[retrotecchie]

@meldrewreborn

Ah a nod to my late grandfather then. He worked as a senior manager in the gas metering division at Schlumberger, prior to his retirement, but did a spell in his younger days as a tank driver in North Africa during the earlier part of WW2. I can't recall exactly the RAL code number for the paint on the meters, but he always called it Battledress Beige.

[retrotecchie]

@Mailman

There are two numbers used in the conversion formula. Calorific Value and Volumetric Adjustment, or Correction Factor.

Cubic meters (m3) used x calorific value x Correction factor (1.02264) ÷ kWh conversion factor (3.6) = kWh.

If your meter works in hundreds of cubic feet, multiply that by 2.83

Calorific value, shown on your bill can be anywhere between 37 and 43 but the 'default' for calculating on an IHD is indeed 40 which gives you a figure that may be reasonably accurate but can vary by +/- 7.5%.

The Correction Factor varies very slightly according to ambient temperature, but most suppliers use the 1.02264 figure as an all year round average.

Similarly, when you look at the display on a petrol or diesel pump, you will see that the pump measurement is calibrated at 15°C which is an industry standard figure. If the temperature is lower than that, you get more petrol or diesel energy for your money, and above that you get less due to the density variation.

[meldrewreborn]

@retrotecchie

do do we have any data on long term calorific values? I can imagine that it varies by region and depending on the sourced gas.

[meldrewreborn]

@retrotecchie

In F1 they weigh the fuel input rather than measure it.

[retrotecchie]

@meldrewreborn

Yes. Same with aviation fuel. The same stuff goes in jet aircraft as goes in my heating tank - kerosene. Planes use lb or kilos for fuel consumption or fuel capacity and they purchase their fuel by the metric tonne. My boiler consumption is litres/day and my fill is paid for in litres.

[retrotecchie]

Originally Posted by meldrewreborn

@retrotecchie

do do we have any data on long term calorific values? I can imagine that it varies by region and depending on the sourced gas.

Digest of UK Energy Statistics, or DUKES, I believe has such info.

https://www.gov.uk/government/statis...lorific-values

[Mailman]

Interestingly I had a closer look at the gas portion of the bill I received for the month of December and compared it to what the IHD shows.

Via the IHD, December monthly total is 1258kWh (cost £136)
Via the IHD, aggregating the daily totals that I record on my spreadsheet gives me 1260.38 kWh
The correct figure from my bill was 1258.9 kWh. (cost £136.85)
The actual CV used in my bill calculation had to be 39.51 to get to the kWh amount on the bill.
On the bill the CV is only shown to 1 decimal place but obviously they must use 2 dps in the actual calculation.
The electricity portion on the IHD showed 248 kWh usage (cost £99.63) compared to the accurate bill and my own spreadsheet of of 248.5 kWh/£95.58 but I'm almost certain that the pre-January 1st rates were inaccurate showing my old v18 fix rate less the 17p EPG reduction rather than the Next Flex rate I was actually being billed to

So my IHD gives a pretty close idea about both kWh and costs (unit rates look right now) although it was not as accurate as Eon Next's billing (or my own calculations for that matter). January might well be better for those that budget on £ if their IHD has updated recently.

[retrotecchie]

@Mailman

When us non smart users send readings, we're told to ignore any decimal points. I know that prepay meters, smart or otherwise, work to two decimal points internally. Do your smart meter submissions to E.On Next show any decimals or do they still use integer values?

[Mailman]

Originally Posted by retrotecchie

Do your smart meter submissions to E.On Next show any decimals or do they still use integer values?

The bills show 1 decimal place although the list of meter readings on the account only show integer values. On the occassions that I 've put in manual reads the system only allows the input in integer values as well. 👍

[retrotecchie]

@Mailman

I guessed that was probably the case but wasn't entirely sure, not having a smart meter myself. I only put integer reads in my spreadsheet, although the calculations of my periodic and rolling averages come out to 2dp. I did used to put my reads in to the same number of places as my meter, but as E.On Next only work to the nearest whole unit, so do I these days. For my calculations, the error over a year can only ever be +/- 1kWh on a consumption of 3500-odd, which is insignificant.