Friday 4 February 2011

The electric blanket is back (article)


OK I admit it, I was wrong about electric blankets. I misjudged them. I always thought they were a bit frivolous - you know, the whole thing about not using useful stuff like electricity just to keep your toes warm. But then I realised something.

People use electric blankets because they are cold at night. If you are not cold at night, then pretty obviously  this particular posting is not about you. But what about if you are cold at night, and you don't have an electric blanket? What do you do then?

Perhaps you knit yourself a pair of bedsocks and go to bed with a nightcap. But more likely these days, you pop downstairs and turn up (or turn on) the central heating. Or you pop to B&Q and buy a cheap portable heater for about £30. (Of course, if you leave it on overnight it'll only take a few weeks to have spent more running it than it cost you to buy.)

Anyway, if those sound like things you might do, then read on. You're a person who should have an electric blanket, and here's why:

  • You can get a decent one now for £35
  • Leave it on overnight, it turns itself off in the morning
  • In a 12 hour night shift, it eats only 0.25 KWh of energy ...
  • ... costing you about 3p in total

Loyal readers will remember, that's about half what it costs me to mow the lawn for 20 minutes. And doing all the calcs, the total carbon impact over 12 hours is about the same as running a 22KW condensing gas boiler for 3 minutes. So the choice is yours: snug and warm all night for 3p, or a 3 minute blast of heat?

On that basis, and in honour of Chinese New Year, I'm making 2011 the Year of the Electric Blanket. 

3 comments:

Katy said...

I prefer to use a hot water bottle. Isn't that what Susan Roaf used as a heating method in the Autonomous House?

The UK Carbon Census Ltd said...

OK good question, here goes:

* A John Lewis Vagabond Hot Water Bottle holds about 1 litre of water

* Boiling a litre of water in a kitchen kettle will use about 0.10 - 0.15 KWh of energy

* At current prices, that will cost you about 1-2p

So yes, on the face of it, a hot water bottle would be marginally better.

BUT...

* A hot water bottle only stays warm for an hour or so

* My 3p estimate for the electric blanket was based on a whole night of heat

* Common models of electric blanket have an option to cut out after 75 minutes, if you set this you will use less than 1p of electricity, perhaps about 1/2p in total but I haven't measured it.

So, if all she needs is warmth for an hour or so as you go to bed, then tell Susan to ditch the HWB - she'd be better off with the electric blanket after all!

The UK Carbon Census Ltd said...

PS this is fun! But just to be clear, it doesn't really matter - what really matters is electric blanket (or HWB) v. the boiler.