Smarter thinking on energy use


Malcolm McCulloch,
Engineering Department,
Oxford University
19 October 2009 – Oxford University develops new meter to analyse and reduce energy usage.

Behavior change is fundamental to saving energy in the home, and Oxford University engineers think they have the answer. Malcolm McCulloch and Jim Donaldson of the university’s engineering department have designed a "smart" electricity meter that can automatically tell which appliances are on and how much energy they are consuming.  

According to a survey by the Energy Savings Trust (EST), eight out of 10 people in England do not know what they are paying for their gas and electricity. The trust also calculates that, if everyone in England switched to smart meters, which allow householders to see how much energy they are using, they would save £985m a year between them.

Measure of the problem
The EST chief executive, Philip Sellwood, says the way people use energy in their homes at the moment seems hard to believe, especially in the context of recent rises in household fuel bills. "Most people would never sign a mobile phone contract if they didn’t know how much it would cost. Similarly, you wouldn’t shop every week and then get the bill three months later and just hope you could pay for it. Smart meters help householders work out how much energy they are using, how much they are paying for it as well as showing in real time which appliances are producing the most CO2."

Though modern smart meters can tell people their energy consumption over a given time, the information they provide is often of little practical use.

"If you’re faced with the task of reducing your energy bills, you can look at a graph of your energy consumption but just because it’s 7kW, that doesn’t mean a lot to many people," said Donaldson, the chief technology officer of Intelligent Sustainable Energy(ISE), the spin-out company from Oxford that will bring the new meter to market.

"It’s much better to say ‘that’s because you’ve got these lights on, the TV on, that heater’ and it allows people to understand exactly where their energy is going so they can change their behaviour."

The ISE meter is more sophisticated than those currently available, which tend only to give a readout of total energy use at a given time – it can analyse the patterns of electricity coming into a home and uses a software algorithm that works out exactly which appliance is using the power.

McCulloch said the information from the meter would allow householders to make informed decisions about their energy use. "For instance, if the amount of electricity your washing machine uses increases considerably, this might indicate that it will be more cost-effective and carbon-efficient to replace it. If there’s a spike in the amount used by the fridge, maybe the door has been left open."

Donaldson says there are a number of ways the information collected by the meter could be presented to users. "You may have a login so you can see your detailed energy usage through a web portal. It could be like your phone bill."

A prototype ISE smart meter has been on test in several Oxford homes for most of this year. More than 1,000 days of energy data have been analysed, equating to about 27,000 hours by the technical team. By using the appliance monitoring data and understanding what energy their appliances were using, users were able to make potential savings of up to 20% on their energy consumption.

Appliance monitoring data can be displayed through an in-home display, PC/laptop, TV screen or iPhone application. The information could also be sent to the user’s energy supplier which could provide them with itemised bills.

If all goes well, the technology will be integrated into a device called the Smart Hub, which will be able track electricity, gas and water use for an entire household by plugging it into the meters already installed in a property. It will be mnufactured by Navetas a co-investor of the ISE technology.