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Natural refrigerant (not a fluorinated gas) · ASHRAE 34 safety group A1

R-744 GWP and CO₂e

Carbon dioxide. Current and growing. Outside the F-Gas phase-down, with pressure and safety engineering in place of refrigerant compliance.

Great Britain

1

GWP of 1 by definition — carbon dioxide is the reference substance for CO₂-equivalent

EU / Northern Ireland

1

GWP of 1 by definition — carbon dioxide is the reference substance for CO₂-equivalent

The figure is the same in both regimes. Both state their values on an IPCC Fourth Assessment Report basis for this substance, so a number quoted from AR5 or AR6 will not match the one that governs compliance.

Charge in kg → tonnes CO₂e

t CO₂e = charge (kg) × GWP ÷ 1,000. This figure, not the charge in kilograms, is what sets the statutory leak-check frequency.

Charget CO₂e (GB)t CO₂e (EU/NI)
1 kg0.000.00
2 kg0.000.00
5 kg0.010.01
10 kg0.010.01
20 kg0.020.02
50 kg0.050.05
100 kg0.100.10

Leak-check thresholds in kg

Carbon dioxide is not a fluorinated greenhouse gas and the F-Gas leak-check thresholds do not apply to it in either regime. It is the substance CO₂-equivalent is measured against, so its GWP is 1 by definition rather than by an annex. The engineering constraints are pressure and safety: transcritical systems run at pressures far above an HFC plant, and CO₂ is an asphyxiant, so plant-room monitoring is a real design requirement.

Where you meet R-744

  • •Commercial hot water heat pumps
  • •Transcritical refrigeration plant
  • •Cascade systems on the low-temperature side

Maintenance checklists for plant that runs on it

Air Source Heat Pump (ASHP) maintenance checklistCondenser maintenance checklistDry Air Cooler / Adiabatic Cooler maintenance checklist
Work out a specific chargeCompare all 10 refrigerants

Frequently asked questions

What is the GWP of R-744?
1, and the same figure applies in Great Britain and in Northern Ireland. The source is GWP of 1 by definition — carbon dioxide is the reference substance for CO₂-equivalent. Both regimes state their values on an IPCC Fourth Assessment Report basis for these substances, so figures quoted from AR5 or AR6 will differ from the ones that actually govern compliance.
How do I convert an R-744 charge into tonnes CO₂e?
Multiply the charge in kilograms by the GWP and divide by 1,000. A 10 kg charge of R-744 is 0.01 tonnes CO₂e in Great Britain. That figure is what sets the statutory leak-check frequency, not the charge in kilograms.
Does R-744 work differently in Northern Ireland?
Carbon dioxide is not a fluorinated greenhouse gas and the F-Gas leak-check thresholds do not apply to it in either regime. It is the substance CO₂-equivalent is measured against, so its GWP is 1 by definition rather than by an annex. The engineering constraints are pressure and safety: transcritical systems run at pressures far above an HFC plant, and CO₂ is an asphyxiant, so plant-room monitoring is a real design requirement.
Where is R-744 used?
Commercial hot water heat pumps; Transcritical refrigeration plant; Cascade systems on the low-temperature side. Current and growing. Outside the F-Gas phase-down, with pressure and safety engineering in place of refrigerant compliance.