Demand is modeled at the ISO sub-region level with hourly resolution. Each ISO has a dedicated forecast pipeline that captures regional load growth drivers and seasonal patterns.
Zonal demand
NYISO — multi-segment load forecasting
NYISO demand uses a bottom-up approach, modeling each load component separately. Total zonal load is built from five additive segments, each with its own growth trajectory and intra-day profile:
- Base load — underlying grid demand excluding electrification and distributed generation effects
- BTM solar — behind-the-meter solar PV reduces net load; modeled as a negative load segment with hourly shapes from weather-year irradiance data
- EV charging — electric vehicle load addition, profiled to reflect charging patterns (overnight residential, daytime workplace)
- Building electrification — heat pump and other electrification load, with strong winter seasonality
- Large loads — data centres and industrial facilities added as node-specific step increments
Peak and annual energy values for each component are sourced from the NYISO Gold Book. Hourly timeseries shapes for each component are derived from historical weather-year data at the 11-zone level, using heating degree days (HDD) and cooling degree days (CDD) from NOAA to capture the temperature-driven seasonality of each segment.
| Input | Source | Link |
|---|---|---|
| Seasonal peak forecasts (Summer/Winter) | NYISO 2025 Gold Book, Table I-4 | NYISO Gold Book |
| Zonal annual energy forecasts | NYISO 2025 Gold Book, Table I-1 | NYISO Gold Book |
| EV penetration forecasts | NYISO 2025 Gold Book, Appendix B | NYISO Gold Book |
| Historical hourly load shapes | EIA-930 Balancing Authority sub-region data | EIA-930 |
| Heating/cooling degree days | NOAA Climate Prediction Center | NOAA |
Forecast
Load profiles
Load sensitivity
The demand forecast is built on a single base weather year (currently 2022). Alternative weather-year shapes can be layered on top to support higher/lower demand scenarios, aligning demand shapes with renewable load-factor weather years for consistent scenario analysis.
Assumptions and caveats
- Each ISO uses a different primary forecast source; cross-ISO consistency is maintained via common weather years and consistent base-year calibration.
- NYISO peak and energy targets are sourced from the Gold Book. PJM, ISO-NE, and MISO use their respective forecast sources.
- Historical flows from Quebec and Ontario are subtracted from NYISO load because those regions are not modeled explicitly in the Eastern Interconnection simulation.
- BTM solar profiles assume clear-sky degradation curves; actual panel density by zone is an input assumption.
- Large load additions (data centres) are node-specific and subject to project likelihood filtering.
Data sources
| Source | Description | Link |
|---|---|---|
| EIA-930 | Real-time BA sub-region demand and generation | EIA-930 |
| NYISO Gold Book | Seasonal peak and annual energy forecasts (2023–2042) | NYISO Gold Book |
| NOAA Degree Days | Heating and cooling degree days for load-weather regression | NOAA |