kWh calculation for gas changed

Hi, I wondered if anyone noticed that when Bulb cut the gas price at the beginning of summer they also changed the calculation for converting gas units used to kWh, meaning a proportion of the reduction was lost by increasing the kWh used?

Or has this already been covered?

Or was it just on my bill?

I doubt the calculation changed, but perhaps the calorific value did. This is the average calorific value of the gas for that month. Your units may thus contain more, sometimes less energy (Kwh) per unit volume of gas which the meter measures.

@Philip_PAL Yes, the calorific value went up from 39.2 to 39.4 meaning the calculation changed - resulting in a slightly higher kWh usage and hence - admittedly a slight - increase in cost.

In my case that amounted to an increase of 25p + VAT per month.

The calculation is unchanged, just one of the inputs different. The average calorific value of the gas is provided by the gas transporter / feeder which varies depending on its source etc. Its not something that would be any different if you had a different company providing the billing.

The standing charge and price per kWh are set by bulb.

@Phillip_PAL Thanks for the info re: CV - I wasn’t aware of that.

But as far as I’m concerned, putting the same figure into two calculations and getting a different result means the two calculations are different. No two ways about it.

It would be very unusual for your start and end readings to be exactly the same every month. Let me try another way of explaining.

You say the calorific value went up slightly, this actually means you used less volume of gas (units on your meter) to consume the same energy as it would have done. You are charged based on your energy kWh not units consumed on your meter. Generally though this alters only slightly.

Check your past statements to see how the calorific value changes occasionally.

39·2 and 39·4 are different figures.
The calculation remains the same: Units × 1·02264 × CV ÷ 3·6 = kWh

1 Like

More information here:

https://www.nationalgrid.com/uk/gas-transmission/data-and-operations/calorific-value-cv

They take the average CV over a monthly period, generally its only a few pence per month and it is not set by Bulb its an industry thing.

1 Like