The refrigerant landscape for commercial HVAC systems has changed more in the past few years than in the previous two decades. The EPA's rules under the American Innovation and Manufacturing (AIM) Act, codified at 40 CFR Part 84, now control which refrigerants can be used in new equipment (the Technology Transitions program) and how leaks from larger existing equipment must be managed (the Emissions Reduction and Reclamation program).
At the center of this transition is a class of refrigerants called A2L, or mildly flammable, that is replacing R-410A in most new comfort cooling equipment. Facility managers who understand the requirements now will avoid enforcement exposure, unplanned equipment retirements, and operational disruptions as the phasedown continues through the late 2020s and into the 2030s.
This guide covers each layer of A2L transition compliance: the legal authority, the phasedown schedule, equipment timelines (including EPA's 2024 and 2026 revisions), leak repair thresholds, safety code requirements, and what your operations team should do now.
What Is the EPA AIM Act?
The American Innovation and Manufacturing (AIM) Act was enacted on December 27, 2020. It gives the EPA authority to phase down the production and consumption of hydrofluorocarbons (HFCs), the class of refrigerants that replaced ozone-depleting substances like R-22 but are themselves potent greenhouse gases.
R-410A, the dominant refrigerant in commercial air conditioning for the past 20 years, has a global warming potential (GWP) of roughly 2,090 times that of carbon dioxide (EPA lists it at 2,090). Under the AIM Act, U.S. HFC production and consumption must fall to 15 percent of the historic baseline by 2036, an 85 percent reduction.
The AIM Act grants EPA authority across three distinct areas:
- Phasedown of HFC production and consumption through an allowance allocation and trading program
- Management of HFCs and their substitutes, including leak repair and reclamation (the Emissions Reduction and Reclamation program)
- Technology Transitions that restrict use of higher-GWP HFCs in specific sectors and subsectors
For commercial facility managers, the Technology Transitions and Emissions Reduction and Reclamation rules, both codified in 40 CFR Part 84, are the most immediately operational. They dictate what equipment can be manufactured, imported, and installed, and how larger systems must be monitored and repaired.
EPA has also stated that there are no requirements to stop using equipment currently in service; existing systems can continue operating and being serviced for their useful life.
The 40 CFR Part 84 Technology Transitions Rule
Legal Authority and Rulemaking History
EPA finalized the Technology Transitions Rule on October 24, 2023. It restricts the manufacture, import, and installation of certain products and systems that use HFCs above subsector-specific GWP limits. EPA has since amended it several times:
- December 2023: An interim final rule extended the installation deadline for residential and light commercial AC and heat pump systems built with higher-GWP components from January 1, 2025 to January 1, 2026.
- December 2024: A final rule allowed variable refrigerant flow (VRF) systems with higher-GWP HFCs manufactured or imported before January 1, 2026 to be installed until January 1, 2027, and until January 1, 2028 for construction projects that received an approved building permit before October 5, 2023.
- May 26, 2026: A reconsideration final rule (effective July 27, 2026) revised requirements for several subsectors, including residential and light commercial AC and heat pumps, supermarket systems, remote condensing units, cold storage warehouses, industrial process refrigeration, and refrigerated laboratory equipment.
Key GWP Limits for Commercial HVAC and Refrigeration
The following table summarizes the current Technology Transitions limits most relevant to commercial facilities, as shown on EPA's sector restrictions page (last updated August 2026). Many subsectors have additional conditions based on charge size or system type, so confirm details for your equipment on EPA's site.
| Subsector | GWP Limit | Compliance Date | Notes |
|---|---|---|---|
| Residential and light commercial AC and heat pumps | 700 | January 1, 2025 (manufacture and import) | May 2026 rule removed the installation deadline for systems whose components were manufactured or imported before January 1, 2025 |
| Variable refrigerant flow (VRF) systems | 700 | January 1, 2027 (installation) | Until January 1, 2028 for projects permitted before October 5, 2023 |
| Chillers for comfort cooling | 700 | January 1, 2025 | In effect |
| Retail food refrigeration, stand-alone units | 150 | January 1, 2025 (manufacture and import) | In effect |
| Supermarket systems and remote condensing units | Interim 1,400; then 150 or 300 | Stricter limits begin January 1, 2032 | Extended by the May 2026 rule; the final limit depends on charge size and system type |
| Cold storage warehouses | Interim 700; then 150 or 300 | Stricter limits begin January 1, 2032 | Extended by the May 2026 rule |
| Industrial process refrigeration (including IPR chillers) | 150 to 700, depending on system | January 1, 2026 through January 1, 2032, depending on system | Semiconductor manufacturing equipment extended to January 1, 2030 |
Check the Current Rule Before You Buy
EPA revised Technology Transitions dates in December 2023, December 2024, and May 2026. Before approving a replacement or a new project, confirm the current GWP limit and compliance date for that exact subsector on EPA's Technology Transitions pages.
