EVALUATION OF ALGORITHM PERFORMANCE /3 GAS YEAR SCALING FACTOR AND WEATHER CORRECTION FACTOR. Background The annual gas year algorithm performance evaluation normally considers three sources of information as follows: daily values of scaling factor () and weather correction factor () reconciliation variance data for each end user category (EUC) daily consumption data collected from the NDM sample The material presented here refers only to and data. The other strands of this evaluation will be available for consideration at a subsequent DESC meeting. At the outset, it is worth setting out the characteristics of the key variables: the scaling factor () and the weather correction factor (). The is a multiplier used to ensure that within each LDZ, aggregate NDM allocations equal total actual NDM demand. The ideal value of the is one, but variations may occur for a number of reasons including imperfections in the algorithms, but also errors in aggregate AQs and in measured LDZ and DM consumption (because aggregate NDM consumption is determined by difference: i.e. LDZ consumption-dm consumption), and deviations in aggregate NDM demand in the LDZ under average weather conditions away from the sum (for all end user categories (EUCs) in the LDZ) of Annual Load Profile (ALP) weighted daily average consumption based on EUC AQs. If other factors (most notably AQs) are not material, a scaling factor of less than one indicates a tendency of the NDM profiling algorithms to over allocate. Up to the end of gas year 7/8, the represented the extent to which actual aggregate NDM demand in the LDZ differed from the forecast (before the year) seasonal normal demand (SND) for aggregate NDM in the LDZ. When actual aggregate NDM demand equalled seasonal normal demand, then was zero. Typically, demand would have been above SND when it was colder than normal and below SND when it was warmer, and the responded accordingly. However, if there had been an unforeseen growth in demand, then this would have been reflected in generally higher values of than implied by the weather alone. Similarly, if demand had been unseasonably depressed (e.g. with early heating load switch-off or sustained demand loss due to high energy prices), then the would have taken on a value lower than that expected solely due to the weather. As a result of adoption of UNC Modification 4, the applied from the start of gas year 8/9 was redefined. is now the extent to which actual aggregate NDM demand in the LDZ differs from the sum for all EUCs of ALP weighted daily average consumption based on EUC AQs in each LDZ. In the computation of, the sum of ALP weighted daily average consumption for all EUCs in each LDZ (based on EUC AQs at the start of the gas year and potentially subject to revision periodically within the gas year) replaced year ahead forecast aggregate NDM SND in each LDZ. Broadly, is still expected to take on positive values under conditions of cold weather and negative values under conditions of warm weather. Moreover, the effect on of unforeseen growth in demand or unseasonably depressed demand would also broadly remain the same as before, with respectively taking on higher or lower values than otherwise in these instances. However, the sum of ALP weighted daily average consumption for all EUCs in a LDZ is clearly not the same as a forecast value of aggregate NDM SND in the LDZ. Thus, the effect on of unforeseen growth in demand or unseasonably depressed demand is now less clear. An excess in EUC AQs would tend to depress and a deficit would tend to inflate from the values it would otherwise have taken. So, UNC Modification 4 has replaced one potential source of error in the calculation with another. Up to the end of gas year 7/8, any bias in caused by seasonal normal demands for aggregate NDM in the LDZ being under or overstated would be observed by monitoring the quantity -E. The E (estimated weather correction factor) is calculated directly from the demand model for aggregate NDM in the LDZ and captures the effects of weather alone on demand. The difference between and E thus isolates the non-weather component of the. From st October 8 onwards, -E merely reflects the difference between actual NDM demand relative to ALP weighted daily average demand (based on EUC AQs) and computed NDM demand relative to NDM SND. The E (derived from a demand model for aggregate NDM as before) still captures the impact of weather alone on demand, but, for gas years 8/9 onwards, the difference -E is no longer a measure of bias in the due to SND for aggregate NDM in the LDZ being under or overstated. An equivalent measure to -ECWF that captures the bias in the new definition of due to EUC AQ error cannot be formulated, since there is no means of - -
