1 UFE 2005 Analysis

UFE 2005 ANALYSIS

Compiled by Load ProfilingERCOT Energy Analysis & Aggregation

2 UFE 2005 Analysis

UFE Basics

Sources of UFE include:■ Generation Measurement Errors■ Load - Missing/Erroneous Usage Data

- Model Error - Load Profile ID Assignment Error

■ Losses - Model Error - Loss Code Assignment Error

Negative UFE indicates load/losses are overestimated

UFE (unaccounted for energy) is computed as follows:UFE = Generation – (Load + Losses)

3 UFE 2005 Analysis

UFE Basics

Net Generation for Settlement Interval

Interval Data Energy Usage

Profiled Energy Usage Non-Interval Data

Non-Metered Accounts

Losses:Transmission &

Distribution

UFEGAP - - - - - - >

Net GenerationCompared toLoad Buildup

4 UFE 2005 Analysis

DATA VERIFICATION IN THE SETTLEMENT PROCESS

UFE is computed for each 15-minute interval of a settlement run.

Initial

Final

Settlement

True-Up

Initial Settlement(posted on day 10 after the operating day)

Final Settlement(posted on day 60 after the operating day)

True-up Settlement (posted 6 months after operating day)

Resettlement statement (posted as needed)

5 UFE 2005 Analysis

Load Weighted Calculation of MCPE

Market Clearing Price for Energy (MCPE) is the highest price by Congestion Zone for a Settlement Interval for Balancing Energy deployed during the Settlement Interval.

In 2005 there were 5 congestion zones – E05, H05, N05, S05 and W05.

The load weighted MCPE is calculated for each 15 min. interval using the LCMZone cuts as follows:

MCPE_LWTD = ((LCMZone_E05_Mwh * MCPEL_E05) + (LCMZone_H05_Mwh * MCPEL_H05) +

(LCMZone_N05_Mwh * MCPEL_N05) + (LCMZone_S05_Mwh * MCPEL_S05) +

(LCMZone_W05_Mwh * MCPEL_W05)) / (LCMZone_E05_Mwh + LCMZone_H05_Mwh +

LCMZone_N05_Mwh + LCMZone_S05_Mwh + LCMZone_W05_Mwh)

6 UFE 2005 Analysis

LOAD AND UFE – ERCOT PEAK 2005Initial Settlement

SR01

ERCOT Load and UFE 2005 Peak Day - August 23, 2005Initial Settlement

-2000

0

2000

4000

6000

8000

10000

12000

14000

16000

1 9 17 25 33 41 49 57 65 73 81 89

Interval

MW

H

-4

-3

-2

-1

0

1

2

3

4

Per

cen

t

ERCOT Load

Percent UFE

UFE

7 UFE 2005 Analysis

LOAD AND UFE – ERCOT PEAK 2005Final Settlement

SR02

ERCOT Load and UFE 2005 Peak Day - August 23, 2005Final Settlement

-2000

0

2000

4000

6000

8000

10000

12000

14000

16000

1 9 17 25 33 41 49 57 65 73 81 89

Interval

MW

H

-4

-3

-2

-1

0

1

2

3

4

Per

cen

t

ERCOT Load

Percent UFE

UFE

8 UFE 2005 Analysis

LOAD AND UFE – ERCOT PEAK 2005True Up Settlement

SR03

ERCOT Load and UFE 2005 Peak Day - August 23, 2005True Up Settlement

-2000

0

2000

4000

6000

8000

10000

12000

14000

16000

1 9 17 25 33 41 49 57 65 73 81 89

Interval

MW

H

-4

-3

-2

-1

0

1

2

3

4

Per

cen

t

ERCOT Load

Percent UFE

UFE

9 UFE 2005 Analysis

UFE MWh by Month in 2005 Initial Settlement

SR04

UFE MWh by Month - Initial Settlement

-400,000

-200,000

0

200,000

400,000

600,000

800,000

1 2 3 4 5 6 7 8 9 10 11 12

MW

h

UFE ABS UFE

Annual UFE = 659,294 MWhABS Annual UFE = 5,681,893 MWh

10 UFE 2005 Analysis

UFE Cost by Month in 2005 Initial Settlement

SR05

UFE Cost by Month - Initial Settlement

-20,000,000

-10,000,000

0

10,000,000

20,000,000

30,000,000

40,000,000

50,000,000

60,000,000

70,000,000

80,000,000

1 2 3 4 5 6 7 8 9 10 11 12

Do

lla

rs

UFE Cost ABS UFE Cost

Annual UFE Cost = $147,994,203ABS Annual UFE Cost = $436,150,285

UFE Cost = Σ(MCPE x UFE_Mwh)

11 UFE 2005 Analysis

UFE MWh by Month in 2005Final Settlement

SR06

UFE MWh by Month - Final Settlement

-200,000

-100,000

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

1 2 3 4 5 6 7 8 9 10 11 12

MW

h

UFE ABS UFE

Annual UFE = 1,035,008 MWhABS Annual UFE = 4,965,437 MWh

12 UFE 2005 Analysis

UFE Cost by Month in 2005 Final Settlement

SR07

UFE Cost by Month - Final Settlement

0

10,000,000

20,000,000

30,000,000

40,000,000

50,000,000

60,000,000

70,000,000

1 2 3 4 5 6 7 8 9 10 11 12

Do

lla

rs

UFE Cost ABS UFE Cost

Annual UFE Cost = $166,016,452ABS Annual UFE Cost = $382,752,259

UFE Cost = Σ(MCPE x UFE_Mwh)

13 UFE 2005 Analysis

UFE MWh by Month in 2005 True-Up Settlement

SR08

UFE MWh by Month - True-Up Settlement

-200,000

-100,000

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

1 2 3 4 5 6 7 8 9 10 11 12

MW

h

UFE ABS UFE

Annual UFE = 1,082,561 MWhABS Annual UFE = 4,979,401 MWh

14 UFE 2005 Analysis

UFE Cost by Month in 2005 True-UP Settlement

SR09

UFE Cost by Month - True-Up Settlement

0

10,000,000

20,000,000

30,000,000

40,000,000

50,000,000

60,000,000

70,000,000

1 2 3 4 5 6 7 8 9 10 11 12

Do

llar

s

UFE Cost ABS UFE Cost

Annual UFE Cost = $174,154,088ABS Annual UFE Cost = $386,005,370

UFE Cost = Σ(MCPE x UFE_Mwh)

15 UFE 2005 Analysis

ABS UFE Mwh by Month in 2005 Initial, Final and True Up Settlements

SR09a

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

1 2 3 4 5 6 7 8 9 10 11 12

MW

h

Initial Final True Up

ABS UFE Mwh by Month - Initial, Final and True Up Settlements

16 UFE 2005 Analysis

UFE Cost by Month in 2005 Initial, Final and True-UP Settlements

SR09b

UFE Cost by Month - Initial, Final and True Up Settlements

0

10,000,000

20,000,000

30,000,000

40,000,000

50,000,000

60,000,000

70,000,000

80,000,000

1 2 3 4 5 6 7 8 9 10 11 12

Do

lla

rs

Initial Final True UpUFE Cost = Σ(MCPE x UFE_Mwh)

17 UFE 2005 Analysis

STATISTICAL SUMMARY - 2005

SR10

MEAN MEDIAN MIN MAX

2002 31,980 30,107 19,209 55,703

2003 32,489 30,824 19,282 59,992

2004 32,909 31,162 20,231 58,528

2005 34,155 31,901 20,482 60,272

2002 32,002 30,116 19,211 56,233

2003 32,517 30,850 19,292 59,996

2004 32,917 31,166 20,231 58,531

2005 34,161 31,911 20,486 60,270

2002 32,052 30,142 19,266 56,248

2003 32,532 30,865 19,310 60,095

2004 32,917 31,166 20,231 58,531

2005 34,162 31,912 20,490 60,274

ERCOT LOAD (MW)

