[richt119]

Hi,
My smart meter IHD shows gas usage in kWh and also calculate the cost as kWh usage x cubic meter tariff.
The meter readings are in cubic meter. How can the IHD be correct to show cubic meter and show the correct cost?

Thanks,

[retrotecchie]

@richt119

You are billed in kWh for the gas, not by the cubic metre. The meter measures in cubic metres, to which they apply a conversion formula.

If you have a look at one of your bills (a full pdf one, not the summary) you will see the consumption in cubic metres and then the conversion factors they use to convert to kWh.

The IHD already does the maths for you, so the cost you see is correct.

m3 To kWh Conversion Formula

Different qualities of natural gas have different energy densities. That’s why they use a slightly complex equation to convert m3 to kWh precisely:

m3 × Calorific Value × Conversion Factor ÷ 3.6 = kWh

The caloric value of natural gas is the parameter that changes. It’s usually around 40.0; depending on the quality of natural gas it can deviate +/-5% hence a correction factor, and 3.6 is the conversion factor for kWh.

[JoeSoap]

@richt119 @retrotecchie

Just found something about the type of IHD I have which states in bold at the bottom of page 2 that due to gas conversion factors your display may not be 100% accurate…
https://www.eonenergy.com/content/da...x127%20(3).pdf

[retrotecchie]

@JoeSoap

Variance is +/- 5% so your actual calorific value could be anywhere from 38 to 42. A cubic metre could then be anywhere between 10.56kWh and 11.67 kWh. So yes, I think the IHD assumes a middle of the road 40 for the calorific value, or 11.11 kWh. The actual bill should be accurate. The IHD is an approximation for gas...just the way these things work.

[JoeSoap]

@retrotecchie

Doesn’t include VAT either.

[richt119]

Thanks for pointing that out.
My Smart meter gives me consumption data in m3.
How can I use the data from the smart meter to calculate my charges if I dont know the calorific value or correction factor being used?
Do those factors vary enough to effect using the smart meter data to calculate cost?
How does the IHD convert the m3 value to kWh without knowing the calorific value and volume correction factor?

Is this a case of obfuscation?

Thanks,

[retrotecchie]

@JoeSoap

No gas here so it's been a very long time since I've seen a gas bill. My old gas meter was an old grey sit up and beg metal tin with mechanical wheels for the numbers...Back then my gas was around 2.9p per kWh and we had a meter reader come round every quarter so I paid the maths very little mind. I don't even think they had VAT on domestic energy then either.

[JoeSoap]

@richt119

See the link in my previous post. The IHD is just a guide to the cost. On the right hand side of your statements it mentions the conversion factors but not something I pay any attention to.

[retrotecchie]

Originally Posted by richt119

Thanks for pointing that out.
My Smart meter gives me consumption data in m3.
How can I use the data from the smart meter to calculate my charges if I dont know the calorific value or correction factor being used?
Do those factors vary enough to effect using the smart meter data to calculate cost?
How does the IHD convert the m3 value to kWh without knowing the calorific value and volume correction factor?

Is this a case of obfuscation?

Thanks,

No, the IHD will give you an approximation of cost to +/- 5% as it will use 40 as a midpoint with no correction factor. If you want to do the sums yourself, then cubic metres x 11.11 will give you your use in kWh, then multiply that by your tariff. Have you not got an option on the IHD to display cost as well as cubic metres?

The actual values used to calculate your bill will be shown on your bill, as @JoeSoap says.

[JoeSoap]

@richt119

I meant right hand side of bill… under Gas Tarff or some such. I’ve edited my post.