ISO-NE enhances long-term forecast as region’s energy use evolves

ISO New England is implementing major enhancements to its long-term forecast for electricity use—crucial innovations at a time when the ways in which the region produces and consumes electricity are rapidly evolving. 

Results of the new forecast methods will be reflected in the 2025 Forecast Report of Capacity, Energy, Loads, and Transmission (CELT Report), to be published May 1. The annual report is a foundational resource for the ISO’s system planning and reliability studies. 

The key forecast improvement involves developing hourly projections over the CELT’s 10-year horizon and beyond. Previously the forecast relied primarily on annual energy and seasonal peak projections.  

The level of geographic detail is increasing too. The base demand forecast will be broken down into eight load zones, a smaller subset of New England’s six states. Projections related to distributed energy resources, heat pumps, and electric vehicles will be generated for each of the region’s 67 counties. 

A higher-resolution forecast is necessary given that patterns of energy use are likely to shift in the years ahead. By the mid-2030s, the electrification of heating systems is expected drive annual peak demand higher in winter than in summer, and shift daily peaks from evening to morning. Meanwhile, continuing adoption of behind-the-meter photovoltaics and energy storage, among other factors, will increase variability in consumer demand for grid electricity. The enhanced forecast methods will provide valuable insights into how the grid may evolve in the coming decades. 

Inputs to the forecast include state energy policies, historical and climate-adjusted weather data, trends in end-use consumer behavior, and economic indicators. 

The improvements have been two years in the making, developed by the ISO’s Load Forecasting team in consultation with regional stakeholders. The team’s work has already supported two forward-looking studies the ISO published in the last two years: Operational Impact of Extreme Weather Events and Economic Planning for the Clean Energy Transition.