Two major change programmes, the Integrated Single Electricity Market (I-SEM) and “Delivering a Secure Sustainable Electricity System” (DS3), took place concurrently in the Irish market. Alongside our role as centralised programme manager for both of these, ESP Consulting served as the I-SEM and DS3 Programme Design Authority for the two Irish energy Regulatory Authorities. The purpose of this piece of work was to provide design integrity assurance, with the scope including: