OWL wireless electricity monitor review

By Jack Ratcliffe,

Have you ever wondered about how much electricity you’re using? No? Well, you should. Because if you use too much, you’re killing the planet and stealing from your children. Don’t have children? Your stealing from your family’s children. Live a solitary, lone existence and hate everyone? Well, okay – this probably isn’t the gadget for you.

OWL is a company that pride themselves on creating devices for lowering your power consumption. It has a beautiful font and uses lots of green on its packaging. It also makes the OWL Wireless Electricity Monitor. We’ve tested it to death (figure of speech: it is still taking pride of place on our mantelpiece) and have got some pretty positive things to say.

OWL

Unlike some energy monitoring kits, the OWL’s Sender and Display units didn’t come paired before use. This meant that there was a bit of instruction-reading and button pushing before it’s ready to monitor. This isn’t much of an issue, but coupled with the fact that it has one of those annoying screw-in battery cases and you’ve got the two annoyances with the product. The only two.

Other than that, you see, it is quite marvellous. Even the aesthetic of the device has a wonderfully retro charm. Intentional or not, it is certainly endearing. If only it had been finished in bakelite.

On the well-designed display unit, the display of the important information was clearly a big deal for OWL’s engineers. The information on current usage takes up over half the screen. Hitting the “Mode” key will scroll the main display through your current KW (electricity) usage, how many kilograms of CO2 you’re pumping out an hour (0.022KG at the time of writing) and your cost per hour.

Under the main information display are two more sections. One provides you with a time, date and temperature reading, all of which prove more useful than one might think. They turn the OWL into a one-stop box for your household data needs.

The other section has a long-term version of the information displayed in the top box. For instance, mine is telling me that I’ve used 90.974KW/H since installation, created 0.0418 tonnes of C02 and spent £11.371 on electricity.

You can reset these totals at any time (with the reset button on the back), or you can hold down the ADJUST key to change it from total to an average reading for the day, week or month. It’s a neat little feature.

Ideally, it would have been nice to enable a scrolling mode which runs through all of the options, or mix and match – to display current energy use combined with total cost. However, as it stands it’s extremely easy to navigate and very responsive.

For a unit with a mere three buttons, there are a plethora of options to set if you want to delve particularly deep. You can change the tariff rate to work out your exact spend based upon your energy suppliers rate, although variable rates are a bit awkward. On/off peak times can be defined (with up to six variables allowed), but the option to drop the cost after a certain usage is not available.

You can also set an alarm to alert you if you go over a certain power usage. It is extremely difficult to find a reason for this function – set it too low, for example, and it’ll go off every time you turn on the kettle or run the iron. Set it too high and you’ll only hear the beep when the dishwasher and washing machine are engaged in an energy death-match, refereed by the fan-assisted oven and his tireless linesman, the power shower.

For green-freaks, the best thing about the device is the PC connectivity. Plug it into your computer and minute-by-minute power usage for the last 30 days will be uploaded to the OWL software. If you forget to do it within thirty days, the device also stores day-by-day power usage for nearly two years. There are plenty of different options to display the data, too. From live usage, to historical usage, to a tariff comparison chart, for finding the best deal for you.

Your usage history can also be displayed on the device, but it is nowhere near as nice a bit fiddly. Only the most neurotic of energy-savers would go to the trouble of viewing the data with the various button-presses that it entails.

Of course, no energy monitoring device would be useful without the guarantee of an accurate reading. It all comes down to the sensor device attached to the transmitting unit, which clips on to the power cable on your electricity meter. Tom at Owl cleared up the technical details for us:

The sensing device is basically a current transformer. It converts the magnetic field generated by the alternating current going through the live cable (coming from your house’s electricity meter) into a low voltage signal which is sent to the transmitter. It is this conversion process which controls the accuracy of the overall device, the better the build quality of the sensor the better the device accuracy can be.”

“We pride ourselves in very well made sensors, accurate down to a starting power load of 40W, and low power usage sensitivity of around 14W. Above 1A the best we guarantee is 10% accuracy and above 3A we deliver better than 5% accuracy.

While we couldn’t test those figures, we did manage to conduct a MacGyver test – that is, a test cobbled together from the things around us. Basically, we turned off everything except for a 100w bulb. Taking into account various electrical anomalies, the power reading should be between 90 and 110 watts – the closer to 100 the better. OWL told us 97. We were thrilled.

You see, we also had another energy meter device installed for comparison, and it rolled in at around 76 watts. The OWL was 11% closer to our prediction than the competing device.

This test was such a low-tech solution that naming the other monitor would be unfair – any number of things could have affected that outcome. However, with such a close relation to our prediction, it does show that the OWL is a pretty accurate monitoring system – and one that is recommended.