CES: Novel home energy monitor is tiny, and designed in Cambridge

Cambridge-based smart meter firm Sentec has announced a tiny home energy monitor that threads onto the pins of a mains plug.


Called MicroMonitor, it is a reference design that transmits the consumption of individual appliances in real-time, needs no batteries, and is expected to be under $9 for a production version.

“Utilities could even give it away or package the MicroMonitor with other services and products,” said Sentec. “The sensing technology can be incorporated into other form factors – it could be included in a wall outlet, embedded into a plug or lead, or built directly into an appliance.”

Measurement is through the firm’s ‘C-strip’ current sensor, and there is an on-chip metrology software library.

Power comes from a tiny ac-dc converter, and stand-by consumption is an excellent sub-10mW.

Per-plug energy monitoring is seen as an alternative to whole house monitoring.

“If consumers are to reduce their consumption, they need to know which appliances are consuming what. Most monitors measure and show only the aggregate consumption for the home. That makes taking action very hard,” said Sentec. “Smart plug based individual appliance monitors are available, but they’re bulky, ugly and costly. It’s also possible to mathematically disaggregate whole-home consumption into separate appliances, but not always in real-time, and not always with 100% accuracy.”

The initial device is 24x22x15mm, operates from 120-240V 50-60Hz, and transmits at 433MHz with a range up to 30m. A 915MHz design is also available, or ZigBee or Z-Wave at extra-cost.

“MicroMonitor could also incorporate other sensors. We’re working on designs that include the ability to sense and report light, sound, temperature, humidity, pressure and human presence [via passive infra-red],” said Sentec. “Other parameters could be sensed too. This means that the same can provide a network of sensors distributed around a home.”

Customers will either licence the reference design to integrate into their own products, or Sentec will create a derivative for them with variations in physical design, branding, sensed parameters, radio or protocols.

The MicroMonitor will be on display at CES on the Current Cost (LVCC, South Hall 1 – 21834) and Electric Imp (LVH Hospitality – Suite 318) stands.

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