separately and differently computing in a manner free of EUC AQ error, the sum for all EUCs of ALP weighted daily average consumption based on EUC AQs in each LDZ. Figures to 3 show graphs of the daily values of and for each LDZ for two whole gas years / and /3. It should also be noted that and values have also been obtained for the period st to th October 3 (the start of the new gas year 3/4) and appended to the graphs of the previous two completed gas years. Tables of average values of, -E and, for gas years / and /3, along with the improvement or degradation in these averages between the two gas years, are presented in Tables to 9. The root mean square (RMS) deviation of from has also been computed for each discrete month during the previous gas years / and /3, and the respective figures can be found in Tables and. The differences in these RMS values between the two gas years are presented in Table. These figures provide a very useful measure of the variability of s about one (the ideal value). In addition, Tables 3 and 4 provide monthly values of weather corrected NDM demand expressed as a percentage of aggregate NDM seasonal normal demand (SND) for each month of gas years / and /3 respectively.. Overall Results These various graphs and tables indicate the following notable points: During gas year / average values were less than or equal to one (over days of the week, Saturdays and winter) in all LDZs. During gas year /3 average values were less than or equal to one (over Mondays to Thursdays, Fridays, weekend days and summer) in 9 out of 3 LDZs. For out of 3 LDZs on Mondays to Thursdays, and 6 out of 3 LDZs on Fridays and Saturdays, average values of were improved in /3 (i.e. were closer to one) compared to the previous gas year (/). WS LDZ showed deterioration from the previous gas year on all days of the week, SC, NE, EA and NT were the same on Sundays. Also, LDZs NW, EM and WM all displayed deterioration over Fridays, Saturdays and Sundays. Over the winter period of /3 average values of were closer to the ideal value of one than over the winter period of the previous gas year (/) in all 3 LDZs. Average values for all of summer /3 showed deterioration over summer / in out of 3 LDZs, with the smallest deterioration being. (in LDZs NO and EA) and largest being.6 (in LDZ SC). The RMS deviation of from the ideal value of one provides a measure of the variability of s. During winter /3, October was colder than the current seasonal normal basis (the 9 th coldest in the last 5 years) with November was slightly colder than seasonal normal. December was a mixed month (the first half of the month being much colder than current seasonal normal and the second half being generally warmer) resulting in it being ranking as the nd coldest in the last 5 years. January 3 was also mixed with the beginning and end of the month being much warmer than seasonal normal and the middle of the month being much colder than seasonal normal. February 3 was colder than season normal (ranking as 6 th coldest in the last 5 years) and March 3 was much colder that seasonal normal (the nd coldest in the last 5 years). During the generally colder than normal winter period (October to March) of gas year /3, in almost all LDZs in each individual month, the RMS deviation of from the ideal value of one was notably lower (i.e. improved) compared to the corresponding periods of the previous gas year. A few exceptions were limited to WM and WN LDZs in the month of December and NW LDZ in January. RMS deviations of from the ideal value of one exhibited a somewhat mixed picture during the summer period (April to September) of gas year /3. For each of the summer months, in a majority (7 or more out of 3) of LDZs and overall across all LDZs, the RMS deviation of from the ideal value of one showed improvement compared to the corresponding months of the previous gas year (/). The summer period of gas year /3 