The Environmental Protection Agency (EPA) is currently phasing down the use of hydrofluorocarbons (HFCs) in the United States. This impacts several industries, with a significant focus on the use of specific refrigerants in air conditioning and heat pump equipment. HFC refrigerants, most notably R-410A, replaced hydrochlorofluorocarbon (HCFC) refrigerants like R-22 in the early 2000s to address ozone depletion and reduce global warming potential. A similar phaseout is now underway, albeit with a different goal in mind. Directed by the American Innovation and Manufacturing (AIM) Act, the primary focus is to reduce greenhouse gas emissions and facilitate the transition to alternative refrigerants with lower Global Warming Potential (GWP). The rule mandates an 85% overall reduction in the production and use of climate-damaging chemicals by 2036.
The newly established limit for next-generation refrigerants is 700 GWP.
- R-410A has a GWP of 2,088
The low-GWP refrigerants slated to replace R-410A are listed below and are classified as A2L refrigerants.
- R-32 has a GWP of 675
- R-454B has a GWP of 467
What are A2L Refrigerants?
Refrigerants are classified based on their flammability and toxicity, with the most widely accepted standard being the one established by ASHRAE in Standard 34. The overall standard is described below.
Flammability Classification:
- Class 1: No Flame Propagation
- Refrigerants in this class do not propagate a flame when tested under standard conditions.
- Class 2: Lower Flammability
- Refrigerants that have a lower flammability limit and burn slowly.
- These refrigerants have a flame propagation but burn with a lower intensity.
- Class 2L: Lower Flammability (Subcategory of Class 2)
- These refrigerants are considered to have very low flammability and are non-combustible. A subclass within Class 2, these refrigerants have very low flammability due to their extremely slow burning velocity (less than 10 cm/s), making them safer to handle than other Class 2 refrigerants.
- Class 3: Higher Flammability
- Refrigerants that are highly flammable and can propagate a flame rapidly.
Toxicity Classification:
- Class A: Lower Toxicity
- Refrigerants for which toxicity has not been identified at concentrations less than or equal to 400 ppm (parts per million) by volume, based on occupational exposure limits.
- Class B: Higher Toxicity
- Refrigerants for which there is evidence of toxicity at concentrations below 400 ppm.
Factoring in these two categories, the following combined classifications exist.
Combined Classification:
- A1: Lower toxicity, no flame propagation
- A2L: Lower toxicity, lower flammability, with low burning velocity
- B2: Higher toxicity, lower flammability
- A3: Lower toxicity, higher flammability
The new refrigerants R-32 and R-454B, while sharing the same toxicity classification as R-410A, are categorized as having very low flammability. Therefore, new equipment using these refrigerants will include safety features and design provisions such as:
- Integrated refrigerant monitoring systems that are linked to supply air fan control. If a leak is detected, the supply fan will continue to operate to prevent refrigerant concentration buildup in one area.
- Isolation valves connected to leak detectors, either within equipment or on distribution piping (for split systems), to minimize the dispersion of refrigerant concentration in a localized area.
- Routing refrigerant risers in fire rated, and ventilated, shaft enclosures.
Current Phasedown Timeline
| System/Application | Manufacture/Import Deadline | Installation/Sell-Through Deadline |
| Chillers for comfort cooling | 1/1/2025* | Install Systems by 1/1/2025 Sell Equipment by 1/1/2028 |
| Industrial process refrigerant chillers with exiting fluid from -58oF to -22oF | 1/1/2026 | Install Systems by 1/1/2028 Sell Equipment by 1/1/2031 |
| Industrial process refrigerant chillers with exiting fluid above -22oF | 1/1/2026 | Install Systems by 1/1/2026 Sell Equipment by 1/1/2029 |
| Industrial process refrigerant chillers with exiting fluid below -58oF | N/A | N/A |
| Packaged Air Conditioning & Heat Pumps (refrigerant loop closed in factory) | 1/1/2025 | No install deadline Sell Equipment by 1/1/2028 |
| Through-wall/window units, PTACs, PTHPs, Portable AC & Residential Dehumidifiers | 1/1/2025 | No install deadline Sell Equipment by 1/1/2028 |
| Split Systems, including single phase VRF (<65,000 BTU/hr) | 1/1/2025 | Install Systems by 1/1/2026 |
| Three Phase VRF (>65,000 BTU/hr) | 1/1/2026 | Install Systems by 1/1/2027** |
| Data Center/Computer Room Air Conditioning Equipment | 1/1/2027 | Install Systems by 1/1/2027 Sell Equipment by 1/1/2030 |
*Chillers in these states had an earlier deadline of 1/1/2024 – CA, CO, DE, MA, MD, ME, NJ, NY RI, VA, VT, WA
**EPA released a proposed amendment on 6/19/24 that would extend the proposed installation deadline from 1/1/26 to 1/1/27 (copy of proposed rule can be found here).
Impact on VRF Designs and Installations
For projects that are well into design or starting construction, owners and developers should be mindful of the manufacture/import dates and make an effort to have equipment orders placed in advance of this deadline, to ensure there is adequate stock.
Manufacture/Import Deadlines
- Split systems, including single phase VRF (<65,000 BTU/hr) – 1/1/2025
- Three phase VRF (>65,000 BTU/hr) – 1/1/2026
There is then a one-year period for installation. The EPA website defines “Install” as follows:
“Install” means to complete a field-assembled system’s circuit, including charging with a full charge, such that the system can function and is ready for use for it’s intended purpose.
Installation Deadlines
- Split systems, including single phase VRF (<65,000 BTU/hr) – 1/1/2026
- Three phase VRF (>65,000 BTU/hr) – 1/1/2027
Availability of A2L Equipment
While these systems are widely available in other parts of the world, product lines are still being developed for the US market. Currently, product literature is not available and consulting engineers are unable to obtain selections for manufacturers’ new A2L offerings. Below are the current expected timeframes for when selections and product data can be implemented in design drawings (these dates may differ slightly by manufacturer).
- Single phase systems – Quarter 4 of 2024
- Three phase systems – Quarter 2/3 of 2025
Impact on New and Existing Installations
Existing R-410A systems can still be serviced and maintained. Components such as compressors, coils, and entire condensing and evaporator units will remain available for purchase and repair, provided they are used for maintaining existing systems. Up to 75% of an existing system may be replaced within a three-year period. These parts will be labeled: “FOR SERVICING EXISTING EQUIPMENT ONLY.”