F-gas
CO₂ equivalent of a refrigerant charge (F-gas)
- where
- CO₂ equivalent (tonnes)
- refrigerant charge (kg)
- global warming potential
- charge equal to 5 t CO₂e (kg)
- charge equal to 50 t CO₂e (kg)
- charge equal to 500 t CO₂e (kg)
Explain this equation
Converts a refrigerant charge into tonnes of CO₂ equivalent, the measure the F-gas rules use for leak-check and record-keeping thresholds. It also shows the charge that would hit each threshold for that gas.
GWP says how much warming one kilogram of the gas causes compared with one kilogram of CO₂. Charge in kg times GWP gives kilograms of CO₂ equivalent; dividing by 1000 gives tonnes. Turning the sum round, a threshold in tonnes times 1000 divided by GWP gives the charge in kg that reaches it.
A straight weighting of mass by warming potential.
Sense check: 10 kg of R404A (GWP 3922) is about 39 t CO₂e. The 5 t threshold is reached at only about 1.3 kg of R404A, but at about 7.4 kg of R32 (GWP 675).
Watch out: GB F-gas uses the AR4 GWP values. Using a different assessment report's figures gives a different answer.
Converts a refrigerant charge in kg to tonnes of CO₂ equivalent, the figure that sets F-gas leak-check, record and labelling duties, and shows the charges at the 5, 50 and 500 t thresholds.
Enter your values to see the result.
Good to know
GB F-gas rules (retained Regulation 517/2014 as amended) use the IPCC AR4 100-year GWPs: R32 675, R134a 1430, R404A 3922, R407A 2107, R407C 1774, R407F 1825, R410A 2088, R448A 1387, R449A 1397, R452A 2141, R507A 3985, R513A 631, R1234yf 4, R1234ze 7 (FETA lists 6), R744 1. Use the GWP on the equipment label where given. Use the total system charge, including any additional charge added on site.
Common mistake
Using AR5 or AR6 GWPs (e.g. R134a 1300 or 1530, R32 677 or 771) from manufacturer brochures or emissions-reporting tables instead of the AR4 values used in the F-gas rules, or forgetting the field-added charge.
Limits
Arithmetic only. The HFC values are the same in Northern Ireland, which follows EU Regulation 2024/573 (also AR4 for HFCs), but that regulation gives HFOs such as R1234yf and R1234ze lower AR6-based values. Check the current GB guidance for any change to GWP basis.
Sources
- GOV.UK: Calculate the carbon dioxide equivalent quantity of an F gas (tonnes CO₂e = kg ÷ 1000 × GWP; 10 kg R404A = 39.2 t)
- Linde: Refrigerants and the F-gas Regulation summary sheet (GWP per Regulation 517/2014 Annex I/IV, AR4: R32 675, R134a 1430, R404A 3922, R407C 1774, R410A 2088, R448A 1387, R449A 1397, R513A 631; kg equal to 5/50/500 t CO₂e)
- EFCTC: Selecting and using GWP values for refrigerants (F-gas Regulation 517/2014 uses IPCC AR4 100-year values)
- Defra: F gas guidance for Great Britain (September 2024) – retained Regulation (EU) No 517/2014 as amended
Results are calculations from the published methods and figures shown, and depend on the data you enter. Follow the equipment manufacturer’s data, CIBSE guidance, BS EN 378, the F-gas Regulations and your company procedures. Refrigerant work needs the correct F-gas certification.