GAS CALORIFIC VALUE AS STATED ON ENERGY BILLS

Carlh93

If you want to check the correctness of your gas bill you need to know the following:-

1. Your gas consumption over the billing period in cubic metre;
2. The energy value of the gas per cubic metre;
3. The tariff rate per kWh
4. The EPG (energy price guarantee) discount per kW. This currently ensures that a "typical medium user" does not pay more than £2,500 p.a. for the fuel/s consumed, and is due to end, or be again reviewed, at the end of the current OFEGEM overall cap period (30/06/2023).;
5. the VAT rate applicable (currently 5%)

(2) is not so straightforward. An equation is needed to convert the volumetric figure in cubic metres, as read off the meter, into kWh. This is so customers are charged for the energy value (heat value) of the gas consumed, which varies irregularly, depending on where you live and the type and source of the NG (natural gas: methane, or methane/ethane) supplied..

Charging by heat energy consumed rather than by volume is fair, and is mirrored by charging for electricity in Watt  hours, usually kiloWatt hours( kWh)), rather than in Amperes, or Volt Amperes (VA).

The heat energy iin kWh s stated on the bill. If you really want to check your bill you need to be sure that this figure is accurate.

The equation to convert volume into the SI unit of power/energy, the Watt (for billing purposes, the kiloWatt hour), is simple, but may look daunting. It is stated on all gas bills, as follows:-

A; The value in kWh/m3

which EQUALS the result of the following calculation:-

B:  Your consumption in cubic metres)

TIMES (C) a value for the heat energy contained in one cubic metre of gas stated in MegaJoules/cubic metre (MJ/m3). ( I can't use superscript for the 3 in the word processer used on this website.) .his is given to only one decimal place, so is rarely 100% accurate.

TIMES (D) a correction factor for your area (C) . For me, this is 1.02264 (5 decimal places needed for ACCURACY

The product of these three figures is DIVIDED by an invariable constant 3.6. (E).

This gives this equation: 

A = (B x C x D)/E

WHY IS THE ENERGY VALUE IN MJ/m3 STATED TO ONLY ONE DECIMAL PLACE, WHEN THE CORRECTION FACTOR IS TO 5 PLACES?

One might assume that a single decimal place is sufficient, but, if you really want to check if your bill is accurate, it often isn't.

My last bill (also from Octopus) stated the calorific value of the gas supplied to be 2,378.20 kWh, and its value per cubic metre (212 m3consumed) to be 39.40 MJ.

The latter gives not 2.378.20 kWh but  2,372.75. It looks as if I am being slightly overcharged.

However, the energy suppliers acknowledge implicitly that only one decimal place is not accurate for the gas calorific value in kWh. But Octopus states that presenting it to only ONE

.

Carlh93

CONTINUED"

.... decimal place is NOT NEGOTIABLE

So what value are they actually using to arrive at 2,372.80 kWh (assuming that THIS is the CORRECT figure?

Invert the equation to find (C):-

C = (A x E) divided by ( B x D).

This gives the c.v. inMJ/ m3 as : (2,372.80 x 3.6)/((212 x 1.02264), or (8,542.08/216.79968). This equates with Octopus/s figure of 39.40. 

OK in this case, but, in earlier bills of mine,  inverting the calculation to find the c.v.in MJ/m3 has produced a figure different from the published one decimal place (within .05 plus or minus), and where the figure published needed to be accurate to four or five places to give the same MJ/m3 as that quoted by Octopus.

So why the refusal to allow the consumer to check his bill accurately - by stating the gas MJ.m3 in up to 5 places?
.

[Deleted User]

Carlh93 said:

If you want to check the correctness of your gas bill you need to know the following:-

1. Your gas consumption over the billing period in cubic metre;
2. The energy value of the gas per cubic metre;
3. The tariff rate per kWh
4. The EPG (energy price guarantee) discount per kW. This currently ensures that a "typical medium user" does not pay more than £2,500 p.a. for the fuel/s consumed, and is due to end, or be again reviewed, at the end of the current OFEGEM overall cap period (30/06/2023).;
5. the VAT rate applicable (currently 5%)

(2) is not so straightforward. An equation is needed to convert the volumetric figure in cubic metres, as read off the meter, into kWh. This is so customers are charged for the energy value (heat value) of the gas consumed, which varies irregularly, depending on where you live and the type and source of the NG (natural gas: methane, or methane/ethane) supplied..

