In my never ending quest to ensure that I limit the impact my family has on the planet (and reduce our household costs), we've recently installed an electricity meter. It gives us instant feedback on how much electricity we are using in 6 second intervals. We can see exactly how much it costs to turn on the lights, run the tumble dryer, boil the kettle for a cuppa or toast a few slices of bread. You can get the feedback in kilowatts, how much CO2 is being released or based on your electricity tariff, how much per hour it is costing.
We have now become obsessed with it. Sebastian has pointed out that it costs about 2p to make toast in the morning. It appears the toaster is the most expensive piece of kit we have in the house. It has also armed me with a pretty good argument back to Marc about why line drying clothes is a much better idea than using the tumble dryer regardless of how much he hates stiff clothing. I am now super careful about how much water I put in the kettle. It's quite handy for using it to tell us when a light has been left on somewhere in the house.
What is astonishing is how much it costs us to sleep. There are certain things in the house, like the refrigerator and the freezer which don't ever get turned off. They cost us about 4.5p/hour all night long.
And it costs us about .5p/hour to read in bed before I go to sleep. Maybe we should get us some candles. Or not take the meter to bed with us.