What "Manufacture, Import, and Installation" Restrictions Mean in Practice
Depending on the subsector, the rule restricts the manufacture and import of products, the installation of field-assembled systems, or both. Existing equipment is not affected; the restrictions apply to new products and systems after each subsector's compliance date.
For commercial projects, ask your equipment supplier to document the manufacture or import date of major components, and confirm that the refrigerant in any new system meets the limit that applies on the installation date.
The HFC Phasedown Schedule: 2024 to 2036
Production and Consumption Allowance Caps
The AIM Act sets the phasedown steps in statute. EPA implements them through an allowance allocation program that caps U.S. HFC production and consumption, measured in exchange value equivalent (MMTEVe, numerically equal to million metric tons of CO2 equivalent).
The phasedown schedule as a percentage of the baseline is:
| Compliance Period | Allowance Cap (% of Baseline) | Effective Reduction from Baseline |
|---|---|---|
| 2020–2023 | 90% | 10% reduction |
| 2024–2028 | 60% | 40% reduction |
| 2029–2033 | 30% | 70% reduction |
| 2034–2035 | 20% | 80% reduction |
| 2036 and beyond | 15% | 85% reduction |
EPA lists the U.S. consumption baseline at 302.5 MMTEVe and the production baseline at 382.5 MMTEVe. The step from 60 percent to 30 percent in 2029 is the largest single reduction in the schedule and is widely expected to tighten supply of legacy HFC refrigerants such as R-410A.
What the Phasedown Means for Your Existing Equipment
The phasedown does not prohibit using HFC refrigerants in existing equipment. However, as allowances shrink, virgin HFC supply contracts, reclaimed refrigerant becomes a larger share of the servicing supply, and servicing legacy R-410A equipment is likely to become more expensive.
The practical planning implication: equipment replacement decisions in your capital planning cycle should factor in the 2029 step-down as a likely inflection point for R-410A availability and cost.
A2L Refrigerants: The Replacement Class
What "A2L" Means
ASHRAE Standard 34, the industry standard for refrigerant designation and safety classification, uses a letter for toxicity (A = lower, B = higher) and a number for flammability:
- 1 = no flame propagation
- 2 = flammable
- 2L = lower flammability (a subset of Class 2 with a burning velocity of 10 cm/s or less)
- 3 = higher flammability
A2L refrigerants are therefore lower-toxicity refrigerants with low flammability and a slow flame speed. They will not ignite below their lower flammability limit (LFL), which is why the safety codes focus on keeping any leaked refrigerant concentration well below the LFL.
Primary A2L Replacements for Commercial HVAC
GWP values below are as listed by EPA's SNAP program (rounded) unless noted.
| Refrigerant | Example Trade Name | GWP | ASHRAE Class | Typical Commercial Application |
|---|---|---|---|---|
| R-454B | Opteon XL41 (Chemours) | About 470 | A2L | Replacement for R-410A in new ducted split systems, packaged units, and other unitary equipment |
| R-32 | Difluoromethane (HFC-32) | 675 | A2L | Ductless mini-splits and other new unitary equipment |
| R-452B | Opteon XL55 (Chemours) | About 700 | A2L | Replacement for R-410A in new equipment, including some chillers and heat pumps |
| HFO-1234ze(E) | R-1234ze(E) | 6 | A2L | New centrifugal chillers and other large equipment |
| R-466A | Solstice N41 (Honeywell) | 733 (manufacturer figure) | A1 (non-flammable) | Non-flammable R-410A alternative; GWP is above the 700 limit that applies to new comfort cooling equipment |
Note on R-466A: R-466A is non-flammable (A1), but its reported GWP of 733 is above the 700 GWP limit for new residential and light commercial AC, VRF, and comfort cooling chillers, so it is not an option for new equipment in those subsectors.
R-454B and R-32 are the most common choices for new unitary equipment that previously used R-410A. Confirm with each manufacturer which refrigerant its current commercial product lines use.
The New 15-Pound Leak Repair Threshold
The Emissions Reduction and Reclamation Rule: What Changed
EPA finalized the Emissions Reduction and Reclamation (ER&R) program in October 2024 (40 CFR Part 84, Subpart C). Its leak repair requirements took effect January 1, 2026 and apply to refrigerant-containing appliances with a full charge of 15 pounds or more of a refrigerant that contains an HFC, or a substitute for an HFC, with a GWP above 53.
