MoneySavingExpert Chair, Martin Lewis · Editor, Marcus Herbert

# Analysis required on this gas bill data please

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Posts: 1 Newbie

Hi. Please would someone explain why, after giving nPower a gas reading, only Rate1 is used. The first bill below, shows two rates used but the revised bill only shows Rate1 used. I have spent considerable time viewing relevant posts and have then put the data into a MS Excel spreadsheet to try and see how nPower have arrived at their figures.

Data input into spreadsheet

ID Name
Rate1Weighting--MaxRate1
1--January---19.30%
882.396
2--February--19.30%
882.396
3--March
5.94%
271.5768
4--April
5.93%
271.1196
5--May
1.00%
45.72
6--June
1.00%
45.72
7--July
1.00%
45.72
8--August----1.00%
45.72
9--September-1.00%
45.72
10 October---5.93%
271.1196
11 November--19.30%
882.396
12 December--19.30%
882.396

100.00%
4572

A--B
C--D
E
F
G
28/08/2008 31/08/2008---3--August
31 9.68%---1.00%--45.72--4.42
31/08/2008 30/09/2008---30-September--30 100.00% 1.00%--45.72--45.72
30/09/2008 30/10/2008---30-October----31 96.77%--5.93%--271.12-262.37

312.52

28/08/2008 31/08/2008---3--August
31 9.68%---1.00%--45.72--4.42
31/08/2008 30/09/2008---30-September--30 100.00% 1.00%--45.72--45.72
30/09/2008 30/10/2008---30-October----31 96.77%--5.93%--271.12 262.37
31/10/2008 12/11/2008---12-November---30 40.00%--19.30% 882.40 352.96

665.48

A = No. of days in the month considered
B = The month name
C = Total number of days in the month
D = 'A' as a percentage of 'C'
E = The Rate1 weighting for the month expressed as a percentage of the annual total (4572)
F = The Rate1 weighting for the month in kWh
G = 'D' multiplied by 'F', giving the Rate1 capacity

Data input into spreadsheet end

Bill dated 6th Nov. 2008
28/08/08E - 8088
30/10/08E - 8175
87 cubic m
975 kWh
234 x Rate1
741 x Rate2

Meter reading taken (12/11/08) and new bill arrives:
Bill dated 10th December 2008
28/08/08E - 7946
12/11/08C - 7985
39 cubic m
437 kWh
437 x Rate1
0 x Rate2

(E = estimate, C = customer)

Why has only Rate1 been used on the second bill? It looks like, regardless of how the gas has been used over the period 28/08 to 12/11, the total usage over the period is taken from the Rate1 allocation for the month in which the last reading is recorded (ie 437kWh has been considered against November's allocation (882.396)).
My calculation of Rate1 capacity for the first bill is 312.52, but only 234kWh are charged at Rate1 and the rest at Rate2.
Should I record a gas reading at the beginning of every month and notify nPower? How is quarterly gas usage spread over the 3 months when nPower do their calculations?
Thankyou.

## Comments

• Posts: 6,156 Forumite
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28/08 to 12/11 is two and a half months. So equally spread your first 952 kWh in that time period would be charged at Tier 1. As you have only used 437kWh they are all charged at the higher rate.

Of course, with nPower, it is not that simple because of their seasonal weighting. In 2007 their weighting was:
```         %      kWh
Jan	13.8	631
Feb	13.6	622
Mar	12.2	558
Apr	 9.8	448
May	 7.1	325
Jun	 4.2	192
Jul	 2.4	110
Aug	 2.4	110
Sep	 4.2	192
Oct	 7.3	334
Nov	10.3	471
Dec	12.7	581
100     4572
```
So for your period, 3 days in Aug should have 3/31*110, 12 days in Nov should have 12/30*471.
So that's 10.6 + 192 + 334 + 188.4 or 725 kWh.

Now about your first bill... (give me another minute or two)

Hmm. The first bill (28 Aug to 30 Oct) should have 525 kWh at Tier 1. And I've just noticed I'm using old weightings so your figures are correct. nPower have an arithmetic all of their own.
• Posts: 6,156 Forumite
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Since our two tables of weightings are completely different who knows what table they were using in November! Hopefully an nPololgist will be along shortly to explain why our antiquated arithmetic is laughably naive.
• Posts: 29,038 Forumite
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Welcome to the forum, and congratulations for understanding the complexity of NPowers 'sculpting'(seasonal weighting)

I am not quite sure of your query about the 437kWh at tier 1 as that is correct, although the earlier bill with estimated readings is puzzling.

You are quite correct that in the period from 28/8 to 12/11 they will charge you for 665kWh at tier 1(Primary) and anything over that at Tier 2.(secondary)

So as you have only used 437kWh in that period it will all be Tier 1.

I also agree with you that according to your figures on seasonal weighting you should have been billed for 312.52kWh at tier1 for the period 28/8 to 30/10.(using those estimated readings) yet you have only been charged for 234kWh - obviously this is to your advantage.

