Which Refrigerant Has the Highest GWP?

Among the refrigerants and substitutes listed in the EPA’s current Technology Transitions GWP reference table, HFC-23, commonly identified in refrigeration as R23, has one of the highest published 100-year GWP values at 14,800. Among listed refrigerant blends, R508B is also extremely high at 13,396. Both are far above widely used legacy refrigerants such as R507A at 3,985, R404A at 3,922, R410A at 2,088, and R134A at 1,430 under the same EPA reference framework.

So, Which refrigerant has the highest GWP? The answer depends on what you mean by refrigerant, which reference assessment you use, and whether you are comparing single-component gases, blends, or all industrial greenhouse gases. For practical HVACR comparison using EPA’s Technology Transitions table, R23 is the standout high-GWP single refrigerant. R508B is one of the highest-GWP blends. Industrial gases such as SF6 can have even higher GWP values, but SF6 is not normally treated as a conventional HVACR refrigerant.

R23 Sits Near the Top of Current Refrigerant GWP Tables

Which refrigerant has the highest GWP? In the EPA Technology Transitions reference used for U.S. HFC rules, HFC-23 is listed at 14,800. The United Nations Ozone Secretariat also lists HFC-23 at 14,800 under Annex F of the Montreal Protocol.

Why R23 Has Such a High GWP

GWP compares the climate effect of releasing one mass unit of a greenhouse gas with the effect of the same mass of carbon dioxide over a specified time horizon, commonly 100 years. A gas can have high GWP because it absorbs infrared radiation strongly, remains in the atmosphere for a long time, or both.

HFC-23 is long-lived and radiatively efficient. That combination gives a relatively small release a very large carbon-dioxide-equivalent impact compared with lower-GWP refrigerants.

R23 Is Not a Typical Residential AC Refrigerant

R23 has been used in specialized very-low-temperature and cascade refrigeration applications rather than ordinary residential split systems or mainstream automotive AC. Its high GWP is therefore important, but the refrigerant should not be confused with high-volume products such as R410A or R134A.

The environmental impact of a refrigerant fleet depends on both GWP and how much refrigerant is installed, leaked, recovered, and replaced.

R508B Is One of the Highest-GWP Refrigerant Blends

R508B is another useful example because its GWP is extremely high even compared with legacy commercial refrigerants. EPA’s current reference table lists R508B at 13,396.

R508B Is Used for Specialized Low-Temperature Work

R508B has been used in ultra-low-temperature refrigeration and cascade systems where standard comfort-cooling refrigerants are not suitable. These specialized applications can include laboratory, medical, scientific, and industrial equipment.

The application context matters because highest GWP does not automatically mean most climate impact in the market. A lower-GWP refrigerant used in millions of systems can account for more total emissions than a very high-GWP refrigerant used in a small specialized installed base.

High GWP Makes Leak Prevention Especially Important

With a GWP above 13,000, a small mass loss of R508B represents a large carbon-dioxide-equivalent emission. Recovery practices, leak prevention, maintenance records, and end-of-life handling are therefore especially important.

How Common Refrigerants Compare by GWP

For contractors and facility managers, a comparison with familiar products makes the scale easier to understand. Using one consistent EPA reference framework, R507A is listed at 3,985, R404A at 3,922, R452A at 2,140, R410A at 2,088, R407C at 1,774, R134A at 1,430, R449A at 1,396, R448A at 1,386, R32 at 675, R454B at 465, and R1234YF at 1.

R404A and R507A Are High-GWP Products With Large Installed Bases

R404A and R507A are much lower than R23 on a per-kilogram GWP basis, but they have historically been used extensively in supermarket and other commercial refrigeration systems. That combination of high GWP and meaningful installed charge is why they have been major targets of refrigerant-transition policies.

Royal’s R404A guide provides additional background on its applications and alternative pathways.

R32 and R454B Are Lower, but Not Zero-GWP

R32 at 675 and R454B at 465 are significantly below R410A, which is why they appear in new-generation comfort-cooling equipment. They are still fluorinated refrigerants and should be recovered and handled correctly rather than treated as environmentally harmless.

Royal’s R32 guide explains the role of R32 in the current HVAC transition.

GWP Values Can Change Depending on the Reference

A technically accurate article should not present one GWP number as if the science never changes. Different regulations and publications may use values from different IPCC or WMO assessment cycles.

EPA Rules Use Specified Reference Values

The EPA Technology Transitions GWP reference table identifies the values used for implementation of that program. Those values are the right starting point when discussing a U.S. regulatory limit under that rule.

A technical paper or another jurisdiction may cite a newer scientific assessment with a different value. Peer-reviewed atmospheric research, for example, has published updated HFC-23 100-year GWP estimates that differ from the AR4 value of 14,800.

Regulatory Consistency and Scientific Updates Serve Different Purposes

Regulators often lock a specific assessment framework into a rule so companies can calculate compliance consistently. Scientists continue refining atmospheric lifetimes and radiative efficiencies as measurement and modeling improve.

When comparing refrigerants for purchasing or equipment planning, state which GWP framework you are using instead of combining values from different sources in one table.

What About SF6, NF3, and Other Gases With Even Higher GWP?