TRUE-UP

INITIAL

FINAL

ERCOT LOAD (MW)

ERCOT LOAD (MW)

18 UFE 2005 Analysis

STATISTICAL SUMMARY - 2005

SR11a

MEAN MEDIAN MIN MAX

2002 -2,176 -2,228 -6,969 5,673

2003 -314 -400 -3,906 3,798

2004 67 -9 -4,558 4,559

2005 75 45 -5,537 3,538

2002 -1,593 -1,575 -5,954 3,427

2003 -14 -126 -3,172 3,728

2004 130 56 -3,929 4,302

2005 118 77 -4,199 3,163

2002 -461 -556 -3,371 3,803

2003 191 71 -2,886 4,065

2004 153 83 -3,879 4,299

2005 124 82 -4,155 3,190

INITIAL

FINAL

TRUE-UP

UFE (MW)

UFE (MW)

UFE (MW)

19 UFE 2005 Analysis

STATISTICAL SUMMARY - 2005

SR11b

MEAN MEDIAN MIN MAX

2002 2,321 2,257 0 6,969

2003 857 759 0 3,906

2004 606 472 0 4,559

2005 649 491 0 5,537

2002 1,666 1,579 0 5,654

2003 711 603 0 3,728

2004 550 414 0 4,302

2005 567 426 0 4,199

2002 838 771 0 3,803

2003 672 528 0 4,065

2004 551 413 0 4,299

2005 568 427 0 4,155

|UFE| (MW)

FINAL

INITIAL

|UFE| (MW)

|UFE| (MW)

TRUE-UP

20 UFE 2005 Analysis

STATISTICAL SUMMARY - 2005

SR12a

MEAN MEDIAN MIN MAX

2002 -7.0 -7.1 -24.1 16.8

2003 -1.3 -1.3 -12.7 9.4

2004 0.1 0.0 -11.5 13.9

2005 0.2 0.1 -18.9 10.3

2002 -5.3 -5.2 -20.6 9.5

2003 -0.2 -0.4 -10.3 9.4

2004 0.3 0.2 -9.9 13.1

2005 0.3 0.2 -14.7 9.3

2002 -1.7 -1.8 -14.8 10.5

2003 0.4 0.2 -7.9 9.9

2004 0.4 0.3 -9.8 13.1

2005 0.3 0.3 -14.6 9.2

TRUE-UP

INITIAL

FINAL

UFE as PERCENT of LOAD

UFE as PERCENT of LOAD

UFE as PERCENT of LOAD

21 UFE 2005 Analysis

STATISTICAL SUMMARY - 2005

SR12b

MEAN MEDIAN MIN MAX

2002 7.5 7.2 0.0 24.1

2003 2.8 2.4 0.0 12.7

2004 1.8 1.5 0.0 13.9

2005 1.9 1.5 0.0 18.9

2002 5.6 5.2 0.0 20.6

2003 2.2 1.9 0.0 10.3

2004 1.7 1.3 0.0 13.1

2005 1.7 1.3 0.0 14.7

2002 2.7 2.5 0.0 14.8

2003 2.0 1.7 0.0 9.9

2004 1.7 1.3 0.0 13.1

2005 1.7 1.3 0.0 14.6

|UFE as PERCENT of Load|

INITIAL

TRUE-UP

FINAL

|UFE as PERCENT of Load|

|UFE as PERCENT of Load|

22 UFE 2005 Analysis

STATISTICAL SUMMARY - 2005

SR13a

MEAN MEDIAN MIN MAX

2002

2003 356 -1,785 -88,773 511,652

2004 2,279 -57 -76,418 200,563

2005 4,224 386 -183,607 730,583

2002 -2,067 -1,841 -23,686 580,173

2003 2,663 -635 -132,426 824,621

2004 2,694 442 -92,510 164,969

2005 4,738 722 -220,201 596,968

2002 -1,777 -2,287 -121,635 933,143

2003 4,993 496 -86,677 904,970

2004 2,923 632 -92,408 168,849

2005 4,970 776 -212,732 603,737

UFE Cost ($)

UFE Cost ($)

Note: UFE and |UFE| costs are not calculated for initial settlement in 2002 because LCMZONE cuts are not available to calculate the load weighted MCPE.

INITIAL

FINAL

TRUE-UP

UFE Cost ($)

23 UFE 2005 Analysis

STATISTICAL SUMMARY - 2005

SR13b

MEAN MEDIAN MIN MAX

2002

2003 8,804 5,560 0 511,652

2004 6,887 4,055 0 200,563

2005 12,447 6,177 0 730,583

2002 5,664 3,579 0.2 580,173

2003 8,596 4,699 0 824,621

2004 6,297 3,630 0 164,969

2005 10,923 5,345 0 596,968

2002 5,251 3,780 0 933,143

2003 8,695 4,137 0 904,970

2004 6,329 3,605 0 168,849

2005 11,016 5,338 0 603,737

|UFE Cost| ($)

|UFE Cost| ($)

Note: UFE and |UFE| costs are not calculated for initial settlement in 2002 because LCMZONE cuts are not available to calculate the load weighted MCPE.

TRUE-UP

|UFE Cost| ($)

FINAL

INITIAL

24 UFE 2005 Analysis

STATISTICAL SUMMARY - 2005

SR14a

MEAN MEDIAN MIN MAX

2002

2003 -1.0 -1.0 -11.4 9.4

2004 0.1 0.0 -11.5 13.9

2005 0.2 0.1 -18.9 10.3

2002 -2.2 -2.1 -9.4 3.0

2003 -0.1 -0.3 -8.7 9.4

2004 0.3 0.2 -9.9 13.1

2005 0.3 0.2 -14.7 9.3

2002 -1.6 -1.8 -14.8 10.5

2003 0.4 0.2 -7.9 9.5

2004 0.4 0.3 -9.8 13.1

2005 0.3 0.3 -14.6 9.2

UFE Cost as % of Total Cost

TRUE-UP

Note: UFE and |UFE| costs are not calculated for initial settlement in 2002 because LCMZONE cuts are not available to calculate the load weighted MCPE.

INITIAL

FINAL

UFE Cost as % of Total Cost

UFE Cost as % of Total Cost

25 UFE 2005 Analysis

STATISTICAL SUMMARY - 2005

SR14b

MEAN MEDIAN MIN MAX

2002

2003 2.6 2.3 0.0 11.4

2004 1.8 1.5 0.0 13.9

2005 1.9 1.5 0.0 18.9

2002 2.7 2.2 0.0 9.4

2003 2.1 1.9 0.0 9.4

2004 1.7 1.3 0.0 13.1

2005 1.7 1.3 0.0 14.7

2002 2.7 2.5 0.0 14.8

2003 2.0 1.7 0.0 9.5

2004 1.7 1.3 0.0 13.1

2005 1.7 1.3 0.0 14.6

|UFE Cost| as % of Total Cost

|UFE Cost| as % of Total Cost

|UFE Cost| as % of Total Cost

Note: UFE and |UFE| costs are not calculated for initial settlement in 2002 because LCMZONE cuts are not available to calculate the load weighted MCPE.

