Scope 1 Refrigerant Leakage Calculator | HFC, HFO, Natural — AR5/AR6, IPCC

What Is Refrigerant Leakage? Scope, Boundary, and Equipment Coverage

Refrigerant leakage is the unintentional release of fluorinated or natural working fluids from refrigeration, air-conditioning, heat-pump, and fire-suppression equipment during normal operation, service, and maintenance. Under the GHG Protocol Corporate Standard, these releases fall under Scope 1 (direct emissions from owned or controlled sources), specifically Category 1.4 — fugitive emissions. They are reported separately from combustion (Category 1.1), process emissions (Category 1.2), and land-use change (Category 1.3) because the emission mechanism is distinct: no chemical conversion is taking place, only escape of high-GWP gas across seals, joints, and connection points.

The boundary is operational. This calculator addresses what leaves the equipment while it is in service on premises the reporting entity owns or operationally controls — including top-up gas added during routine maintenance, which is itself evidence of prior leakage. Refrigerant manufacture, equipment manufacture, end-of-life disposal recovery losses, and the electricity to run the equipment all fall outside this boundary and belong elsewhere in the inventory.

Equipment in Scope

• Stationary air-conditioning: split systems, packaged units, VRF / VRV, rooftop units
• Chillers: building chilled-water plant, process chillers, data-centre cooling loops
• Commercial refrigeration: supermarket display cabinets, walk-in coolers, beverage dispensers
• Industrial refrigeration: cold storage, food processing, pharmaceutical, ice rinks
• Domestic refrigeration (where owned by the reporting entity — typically hospitality, dorms, staff residences)
• Heat pumps: air-source, ground-source, water-source, hybrid systems
• Mobile air-conditioning: own-fleet passenger cars, vans, buses, light commercial
• Transport refrigeration: reefer trucks, refrigerated rail wagons, ship-side reefer containers
• Fire protection: clean-agent suppression systems (FK-5-1-12, HFC-227ea, HFC-125)

What Refrigerant Leakage Is Not — the Manufacturing & Use-Phase Boundary

Four adjacent emission categories are routinely confused with operational refrigerant leakage and should be reported separately:

• Refrigerant manufacture belongs in Scope 3 Category 1 (Purchased Goods and Services). The cradle-to-gate emissions of producing virgin HFC-134a are material — roughly 9 to 14 kgCO₂e per kg refrigerant — but they are an upstream value-chain impact, not a direct emission.
• Equipment manufacture and end-of-life disposal belong in Scope 3 Category 2 (Capital Goods) and Category 12 (End-of-Life Treatment) respectively.
• Electricity to run the equipment is Scope 2. Use the Scope 2 Electricity Calculator for purchased electricity and the location/market-based dual reporting required under GHG Protocol Scope 2 Guidance.
• End-of-life recovery losses (refrigerant lost during equipment decommissioning) are a Tier 2 disposal-phase emission, not a Tier 1 operational emission, and are out of scope for this calculator.

Included vs. Excluded Emissions

For combustion-sourced Scope 1, see the sibling Scope 1 Stationary Combustion Calculator and Scope 1 Mobile Combustion Calculator.

The Calculation Methodology — Tier 1, Tier 2, and Mass Balance

The IPCC 2019 Refinement to the 2006 Guidelines describes three methods for quantifying refrigerant leakage. They differ in data burden, accuracy, and the operator profile they suit. This calculator implements Tier 1; the partner mass-balance methodology reference covers the full comparison.

IPCC Tier 1 — Charge × Leak Rate × GWP (this calculator)

The Tier 1 equation is: emissions (kg CO₂e) = charge (kg) × annual_leak_rate (%) ÷ 100 × GWP-100.