was, overall, slightly colder than seasonal normal. April 3 started off colder than seasonal normal but became milder towards the later half of the month (ranking th coldest in the last 5 years). The month of May 3 started off with a week of mild weather ending with a few weeks of notable colder periods. Despite having a few warmer days, June 3 was generally colder than normal. July 3 began with a short, 3 day period of particularly colder weather but the remainder of the month experienced consistently warmer than normal temperatures making it the 3 rd warmest July in the last 5 years. August 3, in general, was predominantly warmer than normal and despite a few colder days it ranked as 9 th warmest August in last 5 years. September 3 was a mixed month with the beginning and end of the month being - -
warmer than seasonal normal and a two week period of notably colder than normal weather in the middle of the month. Considered overall s during /3 generally were less variable than over the previous gas year. Examination of the average weekday and weekend day values of -E in Tables 4, 5 and 6 indicates that the deviation of from E, appeared to be less marked (i.e. closer to zero) for 3 LDZs (EM, SE and SO) and more marked (i.e. further from zero) for LDZs (namely NE and NT), compared to that over the equivalent days of the previous gas year. For winter /3 as a whole the deviation of from E was more marked than for winter / in 7 LDZs. For summer /3 as a whole the deviation of from E was less marked over that for summer / in all but 3 LDZs (namely SC, NO and NT). However, as previously explained -E is no longer a measure of bias in the due to SND for aggregate NDM in the LDZ being under or overstated. is the difference between actual aggregate NDM demand and ALP weighted daily average consumption in each LDZ (based on EUC AQs) divided by the ALP weighted daily average consumption in each LDZ. During gas year / average values were positive for all LDZs on Fridays, Saturdays and Sundays (except for LDZs on Fridays and LDZ on Saturdays) and for all LDZs during the summer period, but were negative for 9 out of 3 LDZs on Mondays to Thursdays and all LDZs in the winter period (See Table 7). Negative values can be caused by factors such as the EUC AQs being too high or by the weather being warmer than seasonal normal. During gas year /3 average values were positive for all LDZs on Mondays to Thursdays, Fridays, Saturdays and Sundays. During the winter and summer periods the average values were also positive for all LDZs (See Table 8). Positive values can be caused by factors such as EUC AQs being too low or by weather being colder than seasonal normal. was further away from zero in /3 than in / on Mondays to Thursdays, Fridays, Saturdays and Sundays in all LDZs (see Table 9). In winter /3 was further away from zero in all LDZs, but was closer to zero in summer /3 in LDZs. The differences between the years are the result of differences in factors such as weather or EUC AQ inaccuracies. There was no notable step change in values following implementation of revised pseudo SND values on st January 3 (LDZ WN) and st July 3 (LDZs SC, SW & SO). However, it is feasible that the unseasonably warm weather in July 3 may have somewhat masked any notable step change in values as a result of the revised pseudo SND values. Comparison of weather corrected aggregate NDM demand as a percentage of aggregate NDM SND in / (Table 3) and /3 (Table 4) indicates that for the majority of the month/ldz combinations in the winter months the percentages for /3 are higher than those for /. This suggests that relative to observed demand on a weather corrected basis, the SND values that applied (for computing DAFs for example) in /3 were generally lower than in /. In contrast the opposite was true for the majority of the summer months where the percentages for /3 are lower than those for /3. This suggests that relative to observed demand on a weather corrected basis, the SND values that applied in the summer of /3 were generally higher than in /. 