How do I estimate refrigerant leakage if I have no top-up records?

Use a screening estimate: take the refrigerant charge from each unit's nameplate, multiply by a default annual leak rate for that equipment type from IPCC 2006 Table 7.9, then by the gas's GWP. Label the result as an estimate and start keeping service records so next year uses actual top-ups.

The screening formula

Leakage (kg CO2e per year) = nameplate charge (kg) x annual leak rate (%) x GWP of the gas.

Do it unit by unit, or group identical units, and add the results. Only HFCs and other Kyoto gases go into Scope 1. Older units on R-22 leak an ozone-depleting gas that the GHG Protocol lets you report separately, outside the Scope 1 total.

Default operating leak rates by equipment type

IPCC 2006 Guidelines, Volume 3, Chapter 7, Table 7.9 gives ranges of annual operating emissions as a share of the charge. The 2019 Refinement kept these defaults for stationary equipment. Ranges for the common types:

• Residential and commercial air conditioning, including split ACs and heat pumps: 1% to 10%
• Chillers: 2% to 15%
• Medium and large commercial refrigeration (supermarket racks): 10% to 35%
• Mobile air conditioning in vehicles: 10% to 20%
• Domestic refrigerators, stand-alone commercial units (bottle coolers, deep freezers), transport refrigeration and industrial refrigeration including cold storage: read the range for each type from the same Table 7.9 before you use it.

Picking a point in the range

• Use the upper end for old equipment, units serviced only on breakdown, or long pipe runs.
• Use the lower end only for new, factory-sealed units with a documented leak check.
• If unsure, use the midpoint and say so. Whatever you pick, write it down and keep it for the base year.

Where to find the charge

The charge in kg and the gas type are printed on the outdoor unit or chiller nameplate. If a plate is missing, use the manufacturer's data sheet for that model. Do not guess the gas: R-32, R-410A and R-134a have very different GWPs.

Moving off the estimate

1. Ask the AMC vendor to record kg of gas added at every service visit, by unit.
2. Keep those service reports with the invoice.
3. Next year, report top-ups as leakage; they are a better measure than a default rate.

Worked example: one split AC and one chiller

• Split AC: 1.2 kg of R-32 (GWP 771, AR6). Range 1% to 10%
• Low: 1.2 x 0.01 x 771 = 9.3 kg CO2e. High: 1.2 x 0.10 x 771 = 92.5 kg CO2e
• Chiller, 300 TR, nameplate 400 kg of R-134a (GWP 1,530, AR6). Range 2% to 15%
• Low: 400 x 0.02 x 1,530 = 12,240 kg CO2e. High: 400 x 0.15 x 1,530 = 91,800 kg CO2e
• Chiller at the 8.5% midpoint: 400 x 0.085 x 1,530 = 52,020 kg CO2e, about 52 t CO2e

The 1.2 kg and 400 kg charges are illustrative; read the real figures off your nameplates. All figures are screening estimates and should be labelled as such.

What Senseible does here

Senseible calculates refrigerant leakage from measured data, such as the kg of gas charged on a service invoice, and keeps that invoice as the evidence for the Scope 1 line. Once your AMC vendor records top-ups, next year's figure comes straight from those invoices.

• Refrigerant top-up invoice to CO2e
• AR5 or AR6 GWP values
• Cold chain refrigerant leaks

Sources: IPCC 2006 Guidelines, Volume 3, Chapter 7, Table 7.9, IPCC AR6 WG1, Chapter 7 supplementary Table 7.SM.7 (GWP values), US EPA Center for Corporate Climate Leadership, fugitive emissions guidance

Last reviewed 2026-10-17. Leak rate ranges checked against IPCC 2006 Table 7.9 (retained in the 2019 Refinement) and AR6 GWPs against Table 7.SM.7 (HFC-32 771, HFC-134a 1,530); recheck if the IPCC updates either table.