Tier 1 is the appropriate method for any operator with an equipment register listing nameplate refrigerant charges and either a measured leak rate or a willingness to apply the IPCC default for the equipment class. It is the lowest-data-burden method and is fully accepted under the GHG Protocol, ISO 14064-1, CDP, and SBTi reporting frameworks. Its weakness is the linearity assumption — Tier 1 assumes leakage scales smoothly with installed charge, which under-reports event-driven leaks (a failed compressor seal, a forklift puncture, a brazed-joint fatigue crack) that release a large fraction of the charge in a single incident.

IPCC Tier 2 — Assembly, Operation, Disposal Phases

Tier 2 disaggregates the equipment lifecycle into three phases — installation losses (typically 0.5% to 2% of initial charge), annual operational losses (the figure Tier 1 captures), and end-of-life recovery losses (driven by the recovery efficiency of the disposal contractor, typically 70% to 95%). It is more data-intensive and more accurate, and is appropriate for organisations that already track equipment lifecycle stages — for example, supermarket chains with centralised refrigeration asset registers. Tier 2 is out of scope for this calculator; readers who need it should consult the refrigerant leakage mass-balance methodology.

Mass Balance — Σ Purchases − Δ Inventory − Retired Charge

The mass-balance equation is: leaked_mass = refrigerant_purchases − Δ_inventory − retired_equipment_charge − transferred_off_site.

The mass-balance method derives leakage as the residual of a closed accounting equation: every kilogram of refrigerant that entered the organisation in the reporting year must, by conservation of mass, be either still in equipment, still in storage, still in retired equipment awaiting disposal, transferred off-site, or leaked. It is the most defensible figure under third-party verification — ISO 14064-3 verifiers prefer it where the data exist — because it cross-checks the equipment register against actual purchase invoices. Its requirement is operational discipline: full purchase records, a year-start and year-end inventory count, and tracking of retired equipment charge until off-site transfer.

Which method should you use?

For the underlying source documents, see IPCC 2019 Refinement Guidelines and GHG Protocol Corporate Standard Chapter 4.

Equipment-Type Presets — The IPCC Tier 1 Leak-Rate Table

The single biggest user-friendliness lever in this calculator is the equipment-type preset: select the equipment class and the IPCC Tier 1 default leak rate is filled automatically, taken from Table 7.9 of the IPCC 2019 Refinement Volume 3 Chapter 7. The table below is the canonical mapping. The “Calc preset” column is the mid-range value the calculator applies; the IPCC source publishes a range, and where measured or supplier-reported leak rates are available, those should override the default.

The wide IPCC range — note transport refrigeration spanning 15% to 50% — reflects the genuine variation in equipment age, service quality, and operating environment that any large global default must encompass. Where the operator has a maintenance contractor’s service log, supplier-reported leak rate data, or a continuous leak-detection system, the measured value should always be used in place of the default. Documentation requirements under ISO 14064-3 verification are: the measurement period (typically a full calendar year), the basis of the measurement (mass-balance, electronic detection log, or service-log reconciliation), and the asset population over which the rate applies. An override without documentary support will be flagged as an estimated figure by any competent third-party verifier.

GWP Basis — AR6 (Current) vs AR5 (Legacy)

For most emission-factor categories, the difference between IPCC AR5 and AR6 global warming potentials is at the noise level. For refrigerants it is not. The atmospheric chemistry community refined the lifetime estimates and radiative efficiencies of several common HFCs between AR5 (2014) and AR6 (2021), and the resulting GWP-100 shifts are material — some HFCs moved by 6% to 30%. Practitioners need to know which basis they are reporting on and why.

Why two values exist

The IPCC publishes GWPs in each Assessment Report. AR5 (2014) was the regulatory default for the GHG Protocol Corporate Standard and most national inventory regimes through 2023. AR6 (2021) is the current scientific consensus and is now mandated by the EU CSRD ESRS E1 disclosure framework (from FY2024), the UK SECR regulations (from FY2025), CDP (from FY2025 disclosures), and the SBTi target validation criteria. ISO 14064-1 accepts either provided the basis is disclosed. Operators reporting against historical baselines (most commonly a 2019 or 2020 base year set under AR5) face a choice between rebaselining to AR6 or maintaining dual reporting; the GHG Protocol’s published guidance is that base-year recalculation is required when the GWP basis change causes a material shift in inventory totals.

