Case Study: Geothermal Heat Pump Installation Generates PA Tier II AECs for Commercial Office Building

The Situation

A Chester County, PA commercial office building owner replaced a 25-year-old gas-fired boiler and DX cooling system with a 60-ton commercial GSHP in 2023 — 15 vertical bore wells to 250 ft, closed-loop glycol-water heat exchange, VRF indoor units on all three floors. Primary motivation: operating cost reduction and system reliability. Projected 40–55% total HVAC energy cost reduction. Emergent Energy was contacted during the design phase — AEC revenue was incorporated into the financial model before ground was broken.

Eligibility Assessment

GSHP systems qualify for PA Tier II AECs as demand-side management resources under Act 213. AEC issuance is based on electricity savings vs. baseline legacy equipment — primarily crediting the electricity savings on the cooling side where GSHP's high EER replaces less efficient DX cooling. Chester County location in PECO territory confirms PJM interconnection eligibility. The system meets IECC 2015 Table 403.2.3(1) minimum efficiency standards, confirmed by Energy Star certification. Emergent Energy's pre-installation assessment projected ~185 AECs/yr from Manual J calculations.

The Stacked Incentive Picture

Total first-year incentive recovery: $87,780 on $260,000 installation = 33.8% first-year recovery rate. Simple payback drops from 14 years (no incentives) to under 5 years. See the VFD AEC revenue guide for a comparable retrofit-class breakdown.

Registration Process and Timeline

PennAEPS certification application submitted 30 days post-commissioning. Documentation: contractor's installation invoice, commissioning report, Manual J load calculation, Energy Star certification, PECO interconnection documentation, AEC calculation methodology. PennAEPS certification received day 58. GATS registration completed within 2 weeks. First AEC issuance month 3 post-commissioning. Full enrollment process walkthrough available on this site.

PRESS Act Implications

If PRESS (HB 501) is enacted, geothermal heat pumps move from Tier II to Tier I — Pennsylvania's premium credit class, at a proposed $35 ACP ceiling. The same 60-ton GSHP would generate Tier I AECs potentially worth $35–$45/AEC rather than $26.92. 15-year AEC revenue grows from $74,700 to approximately $100,000–$120,000. Building owners planning geothermal installations should register now under current Tier II standards while tracking the PA PRESS legislation update.

Key Takeaway

Most GSHP installers do not mention AEC eligibility to their clients. Most building owners who completed geothermal projects in the last decade have never been approached about registration. The AEC revenue on a commercial GSHP project is not transformative on its own — but as part of the complete incentive stack (ITC + utility rebate + AECs + operating savings) it materially improves project economics and the simple payback timeline.

Comparative Economics: GSHP vs Air-Source Heat Pump

The Chester County project owner evaluated three HVAC replacement scenarios before committing to GSHP. (1) High-efficiency air-cooled chiller plus condensing boiler: $145,000 install, partial Tier II AEC eligibility (cooling side only), no Section 25D ITC, 12% operating savings. (2) Variable-refrigerant-flow air-source heat pump: $185,000 install, partial Tier II AEC eligibility, 30% Section 48 ITC for commercial, 25% operating savings. (3) 60-ton GSHP: $260,000 install, full Tier II AEC eligibility for both heating and cooling shifts, 30% Section 25D ITC, 40% operating savings. The full incentive stack made GSHP the lowest 15-year total cost of ownership despite the highest install cost — a result that without AEC enrollment would have been a closer decision.

Geothermal Drilling and Site Constraints

The 15 vertical bore wells were drilled in a 2.5-week window over a holiday period to minimize tenant disruption. Each well: 6-inch bore, 250 ft depth, fitted with HDPE U-tube heat exchangers. Total grout volume: ~28,000 lbs of thermally enhanced bentonite. Site selection was constrained by an existing parking footprint — wells were drilled in two staggered rows under what is now the back surface lot. For Pennsylvania commercial sites, the most common drilling-cost driver is overburden depth and bedrock variability; in Chester County (predominantly Wissahickon schist) drilling costs ran $18/ft, on the lower end for PA. Sites in the Pocono region or Lake Erie basin may see $24–$32/ft for comparable bores due to harder bedrock or unconsolidated overburden.

M&V Plan and PennAEPS Submission

The AEC submission used IPMVP Option D (calibrated simulation) given the equipment-level system change. Pre-retrofit baseline: gas boiler at 78% AFUE for heating, 8.5 EER air-cooled DX for cooling. Post-retrofit performance: 4.2 COP heating, 24 EER cooling per Energy Star-listed equipment. Annual building loads: 720 MMBtu heating, 540 MMBtu cooling at 14,000 cooling-degree-days and 4,800 heating-degree-days normalized to TMY3 weather data for the Philadelphia airport station. Net electricity savings vs. baseline: ~185,000 kWh/yr, yielding ~185 Tier II AECs annually. The simulation model was built in eQUEST 3.65 and submitted with the PennAEPS application package.

Section 25D vs Section 48 ITC: Which Applies

The owner is a partnership-owned commercial real estate LLC that elected to use the Section 25D residential energy efficient property credit because the property is held in a structure where partner allocations qualify under Treasury guidance for ground-source heat pumps placed in service after 2022. For most C-corporation owners or REITs, the Section 48 commercial ITC at 30% applies instead — same headline rate, different procedural requirements (prevailing wage, apprenticeship for projects above 1 MW). Tax counsel review is essential before claiming either credit; Emergent Energy refers clients to specialized tax practitioners but does not advise directly on tax matters.

Drilling Permits and PADEP Requirements

Closed-loop vertical bore systems in Pennsylvania require notification to the PA Department of Environmental Protection and conformance with the Bureau of Topographic and Geologic Survey's water well construction standards. Permits are typically issued within 30–45 days. Wells deeper than 300 ft trigger additional review; the Chester County project capped depth at 250 ft to stay within the streamlined permit pathway. AEC eligibility is unaffected by permit pathway, but project schedule should account for the 30–45 day permit lead time when forecasting commissioning and AEC issuance dates.

Five-Year Performance Tracking

At project month 36, measured electricity savings tracked within 4% of the eQUEST simulation prediction — well inside the ±15% PennAEPS accepts as in-spec performance. Year-over-year AEC issuance has been steady at 180–192 AECs depending on weather variability. The owner has not had to re-baseline or adjust the M&V plan. This stability is typical for GSHP installations because the geothermal loop temperature is highly consistent year-over-year — a key advantage over air-source systems whose seasonal performance varies more with ambient conditions.

Replication Across the Owner's Portfolio

The same owner is now evaluating GSHP retrofits at two additional Class B office properties in Bucks and Delaware counties. The first project's documentation set — eQUEST model template, PennAEPS application format, PADEP permit boilerplate, GATS registration playbook — significantly reduces incremental engineering and registration cost on subsequent projects. Portfolio-scale GSHP enrollment with consolidated GATS registration is increasingly common among Pennsylvania commercial real estate owners.

Q: Does the AEC revenue flow to the building owner, the tenants, or split?

By default, AEC revenue flows to the project payer — the building owner who funded the GSHP install. Triple-net leases with energy pass-through clauses can complicate this; lease counsel should review before AEC assignment to confirm the owner has unencumbered rights.

Q: What happens to AEC eligibility if the building is sold?

Facility registration transfers with the property after the buyer re-registers in GATS and PennAEPS. Pre-existing unsold AECs in the seller's GATS account remain seller property unless explicitly assigned in the purchase and sale agreement.