Publication of Zonal Flex Data September 2009

Background Mod 195AV, which introduced Enduring NTS Exit Capacity Arrangements was implemented 1st April 2009. Within the modification, was the requirement for NG NTS to publish Zonal NTS Exit Flex Utilisation information from October 2009. In relation to each NTS Exit Zone and each day (D), National Grid NTS will publish by not later than 12:00 on D+1 and D+6: The aggregate quantity of gas offtaken by all Users between 06:00 and 22:00 The aggregate quantity of gas offtaken by all Users; and The sum of the NTS Exit Flexibility Quantity utilised by all Users. The Flex Utilisation data to be published is a calculation of diurnal flex which is predominately driven by customer demand profiles within the LDZ, and therefore does not necessarily represent the flexibility provided to industrial users.

Methodology The NTS Exit Flexibility Quantity (EFQ) is determined as follows: EFQ = (Q2200 * (1-FT) – (QD * 16/24)) Where: Q2200: is the quantity of gas offtaken by all Users in an NTS Exit Zone between 06:00 hours and 22:00 hours on the day; FT: is 0.015 (a 1.5% flexibility tolerance, incorporated as per UNC requirements); QD: is the quantity of gas offtaken by all Users in an NTS Exit Zone in the whole of the day.

High Level Overview of Flex EFQ = (Q2200 * (1-FT) – (QD * 16/24)) Q2200 = 1.1 * 16 = 17.6 QD = 1.0 * 24 = 24.0 17.6 * (1 – 0.015) – (24.0 * 16/24) = 17.6 * 0.985 – 16.0 = 1.33 EFQ = (Q2200 * (1-FT) – (QD * 16/24)) Q2200 = 1.1 * 16 = 17.6 QD = 1.0 * 24 = 24.0 17.6 * (1 – 0.015) – (24.0 * 16/24) = 17.6 * 0.985 – 16.0 = 1.33 (mcm) Flex Utilised 1.1 06:00 – 22:00 06:00 – 22:00 1.0 End of Day Measurement 0.8 06:00 22:00 06:00

What is Being Published Negative Zonal Flex Utilization figures are reported as 0 Total Zonal Flex Utilization reflects the National Position accounting for negatives, and therefore will not equal the sum of the flex zone figures for a given day.

What is this telling me

What is this telling me

What does this mean – Impact on Linepack Assuming consistent entry and exit flows, linepack is utilised within day to cover any flex requirements. 06:00 22:00 Zone E3 Linepack

Data Location For 2009, the Zonal Flex utilisation information will be created in an offline model and uploaded as a spreadsheet daily to the National Grid Website. Located in the Operational Summary Section. For enduring reporting, this requirement has been captured, and is being developed as part of the Exit Reform 2010 Systems update through MIPI, where the information provision will be enhanced to be provided as: Data Items for downloading Report Exit Zone information is contained within Appendix B of the ExCR, and is proposed to be published on the Web alongside this report. Final details of report publication and location will be notified through the National Grid website News Section. If you have any queries, please contact: ExitReform.PMO@uk.ngrid.com