| Emissions Source | Unit | kg CO₂–e/unit |
|---|---|---|
| Refrigerants | ||
| Propane (R–290) – C₃H₈ | kg | 0.06 |
| Isobutane(R–600a) – C₄H₁₀ | kg | 3 |
| Nitrous oxide (R–744a) – N₂O | kg | 265 |
| Carbon dioxide (R – 744) – CO₂ | kg | 1 |
| Methane – CH₄ | kg | 28 |
| Substances controlled by the Montreal Protocol | ||
| CFC–13 (R–13) – CClF₃ | kg | 13900 |
| HCFC–123 (R–123) – CHCl₂CF₃ | kg | 79 |
| Carbon tetrachloride (R–10) – CCl₄ | kg | 1730 |
| HCFC–225ca (R–225ca) – CHCl₂CF₂CF₃ | kg | 127 |
| HCFC–225cb (R– 225cb) – CHClFCF₂CClF₂ | kg | 525 |
| Halon–1211 (R–1211) – CBrClF₂ | kg | 1750 |
| HCFC–124 (R–124) – CHClFCF₃ | kg | 527 |
| HCFC–141b (R–141b) – CH₃CCl₂F | kg | 782 |
| HCFC–142b (R–142b) – CH₃CClF₂ | kg | 1980 |
| CFC–115 (R–115) – CClF₂CF₃ | kg | 7670 |
| HCFC–21 – CHCl₂F | kg | 148 |
| CFC–114 (R–114) – CClF₂CClF₂ | kg | 8590 |
| CFC–11 (R–11) – CCl₃F | kg | 4660 |
| CFC–113 (R–113) – CCl₂FCClF₂ | kg | 5820 |
| Halon–1301 (R–1301) – CBrF₃ | kg | 6290 |
| Halon–2402 (R–2402) – CBrF₂CBrF₂ | kg | 1470 |
| Methyl bromide – CH₃Br | kg | 2 |
| Methyl chloroform – CH₃CCl₃ | kg | 160 |
| CFC–12 (R–12) – CCl₂F₂ | kg | 10200 |
| HCFC–22 (R–22) – CHClF₂ | kg | 1760 |
| Hydroflurocarbons | ||
| HFC–32 (R–32) – CH₂F₂ | kg | 677 |
| HFC–236fa (R–236fa) – CF₃CH₂CF₃ | kg | 8060 |
| HFC–245fa (R – 245fa) – CHF₂CH₂CF₃ | kg | 858 |
| HFC–236cb – CH₂FCF₂CF₃ | kg | 1210 |
| HFC–23 (R–23) – CHF₃ | kg | 12400 |
| HFC–227ea (R–227ea) – CF₃CHFCF₃ | kg | 3350 |
| HFC–245ca – CH₂FCF₂CHF₂ | kg | 716 |
| HFC–134 – CHF₂CHF₂ | kg | 1120 |
| HFC–134a (R–134a) – CH₂FCF₃ | kg | 1300 |
| HFC–125 (R–125) – CHF₂CF₃ | kg | 3170 |
| HFC–152 – CH₂FCH₂F | kg | 16 |
| HFC–143 – CH₂FCHF₂ | kg | 328 |
| HFC–43–10mee – CF₃CHFCHFCF₂CF₃ | kg | 1650 |
| HFC–365mfc (R– 365mfc) – CH₃CF₂CH₂CF₃ | kg | 804 |
| HFC–236ea – CHF₂CHFCF₃ | kg | 1330 |
| HFC–161 – CH₃CH₂F | kg | 4 |
| HFC–152a (R–152a) – CH₃CHF₂ | kg | 138 |
| HFC–143a (R–143a) – CH₃CF₃ | kg | 4800 |
| HFC–41 – CH₃F | kg | 116 |
| Perfluorinated Compounds | ||
| Perfluorocyclopropane – c–C₃F₆ | kg | 9200 |
| PFC–91–18 – C₁₀F₁₈ | kg | 7190 |
| Sulphur hexafluoride – SF₆ | kg | 23500 |
| Trifluoromethyl sulphur pentafluoride – SF₅CF₃ | kg | 17400 |
| PFC–318 – c–C₄F₈ | kg | 9540 |
| PFC–51–14 – n–C₆F₁₄ | kg | 7910 |
| PFC–41–12 – n–C₅F₁₂ | kg | 8550 |