Material AR5 → AR6 drift for common refrigerants

Practical impact on reporting

• SBTi, CDP, EU CSRD ESRS E1, UK SECR (2025+): use AR6 (calculator default).
• UK SECR pre-2025, legacy ISO 14064-1 baselines, historical national inventory submissions: AR5 may still be required.
• Comparability across years: if the base year was set under AR5, either rebaseline to AR6 (preferred under GHG Protocol guidance) or maintain dual disclosure with explicit basis flagging.

The calculator surfaces drift as an inline insight when |AR5−AR6 drift| ≥ 3%, so users switching basis can see the impact on their specific gas mix before exporting. See IPCC AR6, CSRD ESRS E1, and ISO 14064-1 for the underlying disclosure requirements.

Worked Example — Supermarket Chiller, R-404A, 50 kg Charge

A regional supermarket operator owns a medium-commercial refrigeration unit serving the chilled and frozen display cabinets of a single store. The unit was installed in 2018 with a nameplate charge of 50 kg R-404A. No measured leak rate is available — service logs record top-up volumes but not a calculated annual rate — so the IPCC Tier 1 default for the equipment class applies.

Inputs:

• Equipment class: Medium / supermarket refrigeration
• Refrigerant: R-404A
• Charge: 50 kg
• Annual leak rate: 20% (IPCC Tier 1 default for class)
• GWP basis: AR6 (2021)

Calculation: leaked mass = 50 kg × 20% ÷ 100 = 10 kg R-404A. Emissions = 10 kg × 4,170 (AR6 GWP-100) = 41,700 kg CO₂e = 41.7 tCO₂e per year.

The reader is encouraged to enter these figures in the calculator above and verify byte-for-byte. The result should agree with the Audit-mode export to the kilogram.

Inline insights the calculator generates for this case:

• F-Gas phasedown alert. R-404A has a GWP-100 of 4,170 (AR6) — well above the 2,500 threshold that triggers the EU F-Gas Regulation 2024/573 service ban from 2025. The calculator flags this and suggests the standard replacement candidates: R-448A, R-449A, R-454C, or a transition to CO₂ trans-critical systems.
• AR5 / AR6 drift insight. R-404A drift is +6.3% (3,922 → 4,170). If the operator’s base year is on AR5, switching the inventory to AR6 will add 2.5 tCO₂e per year for this single asset.
• Mass-balance cross-check pointer. Single-asset emissions of 41.7 tCO₂e exceed the 10 tCO₂e threshold at which the calculator recommends graduating from Tier 1 defaults to a mass-balance figure for verification defensibility.
• Next-step ladder. Document this as the asset’s baseline. Tighten the service schedule and consider an electronic leak-detection retrofit (typical payback under 18 months for assets at this emissions tier). Pre-budget the F-Gas-compliant replacement before the 2025 service-ban deadline.

EU F-Gas Regulation 2024/573 and the Global Phasedown

The single most consequential piece of regulatory context for any refrigerant inventory is the global HFC phasedown — the binding multilateral commitment to reduce HFC consumption to a fraction of current levels by mid-century. The phasedown is structured globally through the Kigali Amendment to the Montreal Protocol and implemented regionally through the EU F-Gas Regulation, the US AIM Act, and equivalent national instruments. An emissions inventory that does not account for the phasedown’s effect on equipment-replacement planning is a snapshot that will be obsolete by next year’s filing.

The EU F-Gas Regulation 2024/573 — Phasedown Schedule

Regulation (EU) 2024/573, in force from 11 March 2024, replaces the 2014 F-Gas Regulation with a substantially tighter phasedown trajectory. It combines a quota system — capping HFC supply on the EU market and reducing the quota in stepped reductions to roughly 5% of the 2015 baseline by 2050 — with sector-specific bans on new equipment and on service of existing equipment with high-GWP gases.