3. Commentary It is customary in this note on and values to identify and provide a commentary on any unusual occurrences of and -E values, in the most recent gas year (/3). This is not a comprehensive set of all observed perturbations, instead it is a set of the more marked instances along with examples of typical cases: Overall October was the 9th coldest October in the last 5 years and, according to the Met Office, was the coldest October since 3. However, there were some warm days around nd to 4th and during this period, aggregate NDM demand was reduced in most LDZs resulting in slightly negative values and corresponding small decreases in. During the last 6 days of the month (6th to 3st) the weather was particularly cold with the 7th being the coldest. During this 6 day period, inflated aggregate NDM demand in all LDZs resulted in sharply positive values The month of November was just below the current seasonal normal basis overall and around the average for the last 5 years. There were some notable periods of cold weather in all LDZs from approximately st to 6th and 8th to 3th (the last two days of the month also saw snowfall in the north of the UK). During these cold periods, aggregate NDM demand increased, resulting in sharply positive values in all LDZs. In contrast, the middle part of the month was generally warmer than normal particularly around 3th, 4th and th, resulting in depressed aggregate NDM demands and negative - 3 -
values in all LDZs during these warm days (with values falling below the ideal value of one in most LDZs). December began with an extended cold spell during the first 4 days which saw wintery showers bringing some snow to the north and east of the UK. As a result, aggregate NDM demand increased forcing values to be sharply positive in all LDZs during this period. While an increased value acts on to depress its value, the direct effect of elevated NDM demand on is to increase its value. In all LDZs this direct effect was predominant leading to corresponding but much smaller increases in on these coldest days. The second half of the month was warmer than normal and during this milder period total NDM demand was depressed, resulting in negative values on most days. While the reduction in would have tended to increase the, the direct effect on the of the reduced total NDM demand resulted in small decreases in the during this period in most LDZs. The month of January 3 was one of some contrasts but overall was around the average for the last 5 years. The month began with very mild conditions with temperatures significantly above average for the time of year. The period from nd to 8th was unseasonably warm and as a result, aggregate NDM demand was depressed leading to negative values in all LDZs on these days. By mid month it had turned significantly colder and there were periods of significant snowfall across most of the country between the 8th & 5th (the heaviest snowfall occurred in LDZ WS on 8th January). During this period, inflated aggregate NDM demand resulted in sharply positive values. Despite the temperature during the last few days of the month being warmer than normal, much of the UK experienced strong or severe gales. Overall, the month of February 3 was much colder than the current seasonal normal, continuing the cold theme of December and January. It was the 6th coldest February in the last 5 years and it was particularly cold in the periods from the 5th to 3th and th to 8th. During these periods, aggregate NDM demand was increased, resulting in sharp positive values in most LDZs. March 3 was the nd coldest March in the last 5 years. Unusually, the month experienced substantial late-season snowfalls in certain areas from 6th to 7th and it was especially cold during the second half of the month. During this extended cold period, inflated aggregate NDM demand in all LDZs resulted in sharply positive values (most clearly seen in SO LDZ). While an increase in value acts on to depress its value, the direct effect of elevated aggregate NDM demand on is to increase its value. In all LDZs this direct effect was predominant leading to corresponding but much smaller increases in on these coldest days. Overall, the month of April 3 ranked as being the th coldest April in the last 5 years. The month started particularly colder than normal but became milder as the month went on. There were, however, some warm days from 4th to 7th and 4th to 5th (particularly in the east) which resulted in depressed aggregate NDM demands in most LDZs and reduced s on these days (most clearly seen in EA LDZ). While a reduced would act on to increase its