Two important exclusions apply:
- Appliances that contain solely an ozone-depleting refrigerant (such as R-22), which remain under the Section 608 rules
- Appliances in the residential and light commercial air conditioning and heat pump subsector, which EPA excluded from the leak repair provisions
For comparison, the legacy Section 608 leak repair rules under 40 CFR Part 82, Subpart F apply to appliances with 50 or more pounds of ozone-depleting refrigerant. EPA rescinded the extension of those 608 leak repair rules to HFC appliances in 2020, so the ER&R rule is now the federal leak repair program for covered HFC equipment. Larger comfort cooling equipment such as chillers, and commercial refrigeration systems, are the most likely assets in a commercial building to fall under it.
Leak Rate Thresholds and Repair Timelines
| Appliance Type | Leak Rate That Triggers Repair | Required Repair Timeline |
|---|---|---|
| Comfort cooling and other appliances | 10% | 30 days |
| Commercial refrigeration | 20% | 30 days |
| Industrial process refrigeration | 30% | 30 days (120 days if an industrial process shutdown is needed) |
How Leak Rate Is Calculated
The owner or operator must calculate the leak rate every time refrigerant is added to a covered appliance, except for additions made right after a retrofit, at installation of a new appliance, or under a seasonal variance. If the calculated rate exceeds the applicable threshold, the leak must be identified and repaired within the repair timeline, followed by initial and follow-up verification tests.
If repairs cannot bring the appliance into compliance, the owner must develop a retrofit or retirement plan within 30 days and generally complete it within one year. Limited extensions are available, for example when necessary parts are unavailable.
Appliances that leak 125 percent or more of their full charge in a calendar year must be reported to EPA by March 1 of the following year.
Automatic Leak Detection System Requirements
The ER&R rule also requires automatic leak detection (ALD) systems, but only for commercial refrigeration and industrial process refrigeration appliances with a full charge of 1,500 pounds or more of a refrigerant with a GWP above 53. Comfort cooling equipment is not covered by the ALD requirement.
- Installed on or after January 1, 2026: ALD must be in place upon installation or within 30 days
- Installed from January 1, 2017 through January 1, 2026: ALD must be installed by January 1, 2027
ALD systems must be audited and calibrated annually, and records of installation, calibrations, and alerts must be kept.
Key Takeaway
The federal 15-pound leak repair rule applies to many chillers and commercial refrigeration systems, but not to equipment in the residential and light commercial AC and heat pump subsector. The federal ALD mandate applies only to commercial refrigeration and industrial process refrigeration systems of 1,500 pounds or more.
Recordkeeping Requirements
Records for covered appliances must be kept for three years, and appliance-specific records for three years after the appliance is retired. Typical records include:
- Full charge and how it was determined
- Date and amount of each refrigerant addition and the calculated leak rate
- Leak inspections, repairs, and verification test results
- Any retrofit or retirement plans and extension requests
A2L Safety Code Requirements for Commercial Buildings
ASHRAE Standard 15
ASHRAE Standard 15, Safety Standard for Refrigeration Systems, is the primary industry safety standard for refrigeration system design, installation, and operation. Recent editions have expanded requirements for A2L refrigerants, and the 2024 edition addresses flammable refrigerants further, including effective dispersal volume charge calculations and ventilation options for Class 2L refrigerants. The edition that applies to your building is the one referenced by your locally adopted mechanical code.
The general approach for A2L systems is to limit the charge relative to the space it could leak into and, where charges are larger, to rely on listed refrigerant detection and mitigation (such as increased airflow or ventilation) so that a leak cannot build up to the LFL. Machinery rooms housing A2L equipment have their own detection and ventilation requirements.
Service and maintenance practice: Because A2L refrigerants can ignite at concentrations above the LFL, technicians should follow manufacturer instructions and A2L safety training for ignition-source control, ventilation, and leak checking before brazing or other hot work on these systems.