The Kigali Amendment — The Global Phasedown Framework

The Kigali Amendment to the Montreal Protocol was adopted in October 2016 and entered into force on 1 January 2019. It extends the Montreal Protocol — the most successful environmental treaty in history, originally targeting ozone-depleting CFCs and HCFCs — to cover HFCs, which do not deplete ozone but have high warming potential. The Amendment commits ratifying countries to phase down HFC production and consumption against differentiated baselines and timelines.

Parties are grouped into three categories:

• Non-Article 5 countries (developed: EU, US, UK, Japan, Australia, etc.) freeze in 2019, with reduction steps to 15% of baseline by 2036.
• Article 5 Group 1 countries (most developing economies) freeze in 2024, with reduction steps to 20% of baseline by 2045.
• Article 5 Group 2 countries (India, Pakistan, Iran, Iraq, GCC states) freeze in 2028, with reduction steps to 20% of baseline by 2047.

By the end of 2025, over 160 countries have ratified the Amendment, covering substantially all global HFC consumption. The UNFCCC IPCC scenario modelling estimates that full implementation will avoid up to 0.4 °C of warming by 2100 — the largest single multilateral climate commitment outside the Paris Agreement itself.

For regulatory framing, see EU F-Gas Regulation 2024/573 and Kigali Amendment to the Montreal Protocol.

Refrigerant-Specific Guidance — Common Gases, Replacement Paths, Common Mistakes

The fifty-one refrigerants surfaced in this calculator span six decades of refrigeration chemistry — from the 1930s CFCs phased out under the original Montreal Protocol to the HFO and natural refrigerants now displacing HFCs under Kigali. The eight gases below cover the great majority of in-service charge by mass in commercial inventories.

R-410A — Stationary AC Workhorse (GWP-100: 2,256 AR6)

R-410A is a 50/50 blend of R-32 and R-125 and has been the dominant refrigerant in residential and light-commercial split-system AC since the early 2000s, when it displaced R-22 under the Montreal Protocol HCFC phaseout. Its 2,256 GWP-100 puts it well above the EU F-Gas 750-GWP threshold for new commercial chillers from 2030, and OEMs have already substantially shifted new-equipment production to R-32 (single-component), R-454B, and R-452B. Standard replacement paths for existing R-410A equipment are: continue servicing with R-410A until end-of-equipment-life (still permitted), or undertake a refrigerant retrofit (rare and rarely cost-effective). A common mistake: confusing R-410A with “R-410” (no such gas exists — R-410A is the only commercial form).

R-134a — Mobile AC and Small Commercial (GWP-100: 1,526 AR6)

R-134a (also written HFC-134a — same gas) is single-component and was the global standard for mobile air-conditioning from the early 1990s, when it replaced the ozone-depleting R-12. In the European Union, all new passenger vehicle MAC systems have been required to use a refrigerant with GWP-100 < 150 since 2017 (the MAC Directive 2006/40/EC), which has driven a near-universal shift to R-1234yf. R-134a remains common in small commercial refrigeration, vending machines, and pharmaceutical refrigeration. Common mistake: HFC-134a and R-134a are identical — the “HFC-” prefix is the chemical-class naming convention; the “R-” prefix is the ASHRAE refrigerant designation.

R-32 — The Current Mid-GWP HFC Standard (GWP-100: 771 AR6)

R-32 (difluoromethane, single-component) is the current global standard for new split AC and is a single component of R-410A. With GWP-100 of 771 it is exempt from the 2025 service ban that targets ≥ 2,500-GWP gases, and its sub-1,000 GWP puts it comfortably below the F-Gas thresholds applying to most equipment classes through 2030. It is classified A2L — mildly flammable — and installations above defined charge thresholds require ventilation or charge-limit safety controls under EN 378 and equivalent national standards. Common mistake: R-32 cannot be used as a drop-in for R-410A because the operating pressures and oil compatibility differ — equipment must be designed for R-32 from the outset.