value, the direct effect of depressed aggregate NDM demand on is to decrease its value. In most LDZs this direct effect was predominant leading to corresponding but smaller decreases in on these days. Conversely on the coldest days of the month (around st to 4th), the was strongly positive with a corresponding small increase in values on these days. The month of May 3 was slightly colder than the current seasonal normal basis overall, continuing the cool theme which characterised spring. The month started slightly colder than normal followed by some warm days around 6th to 8th May. On these warm days most LDZs displayed negative values. A corresponding decrease in in most LDZs is also observed over these warm days of the month, particularly on the 7th. While a reduced would act on to increase its value, the direct effect of depressed aggregate NDM demand on is to decrease its value and this appears to have been the predominant effect on these days. The remainder of May was generally colder than normal, particularly around 3th to 6th and 3rd to 4th, resulting in inflated aggregate NDM demands and positive values in all LDZs, with values raising above one on these days in all LDZs (except SC LDZ on 4th). Overall, June 3 was slightly cooler than the current seasonal normal basis and around the average over the last 5 years. The month began settled and, according to the Met Office, temperatures barely exceeded their seasonal averages over England whereas western parts of Scotland was slightly warmer than average. The remaining 3 weeks of the month were colder than the current seasonal normal (especially in the south-east) although there was a brief warm spell from 8th to st. During this colder period, inflated aggregate NDM demand resulted in sharply positive values in most - 4 -
LDZs (most notable in EA, NT & SE LDZs around the 9th). An increased value acts on to reduce its value, but again the direct effect on the of increased total NDM demand resulted in a corresponding but smaller increase in in most LDZs. Overall, July 3 ranked as the 3rd warmest July over the last 5 years. The month began with a short period (st to 4th) of colder than normal temperatures. The remainder of the month saw temperatures creep high above seasonal normal, particularly the period from 6th to 4th, such that the max CWV value was achieved on most days in each LDZ during this period. According to the Met Office, this was the UK s most notable heat wave since 6. During this extended warm period reduced aggregate NDM demand resulted in negative values in most LDZs. The month of August 3 was slightly warmer than the current seasonal normal basis overall, ranking as the 9th warmest August in the last 5 years. It was particularly warm in the periods from the st to 3rd and st to 3th. During these periods aggregate NDM demand was depressed, resulting in negative values in most LDZs. Conversely on the coldest days of the month (around 3th), the was strongly positive with a corresponding small increase in values on these days. Overall, September 3 was slightly colder than the current seasonal normal basis and around average for the last 5 years. The majority of the month (6th to th) saw colder than normal temperatures with particularly cold weather occurring during the period of the 4th to th. During this particularly cold spell, inflated aggregate NDM demand resulted in sharply positive values. While the increase in would have tended to depress the, the direct effect on the of the increased aggregate NDM demand resulted in a corresponding increase in the in most LDZs (except NT). The remainder of the month (nd to 3th) saw temperatures creep above seasonal normal, resulting in reduced aggregate NDM demands, resulting in negative values (and corresponding small reductions in ) in most LDZs. In WS LDZ on 4th September 3 there was a sharp positive spike in (and an increased value). This was probably caused by an erroneous low consumption reading for a single very large DM supply point (or an incorrect overstated LDZ measurement value) in the LDZ. This resulted in a corresponding error in actual aggregate NDM consumption (total LDZ demand less LDZ shrinkage less sum of DM consumption) which was incorrectly too high giving a value that was much too high. 4. Assessment In the demand attribution process as currently