1. Place your chosen image here. The four corners must just cover the arrow tips. For covers, the three pictures should be the same size and in a straight line. Danalyzer Daily Automated Calibration Sequence Failures Stuart Gibbons - Offtake Arrangements 20 August 2013

2. Topics  Background  Issue  Mitigation

3. 3 Background  FWACV methodology utilised to determine daily CVs  Calculated for individual relevant inputs to and outputs from a particular charging zone  Based on individual determinations of CV made by gas transporters using instruments and software approved by Ofgem  Letter of Approval (LOA)  Ofgem to gas transporter for CVDD and software  Letter of Direction (LOD)  Ofgem to gas transporter - Prescribes manner and location to determine CV

4. 4 Issue  LOA mandates daily calibration of CVDD  Since 2008 NGGD directed sites have experienced sporadic failure to initiate automatic calibration  Visibility of issue recently come to light  Issue lies with Ofgem approved software interface to CVDD controller  Approx 10% of calibrations not initiated

5. 5 Mitigation  (FWACV) methodology utilised since 1997  Vast data set  Showing instrument stable and no evidence of drift  NGGD tasked GL Noble Denton to establish materiality  Summary  Study concludes no detrimental impact on determined CV  No impact on LDZ energy calculations or NTS shrinkage  Whilst issue needs resolving – no detriment to consumers

6. Danalyzer Daily Automated Calibration Sequence Failures Thank You