Refrigerant GWP Rankings

GWP by refrigerant family — the climate-driven transition

HVAC refrigerants cluster into four broad chemical families with characteristic GWP ranges. The history of refrigerant transitions tracks each family's environmental issues: chlorine-bearing CFCs and HCFCs phased out for ozone depletion (Montreal Protocol 1987, US EPA SNAP), then high-GWP HFCs phased down for climate impact (Kigali Amendment 2016, EU F-Gas 2014, EPA AIM Act 2020).

• HCFCs (ozone-depleting): R-22 (GWP 1810), R-123 (GWP 79). Being phased out worldwide under Montreal Protocol. Production stopped in developed countries 2020. R-22 service continues from reclaimed stock; new equipment uses HFC or HFO alternatives.
• HFCs (high-GWP, no ozone depletion): R-410A (GWP 2088), R-134a (GWP 1430), R-404A (GWP 3922). Currently being phased down under AIM Act (700 GWP cap for new residential AC equipment as of 2025) and EU F-Gas (150 GWP cap for most stationary refrigeration). Service supply persists during the wind-down via reclaimed and allocated production.
• HFCs / HFOs blends (low to medium GWP): R-32 (GWP 675), R-454B (GWP 466), R-454C (GWP 148), R-455A (GWP 148), R-448A (GWP 1387), R-449A (GWP 1397). The AIM Act-compliant new-equipment refrigerants for the next decade. R-454C and R-455A sit below the EU F-Gas 150 threshold.
• HFOs (low-GWP, short atmospheric lifetime): R-1234yf (GWP 4), R-1234ze (GWP 7), R-1233zd (GWP 1), R-1336mzz (GWP 9). Engineered for very low GWP via short atmospheric lifetime. Used in mobile AC (R-1234yf) and chillers (R-1234ze, R-1233zd, R-1336mzz).
• Natural refrigerants (~zero GWP): R-744 (CO₂, GWP 1 by definition), R-717 (NH₃, GWP 0), R-290 (propane, GWP 3), R-1270 (propylene, GWP 2), R-600a (isobutane, GWP 3). Used in commercial refrigeration (R-744, R-290), industrial refrigeration (R-717), and small appliances (R-290, R-600a).

Sector-by-sector transition timeline (AIM Act + EU F-Gas)

The EPA AIM Act and EU F-Gas Regulation set sector-specific phase-down schedules with GWP caps for new equipment by category. Most major sectors have 2024-2026 transition dates for new equipment; service of existing equipment continues indefinitely with declining refrigerant allocations.

• Residential / light commercial AC (US, 2025+): GWP cap 700. R-410A (GWP 2088) prohibited in new equipment. Replaced by R-32 (GWP 675) or R-454B (GWP 466).
• Commercial refrigeration MT / LT (US, 2025+): GWP cap 150-300 depending on sub-sector. R-404A (GWP 3922) and R-507A (GWP 3985) prohibited in new equipment. Replaced by R-454C, R-455A, R-448A, R-449A, R-744 transcritical.
• Centrifugal chillers (US, 2025+): GWP cap 700. R-134a (GWP 1430) phasing out in new equipment. Replaced by R-513A (GWP 631), R-1234ze (GWP 7), or R-1233zd (GWP 1) depending on chiller manufacturer.
• Mobile AC (US, 2021+ per SNAP): GWP cap 150. R-134a (GWP 1430) prohibited in new vehicles. Replaced by R-1234yf (GWP 4). Most 2017+ vehicles in US already on R-1234yf.
• EU stationary refrigeration (most categories): GWP cap 150 since 2022-2025. Tighter than AIM Act in most sectors — drove early adoption of R-454C, R-455A, R-744 in European markets.

AR5 vs AR6 — which one applies?