formulated, it is principally deviations of scaling factor from the perfect value of one that cause misallocations of aggregate NDM demand to individual EUCs. Scaling factor deviations from one (offsets from one and also day to day volatility) are related to the closeness of correspondence (or otherwise) between aggregate NDM seasonal normal demand on the day and the sum for all EUCs of ALP weighted daily average demand on the day (in other words the ALP*(AQ/365) term in the NDM demand attribution formula summed across all EUCs in the LDZ). Since NDM SND has hitherto been a forecast quantity while AQ is a backward looking quantity based on historical meter read data, this correspondence could never be perfect. However, adoption of Modification 4 has resulted in this correspondence now essentially being met - except for perturbations due to small day to day changes in EUC AQs and unexpectedly high or low actual NDM demand levels (whether these are real or due to LDZ or DM measurement error). This is the main reason for the markedly improved behaviour since the start of gas year 8/9. Prior to st October 8, the ratio of aggregate NDM SND to the sum across all EUCs of ALP weighted daily average demand [ EUC ALP *( AQ / 365) ] was broadly inversely related to the deviation of from the ideal value of one. However, the effect was more pronounced in summer than in winter, and moreover, the summer was also affected by warm weather cut-off and summer reduction effects in some EUC models. Warm weather cut-offs in EUC demand models give rise to summer scaling factor volatility by a mechanism involving the DAF parameter. If weather on a day in summer is significantly different from normal for that time of year, the DAF value that is applied on that day to EUCs with cut-offs may not be appropriate for the prevailing weather. Thus overall the ( + *DAF) terms in the demand attribution formula may be either too low or too high and the scaling factor has to change abnormally to compensate. This effect is not mitigated by the changes brought about by Modification 4. Thus, greater scaling factor volatility may still be seen in a number of LDZs in the summer in gas years / and /3. In years prior to 8/9, examination of the average monthly value of -E and weather corrected aggregate NDM demand as a percentage of aggregate NDM SND allowed an approximate assessment to be made of the equilibrium level of in each LDZ; that is to say the likely level of if any deviation is - 5 -
discounted. This assessment was an approximate one and was based on identifying a period (of a month s duration preferably during the winter period) over which deviation was small (at or near zero) and weather corrected aggregate NDM demand was close to (~% of) aggregate NDM seasonal normal demand over the period, then identifying the average value of that applied to the period and adjusting this for any residual deviation that applied in the period. When applicable to a LDZ, this assessment then provided an approximate indication of the prevailing level of aggregate NDM AQ in the LDZ. As previously noted, with the implementation of UNC Modification 4 the difference -E is no longer a measure of bias in the due to SND for aggregate NDM in the LDZ being under or overstated. From st October 8 onwards, -E merely reflects the difference between actual NDM demand relative to ALP weighted daily average demand (based on EUC AQs) and computed NDM demand relative to NDM SND. In other words, the itself now depends on NDM EUC AQs, and therefore assessing and removing the impact of a notional bias on observed values to ascertain the impact of the prevailing level of aggregate NDM AQ on the residual is no longer feasible. One consequence of this is that the previously applied approach to inferring AQ excess or deficiency in each LDZ from an assessment of the impact of bias on values, is no longer valid. Table 5 shows the percentage changes in aggregate NDM AQs at the start of gas year 3/4 as observed on the Gemini system. From this it can be seen that a reduction in aggregate NDM AQs has taken place for gas year 3/4 in all LDZs except NO, WN and SO LDZs. The reduction is.7% overall across all LDZs and the changes range from a.% increase in NO and WN LDZs to a.9% decrease in SC LDZ. - 6 -