INITIAL

FINAL

TRUE-UP

26 UFE 2005 Analysis

STATISTICAL SUMMARY – MONTHLY for 2005

SR15

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

ERCOT Total Load (MW) 30,500 30,611 20,857 41,503 ERCOT Total Load (MW) 29,659 30,020 21,583 41,296

FINAL FINALERCOT Total Load (MW) 30,506 30,615 20,859 41,504 ERCOT Total Load (MW) 29,662 30,022 21,587 41,298

TRUE_UP TRUE_UPERCOT Total Load (MW) 30,507 30,615 20,859 41,504 ERCOT Total Load (MW) 29,666 30,024 21,589 41,303

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

ERCOT Total Load (MW) 28,017 28,822 20,879 36,156 ERCOT Total Load (MW) 28,432 28,645 20,482 41,265

FINAL FINALERCOT Total Load (MW) 28,020 28,825 20,882 36,156 ERCOT Total Load (MW) 28,435 28,647 20,486 41,266

TRUE_UP TRUE_UPERCOT Total Load (MW) 28,022 28,827 20,885 36,158 ERCOT Total Load (MW) 28,437 28,649 20,490 41,268

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

ERCOT Total Load (MW) 33,461 32,193 20,758 52,001 ERCOT Total Load (MW) 41,322 41,587 26,123 58,184

FINAL FINALERCOT Total Load (MW) 33,462 32,196 20,759 52,001 ERCOT Total Load (MW) 41,326 41,590 26,126 58,186

TRUE_UP TRUE_UPERCOT Total Load (MW) 33,464 32,196 20,758 52,003 ERCOT Total Load (MW) 41,324 41,588 26,126 58,183

MAY JUNE

JANUARY FEBRUARY

MARCH APRIL

27 UFE 2005 AnalysisSR16

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

ERCOT Total Load (MW) 41,751 41,802 27,202 57,457 ERCOT Total Load (MW) 43,054 43,126 28,730 60,272

FINAL FINALERCOT Total Load (MW) 41,761 41,821 27,261 57,461 ERCOT Total Load (MW) 43,073 43,148 28,797 60,270

TRUE_UP TRUE_UPERCOT Total Load (MW) 41,759 41,821 27,262 57,458 ERCOT Total Load (MW) 43,076 43,149 28,798 60,274

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

ERCOT Total Load (MW) 40,527 39,923 25,246 59,591 ERCOT Total Load (MW) 31,770 30,493 20,954 52,186

FINAL FINALERCOT Total Load (MW) 40,533 39,931 25,247 59,594 ERCOT Total Load (MW) 31,774 30,495 20,959 52,191

TRUE_UP TRUE_UPERCOT Total Load (MW) 40,533 39,931 25,247 59,594 ERCOT Total Load (MW) 31,774 30,495 20,959 52,191

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

ERCOT Total Load (MW) 29,708 29,803 21,293 42,574 ERCOT Total Load (MW) 31,330 30,687 20,972 48,136

FINAL FINALERCOT Total Load (MW) 29,712 29,807 21,293 42,580 ERCOT Total Load (MW) 31,334 30,689 20,972 48,141

TRUE_UP TRUE_UPERCOT Total Load (MW) 29,712 29,807 21,293 42,580 ERCOT Total Load (MW) 31,334 30,689 20,972 48,141

NOVEMBER DECEMBER

JULY AUGUST

SEPTEMBER OCTOBER

28 UFE 2005 AnalysisSR17

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE (MW) 154 47 -2,889 2,766 UFE (MW) 51 -78 -1,687 2,491

FINAL FINALUFE (MW) 60 -37 -2,467 2,806 UFE (MW) 227 123 -1,324 2,376

TRUE_UP TRUE_UPUFE (MW) 34 -65 -2,489 2,782 UFE (MW) 194 90 -1,384 2,353

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE (MW) 44 46 -2,140 2,275 UFE (MW) -7 -5 -1,503 1,532

FINAL FINALUFE (MW) 219 222 -1,586 2,273 UFE (MW) 87 78 -1,228 1,521

TRUE_UP TRUE_UPUFE (MW) 200 203 -1,603 2,257 UFE (MW) 66 54 -1,249 1,494

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE (MW) 469 344 -1,531 2,803 UFE (MW) -86 -150 -2,092 1,941

FINAL FINALUFE (MW) 167 77 -1,577 2,156 UFE (MW) -8 -123 -1,620 1,806

TRUE_UP TRUE_UPUFE (MW) 157 68 -1,573 2,129 UFE (MW) -4 -118 -1,614 1,802

MAY JUNE

JANUARY FEBRUARY

MARCH APRIL

29 UFE 2005 AnalysisSR18

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE (MW) -411 -414 -3,038 1,795 UFE (MW) 55 -71 -2,076 2,554

FINAL FINALUFE (MW) -139 -144 -2,622 1,873 UFE (MW) 39 -71 -1,765 2,418

TRUE_UP TRUE_UPUFE (MW) -127 -135 -2,608 1,884 UFE (MW) 71 -43 -1,737 2,470

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE (MW) -476 -337 -5,537 3,272 UFE (MW) 451 388 -1,590 3,450

FINAL FINALUFE (MW) -90 -73 -4,199 3,163 UFE (MW) 304 262 -1,419 2,960

TRUE_UP TRUE_UPUFE (MW) -51 -38 -4,155 3,190 UFE (MW) 341 296 -1,361 2,989

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE (MW) 241 245 -1,603 2,251 UFE (MW) 394 342 -2,396 3,538

FINAL FINALUFE (MW) 130 142 -1,202 1,724 UFE (MW) 422 357 -1,717 2,998

TRUE_UP TRUE_UPUFE (MW) 162 176 -1,181 1,720 UFE (MW) 435 363 -1,702 3,013

NOVEMBER DECEMBER

JULY AUGUST

SEPTEMBER OCTOBER

30 UFE 2005 AnalysisSR19

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE| (MW) 713 567 0 2,889 |UFE| (MW) 612 498 0 2,491

FINAL FINAL|UFE| (MW) 687 573 1 2,806 |UFE| (MW) 560 411 1 2,376

TRUE_UP TRUE_UP|UFE| (MW) 690 582 1 2,782 |UFE| (MW) 561 419 1 2,353

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE| (MW) 446 354 0 2,275 |UFE| (MW) 337 269 0 1,532

FINAL FINAL|UFE| (MW) 437 344 0 2,273 |UFE| (MW) 315 253 0 1,521

TRUE_UP TRUE_UP|UFE| (MW) 431 335 0 2,257 |UFE| (MW) 312 252 0 1,494

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE| (MW) 665 483 0 2,803 |UFE| (MW) 530 461 0 2,092

FINAL FINAL|UFE| (MW) 519 399 0 2,156 |UFE| (MW) 512 393 0 1,806

TRUE_UP TRUE_UP|UFE| (MW) 515 397 0 2,129 |UFE| (MW) 512 390 0 1,802

MAY JUNE

JANUARY FEBRUARY

MARCH APRIL

31 UFE 2005 AnalysisSR20

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE| (MW) 720 613 0 3,038 |UFE| (MW) 679 556 0 2,554

FINAL FINAL|UFE| (MW) 600 528 0 2,622 |UFE| (MW) 633 501 0 2,418

TRUE_UP TRUE_UP|UFE| (MW) 598 524 1 2,608 |UFE| (MW) 635 493 0 2,470

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE| (MW) 1,050 712 1 5,537 |UFE| (MW) 632 493 0 3,450

FINAL FINAL|UFE| (MW) 871 620 0 4,199 |UFE| (MW) 483 370 0 2,960

TRUE_UP TRUE_UP|UFE| (MW) 870 617 0 4,155 |UFE| (MW) 502 387 1 2,989

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE| (MW) 503 419 0 2,251 |UFE| (MW) 886 706 0 3,538

FINAL FINAL|UFE| (MW) 431 370 0 1,724 |UFE| (MW) 749 610 1 2,998

TRUE_UP TRUE_UP|UFE| (MW) 437 370 1 1,720 |UFE| (MW) 752 608 0 3,013

NOVEMBER DECEMBER

JULY AUGUST

SEPTEMBER OCTOBER

32 UFE 2005 AnalysisSR21

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE as % of Load 0.4 0.2 -12.7 9.2 UFE as % of Load 0.1 -0.3 -5.8 7.9

