National Grid currently forecasts maximum demand to an accuracy of approximately 1%. Decarbonisation to meet the EU and Government 2020 CO2 emission targets will change the nature of electricity demand and potentially reduce our ability to accurately forecast it. Increasing amounts of intermittent generation being connected to the transmission system, 30GW by 2020, also means that demand at all times of the day becomes important and not just the historic evening peak. Accurate demand forecasting ensures that the correct amount of response and reserves are held to ensure that electricity is supplied securely and reliably, and at an economic cost that is ultimately borne by electricity consumers.