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Unaccounted for Gas (UAG)

We're incentivised to investigate the causes of Unaccounted for Gas (UAG), one of the components of NTS Shrinkage. This is gas that is lost, or otherwise not accounted for, as delivered to or offtaken from the National Transmission System (NTS). On this page you will find the data we publish on UAG and how to contact us with questions.

UAG  in the National Transmission System (NTS) is considered to be the consequence of data and or meter error. So, it's a relatively complex component of shrinkage, involving not only the mechanical behaviour of high-pressure metering systems, but statistical variations in their operation.

We've published daily UAG data on our website since October 2012. We make weekly updates to this information and cover the period from 1 March 2007 up to seven days previous. Due to the process of data close out (day plus 5 and month plus 15), the recent values are subject to change and are available to download:

Daily UAG to 01 December 2017

We regularly report on our activity to investigate potential causes of UAG - the most recent report is available below. This report covers the latest UAG trends, and provides updates of our data analysis and meter validation activities.