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Trial: OWL energy monitors

Ever argued over whether it’s worth switching appliances off standby mode to save power? An energy monitor could be the tool you need to settle the score.


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Energy monitors display how much electricity your household’s using, and how much you’re paying for it (not to be confused with smart meters, which send power consumption data back to your energy provider). I trialled the OWL Micro+ ($120) and the more advanced OWL Intuition-e ($247) to see how easy they were to install and use, and whether they helped rein in wasteful energy use.

The Micro+ consists of an LCD monitor, a power sensor and a transmitter to send data from the sensor to the display. The sensor clamps around the power cable running in to your fuse box, and uses magnetic fields to measure how much electricity your home’s using, so there’s no need to wire it in.

16apr owl energy monitors fuse box
The sensor clamps around the power cable running in to your fuse box, and uses magnetic fields to measure how much electricity your home’s using.

If the insulated supply cable going from your meter to your fuse box is accessible, then you can clamp the sensor on yourself. But if it comes straight out of the wall into the fuse box then you’ll need to get an electrician to install the sensor, as our electrical regulations do not permit homeowners to tinker with the fuse box.

First, you need to enter the time, date and your electricity tariff into the monitoring display, which is the brains of the operation and can record and graph cumulative consumption data. You’re given the option of entering a single tariff, a block tariff (which changes based on the amount of power consumed) or up to three time-of-use tariffs, for example day/night rates.

This is where things came a bit unstuck for me, as my electricity retailer offers tariffs based on spot prices, which vary every half-hour. But I entered in a couple of tariffs based on the average prices I pay at different times and forged ahead.

I found the set-up process straightforward, and once everything’s connected you can place the display anywhere within 30m of the transmitter and sensor. You can then cycle between:

  • cost (if the electricity in use at that time is used at that level for an hour)
  • amount of energy in use (kW) and cumulative consumption (kWh)
  • equivalent CO₂ emissions for the amount of electricity used at the time (kg).

Each mode includes a “history” option, allowing you to view the total amount of energy you’ve used and what you’ve paid for it over the past day/week/month, along with your average use statistics. However, you can’t download data from the monitor to plug into a spreadsheet.

The CO₂ display isn’t much use in New Zealand, as the mix between renewables/non-renewables is constantly changing during the day. A better option for eco-conscious consumers is Flick Electric’s “Choice” app, which has a detailed breakdown of the current mix of generation in the grid and associated emissions every half-hour. It’s free to everyone, not just Flick customers.

16apr owl energy monitors
The Intuition-e allows you to access your info anywhere you can get an internet connection, and download it into a spreadsheet.

The Intuition-e uses the same sensor and transmitter as the Micro+, but ditches the LCD in favour of a “network gateway”. This plugs into your WiFi router and uploads your power data to the cloud (remote servers), where it can be accessed by logging in to a website or mobile app. It offers the same measurements and features as the Micro+’s LCD, the difference being you can access this info anywhere you can get an internet connection, and download it into a spreadsheet for further analysis.

The Intuition-e’s web and mobile apps have an easy-to-navigate interface. The accuracy of both meters was sometimes off by a few watts, but they’re more than accurate enough to give you a good read on where your power’s going and how much it’s costing you. A minor irritation was that the sensor only sends information every 12 seconds, but this is being picky and it doesn’t detract from its usefulness.

Surprisingly, I found the simpler Micro+ the better option for keeping my power use in check. Neglecting to check an app or log in to the web portal is easy, but it’s a lot harder to ignore an ever-present LCD showing how much it costs to fire up an electric heater (more than 50¢ an hour) instead of throwing on a jersey.

Overall, both energy monitors are worth considering if you’re looking to keep your power use in check this winter, especially if you’re keen to take advantage of time-of-use tariffs. The Intuition-e is also a great option for small businesses owners wanting to keep tabs on their business’s energy consumption, since it allows you to connect multiple sensors to monitor various locations.

As for how much I was wasting leaving my TV on standby? The OWL reckons 0.2¢ an hour, which works out at about $18 per year.

OWL Micro+ $120
OWL Intuition-e $247 (Android and iOS apps free to download)
Available from theowl.com

by George Block

This was a trial from the perspective of our product expert. Our lab-based tests offer truly objective product comparisons.