Calculating energy usage in gas account: why is calorific value displayed in bill?

It used to be that at the bottom of my bills there was a detailed calculation of how the kilowatt hours were calculated for the last month, using the actual cubic metres used as a start point and using a calorific value that changed month by month. More recently the bill shows an illustrative box that shows how you would calculate 100 cubic metres of consumption; I’d been assuming that the illustration nevertheless still uses the current month’s calorific value, but this has not changed for months and now I realise (by calculating backwards using the formula) that the calorific values are changing but Bulb is not telling me what the calorific value is month by month. I want to be able to keep track of kilowatt hours used by my own calculations based on my own readings, but if Bulb does not tell me the latest cal. value I cannot do this without using such convoluted back-calculations. Why the change?

The title for this should, of course, have included “why is calorific value not displayed in bill?”

gs693…I already questioned that as it knocked my figures out initially, I now check with the National grid at:

http://mip-prod-web.azurewebsites.net/DataItemExplorer/Index
Click on CV/ your area/ adjust dates to suit, and you can get the average from there.

Not ideal and a bit long winded but it does allow one to check that the proper CV rate has been applied.

@gs693 Calorific value is a factor that changes every day so is something that is not really appropriate to list 30 different figures on every bill, we instead put an average for the area. @scudo has a good link to find the calorific values.

gs693.....I already questioned that as it knocked my figures out initially, I now check with the National grid at:

http://mip-prod-web.azurewebsites.net/DataItemExplorer/Index
Click on CV/ your area/ adjust dates to suit, and you can get the average from there.

Not ideal and a bit long winded but it does allow one to check that the proper CV rate has been applied.

Thanks for your response, scudo.

@gs693 Calorific value is a factor that changes every day so is something that is not really appropriate to list 30 different figures on every bill, we instead put an average for the area. @scudo has a good link to find the calorific values.

When you say you put an average for the area, DanP, do you mean that it’s an average for the calorific value over the course of that bill’s month, because if it is it has become very stable since you also moved to the illustrative 100 units rather than showing how it applied to my variable month-by-month consumption (ie never now changing at all). Other suppliers still show changes in their customers’ calorific values, so why has Bulb changed from its former practice?

@gs693 The calorific value changes on a daily basis and our system will use those daily values to generate these bills.

The calorific value that shows on the bill will be the most recent calorific value to help show how the calculation works.

We’re currently aware that there is a critical issue in the gas calculations not being correct for some bills that are generated. So we’re looking to fix our gas billing in general.

I’ve noticed that my mother-in-law’s latest bill from Bulb does give (in the explanation box ‘Explaining your gas usage’) the actual number of meter units she used for the month for the calculation (rather than the 100 that has continued to be used in mine up to the most recent bill. I’m hoping this indicates Bulb has reverted to really explaining how energy used has been calculated for the latest month. Unfortunately (and hopefully by pure coincidence) the calorific value is the same as it was when the purely illustrative version was being used for 100 meter units.

@gs693 The calorific value changes on a daily basis and our system will use those daily values to generate these bills.

The calorific value that shows on the bill will be the most recent calorific value to help show how the calculation works.

We’re currently aware that there is a critical issue in the gas calculations not being correct for some bills that are generated. So we’re looking to fix our gas billing in general.

Hi @gs693 the calorific figure is usually around 39…1-39.5 most of the time. So it may be the same figure shown on each statement.

@gs693 Calorific value is a factor that changes every day so is something that is not really appropriate to list 30 different figures on every bill, we instead put an average for the area. @scudo has a good link to find the calorific values.

When you say you put an average for the area, DanP, do you mean that it’s an average for the calorific value over the course of that bill’s month, because if it is it has become very stable since you also moved to the illustrative 100 units rather than showing how it applied to my variable month-by-month consumption (ie never now changing at all). Other suppliers still show changes in their customers’ calorific values, so why has Bulb changed from its former practice?

I may be wrong but I think one of the issues is that there is no set date for all when the readings are due as we appear to have different submission dates, this would mean that the 31 days in the month would be different for each account. This could mean 250,000 separate calculations to give each an accurate CV average. Other suppliers (that I have used) have the readings from all customers set to be given on a certain date so much simpler to give an average CV for their region.

I agree it is a pain but sometimes we have to give and take to get a more personalized flexible system with regard to payments that suit an individuals financial situation.

If I remember correctly, the calorific value on my statements from previous suppliers never changed.

As much as it varies slightly all the time, it doesn’t tend to change very much in one area averaged over time as you’re being supplied primarily from the same gas plants with the same gas source (bio-methane etc.)