Allocation of Unidentified Gas Statement 2013/146th February 2012

Areas Covered

• Consumption Method• Overview• Comparison with RbD Method• Scaling and Sample Size

• Permanent and Temporary UG• Theft Analysis• AQ Variation• Outstanding Data

• This is not an in-depth explanation of everything in the AUGS

Consumption Analysis: Background

• Estimate of Unidentified Gas total• Simple and intuitive concept

Total UG = Gas into LDZ – Metered Gas Out

Total UG = Aggregate LDZ Load – DM Load – Shrinkage – (Metered SSP + Metered LSP)

• Uses meter read data for both SSP and NDM LSP market sectors• Calculated figure covers all sources of UG

• SSP-assigned• LSP-assigned

Consumption Analysis: Comparison with RbD Method

• RbD Method estimates LSP-assigned UG only• Relies on an assumption that SSP-assigned UG is small• This is only true where LSP AQ bias is larger than SSP AQ bias• This is no longer necessarily

true

Consumption Analysis: Comparison with RbD Method

• RbD Method relies on long-term trends in data• It requires RbD and AQ bias to be steady• When this is not the case, accuracy will be further affected• AQ bias chart on previous slide shows it is not the case

Consumption Analysis: Scaling and Sample Size

• Actual consumptions based on meter reads can be calculated for a certain proportion of the population

• This is the sample• Meters can lie outside the sample for a number of reasons

• Consumption calculation failed (AQ check/negative consumption)• Site has no/insufficient valid meter reads• Site is in a CSEP

• Sample consumption must be accurately scaled to cover full population

Consumption Analysis: Scaling and Sample Size

Consumption Analysis: Scaling and Sample Size

• Non-consuming sites outside the sample must be handled correctly• AQ=1 sites and non-consuming sites are not necessarily the same

thing• Some sites with AQ=1 are consuming gas• Some sites with AQ>1 are not consuming gas

• Sites in CSEPs are always outside the sample

• Scale up correctly to cover all cases

Consumption Analysis: Scaling and Sample Size

Consuming Meters

Non-Consuming Meters

Consuming Meters

Non-Consuming Meters

Non-Consuming Meters

Consuming Meters

Non-Consuming Meters

Consuming Meters

Individual Meter ConsumptionCalculations

Meters withConsumptionCalculatedSuccessfully

CalculatedConsumption

CalculatedConsumption

= Zero

Meters whereConsumptionCalculationFailed Average EUC

Consumption

ZeroConsumption

Consumption Used

CSEPs

Consumption Analysis: Scaling and Sample Size

• Scaling up procedure example

EUCSample

Size

Sample Metered Consumption

(GWh) SDFailed Sites

Sites in CSEPs

Population Size

Population Metered

Consumption (GWh)

01B 1,855,569 30,016.9 0.009 281,011 132,732 2,269,312 36,709.802B 16,418 2,231.4 0.057 4,318 138 20,873 2,837.003B 4,008 1,795.0 0.118 828 31 4,867 2,179.804B 1,541 1,837.2 0.384 290 94 1,925 2,295.305B 419 1,414.0 0.937 78 6 503 1,696.806B 138 1,213.8 2.284 23 4 165 1,453.407B 45 937.9 4.286 13 0 58 1,211.208B 11 404.2 5.003 6 0 17 648.809B 1 60.6 0.000 0 0 1 60.6

Consumption Analysis: Scaling and Sample Size

• Effect of sample size on UG estimate

0%

1%

2%

3%

4%

5%

25% 50% 75% 100%

UG

%

Sample Size

Sample Size Sensitivity - EA LDZ

Average

Min

Max

Permanent and Temporary UG

• The Consumption Method calculates total UG including both Permanent and Temporary

• Therefore Temporary UG has to be estimated and removed from the calculated total

• This has been done according to current UNC definitions• Temporary UG can arise from all elements of UG depending on source• Mods 410, 424, 425 and 429 have been proposed and may change this

• Mod 425 implemented as of 25th January – will need to assess impact going forward

