Everything's gone green*

E·on Envi LCD monitor in action**

Well, more accurately, our household has gone green.

Our electricity company, E·on, sent us a free home energy monitor recently. The device is an E·on badged Current Cost meter – the Envi. I found the device easy to install. In the box there was an E·on Envi LCD monitor pictured and a wireless transmitter. Also included in the box was a LIME energy saving plug.

PLEASE FOLLOW THE INSTRUCTIONS THAT CAME WITH YOUR OWN DEVICE VERY CAREFULLY. The wireless transmitter is fitted to the electricity meter and communicates with the E·on Envi LCD monitor. Once connected and setup, the E·on LCD monitor, which can be sited anywhere in the home near a power socket, displays the actual cost of electricity at six second intervals. It is then simple to switch something on or off, such as a light or a cooker, and nearly instantly find out how much it costs. We have been going around the house unplugging phone chargers, laptop charger, desktop computer on standby and switching off lights. The additional free LIME energy saving plug allows the TV, set top box and other connected devices to all be switched off using a remote control. So far we believe we can save at least £10 per month, if not more. This additional saving is in a household that thought it was economical with electricity. For example, I had thought that a phone or laptop charger was not consuming electricity if it was plugged in and switched on but not connected to the phone or laptop. This is not the case! I can be so naïve.
 

The E·on Envi LCD monitor can be connected to the Internet, such as through Google Powermeter, updating every ten minutes. The advantage of this is that it allows secure live monitoring of usage from the Internet too; very useful for smart phone users or monitoring from the office. The disadvantage of this setup is that the E·on Envi LCD monitor, the laptop and the broadband router all need continuous power. In my case, this consumes around 30 Watts (W) which equates to around £3 per month. I intend to keep monitoring online in this way for two months so I have a good set of data to work with.

Google powermeter graph

The gap in the Google powermeter graph pictured for Monday was me accidentally switching off the laptop that was uploading the readings to Google. The dark green line on graph shows the power in watts used by equipment on standby – Google terms this always-on power. I am informed this value should be very low at night. What low means seems to depend on where you live, what you live in and how you live in it. Searching the Internet for example reveals at least one household running at 1.2 kilowatt (kW) always-on which is 30 kilowatt hour (kW·h) per day! Look at my night-time graph carefully and you will see our fridge/freezer switch on every two hours or so. After my first day of using the LCD monitor my always-on value was 300 W (7.2 kW·h/day) whilst yesterday my always-on value was 110 W (2.64 kW·h/day) – if I can keep this up it represents an incredible yearly saving of over £200! This exercise has made us look more carefully at our electricity usage. We had thought that we had fully converted to low-energy (CFL) lighting. A more thorough survey, backed up by our LCD monitor, revealed we still had a little way to go. We had some tungsten spotlights for example which have since been replaced by IKEA low-energy spotlights.

Go green guide

How is the cost of electricity calculated? First obtain the charge per kilowatt-hour (kW·h) from the electricity bill. In my case, I am charged one rate for the first 900 kW·h used per year then a smaller rate for all subsequent kW·h's used in that year. Some people have cheaper night-time electricity, called Economy‑7, which complicates the calculation a little. In any case, I arrived at an average of £0.13 for each kW·h by dividing last years total electricity bill by the number of kW·h used in that year. So my 110 W always-on figure costs 110 W / 1000 kW x 24 hours x 365 days x £0.13 = £125.27 per year. My annual electricity cost is of course more than this.

See also 2 February 2011 entry Going greener in this blog.

* 1981 pop song by New Order
** Photo © 2011 John McCullough