How to kill vampires

For some light relief from all this end-of-civilisation stuff, I have just spent a couple of happy half hours killing vampires, or at least identifying them for liquidation. I thought I would share the details with you, as not only has it been a lot of fun, it also promises to save our household significant amounts of money and reduce our carbon footprint into the bargain. Your pockets could probably benefit in the same way, as could your planet, which I believe we share.

The vampires in question are not the traditional kind with the long side teeth, but the kind that live in your house, sucking electricity out of your sockets when you think there's nothing going on. I have the chapter on gadgets in David MacKay's wonderful book on sustainable energy to thank for pointing out the full extent of their activities, and a group whose "carbon conversations" course I am attending for lending me an energy meter (a Wetekom PM-30-UK, for the record), which I think costs about £10 to buy.

So here is what the devices in our house suck out of our pockets when they're doing absolutely nothing of any use. To be clear, I'm talking about what has been the usual situation in our house until now: the devices themselves are switched off, but are left plugged in, with the wall switch on.

We pay about 14.1 pence per kilowatt hour, so if a vampire is running all the time, it costs us £1.24 per year for every watt it consumes. For shock value, I will express everything in pounds per year rather than actual power consumptions. American readers should add about half as much again to each figure to get the equivalent number of dollars, and Europeans add about 5% to get Euros.

Starting with audio: our much-listened to digital radio (a Pure Evoke 2) costs us £27 per year. Or to be specific, the radio itself only seems to cost us £4 per year; the real culprit is the transformer, which sucks away £23 per year even when the radio's not plugged into it. And we have another one down in Dora's studio, so that's £54 in total. Our CD player/radio in the next room is positively abstemious by comparison, sucking out a mere £9 per year, while the phone base and handset cost £12. So, £75 per year is wasted on not listening to radio or music or talking to our friends. We don't have a TV, in case you're wondering.

Dora's hair styler sucks £27 per year even when switched off. Or at least, it would if she didn't make sure it's always switched off at the wall socket when not in use, for the sake of The Bean's fingers when he accidentally turns it on (he calls this device "Ow! Very Hot"). Meanwhile, the bread machine costs us £21 per year even before it makes us any bread.

Then we push open the creaking door of my study and encounter, among the dark and cobwebs, the nest of computer equipment. Here is where the real horror starts. (Dora can feel very virtuous at this point: her wonderful 6-year-old Dell Inspiron laptop consumes no measurable power at all in standby mode).

The computer itself (6 year old Dell Latitude desktop) costs £15 per year when turned off, and the monitor £9 a year on standby (nothing when actually switched off). Not too bad, you might think. But wait, what are those little gizmos in the corner of the room? Well, there's the laser printer: £21 per year on standby (nothing when switched off); the colour deskjet (£19 per year); the cable modem (£17); the wireless router (£27, nearly all of which is consumed by the transformer); and the speakers (£19); totalling a whopping £108 per year, not counting the colour printer, which we normally do leave off.

I make that a total of £204 (about $322 or 218 Euros) per year, just for the stuff which we usually leave switched on. Using MacKay's figure (page 335) of 580 grams CO2 per kWH of UK electricity, we are therefore paying £204 to pump 0.84 tons of CO2 into the atmosphere, completely against our wishes. That's even more than the £180 (0.74 tons) per year I estimate we saved by changing nine of our light bulbs a few months ago.

I once knew an old woman who believed you should always turn off electric sockets at the wall otherwise the electricity would leak into the air. I used to laugh at her, but now I can see she was more than half right.