Starting June 1, 2027, PJM Interconnection (PJM) will expect demand response to be ready at any hour of the year, so facilities enrolling now are pricing a promise that runs through the night. The market has already rewarded the change, which leaves the cost of keeping that promise as the number to check.

Demand response pays large electricity users to cut consumption when the grid operator calls. In PJM's 2027/2028 Base Residual Auction, the accredited value of that service, measured as effective load carrying capability (ELCC), rose from 69% to 92%. PJM's auction report names two rule changes as major drivers, all-hours availability and a new method for calculating each customer's winter peak load. Every megawatt offered cleared, 7,298.6 megawatts (MW) of unforced capacity, at $333.44 per MW-day.

The New Window Covers the Hours the Old One Left Out

Annual demand response currently has to be available from 6 a.m. to 9 p.m. Eastern Prevailing Time in winter and from 10 a.m. to 10 p.m. in summer, as laid out in PJM's March 2025 filing. The Federal Energy Regulatory Commission (FERC) accepted PJM's proposal on May 5, 2025, replacing those windows with 24-hour availability throughout the year beginning with the 2027/2028 delivery year. Summer-period resources get the same round-the-clock window during their season.

The overnight hours are the new part. An office campus, a school or a single-shift plant may have plenty of flexible load at 3 p.m. and very little at 4 a.m., when heating systems work hardest and few people are on site. Facilities that signed up on the strength of afternoon reductions should measure what they can actually shed in the dark.

A Winter Baseline Built Around 9 a.m.

The second change reaches payments. The same filing sets each customer's winter peak load from a single hour, defined in PJM's manuals as the hour ending 9 a.m., on five coincident peak days between December and February. The current method uses each customer's own highest hour between 7 a.m. and 9 p.m. A site whose heaviest use comes later in the day may find that PJM's figure differs from the one in its own energy records.

Thirty Minutes, Staffed or Not

The response clock stays tight. Under PJM's exception guidelines, load management must respond fully within 30 minutes of notification unless the curtailment service provider (CSP) secures an exception for 60 or 120 minutes. Only four reasons qualify, among them equipment damage from a fast shutdown, a manual switch to backup generation and on-site safety concerns. Staffing availability is expressly excluded.

A January call at 4 a.m. therefore needs a person or an automated control ready to act within half an hour. Sites relying on a manual sequence run by day staff will have to automate it, staff for it or commit less load.

Pricing the Cold-Weather Commitment

Backup generation brings its own questions. Running units for curtailment requires permits that allow it, plus fuel on hand during the same weather that slows deliveries. Battery-based plans need enough stored energy to cover an overnight event while still holding the reserve the site needs for itself.

Contract terms decide who absorbs a missed event. Facilities should get in writing how penalties, failed tests and changes in available load flow back to them, and who answers a dispatch call outside business hours. Companies that treat flexibility as a growth tool need those terms settled before the first winter dispatch. As grid constraints turn into commercial terms, the paperwork carries as much weight as the controls.

Demand Response Is Being Counted More Like a Power Plant

The direction has held since PJM's first Capacity Performance auction a decade ago, when the market began paying more for resources that deliver in any conditions and charging those that fail. All-hours availability carries that logic over to demand response, and the jump in accredited value shows PJM now counts it closer to a generator.

Higher accreditation tends to bring higher expectations. As more facilities enroll under the new rules, grid operators will learn how much load actually responds at night, and that record will shape how demand response is valued in auctions after 2027/2028. Sites that rehearse an overnight dispatch this winter, while the old window still applies, will know their answer before PJM does.