FINAL FINALUFE as % of Load 0.1 -0.1 -10.8 9.3 UFE as % of Load 0.7 0.4 -4.6 7.5

TRUE_UP TRUE_UPUFE as % of Load 0.0 -0.2 -10.9 9.2 UFE as % of Load 0.6 0.3 -4.8 7.4

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE as % of Load 0.2 0.2 -8.3 9.3 UFE as % of Load 0.0 0.0 -5.4 5.7

FINAL FINALUFE as % of Load 0.8 0.8 -6.3 9.2 UFE as % of Load 0.3 0.3 -4.4 5.7

TRUE_UP TRUE_UPUFE as % of Load 0.8 0.7 -6.3 9.1 UFE as % of Load 0.3 0.2 -4.5 5.6

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE as % of Load 1.3 1.1 -5.0 7.2 UFE as % of Load -0.3 -0.4 -5.1 4.6

FINAL FINALUFE as % of Load 0.4 0.3 -5.1 5.4 UFE as % of Load -0.2 -0.3 -4.5 3.9

TRUE_UP TRUE_UPUFE as % of Load 0.4 0.2 -5.1 5.3 UFE as % of Load -0.2 -0.3 -4.5 3.9

MAY JUNE

JANUARY FEBRUARY

MARCH APRIL

33 UFE 2005 AnalysisSR22

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE as % of Load -1.1 -1.0 -6.2 4.1 UFE as % of Load -0.1 -0.2 -4.9 5.2

FINAL FINALUFE as % of Load -0.4 -0.4 -5.1 4.3 UFE as % of Load -0.1 -0.2 -4.8 4.8

TRUE_UP TRUE_UPUFE as % of Load -0.4 -0.3 -5.1 4.3 UFE as % of Load 0.0 -0.1 -4.7 4.9

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE as % of Load -1.5 -0.9 -18.9 8.9 UFE as % of Load 1.3 1.3 -5.4 10.3

FINAL FINALUFE as % of Load -0.5 -0.2 -14.7 8.6 UFE as % of Load 0.9 0.9 -4.8 8.8

TRUE_UP TRUE_UPUFE as % of Load -0.4 -0.1 -14.6 8.7 UFE as % of Load 1.0 1.0 -4.7 8.9

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE as % of Load 0.8 0.8 -5.4 6.7 UFE as % of Load 1.1 1.2 -10.3 9.2

FINAL FINALUFE as % of Load 0.5 0.5 -3.7 5.8 UFE as % of Load 1.3 1.2 -6.5 8.3

TRUE_UP TRUE_UPUFE as % of Load 0.6 0.6 -3.7 5.9 UFE as % of Load 1.3 1.2 -6.6 8.4

NOVEMBER DECEMBER

JULY AUGUST

SEPTEMBER OCTOBER

34 UFE 2005 AnalysisSR23

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE as % of Load| 2.3 1.8 0.0 12.7 |UFE as % of Load| 2.0 1.7 0.0 7.9

FINAL FINAL|UFE as % of Load| 2.3 1.9 0.0 10.8 |UFE as % of Load| 1.9 1.4 0.0 7.5

TRUE_UP TRUE_UP|UFE as % of Load| 2.3 1.9 0.0 10.9 |UFE as % of Load| 1.9 1.5 0.0 7.4

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE as % of Load| 1.6 1.3 0.0 9.3 |UFE as % of Load| 1.2 1.0 0.0 5.7

FINAL FINAL|UFE as % of Load| 1.6 1.2 0.0 9.2 |UFE as % of Load| 1.1 0.9 0.0 5.7

TRUE_UP TRUE_UP|UFE as % of Load| 1.6 1.2 0.0 9.1 |UFE as % of Load| 1.1 0.9 0.0 5.6

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE as % of Load| 1.9 1.6 0.0 7.2 |UFE as % of Load| 1.3 1.2 0.0 5.1

FINAL FINAL|UFE as % of Load| 1.5 1.2 0.0 5.4 |UFE as % of Load| 1.2 1.0 0.0 4.5

TRUE_UP TRUE_UP|UFE as % of Load| 1.5 1.2 0.0 5.3 |UFE as % of Load| 1.2 1.0 0.0 4.5

MAY JUNE

JANUARY FEBRUARY

MARCH APRIL

35 UFE 2005 AnalysisSR24

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE as % of Load| 1.7 1.5 0.0 6.2 |UFE as % of Load| 1.5 1.4 0.0 5.2

FINAL FINAL|UFE as % of Load| 1.4 1.3 0.0 5.1 |UFE as % of Load| 1.4 1.2 0.0 4.8

TRUE_UP TRUE_UP|UFE as % of Load| 1.4 1.3 0.0 5.1 |UFE as % of Load| 1.4 1.2 0.0 4.9

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE as % of Load| 2.8 1.8 0.0 18.9 |UFE as % of Load| 1.9 1.7 0.0 10.3

FINAL FINAL|UFE as % of Load| 2.2 1.6 0.0 14.7 |UFE as % of Load| 1.5 1.3 0.0 8.8

TRUE_UP TRUE_UP|UFE as % of Load| 2.2 1.5 0.0 14.6 |UFE as % of Load| 1.5 1.3 0.0 8.9

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE as % of Load| 1.7 1.4 0.0 6.7 |UFE as % of Load| 2.8 2.3 0.0 10.3

FINAL FINAL|UFE as % of Load| 1.5 1.3 0.0 5.8 |UFE as % of Load| 2.4 2.0 0.0 8.3

TRUE_UP TRUE_UP|UFE as % of Load| 1.5 1.3 0.0 5.9 |UFE as % of Load| 2.4 2.0 0.0 8.4

NOVEMBER DECEMBER

JULY AUGUST

SEPTEMBER OCTOBER

36 UFE 2005 AnalysisSR25

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE Cost ($) 3,221 270 -50,446 82,874 UFE Cost ($) 959 -552 -69,552 70,134

FINAL FINALUFE Cost ($) 2,148 -266 -41,158 73,848 UFE Cost ($) 2,688 865 -27,832 76,055

TRUE_UP TRUE_UPUFE Cost ($) 1,880 -410 -42,147 73,126 UFE Cost ($) 2,366 619 -37,311 75,277

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE Cost ($) 982 359 -32,711 52,084 UFE Cost ($) 392 -46 -40,079 47,997

FINAL FINALUFE Cost ($) 3,062 2,041 -25,632 63,283 UFE Cost ($) 1,656 732 -32,201 50,187

TRUE_UP TRUE_UPUFE Cost ($) 2,832 1,848 -26,059 61,695 UFE Cost ($) 1,380 483 -33,125 48,314

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE Cost ($) 9,703 2,709 -12,618 290,366 UFE Cost ($) 1,153 -1,292 -56,531 292,487

FINAL FINALUFE Cost ($) 5,218 532 -13,654 218,656 UFE Cost ($) 2,834 -1,035 -34,604 329,203

TRUE_UP TRUE_UPUFE Cost ($) 5,058 465 -13,789 214,026 UFE Cost ($) 2,930 -1,012 -34,370 328,174

MAY JUNE

JANUARY FEBRUARY

MARCH APRIL

37 UFE 2005 AnalysisSR26

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE Cost ($) -4,102 -4,801 -66,998 226,208 UFE Cost ($) 7,601 -1,033 -36,643 234,594

FINAL FINALUFE Cost ($) 848 -1,530 -51,069 223,187 UFE Cost ($) 6,754 -998 -33,361 222,786

TRUE_UP TRUE_UPUFE Cost ($) 1,095 -1,408 -50,795 225,620 UFE Cost ($) 7,576 -579 -32,543 226,217

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE Cost ($) -5,362 -4,276 -171,533 383,729 UFE Cost ($) 16,029 6,542 -52,820 304,390

FINAL FINALUFE Cost ($) 4,608 -881 -126,420 440,418 UFE Cost ($) 11,690 4,259 -39,982 280,905

