Conversion of M3 to Kwh (as opposed to Khw!)

calorificvalue

OCTOPUS have a new method of achieving this. The result does not conform to the industry standard.
Anybody out there; if you use OCTOPUS, please check the calculation, you will get an unwanted surprise.
units (m3 used x 1.02264 x cal val (40ish) / 3.6) will not be the same as you will get with your calculator.

Complain as soon as you have checked the result.

BUFF

m3 × Calorific Value (as you say 40ish) × 1.02264 ÷ 3.6 = kWh

(btw you should be able to delete your other post).

QrizB

calorificvalue said:

OCTOPUS have a new method of achieving this.

This seems unlikely. Can you post an excerpt from your bill showing whatever-it-is that you are disputing?

calorificvalue

QrizB said:

calorificvalue said:

OCTOPUS have a new method of achieving this.

This seems unlikely. Can you post an excerpt from your bill showing whatever-it-is that you are disputing?

It is NOT unlikely. It is true. Since spring 2022. OMBUDSMAN informed.
example : 4.1 x 1.02264 x 40.2 / 3.6 = 47.2
CHECK IT - It's not is it? 
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[Deleted User]

calorificvalue said:

QrizB said:

calorificvalue said:

OCTOPUS have a new method of achieving this.

This seems unlikely. Can you post an excerpt from your bill showing whatever-it-is that you are disputing?

It is NOT unlikely. It is true. Since spring 2022. OMBUDSMAN informed.
example : 4.1 x 1.02264 x 40.2 / 3.6 = 47.2
CHECK IT - It's not is it? 
===================

Can you please stop spamming everywhere - it messes up the board for anyone trying to give other people advice.

As QrizB said - post a picture of the bit of the bill that has the calculation you dispute.  Post what you think the calculation should be.  Maybe then we can help you understand.

QrizB

FWIW I've checked my latest Octopus gas bill and the calculation is correct.

[Deleted User]

QrizB said:

FWIW I've checked my latest Octopus gas bill and the calculation is correct.

I expect it's always been entirely correct, and there is a simple misunderstanding - would love to see the OPs actual comparison to try and help though.

Astria

calorificvalue said:

QrizB said:

calorificvalue said:

OCTOPUS have a new method of achieving this.

This seems unlikely. Can you post an excerpt from your bill showing whatever-it-is that you are disputing?

It is NOT unlikely. It is true. Since spring 2022. OMBUDSMAN informed.

So you already have an official complaint that's been deadlocked then? What did octopus say?

peter3hg

On the face of it the calculation is off on my latest bill. I have two periods of gas usage with their calculation as follows:

1.2 × 1.02264 × 39.8† ÷ 3.6 = 13.3

0.7 × 1.02264 × 40.0† ÷ 3.6 = 8.2

The first I would calculate as 13.6 kWh and the second 8.0 kWh (to one decimal place).

My guess is that they are using the actual calorific values when gas was used, but stating an average in the formula. I only used gas on a few days so this could look very off. I'll try and dig down and see if I can make more sense of it.

Edit: My hypothesis above is wrong so I'm not sure what this difference is caused by.

Edit 2: I think it might just be due to rounding of the m3 value  For both the final figure is within a rounding difference on the m3 value. I've checked older bills with higher gas usage and the "error" is the same order of magnitude, which would back this up. If it was an incorrect calculation then the higher usage bills would have a bigger difference.

[Deleted User]

In the absence of any other information, this appears to be the calculation that the OP is disputing:

4.1 x 1.02264 x 40.2 / 3.6 = 47.2

Which, they correctly determine, is mathematically inconsistent.  The strict result of that calculation should be 46.8199 (to 4dp).

However, the 40.2 is only correct to 1dp, and it is unclear whether it is rounded or truncated.  That gives a possible true value of somewhere between 40.15 (resulting in 46.7616kWh) and 40.2999 (resulting in 46.9362kWh).  Still doesn't come to the 47.2 quoted, but would give some indication to the potential range of variation just from the simplification of this single component.

As @peter3hg says, it could be something to do with using a weighted average of the daily numbers - I can't find any clear information about that.

[Deleted User]

[Deleted User] said:

In the absence of any other information, this appears to be the calculation that the OP is disputing:

4.1 x 1.02264 x 40.2 / 3.6 = 47.2

Which, they correctly determine, is mathematically inconsistent.  The strict result of that calculation should be 46.8199 (to 4dp).

However, the 40.2 is only correct to 1dp, and it is unclear whether it is rounded or truncated.  That gives a possible true value of somewhere between 40.15 (resulting in 46.7616kWh) and 40.2999 (resulting in 46.9362kWh).  Still doesn't come to the 47.2 quoted, but would give some indication to the potential range of variation just from the simplification of this single component.

As @peter3hg says, it could be something to do with using a weighted average of the daily numbers - I can't find any clear information about that.

Under Ofgem CV guidance dated April 2014, all average CVs used for billing purposes are truncated to one decimal point. 

My statement arrived this morning, and I have just checked the CV used with the National Grid. The supplier uses the average CV for the billing period. My gas bill is spot on. The CV is independently checked AFAIK.