IPCC publishes updated GWP values with each Assessment Report. AR5 (2013) is the figure most regulations anchor to — including the EPA AIM Act, EU F-Gas Regulation, and the Kigali Amendment to the Montreal Protocol. AR6 (2021) provides updated values that are gradually being adopted in newer standards. Where the two differ meaningfully, both are shown.

For regulatory compliance and reporting, the AR5 value is what you reference unless a specific regulation cites otherwise. AR6 values are typically slightly higher for HFCs (revised methodology accounts for additional atmospheric effects) and slightly lower for some HFOs. The methodology change does not affect the regulatory threshold positions — a refrigerant above 700 GWP per AR5 remains regulated by AIM Act regardless of its AR6 value.

TEWI and LCCP — beyond direct GWP

Total Equivalent Warming Impact (TEWI) and Life Cycle Climate Performance (LCCP) account for both direct refrigerant emissions (from leakage and end-of-life disposal) and indirect emissions from energy consumption over the equipment's lifetime. A high-GWP refrigerant in a hermetic system with very low leak rate and high efficiency can have a lower total impact than a low-GWP refrigerant in a leakier or less efficient system.

For chillers, the indirect (energy) component typically dominates TEWI by 80-90% — meaning chiller efficiency matters more than refrigerant GWP for total climate impact. For residential AC and commercial refrigeration with higher leak rates, the balance shifts: a 5-10% annual leak rate over a 15-year equipment life can tip TEWI in favor of low-GWP refrigerants. The right metric depends on the application.

International regulatory landscape

The Kigali Amendment to the Montreal Protocol (signed 2016, entered force 2019) commits 198 countries to a coordinated HFC phase-down. The schedule differs by country group: developed countries (Article 5 non-parties) cut from 2019 with 85% reduction by 2036; developing countries follow a delayed schedule. The AIM Act (US) and EU F-Gas Regulation are the regional implementations of Kigali for those jurisdictions.

Japan's Fluorocarbon Emissions Control Law (1998, amended several times) was an early national HFC management framework. China's implementation of Kigali started in 2024 with a freeze schedule. The international landscape continues to evolve; for current compliance, check the regulatory framework in your jurisdiction.

What's not in this table

Energy efficiency and operational emissions matter as much as direct refrigerant emissions for total climate impact (TEWI, LCCP). A high-GWP refrigerant in a hermetic system with very low leak rate can have a lower total impact than a low-GWP refrigerant in a leakier system with worse efficiency. GWP alone is necessary but not sufficient for environmental decision-making.

How GWP is actually computed

Global Warming Potential expresses the radiative forcing impact of a refrigerant relative to CO₂ over a chosen time horizon. The default for HVAC regulatory use is the 100-year value (GWP₁₀₀), though 20-year (GWP₂₀) is sometimes referenced for short-lived refrigerants where the short-term impact dominates. The calculation involves three factors: the refrigerant's radiative efficiency (how strongly it absorbs infrared per molecule), its atmospheric lifetime (how long it persists before decomposing), and the chosen integration horizon.

Higher radiative efficiency + longer lifetime = higher GWP. R-23 (trifluoromethane) has a GWP of 14,800 because of its 222-year atmospheric lifetime; the much stronger absorber R-32 has GWP 675 because its lifetime is only 4.9 years; the HFOs (R-1234yf, R-1234ze) have very low GWP (1-7) primarily because of their short atmospheric lifetimes (10-13 days for R-1234yf).

For zeotropic blends, GWP is computed as the mass-weighted average of the component GWPs per IPCC AR5 methodology. R-454B (68.9% R-32 + 31.1% R-1234yf): GWP = 0.689 × 675 + 0.311 × 4 = 466. R-454C (21.5% R-32 + 78.5% R-1234yf): GWP = 0.215 × 675 + 0.785 × 4 = 148. Same components, different proportions, very different GWPs.

