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Draft 2017-2026 forecast: energy usage will decline slightly and peak demand will remain flat

Every year, ISO New England develops a projection of how much electricity the region will use and how high demand will peak during each of the next 10 years. The 10-year forecast is a key system planning tool, helping ensure New England has an adequate supply of resources to meet future demand, and a transmission system that can do the job of carrying power to residents and businesses.

The draft long-term forecast for 2017 to 2026 projects that energy usage will decline slightly in New England and peak demand will remain flat over the 10-year period. The primary factors are continuing robust installation of energy-efficiency measures and behind-the-meter solar arrays throughout the region, as well as a slightly lower forecast for economic growth in New England.

The long-term forecast for electricity use is developed each year using state and regional economic forecasts, 40 years of weather history in New England, federal appliance efficiency standards, the results of both the ISO’s energy-efficiency (EE) forecast and solar photovoltaic (PV) forecast, and other factors. The ISO calculates a gross forecast and then applies the EE and PV forecasts to develop a net forecast. The draft EE forecast and draft PV forecast are still being finalized.

Draft projections for 2017–2026

The draft 2017 gross forecast projects a compound annual growth rate (CAGR) of 0.9% in total energy usage in New England, from 140,583 gigawatt-hours (GWh) this year to 152,593 GWh in 2026. When the preliminary EE and PV forecast estimates are taken into account, net energy usage is expected to drop by a CAGR of -0.6%, from 126,800 GWh this year to 120,181 GWh in 2026. The draft EE forecast projects annual savings that will average about 1,908 GWh each year through 2026.

Peak demand, a measure of the highest amount of electricity used in a single hour in New England, is projected in the draft gross forecast to rise by a compound annual growth rate of 1.0%, from 29,146 MW this year to 31,820 MW in 2026 with normal summer weather. However, when the demand-reducing effects of PV and EE are taken into account, the draft forecast projects that peak demand will remain flat over the 10-year period. If extreme summer weather were to occur, preliminary numbers indicate peak demand could rise by an average of 0.1% annually. The draft EE forecast projects that EE will shave about 262 MW, on average, off the peak demand each year of the forecast period.

The draft PV nameplate forecast estimates the level of behind-the-meter PV capacity that will be added each year through 2026. (Nameplate refers to the maximum amount of energy a resource is capable of producing.) The draft nameplate forecast projects about 2,444 MW of behind-the-meter PV will be added through 2026, for a total of 4,362 MW installed in New England. The final PV forecast will also include estimates of energy and peak demand reductions for the entire New England system, each state, and Regional System Plan subareas.

Long-term load forecast 2017-2026
(compound annual
growth rate)

Gross Forecast
Net Forecast
(minus load reductions
from EE & PV)
Annual Energy Usage 0.9%


Peak Demand (extreme weather)

1.0% 0.1%

2016 energy and demand

Looking back at 2016, weather-normalized electric energy usage declined by 1.5%, to 123,953 GWh, compared to 2015 energy consumption. Those figures are based on energy use adjusted for variations in weather, as well as the impact of energy-efficiency measures delivered through the Forward Capacity Market. Actual energy usage numbers show a 2.1% decline, from 126,955 GWh in 2015 to 124,261 GWh last year.

In 2016, actual demand peaked at 25,596 MW on August 12, 2016. Without the energy-efficiency measures installed in New England, as well as reductions by demand-response resources, price-responsive demand-side resources, and behind-the-meter solar resources, the peak would have come in at about 28,504 MW.

The finalized long-term load forecast, including the final EE and PV forecasts, will be part of the annual Forecast Report of Capacity, Energy, Loads, and Transmission (CELT) which is published May 1. The CELT report is a primary source for assumptions used in ISO system planning and reliability studies.



  The gross load forecast (projected regional energy use)

  The gross load forecast minus forecasted behind-the-meter (BTM) solar photovoltaic (PV) resources

  The gross load forecast minus forecasted BTM PV, minus energy-efficiency (EE) resources in the Forward Capacity Market (FCM) 2017–2020 and forecasted EE 2021–2026



Note: Summer peak demand is based on the "90/10" forecast, which accounts for the possibility of extreme summer weather, such as an extended heat wave of about 94°F.