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As any attendee of February's annual AHR Expo will tell you, conversations on topics pertaining to R-410A's impending phaseout were unavoidable, as next January's deadline for the manufacture and import of new R-410A units looms. And, while the commercial HVAC industry is affected most prevalently by EPA mandates aimed at reducing industry's contribution to climate change, regulation will soon impact several other refrigerants and markets as well. In this article, we'll focus on some medium-temperature refrigerants with approaching deadlines of their own and how the markets in which they're commonly used can prepare for their forthcoming phaseouts. Specifically, we'll look at the phaseout of R-448A and R-449A; specifics and deadlines for pertinent legislation and some notable replacement options being weighed by OEMs in the commercial refrigeration market.
Like the bulk of HFC substances facing phasedowns, R-448A and R-449A's regulation is the result of authority granted to the EPA in 2020's American Innovation and Manufacturing (AIM) Act, which empowered EPA to regulate HFC substances. EPA then used that authority to propose a multi-year phasedown schedule, the objective of which is an 85% reduction of HFC production and consumption by 2036.
Among the measures set forth by EPA to meet that reduction goal was the final rule titled "Phasedown of Hydrofluorocarbons: Restrictions on the Use of Certain Hydrofluorocarbons under Subsection (i) of the American Innovation and Manufacturing Act of 2020." Included among its mandates were restrictions on the use of higher-GWP HFCs in new aerosol, foam, and refrigeration, air conditioning, and heat pump products and equipment.1
R-448A and R-449A, both of which were developed as more environmentally friendly alternatives to high-GWP refrigerants like R-404A - itself a replacement for refrigerants like R-12 - are included among HFC refrigerants slated for phasedowns due to the presence of the HFC R-134a in their respective formulas. Additional environmental impact and safety-related properties for both refrigerants can be found in the table below.
| R-448A | R-449A | |
| Global Warming Potential (GWP) | ~1360 | ~1280 |
| Ozone Depletion Percentage (ODP) | 0 | 0 |
| ASHRAE Safety Group | A1 | A1 |
While existing equipment running on R-448A and R-449A should be viable through the end of its service life, manufacturers of new medium-temp refrigeration equipment have a decision to make. A few potential synthetic replacement candidates include R-454A (zeotropic HFO blend), R-454C, R-455A (zeotropic, natural/HFO blend), and R-471A (zeotropic HFO blend). Additional environmental impact and safety-related properties for both refrigerants can be found in the table below.
| R-454A | R-454C | R-455A | R-471A | |
| Global Warming Potential (GWP) | 238 | 146 | 146 | 148 |
| Ozone Depletion Percentage (ODP) | 0 | 0 | 0 | 0 |
| ASHRAE Safety Group | A2L | A2L | A2L | A1 |
It's likely that individual preference and application-specific nuance will inform the replacement decision of many manufacturers, but the four refrigerants above will probably make most short lists for those going the synthetic route. It's worth noting that, like with the higher temp HVAC refrigerant transition, A2L refrigerants, an ASHRAE safety designation that indicates "mild flammability" (exhibiting a maximum burning velocity of no more than 3.9 inches per second at 73.4F and 14.7 psia) appear positioned to become the norm. Several states have updated their building codes to allow for A2L systems and there's ample information on the implications of the designation, which should help facilitate a smoother transition.
On the other hand, natural medium-temp alternatives for commercial refrigeration applications have a more arduous path to widespread adoption. Two refrigerants with performance profiles well suited for such applications are R-290 (propane) and R-600a (isobutane). With GWPs under 5, both refrigerants are among the most environmentally friendly options available and feature sufficient thermal performance for a number of commercial refrigeration applications. However, it's their ASHRAE safety designations of A3 (exhibiting flame propagation in air at 140F and 14.7 psia and lower flammability limits (LFL) less than or equal to 0.0062 lb./ft³ at 73.4F and 14.7 psia or heat of combustion greater than or equal to 8169 Btu/lb.) that currently limit their practical viability in larger systems.
| R-290 (propane) | R-600a (isobutane) | |
| Global Warming Potential (GWP) | ~3 | ~3 |
| Ozone Depletion Percentage (ODP) | 0 | 0 |
| ASHRAE Safety Group | A3 | A3 |
However, given that isobutane and propane systems - especially smaller, self-contained systems - can be viable below current charge limits, coupled with an industry push for greater charge limits in building codes, natural refrigerants are becoming increasingly viable in commercial refrigeration applications. Currently, EPA and safety codes allow for 150 grams of A3 refrigerant per circuit in appliances. UL has approved 500 grams in Std. 60335-2-892, but this has yet to be approved by EPA, ASHRAE Std. 15, and building codes.
2 https://www.achrnews.com/articles/145706-ul-approves-increased-r-290-charge-limits
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