2024 International Mechanical Code (IMC) A2L Provisions
The International Code Council approved A2L-related changes that take effect with the 2024 editions of the International Building, Fire, and Mechanical Codes. Earlier IMC editions generally did not permit A2L refrigerants for human comfort applications. Key 2024 IMC provisions include:
| Code Provision | Requirement |
|---|---|
| Equipment listing | High-probability equipment using A2L refrigerant must comply with UL 484, UL/CSA 60335-2-40, or UL/CSA 60335-2-89 |
| Refrigerant groups for comfort cooling | High-probability systems used for human comfort may use Group A1 or A2L refrigerants |
| Machinery room: ignition sources | Open-flame devices and continuously operating hot surfaces over 1,290°F (700°C) may not be permanently installed in A2L machinery rooms |
| Machinery room: detection and ventilation | Refrigerant detectors must alarm and activate the mechanical ventilation system, which must comply with ASHRAE 15 |
Adoption of the 2024 IMC varies by jurisdiction. Confirm which code edition your local Authority Having Jurisdiction (AHJ) has adopted, and any local amendments, before designing or specifying A2L systems.
Technician Certification and Training
Under EPA Section 608 (40 CFR Part 82, Subpart F), technicians who add or remove refrigerant or attach hoses and gauges on stationary refrigeration and AC equipment must hold Section 608 certification. This applies to equipment using HFC-based A2L refrigerants such as R-454B and R-32.
Beyond certification, A2L service work calls for specific field practices:
- Controlling ignition sources near open refrigerant circuits during recovery and charging
- Using leak detectors, recovery equipment, and cylinders rated for A2L refrigerants
- Following manufacturer installation and service instructions for the listed equipment
- Recording refrigerant additions so leak rates can be calculated where the ER&R rule applies
Facility managers contracting HVAC service work should confirm that their service providers have completed current A2L safety training.
Equipment Replacement Planning: A Practical Timeline
Assessing Your Current Refrigerant Inventory
The first operational step is a complete refrigerant inventory of all equipment under your management. For each system, document:
- Refrigerant type currently in use
- Full charge in pounds
- Equipment manufacture date and estimated remaining useful life
- EPA subsector (for example, residential and light commercial AC, VRF, chiller, commercial refrigeration)
- Whether the system falls under the 15-pound ER&R leak repair rule or the 1,500-pound ALD rule
When a system in a restricted subsector is replaced, the new system must meet the GWP limit in effect for that subsector. For most new comfort cooling equipment, that means a refrigerant with a GWP below 700, which in practice usually means an A2L refrigerant.
Key Milestones
| Date | What Happens | Applies To |
|---|---|---|
| January 1, 2025 (passed) | 700 GWP limit for new residential and light commercial AC and heat pumps and comfort cooling chillers | New equipment procurement |
| January 1, 2026 (passed) | Emissions Reduction and Reclamation leak repair requirements begin for covered appliances of 15 lbs or more; ALD required on new commercial refrigeration and IPR systems of 1,500 lbs or more | Chillers, commercial refrigeration, IPR, and other covered appliances |
| March 1, 2027 | First reports due for appliances that leaked 125 percent or more of full charge in 2026 | Covered appliances |
| January 1, 2027 | ALD required on existing commercial refrigeration and IPR systems of 1,500 lbs or more installed since January 1, 2017; VRF installation deadline for higher-GWP systems | Large refrigeration systems; VRF projects |
| 2029 | HFC allowances drop to 30% of baseline | All facilities using legacy HFC refrigerants |
| January 1, 2032 | Stricter GWP limits for supermarket systems, remote condensing units, and cold storage warehouses | Food retail and cold storage refrigeration |
| 2036 | HFC allowances capped at 15% of baseline | All HFC-dependent equipment |
Capital Planning Considerations
For facilities with aging R-410A equipment, consider the following when setting replacement priorities:
Cost trajectory of R-410A: With allowances at 60 percent of baseline through 2028 and falling to 30 percent in 2029, servicing R-410A equipment is likely to become more expensive as the decade advances.
Leak repair exposure: Covered systems that exceed the applicable leak rate face a 30-day repair window, verification testing, and, if repairs fail, a retrofit or retirement plan. Systems with a history of refrigerant loss deserve early evaluation.
ALD costs for large refrigeration: If you operate commercial refrigeration or process refrigeration systems of 1,500 pounds or more, budget for ALD installation by January 1, 2027, and weigh that cost against replacement for systems near end of life.
Lead times: Build realistic manufacturer lead times into replacement schedules, and confirm the refrigerant and compliance status of any unit before ordering.
Common Compliance Mistakes to Avoid
Assuming drop-in substitution is possible. R-410A equipment should not be recharged with an A2L refrigerant. Equipment is designed, tested, and listed for a specific refrigerant, and A2L equipment carries safety features and listing requirements that legacy units do not.
Misreading the 15-pound threshold. The ER&R leak repair rule applies to covered appliances of 15 pounds or more, but it excludes the residential and light commercial AC and heat pump subsector. Identify each system's subsector before assuming it is in or out.