TRUE_UP TRUE_UPUFE Cost ($) 5,636 -451 -125,062 447,178 UFE Cost ($) 12,672 5,051 -38,572 286,461

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE Cost ($) 4,882 2,434 -88,388 159,282 UFE Cost ($) 14,377 5,220 -183,607 730,583

FINAL FINALUFE Cost ($) 2,572 1,202 -95,017 115,065 UFE Cost ($) 12,330 5,076 -220,201 596,968

TRUE_UP TRUE_UPUFE Cost ($) 3,094 1,533 -95,966 115,453 UFE Cost ($) 12,636 5,086 -212,732 603,737

NOVEMBER DECEMBER

JULY AUGUST

SEPTEMBER OCTOBER

38 UFE 2005 AnalysisSR27

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE COST| ($) 8,043 5,266 1 82,874 |UFE COST| ($) 6,256 3,952 0 70,134

FINAL FINAL|UFE COST| ($) 7,592 5,302 2 73,848 |UFE COST| ($) 5,727 3,425 1 76,055

TRUE_UP TRUE_UP|UFE COST| ($) 7,577 5,307 4 73,126 |UFE COST| ($) 5,744 3,429 1 75,277

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE COST| ($) 5,263 3,880 2 52,084 |UFE COST| ($) 4,598 3,029 2 47,997

FINAL FINAL|UFE COST| ($) 5,309 3,663 1 63,283 |UFE COST| ($) 4,356 2,871 4 50,187

TRUE_UP TRUE_UP|UFE COST| ($) 5,230 3,587 2 61,695 |UFE COST| ($) 4,299 2,825 5 48,314

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE COST| ($) 11,368 4,360 1 290,366 |UFE COST| ($) 8,827 6,061 0 292,487

FINAL FINAL|UFE COST| ($) 8,357 3,718 0 218,656 |UFE COST| ($) 8,832 4,953 6 329,203

TRUE_UP TRUE_UP|UFE COST| ($) 8,257 3,743 0 214,026 |UFE COST| ($) 8,854 4,893 2 328,174

MAY JUNE

JANUARY FEBRUARY

MARCH APRIL

39 UFE 2005 AnalysisSR28

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE COST| ($) 12,243 8,805 1 226,208 |UFE COST| ($) 17,535 9,174 3 234,594

FINAL FINAL|UFE COST| ($) 11,065 7,259 0 223,187 |UFE COST| ($) 16,282 8,503 4 222,786

TRUE_UP TRUE_UP|UFE COST| ($) 11,088 7,222 0 225,620 |UFE COST| ($) 16,548 8,387 8 226,217

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE COST| ($) 25,173 13,565 9 383,729 |UFE COST| ($) 20,009 9,684 4 304,390

FINAL FINAL|UFE COST| ($) 22,879 11,385 5 440,418 |UFE COST| ($) 15,554 7,261 2 280,905

TRUE_UP TRUE_UP|UFE COST| ($) 23,086 11,508 7 447,178 |UFE COST| ($) 16,142 7,475 1 286,461

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE COST| ($) 8,704 5,310 1 159,282 |UFE COST| ($) 20,647 11,768 0 730,583

