Demand Response and PA Tier II AECs: What Building Owners Need to Know

Demand response — voluntarily curtailing electricity consumption during grid stress in exchange for utility or PJM payments — is widely adopted across Pennsylvania. What many participants don't know: those same curtailments may qualify for PA Tier II AECs. Demand-side management and demand response are explicitly recognized as Tier II eligible resources under Act 213. One action, two separate revenue streams.

How Demand Response Qualifies for Tier II AECs

Act 213 Tier II includes demand-side management, demand response, and energy efficiency. For demand response, the qualifying activity is the documented reduction in electricity consumption during curtailment events — one AEC per 1,000 kWh of demand response reduction verified by PennAEPS. See the Act 213 legal framework for the underlying statute.

The Measurement Challenge: Establishing a Baseline

Unlike LED retrofits with fixed wattage reductions, demand response savings depend on what the facility *would have* consumed without the curtailment. PennAEPS accepts the Customer Baseline (CBL) method used by PJM for demand response programs — expected consumption based on recent non-event days, adjusted for temperature and load drivers. Facilities already registered in PJM demand response can use their CBL data directly for AEC certification.

Stacking Demand Response Payments and AEC Revenue

PJM Emergency Load Response Program performance payments are separate from and stackable with Tier II AEC revenue for the same curtailment. Example: a building with 2 MW curtailable load, 15 events/yr averaging 4 hours each = 120 MW-hours of annual curtailment. PJM payments at current capacity prices = $18,000–$30,000/yr. The same 120,000 kWh curtailment = 120 Tier II AECs = $3,230 at $26.92. AEC revenue is incremental and permanent for the life of program registration.

The More Compelling Opportunity: Behind-the-Meter Storage

Battery storage that charges off-peak and discharges on-peak reduces net grid electricity consumption — and that net reduction qualifies for Tier II AECs. As commercial battery storage costs decline and Pennsylvania utilities develop battery-compatible demand response programs, this will become a significant AEC source. Building owners considering battery storage for demand charge management should factor Tier II AEC revenue into their storage economics model.

Limitations: What Demand Response Doesn't Include

Curtailments involving on-site backup generators — diesel or natural gas substituting for grid electricity — do not qualify. Only true curtailment (switching off loads, reducing consumption) qualifies. Generator-backed curtailments consume fuel and generate emissions rather than actually reducing consumption.

Frequently Asked Questions

Q: Can a facility participate in both PJM demand response and register for Tier II AECs for the same curtailments?

Yes. PJM demand response registration is managed through PJM's capacity market systems; Tier II AEC registration is managed through PennAEPS and PJM-GATS. The two programs have separate regulatory structures and there is no prohibition on dual participation. Emergent Energy coordinates AEC registration for facilities already enrolled in PJM demand response programs as part of the enrollment process.

How PJM Demand Response Programs Map to Tier II AECs

PJM operates several demand response programs — the Capacity Performance product (formerly the Emergency Load Response Program), the Synchronized Reserve Market, and the Day-Ahead Scheduling Reserves Market. Tier II AEC eligibility attaches only to the verified kWh reduction during called events; it does not attach to capacity payments, availability payments, or test events. The implication: a facility enrolled in Capacity Performance that receives a $/kW-month payment for being available, but is never actually called in a given delivery year, generates no Tier II AECs that year because there is no measured curtailment. Years with active grid stress — heat domes, polar vortex events, generation outages — produce both higher PJM payments and higher AEC issuance.

CBL Methodology and Its Limits

The Customer Baseline (CBL) method PJM uses for performance verification — typically the highest-load 4 of the 5 most recent non-event business days, weather-adjusted — is the same calculation PennAEPS accepts for AEC issuance. This is a meaningful efficiency: facilities do not need to maintain a parallel measurement system. Where CBL methodology breaks down — for example, in facilities with highly irregular operating schedules, or on the first event of the season after a long inactive period — Emergent Energy works with the facility's curtailment service provider (CSP) to substitute an engineering-based baseline acceptable to PennAEPS.