This is where the wording refrigerant matters. Some industrial greenhouse gases have GWP values above most refrigerants but are used mainly for other functions.

SF6 Has a Very High GWP but Is Not a Mainstream HVACR Refrigerant

EPA greenhouse-gas inventory guidance has listed sulfur hexafluoride, or SF6, at a 100-year GWP of 22,800 under the AR4 framework. SF6 is widely associated with electrical-insulation and switchgear applications rather than ordinary refrigeration cycles. Calling it the highest-GWP refrigerant without that context can mislead HVAC readers.

HFC-23 Is the More Relevant Answer for Refrigerant Comparisons

For readers comparing recognized refrigerants and refrigerant substitutes in EPA’s current Technology Transitions reference, HFC-23 at 14,800 is the clearer answer. The UN Ozone Secretariat’s controlled-substance list also identifies HFC-23 at 14,800.

Why High GWP Changes Refrigerant Policy

GWP does not determine equipment performance by itself, but it strongly influences climate policy because refrigerant emissions can translate into large carbon-dioxide-equivalent totals.

The AIM Act Phasedown Targets HFC Supply and Use

U.S. policy under the AIM Act includes an HFC phasedown and Technology Transitions restrictions for certain new products and equipment. Limits vary by subsector and effective date, so a refrigerant that is allowed for servicing existing equipment may not be suitable for a new installation.

Facility managers should distinguish between maintaining an installed system and choosing the refrigerant platform for its replacement.

Leak Reduction Can Deliver Immediate Climate Benefits

Replacing a high-GWP refrigerant in future equipment matters, but so does preventing leaks from existing systems. A well-maintained R404A or R507A system that retains its charge creates less direct refrigerant emission than a poorly maintained system with repeated losses.

GWP Is Not the Only Factor in Refrigerant Selection

The lowest GWP number does not automatically identify the correct refrigerant for every system. Safety, pressure, capacity, efficiency, materials compatibility, code requirements, and equipment design all matter.

Safety Classification Must Be Considered

Some very-low-GWP refrigerants are mildly flammable or highly flammable, while others operate at very high pressure or have toxicity considerations. Equipment is engineered around those characteristics.

R1234YF, for example, has very low GWP but an A2L classification. Honeywell’s Solstice R1234YF data lists the product as A2L and reports a GWP below 1 under its current technical reference.

Equipment Approval Comes Before Refrigerant Preference

Do not put a lower-GWP refrigerant into an existing system simply because its climate number looks better. Compressor maps, expansion devices, oils, pressure ratings, heat exchangers, controls, sensors, and safety measures are refrigerant-specific.

Use the equipment manufacturer’s approved refrigerant or a documented retrofit procedure.

How Buyers Should Use GWP Information

GWP is most useful when it becomes one input in a broader equipment and inventory plan rather than a stand-alone shopping metric.

Separate Legacy-Service Inventory From New-Equipment Strategy

A contractor may still need R404A, R410A, or R134A to maintain installed equipment even while purchasing new systems built around R448A, R449A, R32, R454B, R1234YF, R744, or another lower-GWP technology. Inventory should reflect the actual equipment population being serviced.

Track Refrigerant Losses, Not Only Purchases

For high-GWP refrigerants, repeated additions can signal a leak problem with significant environmental and financial impact. Track recovered quantities, added refrigerant, leak repairs, and equipment history so purchasing data also supports maintenance decisions.

Frequently Asked Questions

These concise answers clarify common questions about refrigerant GWP.

Which Refrigerant Has the Highest GWP in the EPA Table?

Among the refrigerants in EPA’s current Technology Transitions reference table, HFC-23, commonly known as R23 in refrigeration, is listed at 14,800.

Which Refrigerant Blend Has a Very High GWP?

R508B is listed at 13,396 in the same EPA reference table, making it one of the highest-GWP refrigerant blends shown there.

Is R404A High GWP?

Yes. EPA lists R404A at 3,922, substantially above many newer commercial-refrigeration alternatives.

What Is the GWP of R410A?

EPA’s Technology Transitions table lists R410A at 2,088.

What Is the GWP of R454B?

EPA lists R454B at 465 in its current Technology Transitions reference table.

What Is the GWP of R1234YF?

The current EPA Technology Transitions table lists R1234YF at 1, while other older or application-specific references may show a value such as 4. Always identify the reference framework.

Does Lower GWP Mean I Can Retrofit Any System?

No. Refrigerant compatibility depends on equipment design, pressure, safety classification, oil, controls, and manufacturer approval.

Conclusion: Use GWP as a Decision Tool, Not a Shortcut

R23 stands out at the top of EPA’s current refrigerant GWP reference with a value of 14,800, while R508B is an exceptionally high-GWP blend at 13,396. More familiar legacy products such as R404A, R507A, R410A, and R134A are lower, but their GWPs are still high enough to influence current refrigerant policy and equipment transitions.

If you are managing an installed equipment fleet and need help sourcing the specific refrigerants its documentation still requires while planning around changing inventory needs, contact Royal Refrigerants with the refrigerant types, package sizes, and quantities involved. That keeps procurement aligned with the systems you actually service instead of choosing product from GWP alone.