FINAL FINAL|UFE COST| ($) 7,174 4,835 3 115,065 |UFE COST| ($) 17,423 9,523 2 596,968

TRUE_UP TRUE_UP|UFE COST| ($) 7,297 4,860 5 115,453 |UFE COST| ($) 17,528 9,442 1 603,737

NOVEMBER DECEMBER

JULY AUGUST

SEPTEMBER OCTOBER

40 UFE 2005 AnalysisSR29

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE Cost as % of Total Cost

0.4 0.2 -12.7 9.2UFE Cost as % of Total Cost

0.1 -0.3 -5.8 7.9

FINAL FINALUFE Cost as % of Total Cost

0.1 -0.1 -10.8 9.3UFE Cost as % of Total Cost

0.7 0.4 -4.6 7.5

TRUE_UP TRUE_UPUFE Cost as % of Total Cost

0.0 -0.2 -10.9 9.2UFE Cost as % of Total Cost

0.6 0.3 -4.8 7.4

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE Cost as % of Total Cost

0.2 0.2 -8.3 9.3UFE Cost as % of Total Cost

0.0 0.0 -5.4 5.7

FINAL FINALUFE Cost as % of Total Cost

0.8 0.8 -6.3 9.2UFE Cost as % of Total Cost

0.3 0.3 -4.4 5.7

TRUE_UP TRUE_UPUFE Cost as % of Total Cost

0.8 0.7 -6.3 9.1UFE Cost as % of Total Cost

0.3 0.2 -4.5 5.6

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE Cost as % of Total Cost

1.3 1.1 -5.0 7.2UFE Cost as % of Total Cost

-0.3 -0.4 -5.1 4.6

FINAL FINALUFE Cost as % of Total Cost

0.4 0.3 -5.1 5.4UFE Cost as % of Total Cost

-0.2 -0.3 -4.5 3.9

TRUE_UP TRUE_UPUFE Cost as % of Total Cost

0.4 0.2 -5.1 5.3UFE Cost as % of Total Cost

-0.2 -0.3 -4.5 3.9

MAY JUNE

JANUARY FEBRUARY

MARCH APRIL

41 UFE 2005 AnalysisSR30

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE Cost as % of Total Cost

-1.1 -1.0 -6.2 4.1UFE Cost as % of Total Cost

-0.1 -0.2 -4.9 5.2

FINAL FINALUFE Cost as % of Total Cost

-0.4 -0.4 -5.1 4.3UFE Cost as % of Total Cost

-0.1 -0.2 -4.8 4.8

TRUE_UP TRUE_UPUFE Cost as % of Total Cost

-0.4 -0.3 -5.1 4.3UFE Cost as % of Total Cost

0.0 -0.1 -4.7 4.9

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE Cost as % of Total Cost

-1.5 -0.9 -18.9 8.9UFE Cost as % of Total Cost

1.3 1.3 -5.4 10.3

FINAL FINALUFE Cost as % of Total Cost

-0.5 -0.2 -14.7 8.6UFE Cost as % of Total Cost

0.9 0.9 -4.8 8.8

TRUE_UP TRUE_UPUFE Cost as % of Total Cost

-0.4 -0.1 -14.6 8.7UFE Cost as % of Total Cost

1.0 1.0 -4.7 8.9

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

UFE Cost as % of Total Cost

0.8 0.8 -5.4 6.7UFE Cost as % of Total Cost

1.1 1.2 -10.3 9.2

FINAL FINALUFE Cost as % of Total Cost

0.5 0.5 -3.7 5.8UFE Cost as % of Total Cost

1.3 1.2 -6.5 8.3

TRUE_UP TRUE_UPUFE Cost as % of Total Cost

0.6 0.6 -3.7 5.9UFE Cost as % of Total Cost

1.3 1.2 -6.6 8.4

NOVEMBER DECEMBER

JULY AUGUST

SEPTEMBER OCTOBER

42 UFE 2005 AnalysisSR31

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE Cost| as % of Total Cost

2.3 1.8 0.0 12.7|UFE Cost| as % of Total Cost

2.0 1.7 0.0 7.9

FINAL FINAL|UFE Cost| as % of Total Cost

2.3 1.9 0.0 10.8|UFE Cost| as % of Total Cost

1.9 1.4 0.0 7.5

TRUE_UP TRUE_UP|UFE Cost| as % of Total Cost

2.3 1.9 0.0 10.9|UFE Cost| as % of Total Cost

1.9 1.5 0.0 7.4

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE Cost| as % of Total Cost

1.6 1.3 0.0 9.3|UFE Cost| as % of Total Cost

1.2 1.0 0.0 5.7

FINAL FINAL|UFE Cost| as % of Total Cost

1.6 1.2 0.0 9.2|UFE Cost| as % of Total Cost

1.1 0.9 0.0 5.7

TRUE_UP TRUE_UP|UFE Cost| as % of Total Cost

1.6 1.2 0.0 9.1|UFE Cost| as % of Total Cost

1.1 0.9 0.0 5.6

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE Cost| as % of Total Cost

1.9 1.6 0.0 7.2|UFE Cost| as % of Total Cost

1.3 1.2 0.0 5.1

FINAL FINAL|UFE Cost| as % of Total Cost

1.5 1.2 0.0 5.4|UFE Cost| as % of Total Cost

1.2 1.0 0.0 4.5

TRUE_UP TRUE_UP|UFE Cost| as % of Total Cost

1.5 1.2 0.0 5.3|UFE Cost| as % of Total Cost

1.2 1.0 0.0 4.5

MAY JUNE

JANUARY FEBRUARY

MARCH APRIL

43 UFE 2005 AnalysisSR32

STATISTICAL SUMMARY – MONTHLY for 2005

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE Cost| as % of Total Cost

1.7 1.5 0.0 6.2|UFE Cost| as % of Total Cost

1.5 1.4 0.0 5.2

FINAL FINAL|UFE Cost| as % of Total Cost

1.4 1.3 0.0 5.1|UFE Cost| as % of Total Cost

1.4 1.2 0.0 4.8

TRUE_UP TRUE_UP|UFE Cost| as % of Total Cost

1.4 1.3 0.0 5.1|UFE Cost| as % of Total Cost

1.4 1.2 0.0 4.9

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE Cost| as % of Total Cost

2.7 1.8 0.0 18.9|UFE Cost| as % of Total Cost

1.9 1.7 0.0 10.3

FINAL FINAL|UFE Cost| as % of Total Cost

2.2 1.5 0.0 14.7|UFE Cost| as % of Total Cost

1.5 1.3 0.0 8.8

TRUE_UP TRUE_UP|UFE Cost| as % of Total Cost

2.2 1.5 0.0 14.6|UFE Cost| as % of Total Cost

1.5 1.3 0.0 8.9

INITIAL INITIALMEAN MEDIAN MIN MAX MEAN MEDIAN MIN MAX

|UFE Cost| as % of Total Cost

1.7 1.4 0.0 6.7|UFE Cost| as % of Total Cost

2.8 2.3 0.0 10.3

FINAL FINAL|UFE Cost| as % of Total Cost

1.5 1.3 0.0 5.8|UFE Cost| as % of Total Cost

2.4 2.0 0.0 8.3

TRUE_UP TRUE_UP|UFE Cost| as % of Total Cost

1.5 1.3 0.0 5.9|UFE Cost| as % of Total Cost

2.4 2.0 0.0 8.4

NOVEMBER DECEMBER

JULY AUGUST

SEPTEMBER OCTOBER

44 UFE 2005 AnalysisUFD01

Percent Distribution of Total UFE (MW) Initial to Final - 2005

0

1

2

3

4

5

6

7

-199

7

-150

0

-100

0-9

00-8

00-7

00-6

00-5

00-4

00-3

00-2

00-1

00 010

020

030

040

050

060

070

080

090

010

0011

0012

0013

0014

00

UFE (MW)

Pe

rce

nt

of

Inte

rva

ls w

ith

UF

E V

alu

es

Initial Final

45 UFE 2005 AnalysisUFD02

Percent Distribution of Total UFE (MW) Final to True-Up - 2005

0

1

2

3

4

5

6

7

-199

9

-149

8

-100

0-9

00-8

00-7

00-6

00-5

00-4

00-3

00-2

00-1

00 010

020

030

040

050

060

070

080

090

010

0011

0012

0013

0014

00

UFE (MW)

Pe

rce

nt

of

Inte

rva

ls w

ith

UF

E V

alu

es

Final True Up

46 UFE 2005 Analysis

2005 Distribution of UFE Percent of ERCOT Load

UFD03

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

20.0

22.0

-5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0

UFE Percent of ERCOT Load

Dis

trib

uti

on

of

UF

E P

erce

nt

of

Lo

ad

Initial Final True-Up

47 UFE 2005 Analysis

UFE Percent of ERCOT Load 2005 Initial Settlement95% Confidence Interval

CIP01

-8

-6

-4

-2

0

2

4

6

8

Day of the Week 2005

UF

E P

erce

nt

of

ER

CO

T L

oad

Median 5th Percentile 95th Percentile

Sun TueMon Wed Thur Fri Sat

48 UFE 2005 AnalysisCIP02

UFE Percent of ERCOT Load 2005 Final Settlement95% Confidence Interval

-6

-4

-2

0

2

4

6

8

Day of the Week 2005

UF

E P

erce

nt

of

ER

CO

T L

oad

Median 5th Percentile 95th Percentile

Sun TueMon Wed Thur Fri Sat

49 UFE 2005 AnalysisCIP03

UFE Percent of ERCOT Load 2005True-Up Settlement95% Confidence Interval

-6

-4

-2

0

2

4

6

8

Day of the Week 2005

UF

E P

erce

nt

of

ER

CO

T L

oad

Median 5th Percentile 95th Percentile

Sun TueMon Wed Thur Fri Sat

50 UFE 2005 AnalysisCIP04

UFE Percent of ERCOT Load 2005Comparison of MediansWith 95% Confidence Interval

-3

-2

-1

0

1

2

3

Day of the Week 2005

UF

E P

erc

en

t o

f E

RC

OT

Lo

ad

Initial Final True Up

Sun Mon Tue Wed Thu Fri Sat

51 UFE 2005 Analysis

Seasonal Comparison - Spring 2005UFE Percent of ERCOT Load and ERCOT Load

SEA01

-3

-2

-1

0

1

2

3

4

5

Day of the Week

UF

E P

erce

nt

of

ER

CO

T L

oad

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

55000

ER

CO

T L

oad

(M

W)

Initial Final True Up Total ERCOT Aggregated Load Adjusted for Losses

Sun Mon Tue Wed Thu Fri Sat

52 UFE 2005 Analysis

Seasonal Comparison - Summer 2005UFE Percent of ERCOT Load and ERCOT Load

SEA02

-5

-4

-3

-2

-1

0

1

2

3

4

5

Day of the Week

UF

E P

erce

nt

of

ER

CO

T L

oad

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

55000

ER

CO

T L

oad

(M

W)

Initial Final True Up Total ERCOT Aggregated Load Adjusted for Losses

Sun Mon Tue Wed Thu Fri Sat

53 UFE 2005 Analysis

Seasonal Comparison - Fall 2005UFE Percent of ERCOT Load and ERCOT Load

SEA03

-3

-2

-1

0

1

2

3

4

5

Day of the Week

UF

E P

erce

nt

of

ER

CO

T L

oad

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

55000

ER

CO

T L

oad

(M

W)

Initial Final True Up Total ERCOT Aggregated Load Adjusted for Losses

Sun Mon Tue Wed Thu Fri Sat

54 UFE 2005 Analysis

Seasonal Comparison - Winter 2005UFE Percent of ERCOT Load and ERCOT Load

SEA04

-4

-3

-2

-1

0

1

2

3

4

5

6

7

Day of the Week

UF

E P

erce

nt

of

ER

CO

T L

oad

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

55000

ER

CO

T L

oad

(M

W)

Initial Final True Up Total ERCOT Aggregated Load Adjusted for Losses

Sun Mon Tue Wed Thu Fri Sat

55 UFE 2005 AnalysisSEA05

Seasonal Comparison of Medians – Initial SettlementUFE Percent of ERCOT Load - 2005