Assuming ALD applies to all large HVAC systems. The federal ALD requirement applies only to commercial refrigeration and industrial process refrigeration systems of 1,500 pounds or more.
Failing to update service contracts. Existing agreements may not require refrigerant-addition records for leak rate calculations, verification tests, or A2L-trained technicians. Update contracts to cover these explicitly.
Ignoring local code adoption status. A2L provisions in the 2024 IMC apply only where that edition (or an amendment) has been adopted. Confirm the adopted code with your local building department before finalizing designs.
Relying on outdated deadlines. EPA has changed Technology Transitions dates several times, most recently in May 2026. Check EPA's current pages before relying on any deadline.
Conclusion
The AIM Act transition affects commercial facilities in two ways: new equipment must meet subsector GWP limits, and larger existing HFC systems now fall under federal leak repair rules. Build a refrigerant inventory that records charge size and EPA subsector for every system, update service contracts for leak rate recordkeeping and A2L practices, and verify current EPA and local code requirements before each replacement decision.
Sources and References
- Regulatory Actions for Technology Transitions -- U.S. EPA. https://www.epa.gov/climate-hfcs-reduction/regulatory-actions-technology-transitions
- Technology Transitions HFC Restrictions by Sector -- U.S. EPA. https://www.epa.gov/hfcs/technology-transitions-hfc-restrictions-sector
- EPA Finalizes Changes to "Technology Transitions" Provisions of the AIM Act -- Holland & Knight, May 2026. https://www.hklaw.com/en/insights/publications/2026/05/epa-finalizes-changes-to-technology-transitions-provisions
- Q4 2025 Update: EPA's Technology Transitions Program Related to A2L Refrigerants -- International Code Council. https://www.iccsafe.org/building-safety-journal/bsj-technical/q4-2025-update-epas-technology-transitions-program-related-to-a2l-refrigerants/
- Frequent Questions on the Phasedown of Hydrofluorocarbons -- U.S. EPA. https://www.epa.gov/climate-hfcs-reduction/frequent-questions-phasedown-hydrofluorocarbons
- Regulatory Actions for Managing HFC Use and Reuse -- U.S. EPA. https://www.epa.gov/hfcs/regulatory-actions-managing-hfc-use-and-reuse
- Emissions Reduction and Reclamation Program Fact Sheet -- U.S. EPA, September 2024. https://www.epa.gov/system/files/documents/2024-09/err-fact-sheet.pdf
- 40 CFR 84.106 -- Leak Repair -- Cornell Legal Information Institute. https://www.law.cornell.edu/cfr/text/40/84.106
- 40 CFR 84.108 -- Automatic Leak Detection Systems -- Cornell Legal Information Institute. https://www.law.cornell.edu/cfr/text/40/84.108
- What You Need to Know: EPA's Emissions Reduction and Reclamation Program for HFC Refrigerants -- International Code Council. https://www.iccsafe.org/building-safety-journal/bsj-technical/what-you-need-to-know-epas-emissions-reduction-and-reclamation-program-for-hfc-refrigerants/
- Regulatory Updates: Section 608 Refrigerant Management Regulations -- U.S. EPA. https://www.epa.gov/section608/regulatory-updates-section-608-refrigerant-management-regulations
- Section 608 Technician Certification Requirements -- U.S. EPA. https://www.epa.gov/section608/section-608-technician-certification-requirements
- Substitutes in Residential and Light Commercial Air Conditioning and Heat Pumps -- U.S. EPA SNAP Program. https://www.epa.gov/snap/substitutes-residential-and-light-commercial-air-conditioning-and-heat-pumps
- Substitutes in Centrifugal Chillers -- U.S. EPA SNAP Program. https://www.epa.gov/snap/substitutes-centrifugal-chillers
- R466A Passed by ASHRAE with A1 Classification -- Cooling Post. https://www.coolingpost.com/world-news/r466a-passed-by-ashrae-with-a1-classification/
- ASHRAE Refrigeration Resources (Standards 15 and 34) -- ASHRAE. https://www.ashrae.org/technical-resources/bookstore/ashrae-refrigeration-resources
- Code Changes on A2L Refrigerants -- International Code Council. https://www.iccsafe.org/building-safety-journal/bsj-technical/code-changes-on-a2l-refrigerants/
- 2024 I-Code A2L Refrigerant Related Changes -- Washington State Building Code Council. https://sbcc.wa.gov/sites/default/files/2024-05/2024_I-Code_A2L_Related_Changes_FINAL_03.01.2023.pdf