Figure Weather Correction and Scaling Factor: SC..5.6 5 5 - - Oct- Jan- Apr- Jul- Oct- Jan-3 Apr-3 Jul-3 Oct-3 Figure Weather Correction and Scaling Factor: NO..5.6 5 5 - - Oct- Jan- Apr- Jul- Oct- Jan-3 Apr-3 Jul-3 Oct-3 Figure 3 Weather Correction and Scaling Factor: NW..5.6 5 5 - - Oct- Jan- Apr- Jul- Oct- Jan-3 Apr-3 Jul-3 Oct-3-7 -
Figure 4 Weather Correction and Scaling Factor: NE..5.6 5 5 - - Oct- Jan- Apr- Jul- Oct- Jan-3 Apr-3 Jul-3 Oct-3 Figure 5 Weather Correction and Scaling Factor: EM..5.6 5 5 - - Oct- Jan- Apr- Jul- Oct- Jan-3 Apr-3 Jul-3 Oct-3 Figure 6 Weather Correction and Scaling Factor: WM..5.6 5 5 - - Oct- Jan- Apr- Jul- Oct- Jan-3 Apr-3 Jul-3 Oct-3-8 -
Figure 7 Weather Correction and Scaling Factor: WN..5.6 5 5 - - Oct- Jan- Apr- Jul- Oct- Jan-3 Apr-3 Jul-3 Oct-3 Figure 8 Weather Correction and Scaling Factor: WS..5.6 5 5 - - Oct- Jan- Apr- Jul- Oct- Jan-3 Apr-3 Jul-3 Oct-3 Figure 9 Weather Correction and Scaling Factor: EA..5.6 5 5 - - Oct- Jan- Apr- Jul- Oct- Jan-3 Apr-3 Jul-3 Oct-3-9 -
Figure Weather Correction and Scaling Factor: NT..5.6 5 5 - - Oct- Jan- Apr- Jul- Oct- Jan-3 Apr-3 Jul-3 Oct-3 Figure Weather Correction and Scaling Factor: SE..5.6 5 5 - - Oct- Jan- Apr- Jul- Oct- Jan-3 Apr-3 Jul-3 Oct-3 Figure Weather Correction and Scaling Factor: SO..5.6 5 5 - - Oct- Jan- Apr- Jul- Oct- Jan-3 Apr-3 Jul-3 Oct-3 - -
Figure 3 Weather Correction and Scaling Factor: SW..5.6 5 5 - - Oct- Jan- Apr- Jul- Oct- Jan-3 Apr-3 Jul-3 Oct-3 - -
Table : Average Values of Gas Year / LDZ Mon-Thur Friday Saturday Sunday Winter Summer SC 94 93 93 94 88 99 NO 9 94 9 9 88 94 NW 94. 98. 9.3 NE 94 99 96 96 9. EM 96 99 96 98 89.4 WM 98 99 99. 94.3 WN 9 99 99. 8.6 WS 93 94 93 95 9 95 EA 93 94 95 96 89 98 NT 94 96 97 97 9. SE 9 9 93 94 89 94 SO 9 93 94 94 85. SW 95 95 97 97 88. AVG 93 96 95 96 89. Table : Average Values of Gas Year /3 LDZ Mon-Thur Friday Saturday Sunday Winter Summer SC 93 9 93 94. 83 NO 99 96 96 96. 93 NW 94 94 94 96. 9 NE 97 96 95 96 99 94 EM 98 95 94 95 98 94 WM 99 97 96 96. 95 WN....3.5 97 WS.9.7.8.9.6. EA 99 98 97 96 99 97 NT 99 99 98 97. 96 SE...... SO. 99... 98 SW. 98 99 99 99. AVG 99 98 98 98. 96 - -
Table 3: Difference Between Average Values of in Gas Year / and /3 LDZ MON-THUR FRIDAY SATURDAY SUNDAY WINTER SUMMER SC -. -.... -.6 NO.8..5.5. -. NW. -.6 -.4 -.4. -.7 NE.3 -.3 -...8 -.6 EM. -.4 -. -.3.9 -. WM. -. -.3 -.4.5 -. WN.. -. -..3.3 WS -. -. -. -.4. -.6 EA.6.4... -. NT.5.3...9 -.4 SE.7.7.6.5..4 SO.9.6.5.6.3 -. SW.5.3.... Table 4: Average Values of E Gas Year / LDZ Mon-Thur Friday Saturday Sunday Winter Summer SC -. -.4 -. -. -. -. NO -.9 -.4 -.3 -.39 -.9 -.9 NW -.5 -.34 -.3 -.3 -.8 -.56 NE -. -. -. -. -.6 -.7 EM -.45 -.44 -.49 -.37 -.36 -.53 WM -.8 -.8 -.3. -.7 -.3 WN -.64 -.43 -.33 -.7 -.4 -.58 WS -.3 -.4 -.8 -.7 -.44 -. EA -.44 -.39 -.8 -.6 -.33 -.43 NT -.4 -.9 -.6 -.9 -.4 -.3 SE -.63 -.6 -.5 -.5 -.49 -.69 SO -.38 -.33 -.35 -.35 -.6 -.47 SW -.48 -.49 -.9 -.35 -.57 -.3 AVG -.39 -.3 -.8 -.6 -.3 -.36-3 -
Table 5: Average Values of E Gas Year /3 LDZ Mon-Thur Friday Saturday Sunday Winter Summer SC -.8 -.7 -.8 -..5 -.45 NO.67.58.36.35.53.6 NW.8.33.4.38.4.5 NE.4.3.5..3.9 EM.3.3 -.7 -.9.8 -.8 WM -.. -.3.. -.8 WN.9.56.66.74.77. WS.7.7 -.35..7. EA.33.49.49.37.39.37 NT.47.6.7.53.6.8 SE.34.48.46.37..54 SO...6..53 -. SW.3.6.8.43.7.4 AVG.3.9..8.3.6 Table 6: Difference between average values of E in Gas Year / and /3 LDZ Mon-Thur Friday Saturday Sunday Winter Summer SC.3 -. -.6 -. -.4 -.33 NO -.48 -.35 -.6.4 -.33 -.3 NW.35..7 -.5 -.4.5 NE -.3 -. -.4 -. -.5.8 EM.4.3.3.9.8.45 WM.6.7. -.9.6.5 WN.35 -.3 -.33 -.57 -.35.46 WS.4.7 -.7.6.7. EA. -. -. -. -.6.6 NT -.6 -.3 -.55 -.34.5 -.57 SE.9.3.6.3.7.5 SO.8..8.4 -.7.7 SW.5.3. -.8.3.6-4 -
Table 7: Average Values of Gas Year / LDZ Mon-Thur Friday Saturday Sunday Winter Summer SC.3.3.8.4 -.6.7 NO.6.39.5.4 -.86.6 NW -..47.47.54 -.93.33 NE.3.59.6.5 -.83 6 EM -..9..6 -.6. WM.3.43.6.63 -. WN -.7.35.4.57 -.5.5 WS -..4.4. -.7 EA -.9 -.3.7.34 -.94.98 NT -...3.34 -..7 SE -.5 -. -.4.4 -.8 SO -.4.4.3.9 -.96. SW -..5.3.7 -.5 AVG -...8.3 -.. Table 8: Average Values of Gas Year /3 LDZ Mon-Thur Friday Saturday Sunday Winter Summer SC.74.67.67.65.38.4 NO.6.5..97.6.75 NW.3.55.54.68. NE.7.3.3.9.59.83 EM.3.6.5.6.5.8 WM.34 8.5.67. WN.93..7.5 WS.6.96.83 6.74 EA 8.65.89.73.88.3 NT.58.74.5.84.7.7 SE.54.69.9.79.76.54 SO.33.64.63.9.96 SW 3.7.9.7.37 AVG.9.39 7.5.69.3-5 -