Charging by heat energy consumed rather than by volume is fair, and is mirrored by charging for electricity in Watt  hours, usually kiloWatt hours( kWh)), rather than in Amperes, or Volt Amperes (VA).

The heat energy iin kWh s stated on the bill. If you really want to check your bill you need to be sure that this figure is accurate.

The equation to convert volume into the SI unit of power/energy, the Watt (for billing purposes, the kiloWatt hour), is simple, but may look daunting. It is stated on all gas bills, as follows:-

A; The value in kWh/m3

which EQUALS the result of the following calculation:-

B:  Your consumption in cubic metres)

TIMES (C) a value for the heat energy contained in one cubic metre of gas stated in MegaJoules/cubic metre (MJ/m3). ( I can't use superscript for the 3 in the word processer used on this website.) .his is given to only one decimal place, so is rarely 100% accurate.

TIMES (D) a correction factor for your area (C) . For me, this is 1.02264 (5 decimal places needed for ACCURACY

The product of these three figures is DIVIDED by an invariable constant 3.6. (E).

This gives this equation: 

A = (B x C x D)/E

WHY IS THE ENERGY VALUE IN MJ/m3 STATED TO ONLY ONE DECIMAL PLACE, WHEN THE CORRECTION FACTOR IS TO 5 PLACES?

One might assume that a single decimal place is sufficient, but, if you really want to check if your bill is accurate, it often isn't.

My last bill (also from Octopus) stated the calorific value of the gas supplied to be 2,378.20 kWh, and its value per cubic metre (212 m3consumed) to be 39.40 MJ.

The latter gives not 2.378.20 kWh but  2,372.75. It looks as if I am being slightly overcharged.

However, the energy suppliers acknowledge implicitly that only one decimal place is not accurate for the gas calorific value in kWh. But Octopus states that presenting it to only ONE

.

It is the Regulator that has set the policy on the use of calorific values and the requirement to truncate to one decimal point:

https://www.ofgem.gov.uk/sites/default/files/docs/2014/08/supplier_guidance_on_cv_calculation.pdf

booneruk

Carlh93 said:

If you want to check the correctness of your gas bill you need to know the following:-

Isn't it as simple as looking at your meter every now and again, submitting the readings and checking the meter readings on bills you then receive?

[Deleted User]

booneruk said:

Carlh93 said:

If you want to check the correctness of your gas bill you need to know the following:-

Isn't it as simple as looking at your meter every now and again, submitting the readings and checking the meter readings on bills you then receive?

Not quite. Unless you look at this website

https://www.nationalgas.com/data-and-operations/calorific-value-cv

and download the calorific values of the gas supplied during the billing period for your region, you cannot be 100% sure that the calorific value stated on the bill is accurate. That said, all calorific values used for billing by suppliers are validated by an independent data collector.

macman

In practical terms, how much variation would there be for the mythical 'average' gas user annually if the correction factor was not truncated?
On the example given by the OP, the bill variation would be around 54p.

Raxiel

macman said:

In practical terms, how much variation would there be for the mythical 'average' gas user annually if the correction factor was not truncated?
On the example given by the OP, the bill variation would be around 54p.

Well, it would almost always be higher (and never lower), since truncating is effectively always rounding down. 38.91 and 38.99 both truncate to 38.9.

It wouldn't be very much though. I learned all about the volume to energy conversion calculation back when I had a supplier that used a fixed CV for simplicity (against OFGEM rules) and I had to calculate the error for my complaint (in retrospect, I needn't have bothered, even with them adding 3p (over six months) to my gas bills, they were still a lot cheaper than the next best tariff available at the time.)