Calorific Value For Gas Conversion

I have noticed that the Calorific Vale within the Gas conversion formula has changed since my previous statement. 39.1 to 39.2
Does this calculation change on a monthly basis ? If so why ?
Just trying to keep my estimates inline with actual usage.



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For reference, it would have been quicker to type in “uk gas calorific value” into Google as I did :slight_smile: But then I suppose I already knew what page I was looking for …

Yes it can and usually does change each month, rarely makes more than a few pence difference to your £s usage for that month.


Actually, it isn’t “pennies”, it’s “pounds”!!! A jump from 39.2, which it was in June '19, to 39.8, what it is this month… is substantial!
Based on 200 units of gas, 2261.2kWH at CV 39.2 and 2227.1kWH at CV 39.8… that equates to just on a pound extra per month! Just the CV difference of last month to this (0.4) made a difference to my bill (80 units) of 27p after VAT.
Might be pennies to you, but it adds up when you’re on a tight budget!! Sneakily creep that up every couple of months multiplied by several thousand customers; and it’s a veritable bonanza for Bulb for nothing at all!

As far as I am aware it is not the energy companies that set the CV rate, it is the National grid, so would not matter which utility company you are with.

If you google who calculates the CV rate you will get more info, Bulb wont let me post links. :frowning:

You would think so… but SSE’s CV is 40.1!! Maybe Bulb just want to play catchup!

Hi @OzBob and @scudo,

This is a very good question.

When we calculate someone’s gas usage, we put their m3 used through the equation on the statements (see below) to convert it to energy (kwh) used.

image (8)
The calorific value inputs vary slightly across different regions and bill periods. This is because, on any given day, the level of actual usable energy contained in someone’s gas supply can be different. This is what determines the calorific value.

The gas transporter has to keep the calorific value between 38 and 41 megajoules per cubic meter (anything outside of this can damage appliances or make them ineffective). The calorific value we see on the bill is the average of the daily calorific values in the supply to that property for the bill period.

I hope this clears things up slightly. Any questions, please do let us know.

Take care,

Niamh :bulb:

You can check your CV for any given month by region, by going to the National Grid data base. I have done this a few times and the billing is accurate with regard to the CV rate.