Common GWP misconceptions

"Low-GWP refrigerants are always better for the climate." Not necessarily. Total Equivalent Warming Impact (TEWI) accounts for both direct refrigerant emissions (leakage, end-of-life disposal) and indirect emissions from equipment energy consumption. For chillers with low annual leak rates and multi-decade equipment lifetimes, the indirect (energy) component dominates TEWI by 80-90% — meaning chiller efficiency matters more than refrigerant GWP for total climate impact. A 5% efficiency improvement on an R-134a chiller can offset the climate benefit of switching to R-513A.

"HFO refrigerants are zero-GWP."They're very low GWP, not zero. R-1234yf is GWP 4 (AR5) — small but not zero. The atmospheric decomposition product trifluoroacetic acid (TFA) is a separate environmental concern under active study; current regulatory consensus is that TFA from R-1234yf atmospheric breakdown is below ecotoxicity thresholds but ongoing monitoring continues.

"Natural refrigerants are GWP-free."Mostly true with caveats. R-744 (CO₂) is GWP 1 by definition (it's the reference compound). R-717 (NH₃) is GWP 0. R-290 (propane) is GWP 3 by AR5. R-1270 (propylene) is GWP 2. The handling and safety implications of natural refrigerants (flammability for hydrocarbons, toxicity for ammonia) shift the trade-off from climate to equipment design — they're not strictly better, just different constraints.

"The AIM Act bans R-410A." Imprecise. The AIM Act caps GWP at 700 for new residential AC equipment as of January 2025 — meaning equipment manufacturers can no longer ship new R-410A residential AC. Service of existing R-410A equipment continues indefinitely; refrigerant production is declining via allocation schedule, not banned outright. Plan refrigerant cost escalation over equipment lifetime.

Refrigerant lifetime context — why GWP differs from atmospheric persistence

Atmospheric lifetime is one of the three inputs to the GWP calculation but it's often the dominant one for high-GWP refrigerants. Examples from IPCC AR5: R-23 (HFC-23) has atmospheric lifetime 222 years and GWP 14,800; R-125 has lifetime 28.2 years and GWP 3,170; R-134a has lifetime 13.4 years and GWP 1,430; R-32 has lifetime 4.9 years and GWP 675; R-1234yf has lifetime 0.029 years (~10.6 days) and GWP 4.

The dramatic drop in GWP from R-134a to R-1234yf comes primarily from the atmospheric lifetime collapse — both have similar radiative efficiency on a per-molecule basis, but R-1234yf decomposes in the atmosphere within weeks while R-134a persists for over a decade. This is why HFO chemistry is the path to ultra-low GWP refrigerants: short atmospheric lifetime drops the GWP arithmetic even if radiative efficiency is similar.

For natural refrigerants, the lifetime argument is different. CO₂ has effectively infinite atmospheric lifetime (it's the reference compound with GWP 1 by definition); the climate impact of CO₂ is integrated into the GWP framework as the baseline rather than computed from lifetime. Ammonia (R-717) has very short atmospheric lifetime (decomposes rapidly), giving it GWP 0 in regulatory accounting. Hydrocarbons (R-290 propane, R-600a isobutane) have short atmospheric lifetimes giving low single-digit GWPs (3 for R-290 per AR5).

Methodology notes — IPCC AR5 vs AR6

IPCC publishes updated GWP values periodically as atmospheric chemistry understanding improves. The shift from AR5 (2013) to AR6 (2021) updated many HFC values slightly upward due to revised radiative-efficiency calculations that account for additional atmospheric effects not previously included. The shift from AR4 (2007) to AR5 was also non-trivial.

Regulatory bodies typically lag the IPCC updates by 5-10 years for compliance stability. The EPA AIM Act, EU F-Gas Regulation, and Kigali Amendment all currently use AR5 values; AR6 adoption is gradual. For ground-truth regulatory compliance, use the value cited by the specific regulation. For scientific analysis or forward-looking planning, AR6 represents the current best estimate. The table on this page shows both where they differ meaningfully.