-5

-4

-3

-2

-1

0

1

2

3

4

5

6

7

Day of the Week

UF

E P

erce

nt

of

Lo

ad

Spring Summer Fall Winter

Sun Mon Tue Wed Thu Fri Sat

56 UFE 2005 AnalysisSEA06

Seasonal Comparison of Medians – Final SettlementUFE Percent of ERCOT Load - 2005

-6

-4

-2

0

2

4

6

Day of the Week

UF

E P

erce

nt

of

Lo

ad

Spring Summer Fall Winter

Sun Mon Tue Wed Thu Fri Sat

57 UFE 2005 AnalysisSEA07

Seasonal Comparison of Medians – True UpUFE Percent of ERCOT Load - 2005

-6

-4

-2

0

2

4

6

Day of the Week

UF

E P

erce

nt

of

Lo

ad

Spring Summer Fall Winter

Sun Mon Tue Wed Thu Fri Sat

58 UFE 2005 Analysis

Percent UFE vs ERCOT LoadInitial Settlement - 2005

MPL01

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

20000 25000 30000 35000 40000 45000 50000 55000

ERCOT Load (MW)

Pe

rce

nt

UF

E

Median 5th Percentile 95th Percentile Regression on Total Aggregated Load

59 UFE 2005 Analysis

Percent UFE vs ERCOT LoadFinal Settlement - 2005

MPL02

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

20000 25000 30000 35000 40000 45000 50000 55000

ERCOT Load (MW)

Pe

rce

nt

UF

E

Median 5th Percentile 95th Percentile Regression on Total Aggregated Load

60 UFE 2005 Analysis

Percent UFE vs ERCOT LoadTrue-Up Settlement – 2005

MPL03

-5.0

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

20000 25000 30000 35000 40000 45000 50000 55000

ERCOT Load (MW)

Pe

rce

nt

UF

E

Median 5th Percentile 95th Percentile Regression on Total Aggregated Load

61 UFE 2005 Analysis

Comparison of Median Percent UFEInitial, Final and True-Up Settlements - 2005

MPL04

-4.0

-3.0

-2.0

-1.0

0.0

1.0

2.0

3.0

4.0

20000 25000 30000 35000 40000 45000 50000 55000

ERCOT Load (MW)

Pe

rce

nt

UF

E

Initial Final True Up

62 UFE 2005 Analysis

Load Weighted Average MCPE vs LoadInitial Settlement - 2005

MPL05

0.0

100.0

200.0

300.0

400.0

500.0

600.0

20000 25000 30000 35000 40000 45000 50000 55000

ERCOT Load (MW)

Lo

ad

We

igh

ted

Av

era

ge

MC

PE

($

/MW

H)

Median 5th Percentile 95th Percentile Regression on MCPE vs Load

63 UFE 2005 Analysis

Load Weighted Average MCPE vs Load Final Settlement - 2005

MPL06

0.0

100.0

200.0

300.0

400.0

500.0

600.0

20000 25000 30000 35000 40000 45000 50000 55000

ERCOT Load (MW)

Lo

ad

We

igh

ted

Av

era

ge

MC

PE

($

/MW

H)

Median 5th Percentile 95th Percentile Regression on MCPE vs Load

64 UFE 2005 Analysis

Load Weighted Average MCPE vs Load True Up Settlement - 2005

MPL07

0.0

100.0

200.0

300.0

400.0

500.0

600.0

20000 25000 30000 35000 40000 45000 50000 55000

ERCOT Load (MW)

Lo

ad

We

igh

ted

Av

era

ge

MC

PE

($

/MW

H)

Median 5th Percentile 95th Percentile Regression on MCPE vs Load

65 UFE 2005 Analysis

Comparison of Median Load Weighted Average MCPE vs Load for Initial, Final and True-Up Settlements - 2005

MPL08

0.0

50.0

100.0

150.0

200.0

250.0

20000 25000 30000 35000 40000 45000 50000 55000

ERCOT Load (MW)

Lo

ad

We

igh

ted

Av

era

ge

MC

PE

($

/MW

H)

Initial Final True Up

66 UFE 2005 Analysis

Load Weighted Average MCPE vs Percent UFE Initial Settlement - 2005

MPL09

-100.0

0.0

100.0

200.0

300.0

400.0

500.0

600.0

700.0

-19.0 -17.0 -15.0 -13.0 -11.0 -9.0 -7.0 -5.0 -3.0 -1.0 1.0 3.0 5.0 7.0 9.0

Percent UFE of Load

Lo

ad

We

igh

ted

Av

era

ge

MC

PE

($

/MW

H)

Median 5th Percentile 95th Percentile Regression on MCPE vs Percent UFE

67 UFE 2005 AnalysisMPL10

Load Weighted Average MCPE vs Percent UFE Final Settlement - 2005

-50.0

0.0

50.0

100.0

150.0

200.0

250.0

-15.0 -12.0 -9.0 -6.0 -3.0 0.0 3.0 6.0 9.0

Percent UFE of Load

Lo

ad

We

igh

ted

Av

era

ge

MC

PE

($

/MW

H)

Median 5th Percentile 95th Percentile Regression on MCPE vs Percent UFE

68 UFE 2005 AnalysisMPL11

Load Weighted Average MCPE vs Percent UFE True-Up Settlement - 2005

-50.0

0.0

50.0

100.0

150.0

200.0

250.0

300.0

-15.0 -12.0 -9.0 -6.0 -3.0 0.0 3.0 6.0 9.0

Percent UFE of Load

Lo

ad

We

igh

ted

Av

era

ge

MC

PE

($

/MW

H)

Median 5th Percentile 95th Percentile Regression on MCPE vs Percent UFE

69 UFE 2005 Analysis

Comparison of Median Load Weighted Average MCPE vs Percent UFE forInitial, Final and True-Up Settlements - 2005

MPL12

0.0

20.0

40.0

60.0

80.0

100.0

120.0

140.0

160.0

180.0

200.0

-19.0 -17.0 -15.0 -13.0 -11.0 -9.0 -7.0 -5.0 -3.0 -1.0 1.0 3.0 5.0

Percent UFE of Load

Lo

ad W

eig

hte

d A

vera

ge

MC

PE

($/

MW

H)

Initial Final True UP

70 UFE 2005 Analysis

Sum of Dollars from Positive UFEacross the Week 2005

UCT02

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

1,600,000

1,800,000

2,000,000

Day of the Week

Do

lla

rs

Sun Mon Tue Wed Thu Fri Sat

71 UFE 2005 Analysis

Sum of Dollars from Negative UFEacross the Week 2005

UCT03

-700,000

-600,000

-500,000

-400,000

-300,000

-200,000

-100,000

0

Day of the Week

Do

lla

rs

Sun Mon Tue Wed Thu Fri Sat

72 UFE 2005 AnalysisUCT04

Sum of Dollars from Absolute Value of UFE across the Week 2005

0

500,000

1,000,000

1,500,000

2,000,000

2,500,000

Day of the Week

Do

llar

s

Sun Mon Tue Wed Thu Fri Sat

73 UFE 2005 Analysis

Sum of Dollars from Net UFE across the Week 2005

UCT05

-1,000,000

-500,000

0

500,000

1,000,000

1,500,000

2,000,000

Day of the Week

Do

lla

rs

Sun Mon Tue Wed Thu Fri Sat

74 UFE 2005 AnalysisUCT06

SUM of UFE DollarsCompare All Seasons in 2005Positive and Negative UFE

-600,000

-400,000

-200,000

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

Day of the Week

Do

llar

s

SUM(+UFE) SUM(-UFE)

Sun Mon Tue Wed Thu Fri Sat

Spring: March 1 - April 30

-600,000

-400,000

-200,000

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

Day of the Week

Do

lla

rs

SUM(+UFE) SUM(-UFE)

Sun Mon Tue Wed Thu Fri Sat

Fall: October 1 - November 30

-600,000

-400,000

-200,000

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

Day of the Week

Do

lla

rs

SUM(+UFE) SUM(-UFE)