I suspect(but don't know) that the answer lies in the fact that you were probably overcharged for Tier 1 units on the bill preceeding the one dated 6th Nov as they changed the allocation of seasonal weighting to each month before that date.
• Posts: 1 Newbie
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Hello Cardew,
I'm new to this forum, and forums in general, seems that you might be the only person who understands 'nPower Arithmetic'; I certainly don't.

I pay by monthly Direct Debit, however I recently received this alarming bill estimating the following

478 kWh consumption between 05/07/08 and 28/08/08 (54 days), with two tier rates:
First 80 kWh at 6.643p and next 398 at 1.990p. (= £13.22)

3992 kWh consumption between 28/08/08 and 03/01/09 (128 days), with another two tier rates:
First 2172 kWh at 8.304p and the next 1820 at 2.488p. (= £225.64)

Given that

128 days / 54 days = 2.3703703

how can they justify charging me more after the rates increased

3992 kWh / 478 kWh = 8.3514644

or indeed

£ 225.64 / £ 13.22 = 17.068078 !!!!!

I'm sure I'm being foolish in expecting there to be anything but a simple and straightforward answer to this from the good nPower folk that I have simply overlooked :P

Could you help me out at all,

mucho thanks!
• Posts: 29,038 Forumite
Options
Hello Cardew,
I'm new to this forum, and forums in general, seems that you might be the only person who understands 'nPower Arithmetic'; I certainly don't.

I pay by monthly Direct Debit, however I recently received this alarming bill estimating the following

478 kWh consumption between 05/07/08 and 28/08/08 (54 days), with two tier rates:
First 80 kWh at 6.643p and next 398 at 1.990p. (= £13.22)

3992 kWh consumption between 28/08/08 and 03/01/09 (128 days), with another two tier rates:
First 2172 kWh at 8.304p and the next 1820 at 2.488p. (= £225.64)

Given that

128 days / 54 days = 2.3703703

how can they justify charging me more after the rates increased

3992 kWh / 478 kWh = 8.3514644

or indeed

£ 225.64 / £ 13.22 = 17.068078 !!!!!

I'm sure I'm being foolish in expecting there to be anything but a simple and straightforward answer to this from the good nPower folk that I have simply overlooked :P

Could you help me out at all,

mucho thanks!

Welcome to the forum.

There are a number of threads on this subject.

I assume you are au fait with the concept of Tier1/Tier2 (or primary/secondary) charging. Essentially this is to recover a 'standing charge' for the supply - instead of a dailly charge of xx pence.

All companies, except Npower, using this method, charge for Tier 1 at a daily pro-rata rate.

So using the most common allocation of 4,572kWh per year at Tier 1 rates, you will pay for 4572/365 = 12.53kWh per day.

Thus if your bill is for a period of 100 days you will pay for 1253kWh at Tier 1 rates. Importantly this is for any period in the year.

However NPower uniquely do not use that method for gas(they do for electricity)

Instead they have introduced the concept of 'Seasonal Weighting' or 'Sculpting' They still have 4,572kWh charged at Tier 1 rates in the year* but they do not charge for them on a daily pro-rata basis.

In this method of charging they charge for very small amounts of Tier 1 units in the Summer months and almost all of the Tier 1 units in the winter months.

ID Name
Rate1Weighting--MaxRate1
1--January---19.30%
882.396
2--February--19.30%
882.396
3--March
5.94%
271.5768
4--April
5.93%
271.1196
5--May
1.00%
45.72
6--June
1.00%
45.72
7--July
1.00%
45.72
8--August----1.00%
45.72
9--September-1.00%
45.72
10 October---5.93%
271.1196
11 November--19.30%
882.396
12 December--19.30%
882.396

From the above you can see that in July and August(62 days) you will be charged for 91.44kWh at Tier 1 ( which accounts for your 54 day and 80kWh)

In December and January(also 62 days) you will be charged for 1764.792kWh at Tier 1

So your next quarterly bill will have around 2,000kWh at Tier 1 rates and the subsequent bill very few at Tier 1.

The reason for this wierd charging system is that some people switch off their gas boiler in the summer months and use an immersion heater for Hot water.
Thus if they had the boiler off for exactly 6 months they would only pay for 50% of the Tier1 4572 kWh allocation when using other companies, but with NPower it would make very little difference as the vast majority of Tier1 units are allocated to the winter months.

The problem with this system is that at a time when your gas consumption is at its highest, you get hit with loads of high priced Tier 1 units - a double whammy!

* If you have been with NPower for some time you will have certainly been overcharged. This is long and very complicated, and largely due to the efforts of one intrepid contributor to this forum, is the subject of an investigation by the Regulator and the Sunday Times has covered his case.

He took NPower to court and won considerable damages and lots of other have been refunded by NPower simply by requesting a refund.

There is a huge long thread on this scam by NPower: see http://forums.moneysavingexpert.com/showthread.html?t=822299&highlight=scam+Npower and Direct Debacle is our hero!!
This discussion has been closed.

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