Battery Storage as the Next Frontier

Behind-the-meter battery storage — particularly lithium-ion systems sized 100 kW to 2 MW — is the most rapidly growing AEC source in the demand-side category. The accounting is straightforward: a battery that charges off-peak and discharges on-peak does not, in net, change a facility's annual energy consumption — but it does shift consumption to lower-grid-impact hours. PennAEPS issues AECs for the time-of-use shifted kWh under specific rules outlined in Act 213 implementing regulations. With Inflation Reduction Act battery ITC at 30% (40% with energy community adders), a 1 MW / 4 MWh storage system installed in PA today can generate ~$15,000–$25,000/yr in Tier II AEC revenue on top of demand charge savings and PJM capacity revenue.

Chillers, Thermal Storage, and Curtailable Process Loads

Demand-side resources are not limited to load shedding. Three under-utilized AEC categories: (1) ice or chilled-water thermal storage that pre-cools off-peak and discharges on-peak — common in hospitals, large office towers, and data centers; (2) curtailable process loads in manufacturing facilities — extruders, melting furnaces, mills — that can be shifted hour-by-hour without disrupting production; and (3) commercial/industrial HVAC pre-cooling using building thermal mass. All three qualify as demand-side management under Act 213 when documented with appropriate metering.

Aggregation and the 100 kW Threshold

Individual facility curtailments below ~100 kW typically don't justify standalone GATS registration overhead. Emergent Energy aggregates smaller facilities into portfolio registrations, allowing 50 kW commercial buildings to participate alongside larger industrial sites under a single GATS generator account. Portfolio aggregation also smooths CBL volatility — across a 20-facility portfolio, irregular event-day baselines wash out and total verified curtailment becomes more predictable.

Measurement and Verification Standards

PennAEPS aligns with IPMVP Option C (whole-facility regression) for most demand response measurements, with Option B (retrofit isolation) accepted where individual curtailable loads are sub-metered. Documentation requirements: 12 months of pre-event interval data, event call logs from the CSP or utility, post-event verification reports, and an annual M&V summary signed by a Certified Measurement and Verification Professional (CMVP) where required. For facilities already enrolled with a major CSP — Enel X, CPower, Voltus, NRG Curtailment Solutions — the M&V package is essentially complete already.

The Stacking Math: A Worked Example

A 5 MW industrial facility with 1.5 MW of curtailable load enrolled in Capacity Performance receives roughly $90/kW-year in capacity payments = $135,000/yr regardless of dispatch. In a year with 8 called events averaging 3 hours each, the facility delivers 36 MWh of curtailment = 36 Tier II AECs ≈ $970. In a high-stress year with 25 events averaging 4 hours, the same facility delivers 150 MWh = 150 AECs ≈ $4,038. The AEC revenue is incremental — the facility was going to curtail anyway — and the documentation burden is marginal because PJM already requires the underlying interval data.

Q: Does enrolling in Tier II AECs trigger any obligation under PJM's market rules?

No. PJM market participation and PennAEPS AEC participation are independent regulatory regimes. Aggregator commissions and AEC sale proceeds are separate from PJM capacity and energy settlements.

Q: Can a facility with on-site solar plus storage stack solar AECs and demand-response AECs?

Yes — but the underlying kWh cannot be double-counted. Solar generation kWh generates Tier I AECs (Solar PV Set-Aside or general Tier I depending on the project); demand-response kWh from battery dispatch generates Tier II AECs. The two streams are tracked separately in GATS based on the underlying generation source and metering point.

Q: Are virtual power plant (VPP) aggregations eligible?

Yes. Where a CSP or utility operates a VPP — bundling residential thermostats, commercial battery storage, and industrial curtailment — the aggregated curtailment can be registered for Tier II AECs at the aggregator level. Emergent Energy partners with several VPP operators in PA to handle the AEC layer.