Sun Mon Tue Wed Thu Fri Sat

Summer: May 1 - September 30

-600,000

-400,000

-200,000

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

Day of the Week

Do

lla

rs

SUM(+UFE) SUM(-UFE)

Sun Mon Tue Wed Thu Fri Sat

Winter: December 1 - February 28

75 UFE 2005 Analysis

SUM of UFE Dollars – Spring 2005Positive and Negative UFE

UCT07

-100,000

-50,000

0

50,000

100,000

150,000

200,000

Day of the Week

Do

lla

rs

SUM(+UFE) SUM(-UFE)

Sun Mon Tue Wed Thu Fri Sat

Spring: March 1 - April 30

76 UFE 2005 AnalysisUCT08

SUM of UFE Dollars – Summer 2005Positive and Negative UFE

-600,000

-400,000

-200,000

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

Day of the Week

Do

lla

rs

SUM(+UFE) SUM(-UFE)

Sun Mon Tue Wed Thu Fri Sat

Summer: May 1 - September 30

77 UFE 2005 AnalysisUCT09

SUM of UFE Dollars – Fall 2005Positive and Negative UFE

-200,000

-100,000

0

100,000

200,000

300,000

400,000

500,000

600,000

Day of the Week

Do

lla

rs

SUM(+UFE) SUM(-UFE)

Sun Mon Tue Wed Thu Fri Sat

Fall: October 1 - November 30

78 UFE 2005 AnalysisUCT10

SUM of UFE Dollars – Winter 2005Positive and Negative UFE

-400,000

-200,000

0

200,000

400,000

600,000

800,000

1,000,000

Day of the Week

Do

lla

rs

SUM(+UFE) SUM(-UFE)

Sun Mon Tue Wed Thu Fri Sat

Winter: December 1 - February 28

79 UFE 2005 AnalysisUCT11

SUM of UFE DollarsCompare All Seasons in 2005Absolute Value and Net UFE

-600,000

-400,000

-200,000

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Spring: March 1 - April 30

-600,000

-400,000

-200,000

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Summer: May 1 - Sept 30

-600,000

-400,000

-200,000

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Fall: Oct 1 - Nov 30

-600,000

-400,000

-200,000

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Winter: Dec 1 - Feb 28

80 UFE 2005 Analysis

SUM of UFE Dollars – Spring 2005Absolute Value and Net UFE

UCT12

-100,000

-50,000

0

50,000

100,000

150,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Spring: March 1 - April 30

81 UFE 2005 AnalysisUCT13

SUM of UFE Dollars – Summer 2005Absolute Value and Net UFE

-600,000

-400,000

-200,000

0

200,000

400,000

600,000

800,000

1,000,000

1,200,000

1,400,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Summer: May 1 - Sept 30

82 UFE 2005 AnalysisUCT14

SUM of UFE Dollars – Fall 2005Absolute Value and Net UFE

-200,000

-100,000

0

100,000

200,000

300,000

400,000

500,000

600,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Fall: Oct 1 - Nov 30

83 UFE 2005 AnalysisUCT15

SUM of UFE Dollars – Winter 2005 Absolute Value and Net UFE

-200,000

0

200,000

400,000

600,000

800,000

1,000,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Winter: Dec 1 - Feb 28

84 UFE 2005 Analysis

Mean of UFE DollarsCompare All Seasons in 2005Positive and Negative UFE

UCT16

-25,000

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

Day of the Week

Do

lla

rs

Mean (+UFE) Mean (-UFE)

Sun Mon Tue Wed Thu Fri Sat

Summer: May 1 - Sept 30

-25,000

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

Day of the Week

Do

lla

rs

Mean (+UFE) Mean (-UFE)

Sun Mon Tue Wed Thu Fri Sat

Fall: Oct 1 - Nov 30

-25,000

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

Day of the Week

Do

lla

rs

Mean (+UFE) Mean (-UFE)

Sun Mon Tue Wed Thu Fri Sat

Winter: Dec 1 - Feb 28

-25,000

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

Day of the Week

Do

llars

Mean (+UFE) Mean (-UFE)

Sun Mon Tue Wed Thu Fri Sat

Spring: March 1 - April 30

85 UFE 2005 AnalysisUCT17

Mean of UFE Dollars – Spring 2005Positive and Negative UFE

-10,000

-5,000

0

5,000

10,000

15,000

20,000

Day of the Week

Do

lla

rs

Mean (+UFE) Mean (-UFE)

Sun Mon Tue Wed Thu Fri Sat

Spring: March 1 - April 30

86 UFE 2005 AnalysisUCT18

Mean of UFE Dollars – Summer 2005Positive and Negative UFE

-25,000

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

Day of the Week

Do

lla

rs

Mean (+UFE) Mean (-UFE)

Sun Mon Tue Wed Thu Fri Sat

Summer: May 1 - Sept 30

87 UFE 2005 AnalysisUCT19

Mean of UFE Dollars – Fall 2005Positive and Negative UFE

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

Day of the Week

Do

lla

rs

Mean (+UFE) Mean (-UFE)

Sun Mon Tue Wed Thu Fri Sat

Fall: Oct 1 - Nov 30

88 UFE 2005 AnalysisUCT20

Mean of UFE Dollars – Winter 2005Positive and Negative UFE

-30,000

-25,000

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

70,000

Day of the Week

Do

lla

rs

Mean (+UFE) Mean (-UFE)

Sun Mon Tue Wed Thu Fri Sat

Winter: Dec 1 - Feb 28

89 UFE 2005 Analysis

Mean of UFE DollarsCompare All Seasons in 2005 Absolute Value and Net UFE

UCT21

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

70,000

75,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Spring: March 1 - April 30

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

70,000

75,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Summer: May 1 - Sept 30

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

70,000

75,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Fall: Oct 1 - Nov 30

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

70,000

75,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Winter: Dec 1 - Feb 28

90 UFE 2005 AnalysisUCT22

Mean of UFE Dollars – Spring 2005Absolute Value and Net UFE

-10,000

-5,000

0

5,000

10,000

15,000

20,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Spring: March 1 - April 30

91 UFE 2005 AnalysisUCT23

Mean of UFE Dollars – Summer 2005Absolute Value and Net UFE

-25,000

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Summer: May 1 - Sept 30

92 UFE 2005 AnalysisUCT24

Mean of UFE Dollars – Fall 2005 Absolute Value and Net UFE

-25,000

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Fall: Oct 1 - Nov 30

93 UFE 2005 AnalysisUCT25

Mean of UFE Dollars – Winter 2005Absolute Value and Net UFE

-20,000

-15,000

-10,000

-5,000

0

5,000

10,000

15,000

20,000

25,000

30,000

35,000

40,000

45,000

50,000

55,000

60,000

65,000

70,000

75,000

Day of the Week

Do

lla

rs

ABS (UFE) Net (UFE)

Sun Mon Tue Wed Thu Fri Sat

Winter: Dec 1 - Feb 28

94 UFE 2005 Analysis

Annual validation 2004 was suspended for residential premises.

PRR’s implemented: PRR488 Weather Responsiveness

Determination

PRR514 Twelve Month Window for Non-IDR Scaling

PRR536 lower IDR Mandatory Installation Threshold to 700 MW (or KVA)

PRR544 12-Month Window for Scaling NIDR to IDR ESI IDs .

Events that Influenced UFE in 2005

95 UFE 2005 Analysis

Improve Business Profile ID assignment process Improve models using Round 2 load research

data Increase the number of IDR’s Leverage AMI capability by increased use of TOU

metering and more frequent meter reads Evaluate Lagged Dynamic sampling techniques

and their application to the ERCOT System Continue to evaluate improvements to algorithms

for missing IDR and NIDR data estimation Continue to make improvements to loss

estimations – updated TDSP loss studies.

Next Steps