R-404A and R-507A — Commercial Refrigeration (GWP-100: ~4,000 AR6)

R-404A (44%/52%/4% R-125/R-143a/R-134a blend, GWP-100 4,170) and R-507A (50/50 R-125/R-143a, GWP-100 4,299) have been the workhorses of supermarket and industrial low-temperature refrigeration since the 1990s. Their high GWP makes them the primary target of the EU F-Gas 2025 service ban — new virgin gas cannot be used to top up these systems from 2025, though reclaimed/recycled product remains permitted. Replacement paths: R-448A (GWP-100 1,387), R-449A (GWP-100 1,397), R-454C (GWP-100 148), or transition to CO₂ trans-critical systems (R-744, GWP-100 1). Common mistake: assuming a 2025 cliff edge — top-ups with reclaimed product remain compliant, so well-managed equipment can continue in service.

R-1234yf and R-1234ze(E) — HFO Replacements (GWP-100: <1)

The hydrofluoroolefins (HFOs) are the long-term low-GWP replacement chemistry for the HFC class. R-1234yf has displaced R-134a in EU passenger-vehicle MAC since 2017; R-1234ze(E) is finding adoption in commercial chillers. Both are mildly flammable (A2L) and carry a cost premium of roughly 4× to 10× per kg over HFCs — a premium that closes rapidly as production scales. The dominant uncertainty for HFOs is atmospheric chemistry: R-1234yf degrades to trifluoroacetic acid, a persistent environmental pollutant whose long-term impact is the subject of ongoing regulatory review.

Natural Refrigerants — R-290 (Propane), R-717 (Ammonia), R-744 (CO₂)

Natural refrigerants have GWP-100 values of approximately 0 to 3 and are growing market share rapidly under the phasedown pressure. R-744 (CO₂) trans-critical systems are now the dominant new-build technology for European supermarket refrigeration. R-717 (ammonia) has long been standard for large industrial refrigeration (cold storage, food processing) with toxicity safety controls. R-290 (propane) is increasingly common in plug-in commercial refrigeration and heat pumps where the small charge size (typically < 150 g) puts equipment outside the flammability safety-control thresholds.

Legacy HCFC and CFC — R-22, R-11, R-12

R-22 (HCFC, GWP-100 1,960 AR6) was phased out of new equipment in developed countries under the Montreal Protocol from 2010 and is no longer produced for new equipment globally as of 2030. R-11 and R-12 (CFCs) were phased out decades earlier under the original Montreal Protocol. The reason these legacy gases remain in the calculator: in-service equipment continues to leak them, and any operator with pre-2010 chillers, old building AC, or vintage refrigeration in their asset register has a real reporting obligation to capture those leaks. For HCFC and CFC framing, see Kigali Amendment.

Audit Checklist — What Gets Flagged in a Third-Party Verification

Below is the checklist a competent ISO 14064-3 verifier will work through when assessing a refrigerant-leakage line item. Reporters who can satisfy the inclusion items and avoid the red-flag items will pass verification without requalification requests.

Inclusion items the verifier expects to see:

• Equipment register documenting nameplate charge per asset. Aggregated charge totals without per-asset detail are routinely qualified by verifiers.
• Leak-rate basis explicitly stated: measured (preferred, with measurement methodology disclosed), supplier-reported, or IPCC Tier 1 default (acceptable with citation of IPCC 2019 Refinement Vol 3 Ch 7 Table 7.9).
• GWP basis stated: AR6 GWP-100 (IPCC 2021) is the current default. Where AR5 is used, the rationale must be disclosed.
• Refrigerant identity matches the equipment service log. Verifiers will spot-check a sample of assets against service records — R-410A in the register but R-22 in the service log is a verification failure.
• End-of-life recovery losses tracked separately if any equipment was decommissioned in the reporting year.
• Top-up gas reconciled to leakage figure. Mass-balance equivalence — top-up volume should be in the same order of magnitude as calculated leakage for the same asset.