Table 9: Difference between absolute average values of in Gas Year / and /3 LDZ Mon-Thur Friday Saturday Sunday Winter Summer SC -.5 -.36 -.49 -.5 -.76. NO -. -.86 -.76 -.83 -.75.5 NW -.9 -.8 -.8 - -.8. NE -.4 -.7 -.69 -.69 -.76.63 EM -. -.7 -.94 -.9 -.36.43 WM -. -.96 -.87 -.87 -.55.64 WN -.3 - -.5-4 -.3.9 WS -.5 -.8 -.78 -.36 -.33.4 EA -.39 -.6 -.7 -.39 -.93 -.34 NT -8 -.7 -.5 -.69 -.63 SE -.9-7 7 -.65 -.6 -.7 SO -.9 -.38 -.5-4 -.94.7 SW - -.35 -.39 -.65 -.44.4 Table : Root Mean Square Deviation of from Gas Year / LDZ Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep SC..4.8.5.44.4.4.9.54.7.5.5 NO.84.4.64.7..88.9.47.7.96.3.376 NW.373.38.59.56.9.64.95.498.4.398.7.35 NE.87..48.49.87.5.74.39.95.74.67.96 EM.375.3.44.57.96.99.78.444.369.38.67.36 WM.3.66.6.38.47..39.65.85.38.65.93 WN.49.4.93.7.57.3.5.535.396.469.46.366 WS.3.55.44.8.88.69.89.4.97.38.7.9 EA.376.45.6.66.5.64.8.356.9.8.37.7 NT.96.4.57.64.9.66.74.9.7.39.4.9 SE.347.38.6.7.9.74.84.396.44.7.49.36 SO.43..9.5.3.49.6.493.3.344.3.39 SW.3..73.93.5.99.68.57.5.4.3.8 AVG.3.34.6.75.4.9.8.389.84.3.5.46-6 -
Table : Root Mean Square Deviation of from Gas Year /3 LDZ Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep SC.6.45.4.44.4.49.5.9.3.6..6 NO.83.33.9.3.9.48.48.4.5.6.8.87 NW.5.53.3.56.5.45.65..8.44.8.3 NE.68.38.5.48.9.34.6.7.9.79.75.78 EM.45.9.4.37.3.5.63.9.99.48.5.78 WM.5..6..6.4.5.6.6.98.65.96 WN.74.77.97.79.55.8.99.35.75.4.57.34 WS.7.46.4.63.65.76.85.96.7.7.64.4 EA.7.36.44.5.34.39.7.38.9.86.84.86 NT.35.9.3...9.47.7.55.4.6.7 SE.6.35..8.6.3.63.3.9.66.43.33 SO.33.7.6.68.33.74..47.54.48.49.74 SW.75.43.38.57.3.4.6.55.5.46.74.7 AVG.84.4.38.46.3.5.7.55.59.3.58.7 Table : Difference between RMS Deviation of from in Gas Year / and /3 LDZ Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep SC.6.96.4.6..75 -..6 -.58 -.384.3 -.66 NO..9.35.4..4.44.33..8.4.89 NW.58.85.8..4.9.3.98.4 -.44 -..5 NE.9.7.3..58.7..73.76.95.9.8 EM.33....64.48.5.354.7.34.5.8 WM.6.44..6.3.6 -.3.59.69.. -.3 WN.38.47 -.4.38..94.6...68.69.4 WS.53.9.3.9.3.93.4.5 -..57.43 -.85 EA.35.9.8.6.7.5 -.5.8.99.3.53.4 NT.6..44.43.8.37.7..5.35.36.8 SE.86.3.4.43.76.43..83.5.4.6.3 SO.9.3.3.37.9.75 -.5.46.67.96.64 -.35 SW.38.67.35.36.73.58.8...68.58 -.4 AVG.7.9.4.8.7.57..34.5.68.9.39-7 -
Table 3: NDM Weather Corrected Demand as % of NDM Seasonal Normal Demand Gas Year / LDZ Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep SC 97.% 93.9% 99.7% 99.% 99.3% 9.9% 96.5% 5.9% 4.6% 8.% 5.7%.% NO 96.5% 94.5% 96.% 96.8% 99.% 89.7% 93.5% 3.7% 4.6% 7.% 6.3% % NW 93.9% 9.6% 94.% 96.5% 96.9% 89.% 9.7% 99.8% 7.8% 9.9% 9.4% 97.7% NE.% 94.% 98.5%.% 97.7% 88.3% 96.4% 7.6% 4.9% 5.% 6.9% 97.% EM 94.% 93.3% 96.9% 97.4% 97.7% 9% 94.6% 5.9% 7.7%.9%.% 96.% WM 9.5% 93.3% 97.% 98.9% 98.3% 9.3% 93.5%.5%.%.5% 7.4% 97.% WN 9.% 9.3% 93.3% 94.7% 94.3% 9.% 93.4%.% 4.8% 6.9%.3% 95.8% WS 9.7% 9% 95.9% 95.% 95.6% 87.% 94.7% 96.% 3.9%.% 8.5% 95.% EA 88.4% 89.9% 94.3% 95.9% 95.9% 93.8% 9.9% 5.7% 6.9% 3.%.6% 9.9% NT 89.% 9.6% 94.3% 95.5% 97.% 9.4% 9.6% 4.3% 4.4%.%.% 88.7% SE 89.7% 9% 93.5% 94.5% 96.5% 9.% 9.%.3%.3% 5.%.8% 89.6% SO 9.9% 9.4% 95.9% 98.% 98.6% 93.6% 93.7% 6.4% 8.%.% 9.7% 97.3% SW 89.5% 89.3% 94.% 93.8% 96.3% 9.% 9.4%.% 8.% 3.%.5% 9.8% Table 4: NDM Weather Corrected Demand as % of NDM Seasonal Normal Demand Gas Year /3 LDZ Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep SC 97.9% 98.4% 96.8% 96.% 96.6%.% 98.8%.7% 97.4% 99.% 96.9% 99.% NO 96.5% 99.8% 97.3% 98.5%.% 5.7% 3.8% 6.9%.%.3% 5.6% % NW 96.% 94.7% 94.% 95.% 95.5% 96.7% 97.6% 97.% 96.7% 9.%.4% 96.5% NE 97.3% 95.8% 94.4% 97.8% 97.% 99.4% 97.6% 99.% 97.% 9.8%.8% 96.% EM 9.6% 95.4% 94.8% 94.5% 95.3% 96.% 95.7% 93.% 93.7%.% 99.9% 9.6% WM 94.4% 95.% 94.6% 95.% 96.4% 98.7% 97.6% 93.3% 97.3% 5.6% 95.7% 9.5% WN 95.% 96.4% 94.5% 97.% 97.5% 98.%.% 99.%.5% 3.3% 7.6% 9.9% WS 93.% 94.% 93.9% 94.% 95.7%.% 3.% 88.% 94.3% 3.% 98.7% 99.% EA 94.4% 95.% 96.5% 96.% 98.3%.4% 95.4% 94.3% 6.8% 6.%.5% 95.5% NT 93.% 93.5% 96.% 95.7% 97.6%.5% 99.% 95.3%.% 3.3%.7%.9% SE 9% 9.6% 95.3% 94.7% 97.% 99.9% 99.9% 94.% 8.9% 5.% 4.3% 98.7% SO 98.% 97.7% 97.8% 97.6% 99.5% 5.4% 97.9% 94.% 4.7%.3% 5.% 5.% SW 9.6% 93.8% 95.8% 94.7% 96.5%.%.8% 9.8% 3.% 3.8% 7.8%.4% - 8 -
Table 5: Aggregate NDM AQs at Start of Gas Year 3/4 Based on data extracted from the Gemini system for gas days 9/9/3 and 8//3 LDZ % NDM AQ Change SC -.9% NO.% NW -.7% NE -.3% EM -.7% WM -.% WN.% WS -% EA -.5% NT -.5% SE -% SO.3% SW -.% Overall -.7% - 9 -