What Is DASI?
The Day-Ahead Ancillary Services Initiative fundamentally changed how ISO-NE procures grid reliability reserves:
- Before (pre-March 2025): ISO-NE used a separate Forward Reserve Market to procure operating reserves on a seasonal basis. Costs were predictable but the system didn’t optimize for efficiency.
- After (DASI): Ancillary services — including 10-minute spinning reserves (TMSR), 10-minute non-spinning reserves (TMNSR), and 30-minute operating reserves (TMOR) — are now co-optimized with energy in the day-ahead market. This theoretically produces more efficient outcomes but introduces price coupling between energy and reserves.
The co-optimization means that when reserve requirements are tight (as they frequently are in winter), reserve prices can spike and pull energy clearing prices higher — a dynamic that wasn’t fully captured in ISO-NE’s pre-implementation cost estimates.
Why Costs Exceeded Estimates
Several factors contributed to higher-than-projected DASI costs in its first year:
- Historic winter severity: Winter 2025/2026 was the coldest in 20 years, driving record gas-fired generation demand. The co-optimized market amplified the price impact — when gas supply tightened, both energy AND reserve prices surged simultaneously.
- Reserve scarcity pricing: ISO-NE’s reserve constraint penalty factors triggered more frequently than modeled, producing higher ancillary service clearing prices during peak hours.
- New England’s structural gas dependency: With ~50% of generation gas-fired and constrained pipeline capacity, DASI’s co-optimization exposed the region’s fuel security vulnerability more starkly than the old market design.
Retail Bill Impact — March 2026
The cost overrun is now visible on retail bills:
- Municipal aggregation programs: Towns like New Marlborough, MA have cited DASI as the specific regulatory event driving March 2026 rate increases for community choice aggregation customers.
- Competitive supply contracts: Retail electricity providers serving commercial C&I customers are adjusting pass-through charges upward. Contracts with “regulatory change” clauses may see mid-term price adjustments.
- ISO-NE wholesale transparency push: On March 11, ISO-NE launched a new consumer fact sheet explaining that ISO-administered wholesale costs represent ~1/3 of a typical retail bill — effectively acknowledging the growing public concern about wholesale cost passthrough.
What This Means for Commercial Buyers
- Budget impact: Commercial buyers in New England should expect ancillary service-related charges to be 15–30% higher than pre-DASI baseline through at least Q2 2026. This stacks on top of the capacity performance payment reforms ISO-NE is also pursuing.
- Contract review: If your supply contract has a regulatory change or market restructuring clause, your provider may have grounds to adjust pricing. Review your terms now.
- Demand response opportunity: DASI increases the value of flexible load. C&I facilities that can reduce consumption during reserve scarcity events may benefit from higher demand response payments.
- Upcoming: NEPOOL meetings (Mar 17–18): The NEPOOL Reliability and Transmission Committee meetings this week will likely address DASI cost performance — watch for any proposed modifications that could affect forward pricing.
Source: ISO New England Mid-Week Market Update (March 12, 2026); Town of New Marlborough Municipal Advisory; ISO-NE Consumer Fact Sheet (March 11, 2026); NEPOOL Calendar.