBee compliant semiconductor system that integrates a programmable microprocessor, RF radio, network protocol stack and memory into a tiny, single-chip solution (7 mm on a side). It offers EOL dramatic reductions in component size, cost and power consumption, and increased range due to its very high sensitivity. The EM250 runs EmberZNet PRO 3.1, Ember’s enhanced ZigBee PRO compliant networking stack.