New England’s Electricity Use

The region’s millions of households and businesses create the demand for electricity, which must be produced the instant it is needed because electricity can’t be effectively stored. (Learn how ISO New England runs the power grid.)

Top 10 Demand Days

These are the days with the highest demand (electricity use) recorded in New England since the ISO began managing the power grid in 1997. The top days typically occur during the work week in summer.

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This demand data comes from the Daily Summary of Hourly Data Report, available on the Zonal Information page. The daily peak load for the regional system is included in the “SYSPeak” column on the “ISONE CA” worksheet. The “DT” (date type) column represents the day of the week, where Monday is 1 and Sunday is 7.

A Summer Peaking System

In New England, the highest demand for electricity during the year typically occurs during the summer season.

  • Peak demand on a normal summer day has typically ranged from 17,500 MW to 22,000 MW. Annual summer peaks, which happen on the hottest and most humid days, have averaged roughly 25,700 MW since 2000.
  • In winter, peak demand on a normal day has typically ranged from approximately 18,000 MW to 19,700 MW. Annual winter peaks, which happen on the coldest days, have averaged roughly 21,000 MW since 2000.
  • Typical spring peak demand ranges from 15,000 MW to 16,900 MW, while typical fall peak demand ranges from 15,900 MW to 17,300 MW. However, the actual spring and fall peaks can be much higher if summer-like weather creeps into the late spring or early fall periods.

Until 1989, New England was a winter-peaking system, and in the early 1990s, the region had nearly twin winter and summer peaks. Many factors have contributed to this dramatic change. For example:

  • In the summer, the growing use of air conditioning has helped push up demand.
  • In the winter, a decline in electric heating use has helped push down demand.
Load Graph

See how hourly load varies by season and with the impact of solar power.

Fast Stats
  • 7.2 million retail electricity customers; population 14.8 million
  • 121,061 gigawatt-hours (GWh) total annual energy served in 2017 (subject to adjustments)
  • 136,355 GWh all-time highest total annual energy served, set in 2005
  • 28,130 megawatts (MW) all-time summer peak demand, set on August 2, 2006
  • 22,818 MW all-time winter peak demand, set on January 15, 2004
  • -0.6% average annual growth in regional electricity demand forecasted through 2026, after factoring in energy efficiency (EE) and distributed generation (DG)
  • -0.07% average annual growth in peak demand forecasted through 2026 under normal weather conditions after subtracting EE and DG; 0.1% under extreme summer weather

Long-Term Changes in Annual and Peak Demand

Since 2005, total annual demand for electricity from the region’s power system has been declining. Several factors have played a role, though weather is typically the biggest determinant of electricity demand in any given year:

  • The Great Recession and slow recovery dampened demand for electricity.
  • The New England states began investing heavily in energy-efficiency programs, which reduce demand from the grid.
  • The region has seen rapid growth in solar power systems installed “behind the meter” directly at consumer sites or utilities, which serve to reduce demand from the grid.

Energy-efficiency measures and behind-the-meter solar power have also been helping to flatten the growth in peak demand, which had previously been rising in New England. Peak demand is the highest amount of electricity used in a single hour, and the ISO must ensure that the region has sufficient power resources or imported electricity to meet it. Learn more about the forecasted effects of energy efficiency and solar power below.

Annual Electricity Use and Peak Demand on the New England Power System

Forecasted Demand

The ISO forecasts that EE measures and behind-the-meter solar photovoltaic (PV) resources will continue to noticeably reduce demand for electricity from the regional high-voltage power system:

  • New England’s annual electricity use is expected to decline by an average of -0.6% over the next decade, from 126,786 gigawatt-hours (GWh) in 2017 to 119,680 GWh in 2026.
  • Peak demand under normal weather conditions of about 90°F (the “50/50” forecast) is expected to fall slightly at an average rate of -0.07%, from 26,482 MW in 2017 to 26,310 MW in 2026.
  • Peak demand under extreme summer weather (the “90/10” forecast), such as an extended heat wave of about 94°F, pushes the expected peak demand up to 28,865 MW in 2017 to 29,021 MW in 2026—an average annual growth rate of 0.1%.

Without the demand-reducing effects of EE and PV, New England’s overall electricity use would be expected to grow an average of 0.9% annually over the next decade, from 140,583 GWh in 2017 to 152,593 GWh in 2026, while peak demand under extreme summer weather would rise at an average annual rate of 1.0%, from 31,529 MW in 2017 to 34,531 MW in 2026. These effects are illustrated in the graphs below.

See Key Stats—Resource Mix for details on the growth in EE, PV, and other clean-energy resources.

annual energy use and summer peak demand

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