1. UFE 2005 Analysis 1 UFE 2005 ANALYSIS Compiled by Load Profiling ERCOT Energy Analysis & Aggregation

2. UFE 2005 Analysis 2 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 3 UFE Basics Net Generation for Settlement Interval Interval Data Energy Usage Profiled Energy Usage Non-Interval Data Non-Metered Accounts Losses: Transmission & Distribution UFE GAP - - - - - - > Net Generation Compared to Load Buildup

4. UFE 2005 Analysis 4 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 5 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 6 LOAD AND UFE – ERCOT PEAK 2005 Initial Settlement SR01

7. UFE 2005 Analysis 7 LOAD AND UFE – ERCOT PEAK 2005 Final Settlement SR02

8. UFE 2005 Analysis 8 LOAD AND UFE – ERCOT PEAK 2005 True Up Settlement SR03

9. UFE 2005 Analysis 9 UFE MWh by Month in 2005 Initial Settlement SR04

10. UFE 2005 Analysis 10 UFE Cost by Month in 2005 Initial Settlement SR05

11. UFE 2005 Analysis 11 UFE MWh by Month in 2005 Final Settlement SR06

12. UFE 2005 Analysis 12 UFE Cost by Month in 2005 Final Settlement SR07

13. UFE 2005 Analysis 13 UFE MWh by Month in 2005 True-Up Settlement SR08

14. UFE 2005 Analysis 14 UFE Cost by Month in 2005 True-UP Settlement SR09

15. UFE 2005 Analysis 15 ABS UFE Mwh by Month in 2005 Initial, Final and True Up Settlements SR09a

16. UFE 2005 Analysis 16 UFE Cost by Month in 2005 Initial, Final and True-UP Settlements SR09b

17. UFE 2005 Analysis 17 STATISTICAL SUMMARY - 2005 SR10

18. UFE 2005 Analysis 18 STATISTICAL SUMMARY - 2005 SR11a

19. UFE 2005 Analysis 19 STATISTICAL SUMMARY - 2005 SR11b

20. UFE 2005 Analysis 20 STATISTICAL SUMMARY - 2005 SR12a

21. UFE 2005 Analysis 21 STATISTICAL SUMMARY - 2005 SR12b

22. UFE 2005 Analysis 22 STATISTICAL SUMMARY - 2005 SR13a

23. UFE 2005 Analysis 23 STATISTICAL SUMMARY - 2005 SR13b

24. UFE 2005 Analysis 24 STATISTICAL SUMMARY - 2005 SR14a

25. UFE 2005 Analysis 25 STATISTICAL SUMMARY - 2005 SR14b

26. UFE 2005 Analysis 26 STATISTICAL SUMMARY – MONTHLY for 2005 SR15

27. UFE 2005 Analysis 27 SR16 STATISTICAL SUMMARY – MONTHLY for 2005

28. UFE 2005 Analysis 28 SR17 STATISTICAL SUMMARY – MONTHLY for 2005

29. UFE 2005 Analysis 29 SR18 STATISTICAL SUMMARY – MONTHLY for 2005

30. UFE 2005 Analysis 30 SR19 STATISTICAL SUMMARY – MONTHLY for 2005

31. UFE 2005 Analysis 31 SR20 STATISTICAL SUMMARY – MONTHLY for 2005

32. UFE 2005 Analysis 32 SR21 STATISTICAL SUMMARY – MONTHLY for 2005

33. UFE 2005 Analysis 33 SR22 STATISTICAL SUMMARY – MONTHLY for 2005

34. UFE 2005 Analysis 34 SR23 STATISTICAL SUMMARY – MONTHLY for 2005

35. UFE 2005 Analysis 35 SR24 STATISTICAL SUMMARY – MONTHLY for 2005

36. UFE 2005 Analysis 36 SR25 STATISTICAL SUMMARY – MONTHLY for 2005

37. UFE 2005 Analysis 37 SR26 STATISTICAL SUMMARY – MONTHLY for 2005

38. UFE 2005 Analysis 38 SR27 STATISTICAL SUMMARY – MONTHLY for 2005

39. UFE 2005 Analysis 39 SR28 STATISTICAL SUMMARY – MONTHLY for 2005

40. UFE 2005 Analysis 40 SR29 STATISTICAL SUMMARY – MONTHLY for 2005

41. UFE 2005 Analysis 41 SR30 STATISTICAL SUMMARY – MONTHLY for 2005

42. UFE 2005 Analysis 42 SR31 STATISTICAL SUMMARY – MONTHLY for 2005

43. UFE 2005 Analysis 43 SR32 STATISTICAL SUMMARY – MONTHLY for 2005

44. UFE 2005 Analysis 44 UFD01 Percent Distribution of Total UFE (MW) Initial to Final - 2005

45. UFE 2005 Analysis 45 UFD02 Percent Distribution of Total UFE (MW) Final to True-Up - 2005

46. UFE 2005 Analysis 46 2005 Distribution of UFE Percent of ERCOT Load UFD03

47. UFE 2005 Analysis 47 UFE Percent of ERCOT Load 2005 Initial Settlement 95% Confidence Interval CIP01

48. UFE 2005 Analysis 48 CIP02 UFE Percent of ERCOT Load 2005 Final Settlement 95% Confidence Interval

49. UFE 2005 Analysis 49 CIP03 UFE Percent of ERCOT Load 2005 True-Up Settlement 95% Confidence Interval

50. UFE 2005 Analysis 50 CIP04 UFE Percent of ERCOT Load 2005 Comparison of Medians With 95% Confidence Interval

51. UFE 2005 Analysis 51 Seasonal Comparison - Spring 2005 UFE Percent of ERCOT Load and ERCOT Load SEA01

52. UFE 2005 Analysis 52 Seasonal Comparison - Summer 2005 UFE Percent of ERCOT Load and ERCOT Load SEA02