Common red flags that trigger requalification:

• 0% reported leakage for in-service equipment with no service-log evidence of zero top-up across the reporting year.
• AR5 used without disclosure of the basis-choice rationale.
• Refrigerant manufacture emissions accidentally included in Scope 1 (these belong in Scope 3 Category 1).
• Top-up gas counted as a fresh purchase rather than as evidence of prior leakage requiring estimation.
• Leased equipment under lessee operational control reported by the lessor (or vice versa) — operational-control boundary must be applied consistently.

For the verification framework, see ISO 14064-3 Verification.

Regulatory Coverage by Jurisdiction

Refrigerant leakage is a high-priority line item in every major jurisdictional carbon-reporting regime. The instrument differs — direct emission disclosure in some, F-Gas-specific reporting in others, often both layered — but the obligation to quantify and disclose is now near-universal for organisations of any size.

United Kingdom — SECR, UK F-Gas, REFCOM

The UK Streamlined Energy and Carbon Reporting (SECR) framework, mandatory for all UK quoted companies and large unquoted companies and LLPs, requires disclosure of total Scope 1 emissions including fugitives. From FY2025 reporting, AR6 GWP-100 values are the default. The UK F-Gas Regulation, retained from EU law post-Brexit and amended in 2024, mirrors the EU phasedown trajectory. Service technicians handling F-gases require certification through REFCOM, City & Guilds 2079, or equivalent. See UK DEFRA Emission Factors.

European Union — CSRD ESRS E1, EU F-Gas 2024/573

The Corporate Sustainability Reporting Directive (CSRD) brings approximately 50,000 EU and EU-active companies into mandatory sustainability disclosure under the European Sustainability Reporting Standards (ESRS). ESRS E1 (Climate Change) mandates AR6 GWP-100 from FY2024 reporting. The F-Gas Regulation 2024/573 is the binding instrument that implements the EU’s HFC phasedown trajectory. See CSRD ESRS E1 and EU F-Gas Regulation 2024/573.

United States — EPA SNAP, AIM Act, SEC Climate Rules

The US EPA Significant New Alternatives Policy (SNAP) approves and disapproves substitute refrigerants by sector use. The American Innovation and Manufacturing (AIM) Act of 2020 directs EPA to phase down HFC production and consumption to 15% of baseline by 2036 — the US implementation of the Kigali commitment. The SEC Climate Disclosure Rules, where applicable to registrants, require Scope 1 disclosure including refrigerant fugitives. See SEC Climate Disclosure Rules.

Singapore — Carbon Pricing Act, NEA F-Gas Reporting

The Singapore Carbon Pricing Act (CPA), administered by the National Environment Agency, levies a carbon tax on facilities emitting 25,000 tCO₂e or more per year. The tax rate is on a published escalator: S$25/tCO₂e in 2024–2025, rising to S$45 in 2026–2027 and S$50–80 by 2030. F-gas reporting thresholds apply additionally for importers and bulk users. See Singapore Carbon Tax Act.

Data Sources, Factor Versioning, and Update Transparency

Every figure this calculator produces is traceable to a named source document and a MasterBrain row version. Audit-mode export includes the calc-hash and MB version stamp on every result, so any reported figure can be reconstructed exactly from the underlying defaults.

GWP-100 Provenance

• IPCC Sixth Assessment Report (AR6), Working Group I, Chapter 7, Table 7.SM.7 — current default for all 51 refrigerants surfaced.
• IPCC Fifth Assessment Report (AR5), Working Group I, Chapter 8, Appendix 8.A — legacy values, stored in row.alternates.gwp_ar5_100 for the AR5 toggle.
• MasterBrain V3 refrigerants.* keyspace, 51 canonical entries covering HFC blends, HFC pure, HFO, HCFC, CFC, PFC, and natural refrigerants.

