Design Working Group

The DWG supports Ofgem in the ELEXON-led project to design and assess the Target Operating Models (TOMs) for Market-Wide Half Hourly Settlement (HHS).

What’s new?

The DWG has issued a consultation (Issue Date 30 April 2018 – Response Date 29 May 2018) to inform stakeholders about the skeleton TOMs. It seeks your input on the design and evaluation work to date. 

About the TOMs

Development of the TOMs forms part of the Ofgem-led Significant Code Review (SCR) for Market Wide HHS.

The DWG is undertaking this in two stages:

Stage 1:

This stage is now complete and involved the DWG’s development and asessment of a set of Skeleton TOMs. The output was a report to Ofgem on 4 April 2018, setting out the five skeleton TOMs to be taken forward for industry consultation. The DWG subsequently issued this consultation on 30 April 2018.

Stage 2:

The DWG will develop the final detailed TOM, taking into account the outcomes of Ofgem’s related policy decisions. Following its decision on the Business Case, Ofgem will then decide if, and when, to implemement Market-Wide HHS.


ELEXON chairs the DWG and Ofgem appoints its members. The DWG’s membership includes experts from all aspects of the energy community: including consumer representatives, industry organisations and innovators/new technology bodies. Ofgem is not a member but attends as an observor and provides strategic input where necessary.

In Stage 2, the DWG will form workgroups supplemented with experts in more detailed areas. These will aid in the development of designs for specific topics. Membership details for these workgroups will be published on this page once confirmed.


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