Gas conversion to kwh formula.

kaybal

I'm sure that everybody knows now that British Gas lowered their prices in February this year but I've today received my latest gas bill & notice something strange:
Up until the price reduction the formula for converting units used to kwh (kilowatt hours) was = UNITS USED X 39.1131 (calorific value) X 1.0226400 divided by 3.6
However now that the price has gone down the formula has been changed to:
UNITS USED X 39.2022 (calorific value) X 1.0226400 divided by 3.6.
This may seem a small increase in the calorific value but it amounts to about £6.00 per quarter or £24.00 per year so if you times this by 6 million British Gas customers this amounts to £144 million extra to them. How can this be right?

SwanJon

Calorific value is the energy content of the gas, and it changes daily.
Try googling calorific value national grid
It is not set by the suppliers, and I imagine they are charged using it too.

Cardew

As stated above the calorific value is something none of the distributers have any control over and it varies by geographic area and is independantly audited.

In any case all that matters is the kWh you consume. If you are Mr Average and use 20,500kWh per year, you will still consume 20,500kWh per year regardless of the calorific value of the gas.

To make things easier to understand if a metric gas unit contained 10kWh, Mr average would use 2,050 gas units and be charged for 20,500kWh.

if a metric gas unit contained, say, 12kWh, Mr average would use 1,708 gas units and be charged for 20,500kWh.

Incidentally unless my calculator is wrong the change in calorific value you gave makes nowhere near £24 a year difference even if you used the same amount of gas units!

An increase from 39.1131 to 39.2022 is an increase 0.2278%. So someone using the UK average of 20,500kWh would be using 1845 imperial gas units with the calorific value at 39.1131.

Someone using 1,845 Imperial gas units with a calorific value of 39.2022 would use 20,546kWh. So an extra 46kWh - an extra £1.50 a year not £24.

However they would, in practice, use only 1841 gas units.