Actions for Mod209 Workgroup

July 15th 2008

Page 2Theme Date Department

Review of minimum base period for AQ calculation Aim to have a twelve months between the two meter reads

forming the AQ base period

Where this cannot be achieved a longer period is assessed first before reducing to a minimum period

Current minimum base period is 6 months and 1 day

Page 3Theme Date Department

Analysis presented as part of review group 177

Data used is data recorder and data logger information from the Demand Estimation sample

Sample size was 3,788 (split between 2,154 SSP and 1,634 LSP)

Data used current live system AQ and daily actual consumption to produce estimated AQ for varying periods after weather correction

Variability was calculated against actual weather corrected consumption for a 12 month period

Page 4Theme Date Department

Variability of estimated AQVariability in AQ dependent on base period

(Random sample of 3800 sites)

0

200

400

600

800

1000

1200

1400

1600

<-1

00

%

-10

0%

to -

50

%

-50

% to

-4

0%

-40

% to

-3

0%

-30

% to

-2

0%

-20

% to

-1

0%

-10

% to

0%

0%

to 1

0%

10

% to

20

%

20

% to

30

%

30

% to

40

%

40

% to

50

%

50

% to

10

0%

>1

00

%

% Error

Co

un

t

Error at 6 month 1 day Error at 9 month

Page 5Theme Date Department

Impact of extended base period on rollover AQ

Longer base period may mean longer between AQ recalculation

Following analysis assesses whether a 6 month base period would provide improvements on continuing with the current AQ

Sample data is consistent with previous analysis

Page 6Theme Date Department

Will benefits be achieved in a change?

For two base periods the analysis assesses those sites where revising the AQ would be closer to actual consumption than the current live AQ

For 6 month base period over 59% of the time it is better to maintain the current AQ

For 9 month base period it is better to maintain the current AQ in only 38% of cases

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

6m+1 improves AQ 9m+1 improves AQ

Revising AQ better

Better to keep old AQ

Page 7Theme Date Department

SSP to LSP Threshold

Data based on sites in 2005/6 and 2006/7 AQ reviews where the site crossed the SSP/LSP threshold at least once

23,916 sites used for the analysis

Results look at the impact on number of rollovers and aggregate AQ of not recalculating where the change is below a tolerance

Additional information concentrating on sites that cross the threshold annually

Page 8Theme Date Department

Threshold tolerance impacts (1)

0.00%

10.00%

20.00%

30.00%

40.00%

50.00%

60.00%

70.00%

80.00%

5% 6% 7% 8% 9% 10%

11%

12%

13%

14%

15%

16%

17%

18%

19%

20%

21%

22%

23%

24%

25%

0.00%

0.50%

1.00%

1.50%

2.00%

2.50%

2005/6 % unchanged 2006/7 % unchanged

2005/6 % difference in total AQ 2006/7 % difference in total AQ 0.5% AQ impact

Page 9Theme Date Department

Threshold tolerance impacts (2)

12% Tolerance % unchanged % AQ impact2005/6 53% 0.49% Overstatement2006/7 16% 0.68% Understatement

10% tolerance % unchanged % AQ impact2005/6 49% 0.34% Overstatement2006/7 12% 0.48% Understatement

Page 10Theme Date Department

Threshold Crosser impacts (3)

Considering sites that cross annually:

2005 AQ LSP2006 AQ SSP2007 AQ LSP

No Tolerances 10% tolerance 12% toleranceSSP LSP SSP LSP SSP LSP

2005 4,984 4,984 4,9842006 4,984 3,926 1,058 3,672 1,3122007 4,984 591 4,393 667 4,317

Moved No Tolerances 10% tolerance 12% tolerance2006 4,984 100% 3,926 79% 3,672 74%2007 4,984 100% 3,335 67% 3,005 60%