Leak-Rate Defaults

• IPCC 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Volume 3, Chapter 7, Table 7.9 — mid-range value of each published range applied as the calculator preset.

AR5 → AR6 Transition

• EU CSRD ESRS E1: AR6 mandatory from FY2024 reporting.
• UK SECR: AR6 mandatory from FY2025 reporting.
• GHG Protocol Corporate Standard: AR6 is the recommended default; AR5 acceptable with disclosure.
• Inline drift insight surfaces when |AR5−AR6 drift| ≥ 3% for the user’s specific gas selection.

MasterBrain Version & Update Schedule

Current MasterBrain version: v2025.55. Refrigerant rows were last updated 2026-05-22 (Phase 17 + 19 cohort). Updates are published quarterly or on the release of a new IPCC Assessment Report. To verify the figures behind any calculation, use Audit-mode export — the resulting JSON includes the calc-hash, the MB version, the per-row source citation, and the timestamp.

For underlying source documents, see IPCC AR6 and IPCC 2019 Refinement Guidelines.

What’s Next? Completing Your Scope 1 Inventory

Refrigerant leakage is one of four core line items in a complete Scope 1 inventory. Typical share by sector — based on aggregated CDP and GHG Protocol scope-disclosure data:

• Commercial real estate and light industrial: refrigerant fugitives are typically 5% to 20% of Scope 1, with stationary combustion (gas-fired heating) dominating.
• Supermarket chains, food retail, and cold-chain logistics: refrigerant fugitives are typically 30% to 70% of Scope 1 — the dominant line item.
• Heavy industry, manufacturing: refrigerant fugitives are typically 2% to 10% of Scope 1, with process emissions and combustion dominating.

Once Scope 1 and Scope 2 are complete, the natural next step is the Scope 3 screening — for most organisations Categories 1 (Purchased Goods), 4 (Upstream Transport), and 6 (Business Travel) carry the largest share of total footprint. For purchased goods, see the Scope 3 Category 1 spend-based calculator.

Frequently Asked Questions

Methodology Notes and Limitations

• Linearity assumption. The IPCC Tier 1 method assumes leak rate scales linearly with installed charge. This is true on average across a large equipment population but does not capture event-driven leaks — a failed compressor seal, a forklift puncture, a brazed-joint fatigue crack — which can release a large fraction of the charge in a single incident.
• Default range variation. IPCC Tier 1 defaults are global mid-range values. Real leak rates vary by ±50% or more depending on equipment age, service-contractor quality, climate, vibration environment, and operating duty cycle. Where measured rates exist, they should always override the default.
• End-of-life recovery not modelled. This calculator does not model end-of-life refrigerant recovery losses (Tier 2 disposal-phase method). Operators decommissioning equipment in the reporting year should report recovery losses separately using the partner methodology reference.
• GWP-100 only. The regulatory default is GWP-100 (the 100-year integrated radiative forcing relative to CO₂). The shorter-horizon GWP-20 metric, relevant for short-lived climate pollutant (SLCP) analyses and increasingly cited in IPCC mitigation scenarios, is not surfaced in this calculator — request separately if needed.
• Blends as composite GWP. Refrigerant blends (R-410A, R-407C, R-448A, etc.) are treated as single-row composite-GWP entries calculated as the mass-weighted average of the constituent gases. The calculator does not model leak fractionation, in which the lighter-vapour-pressure component of a blend escapes preferentially during a slow leak — a second-order effect that becomes material only for blend systems operated near end-of-charge.
• Per-equipment result; aggregate manually. The current calculator returns a per-equipment figure. Aggregation across an equipment register is a manual step; the planned portfolio-mode upgrade (Phase 21 roadmap) will lift this limitation.

For the full method comparison covering IPCC Tier 1, mass-balance, and Tier 2 lifecycle accounting, see the refrigerant leakage mass-balance methodology.