Gas conversion to kWh

flex9

Has anyone ever look at the formula used to convert your gas usage to kWh for billing purposes?
I have noticed that the formula used has increased from the usual (39.2*1.02264/3.6= 11.135413) to (39.3*1.02264/3.6= 11.16382) giving an increased difference of (0.028407). While it may not look a lot for one unit but it all adds up when multiplied by total kWh used and the number of Customers. Is this a stealth increase?
So my question - is there a formula that is issued/accepted by Ofgem or another authority? If so what is it?
Has anyone ever added up all the days charged in their bills because I have found I was charged more than 365 days and it wasn't a leap year. So I totally support the removal of the daily charge as it is used to manipulate prices.
   

JGB1955

The calorific value can be anything between 39 and 41.  See Gas meter readings and bill calculation - GOV.UK (www.gov.uk)

molerat

The calorific value is a variable according to the quality of the gas going through the network.  It is sampled at least twice daily and the average daily value over the billing period truncated to one decimal place is used.  The values for your region can be downloaded from the National Grid website. https://mip-prd-web.azurewebsites.net/DataItemExplorer/Index

Ultrasonic

Note that when the calorific value is higher, you need to use a smaller volume of gas for the same heat output. So changes in this don't obviously affect what is actually paid.