Daily Archives: April 27, 2008

Current Cost

Current Cost meterThe buzz
There’s a bit of a buzz going on at work at the moment – a bunch of us from “the Hursley crowd” have started playing with Current Cost meters. These devices are intended to enable consumers to see exactly what their energy usage is and, hopefully, modify behaviour to save electricity accordingly. The idea, simply, is that it provides real-time information about energy consumption.

Rich, James, Nick and Ian have all written about their Current Cost meters already, amid much twittering and the support of @andysc.

The product
The device itself comes in two parts. The unit that goes inside the house is a wireless LCD display which shows the current usage in watts, the current estimated cost per day assuming that usage is maintained, a bar chart with yesterday’s usage, overall KWH in the past day and month, and the time and temperature.Current Cost meter The other half of the device is a somewhat larger and heavier transmitter (shown at the top of the picture, the top of the two black boxes inside our cupboard) which sits next to the electricity meter, with a clip that gently attaches around the cable (you can see that hanging off the cable at the bottom of the picture). The product is completely non-invasive and it’s incredibly easy for anyone to install: there’s no rewiring, just a clip. I was extremely impressed. It “just worked”.

Update: I should point out, given some comments, that we’re using an early batch of the meters and I’m not certain when they will be generally available.

Update: Roo points out that Eco Gadget Shop have them for sale to consumers, minus data cable.

The impact

One of the other features of the device is that it can be plugged in to a computer, and the data can then be captured and analysed over time. We are using some homebrew software to do this, pulling the data from the serial port (most of the meters use 9600 baud, it turns out that mine is set to 2400 for some reason).

Current Cost graph

It’s kind of scary to see some of the spikes in the graph, and just watching this has certainly made me adjust my behaviour in terms of switching things off and unplugging chargers and so on when they are not in use. We’ve all got our meters hooked up via a Microbroker, and this has been my first opportunity to really play around with MQTT technology… I’ve obviously been aware of it for a very long time, but it’s nice to have something tangible to hack around with. It has also led me into a bunch of interesting discussions about home automation, tweetjects and low-power servers. Fascinating stuff.

The ideas

I have a bunch of thoughts about this. I have it hooked up to an old Linux box, but I’ve also successfully attached it to my Macbook Pro and a Windows Thinkpad. Currently the software is sending the MQTT data to a Microbroker and a Java app is drawing the graph shown above, but it would be fairly straightforward, for example, to squirrel the data locally and do some interesting analytics using Project Zero (aka WebSphere sMash) and some AJAX-y Google Chart goodness. I can also capture ambient temperature over time. It’s all just a matter of finding the hacking opportunity!