53. UFE 2005 Analysis 53 Seasonal Comparison - Fall 2005 UFE Percent of ERCOT Load and ERCOT Load SEA03

54. UFE 2005 Analysis 54 Seasonal Comparison - Winter 2005 UFE Percent of ERCOT Load and ERCOT Load SEA04

55. UFE 2005 Analysis 55 SEA05 Seasonal Comparison of Medians – Initial Settlement UFE Percent of ERCOT Load - 2005

56. UFE 2005 Analysis 56 SEA06 Seasonal Comparison of Medians – Final Settlement UFE Percent of ERCOT Load - 2005

57. UFE 2005 Analysis 57 SEA07 Seasonal Comparison of Medians – True Up UFE Percent of ERCOT Load - 2005

58. UFE 2005 Analysis 58 Percent UFE vs ERCOT Load Initial Settlement - 2005 MPL01

59. UFE 2005 Analysis 59 Percent UFE vs ERCOT Load Final Settlement - 2005 MPL02

60. UFE 2005 Analysis 60 Percent UFE vs ERCOT Load True-Up Settlement – 2005 MPL03

61. UFE 2005 Analysis 61 Comparison of Median Percent UFE Initial, Final and True-Up Settlements - 2005 MPL04

62. UFE 2005 Analysis 62 Load Weighted Average MCPE vs Load Initial Settlement - 2005 MPL05

63. UFE 2005 Analysis 63 Load Weighted Average MCPE vs Load Final Settlement - 2005 MPL06

64. UFE 2005 Analysis 64 Load Weighted Average MCPE vs Load True Up Settlement - 2005 MPL07

65. UFE 2005 Analysis 65 Comparison of Median Load Weighted Average MCPE vs Load for Initial, Final and True-Up Settlements - 2005 MPL08

66. UFE 2005 Analysis 66 Load Weighted Average MCPE vs Percent UFE Initial Settlement - 2005 MPL09

67. UFE 2005 Analysis 67 MPL10 Load Weighted Average MCPE vs Percent UFE Final Settlement - 2005

68. UFE 2005 Analysis 68 MPL11 Load Weighted Average MCPE vs Percent UFE True-Up Settlement - 2005

69. UFE 2005 Analysis 69 Comparison of Median Load Weighted Average MCPE vs Percent UFE for Initial, Final and True-Up Settlements - 2005 MPL12

70. UFE 2005 Analysis 70 Sum of Dollars from Positive UFE across the Week 2005 UCT02

71. UFE 2005 Analysis 71 Sum of Dollars from Negative UFE across the Week 2005 UCT03

72. UFE 2005 Analysis 72 UCT04 Sum of Dollars from Absolute Value of UFE across the Week 2005

73. UFE 2005 Analysis 73 Sum of Dollars from Net UFE across the Week 2005 UCT05

74. UFE 2005 Analysis 74 UCT06 SUM of UFE Dollars Compare All Seasons in 2005 Positive and Negative UFE

75. UFE 2005 Analysis 75 SUM of UFE Dollars – Spring 2005 Positive and Negative UFE UCT07

76. UFE 2005 Analysis 76 UCT08 SUM of UFE Dollars – Summer 2005 Positive and Negative UFE

77. UFE 2005 Analysis 77 UCT09 SUM of UFE Dollars – Fall 2005 Positive and Negative UFE

78. UFE 2005 Analysis 78 UCT10 SUM of UFE Dollars – Winter 2005 Positive and Negative UFE

79. UFE 2005 Analysis 79 UCT11 SUM of UFE Dollars Compare All Seasons in 2005 Absolute Value and Net UFE

80. UFE 2005 Analysis 80 SUM of UFE Dollars – Spring 2005 Absolute Value and Net UFE UCT12

81. UFE 2005 Analysis 81 UCT13 SUM of UFE Dollars – Summer 2005 Absolute Value and Net UFE

82. UFE 2005 Analysis 82 UCT14 SUM of UFE Dollars – Fall 2005 Absolute Value and Net UFE

83. UFE 2005 Analysis 83 UCT15 SUM of UFE Dollars – Winter 2005 Absolute Value and Net UFE

84. UFE 2005 Analysis 84 Mean of UFE Dollars Compare All Seasons in 2005 Positive and Negative UFE UCT16

85. UFE 2005 Analysis 85 UCT17 Mean of UFE Dollars – Spring 2005 Positive and Negative UFE

86. UFE 2005 Analysis 86 UCT18 Mean of UFE Dollars – Summer 2005 Positive and Negative UFE

87. UFE 2005 Analysis 87 UCT19 Mean of UFE Dollars – Fall 2005 Positive and Negative UFE

88. UFE 2005 Analysis 88 UCT20 Mean of UFE Dollars – Winter 2005 Positive and Negative UFE

89. UFE 2005 Analysis 89 Mean of UFE Dollars Compare All Seasons in 2005 Absolute Value and Net UFE UCT21

90. UFE 2005 Analysis 90 UCT22 Mean of UFE Dollars – Spring 2005 Absolute Value and Net UFE

91. UFE 2005 Analysis 91 UCT23 Mean of UFE Dollars – Summer 2005 Absolute Value and Net UFE

92. UFE 2005 Analysis 92 UCT24 Mean of UFE Dollars – Fall 2005 Absolute Value and Net UFE

93. UFE 2005 Analysis 93 UCT25 Mean of UFE Dollars – Winter 2005 Absolute Value and Net UFE

94. UFE 2005 Analysis 94  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 95  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