The historic half hourly day ahead national demand forecast as published via BMRS, alongside the outturn values, adjustments for TRIAD avoidance estimates and Absolute Percentage Error (APE) for each half hour from April 2021 onwards. TRIAD avoidance estimates may be revised after publication if required. For data further back in time, please see the data submitted to OFGEM for the 1B metric here: https://www.ofgem.gov.uk/publications/decisions-eso-guidance-documents-2021-23