Demand Side Management involves users of electricity having the capability to change their usage from their normal or current consumption patterns. It can provide significant benefits for customers in terms of reduced bills and gives them greater control over the energy they use and produce. 

It can help EirGrid in managing the power system efficiently; including accommodating increased renewable electricity generation and providing enhanced capacity. Demand Side Management has been and is expected to remain a key operational service to maintain system security for the island and we supports the development of a smart grid where Demand Side Management is an important element.

Electricity consumers can currently participate in Demand Side Management through tariff-based schemes where they are encouraged to move their usage to cheaper off-peak times. Examples include Economy 7 (Northern Ireland) and NightSaver (Ireland).  EirGrid also operates two system operator-based schemes in Ireland, Short Term Active Response (STAR) and Powersave, which are used to keep the system secure at times when the system is stressed. These schemes are aimed at large electricity users.

In addition to customers individually participating in the schemes operated by EirGrid, medium to large electricity users can participate in a Demand Side Unit (DSU) or Aggregated Generating Unit (AGU). A Demand Side Unit consists of one or more demand sites that can reduce their demand when instructed by EirGrid or SONI.  The Demand Side Unit has one hour to reduce its demand and must be capable of maintaining the demand reduction for at least two hours. 

The Demand Side Unit, usually third-party company specialising in demand side management, may contract with a number of demand sites and aggregate them together to operate as a single Demand Side Unit. Instructions to reduce demand are issued to the Demand Side Unit by EirGrid or SONI at an aggregate level and the Demand Side Unit then co-ordinates the reduction from all its demand sites. Demand sites typically use on-site generation, plant shutdown or storage technology to deliver the demand reduction.  An Aggregated Generating Unit is similar to a Demand Side Unit, a key difference being it is composed of on-site generation only.