James O'Neill's Blog

January 2, 2009

Gas bills and the people ready business.

Filed under: General musings — jamesone111 @ 3:29 pm

It’s a constant puzzle to people from the US and Europe that Britain seems to be split brained about weights and measures. We buy our petrol in Litres, but our beer in Pints. My French car gives me a read-out of fuel consumption in Miles per Gallon, but is taxed in Grams of CO2 per Kilometre. Yet our roads are measured in miles. I think of the pressure in my car tyres in pounds per square inch, but the pressure in a diving cylinder in Bar.  The two pound Christmas pudding which is currently waiting to be turned into ice cream only says on its label that it is 908 Grams.  The list is endless. The BBC reported just before Christmas that the pint was to be allowed to stay. (It’s not the first time that has been reported ). Of course the 20 ounce Imperial pint perplexes Americans where the 16 ounce pint rules (after all with 16 ounces in a pound, why shouldn’t it … ) And giving body weight in Stones … I might was well give my height in Atto-parsecs

Still… in an age when things are supposed to measured metrically its a wonder to me that the Gas meter we had installed a few years ago measures gas in Cubic feet. Or to be strictly correct about it hundreds of cubic feet. I mention this, only because I have spent more of this morning than I care to admit trying to figure out how my estimated gas bill for the next year was worked out. Gas is priced in Kilowatt hours, so there is a conversion from  Hundreds of cubic feet,which goes.

  • Take the difference between the two meter readings.
  • Multiply by an unexplained correction factor of 1.02264
  • Multiply by 100 to get cubic feet, then multiply by 0.02831 to get cubic meters.  Truncate this number to 2 decimal places.
  • Multiply volume by calorific value, which isn’t in calories, but in Joules per cubic meter (39,099,990 on my bill) ,
  • Since a watt is a Joule per second, 3600 Joule Seconds is a Watt hour, and 3,600,000 is a kilowatt hour, so divide joules by that

This gives a number to the nearest 0.01 kwH, even the reading is only accurate to the nearest +/- 50 CU ft (about 15 kWh)

Once upon a time the Gas company would send a little man round to read the meter every so often, but my last bill was an “estimate” which was more than double the amount of gas I’d used. Based on this estimate they made a guess at how much gas I would use next year.  So I tried to work out what that would be, and I was left thinking that a people ready gas company would quote their conversion numbers in kWH per measured cubic foot (0.314 on my bill), then you could get there in one step. What surprised me is having told the gas company I used LESS gas than they estimated, they’ve sent me a recalculated forecast for my usage will be for the next year … and they’re estimating it will be More !  Of course there is no hint for how the estimates are arrived at, but my simple estimate of “average of the last few years” , suggests a far smaller number.  It’s well within the capabilities of the systems the company has to put this information on a bill.

This post originally appeared on my technet blog.

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