Theft

• The recommended approach is to move to the Throughput Method for estimating the split of theft between the SSP and LSP market sectors

LSP (GWh) SSP (GWh) Total (GWh) % Split2007 4.01 16.82 20.83 19.22008 5.84 21.55 27.40 21.32009 5.05 17.27 22.32 22.62010 3.24 12.52 15.76 20.6

2008-2010 21.5%

Sector 2006 2007 2008 2009 2010 FinalNDM LSP 135.1 134.4 134.5 125.0 124.1

SSP 348.7 368.4 379.4 363.2 376.2 Total 483.7 502.9 514.0 488.2 500.3

LSP % 27.9% 26.7% 26.2% 25.6% 24.8% 23.3%

Consumption plus Theft Method LSP Percentage

Throughput Method LSP Percentage (TWh)

Theft

• LSP throughput percentage trendLSP Throughput Percentage - National

23.3%23.0%

24.0%

25.0%

26.0%

27.0%

28.0%

06/07 07/08 08/09 09/10 10/11 11/12 12/13

• Trend will be reviewed each year and the most appropriate extrapolation method applied

Theft

• Consumption plus Theft Method suffers from the following issues:• The calculations are heavily dependent on the accuracy of the estimate and duration of theft.• Use of AQs - particularly as we can only calculate metered consumption for 50% of the data set.• Accuracy of the metered consumption calculation.• Potential effect of customer changes on pre/post theft AQs.• Site classification issues – e.g. Unregistered sites.• An assumption that the market sector split of unknown theft is the same as that of detected theft.

• Throughput method preferred and therefore recommended for future use

AQ Variation

• This issue affects Unregistered sites• Setting of a representative AQ is in three stages• Requested AQ Confirmed AQ AQ Following AQ Review

• Requested AQ is contained in the Unregistered Sites report sent to the AUGE• This undergoes no validation• It regularly differs from the Confirmed AQ and can be several orders of magnitude out

• Confirmed AQ is still on average much higher than the first AQ set by the AQ review for the site

• Factors to convert between all stages to give the best possible final estimate of Unregistered UG

General Enhancements to UG Calculation

• Unregistered Sites: two-stage AQ adjustment process• iGT CSEPs: sufficient snapshot data now exists to identify a trend rather than

simply taking forward a fixed value• LDZ offtake meter errors: these are applied to the UG estimate from the

Consumption Method

Current UG Estimates from Consumption Method

LDZ

Total UG (GWh)Total UG as Percentage of NDM

Allocations

2009 2010 2011 2009 2010 2011

EA 799 1,562 147 2.01% 3.80% 0.43%

EM 948 1,356 -686 1.89% 2.63% -1.59%

NE 753 1,293 83 2.40% 4.02% 0.30%

NO 481 802 -62 1.82% 3.00% -0.27%

NT 170 1,046 -1,036 0.31% 1.89% -2.24%

NW 951 1,112 -952 1.58% 1.84% -1.86%

SC 1,193 1,515 -284 2.61% 3.30% -0.71%

SE -237 990 -1,058 -0.46% 1.85% -2.42%

SO 614 955 181 1.73% 2.65% 0.61%

SW 510 572 -109 1.76% 1.96% -0.45%

WM 237 802 -394 0.53% 1.76% -1.04%

WN 192 223 -31 3.61% 4.15% -0.69%

WS 658 589 -201 3.60% 3.26% -1.33%

Total 7267 12819 -4401 1.48% 2.56% -1.05%

Current UG Estimates from Consumption Method

• There is currently a step change in 2011• This is likely to be due to a lack of corrections in the LSP consumption dataset

for this year• There are significantly fewer corrections in the 2011 dataset at this stage due to

the smaller time that has elapsed since it ended• Updated 2011 figures will be calculated when datasets for next year’s

calculations are received• In the meantime, 2011 is excluded from the analysis

Outstanding Data

• Some data items are still required from Xoserve• All were received for last year’s analysis but need to be updated

• Composition of known CSEPs• Opening meter readings of Orphaned sites• Connection details for Unregistered sites• Gas Safety Visit data

Thank you for your attention