| Nitrogen trifluoride – NF₃ | kg | 16100 |
| PFC–31–10 – C₄F₁₀ | kg | 9200 |
| PFC–116 – C₂F₆ | kg | 11100 |
| PFC–14 – CF₄ | kg | 6630 |
| PFC–218 – C₃F₈ | kg | 8900 |
| Fluorinated Ethers | ||
| HFE–338pcc13 (HG–01) – CHF₂OCF₂CF₂OCHF₂ | kg | 2910 |
| HFE–338mcf2 – CF₃CH₂OCF₂CF₃ | kg | 929 |
| HFE–329mcc2 – CHF₂CF₂OCF₂CF₃ | kg | 3070 |
| HCFE–235da2 (Isoflurane) – CHF₂OCHClCF₃ | kg | 491 |
| HFE–227ea – CF₃CHFOCF₃ | kg | 6450 |
| HFE–125 – CHF₂OCF₃ | kg | 12400 |
| HFE–134 – CHF₂OCHF₂ | kg | 5560 |
| HFE–143a – CH₃OCF₃ | kg | 523 |
| HFE–347mcc3 – CH₃OCF₂CF₂CF₃ | kg | 530 |
| HFE–347mcf2 – CHF₂CH₂OCF₂CF₃ | kg | 854 |
| HFE–347pcf2 – CHF₂CF₂OCH₂CF₃ | kg | 889 |
| HFE–356mec3 – CH₃OCF₂CHFCF₃ | kg | 387 |
| HFE–356pcc3 – CH₃OCF₂CF₂CHF₂ | kg | 413 |
| HFE–356pcf2 – CHF₂CH₂OCF₂CHF₂ | kg | 719 |
| HFE–356pcf3 – CHF₂OCH₂CF₂CHF₂ | kg | 446 |
| HFE–365mcf3 – CF₃CF₂CH₂OCH₃ | kg | 1 |
| HFE–374pc2 – CHF₂CF₂OCH₂CH₃ | kg | 627 |
| HFE–245fa1 – CHF₂CH₂OCF₃ | kg | 828 |
| HFE–245fa2 – CHF₂OCH₂CF₃ | kg | 812 |
| HFE–254cb2 – CH₃OCF₂CHF₂ | kg | 301 |
| HFE–245cb2 – CH₃OCF₂CF₃ | kg | 654 |
| HFE–236ca12 (HG–10) – CHF₂OCF₂OCHF₂ | kg | 5350 |
| HFE–236ea2 – CHF₂OCHFCF₃ | kg | 1790 |
| HFE–236fa – CF₃CH₂OCF₃ | kg | 979 |
| HFE–263fb2 – CF₃CH₂OCH₃ | kg | 1 |
| HFE–43–10pccc124 (H–Galden 1040x) – CHF₂OCF₂OC₂F₄OCHF₂ | kg | 2820 |
| HFE–449sl (HFE–7100) – C₄F₉OCH₃ | kg | 421 |
| HFE–569sf2 (HFE–7200) – C₄F₉OC₂H₅ | kg | 57 |
| Perfluoropolyethers | ||
| PFPMIE – CF₃OCF(CF₃)CF₂OCF₂OCF₃ | kg | 9710 |
| Hydrocarbons and other compounds – Direct Effects | ||
| Chloroform – CHCl₃ | kg | 16 |
| Halon–1201 – CHBrF₂ | kg | 376 |
| Methyl chloride – CH₃Cl | kg | 12 |
| Methylene chloride – CH₂Cl₂ | kg | 9 |
| Dimethylether – CH₃OCH₃ | kg | 1 |
| Refrigerant blends: Zeotropes | ||
| 416A – R–134a/124/600 (59.0/39.5/1.5) | kg | 975.21 |
| 422A – R–125/134a/600a (85.1/11.5/3.4) | kg | 2847.272 |
| 409A – R–22/124/142b (60.0/25.0/15.0) | kg | 1484.75 |
| 436A – R–290/600 (56.0/44.0) | kg | 1.3536 |
| 406A – R–22/600a/142b (55.0/4.0/41.0) | kg | 1779.92 |
| 403B – R–290/22/218 (5.0/56.0/39.0) | kg | 4456.603 |
| 410A – R–32/125 (50.0/50.0) | kg | 1923.5 |
| 407C – R–32/125/134a (23.0/25.0/52.0) | kg | 1624.21 |
| 407F – R–32/125/134a (30.0/30.0/40.0) | kg | 1674.1 |
| 408A – R–125/143a/22 (7.0/46.0/47.0) | kg | 3257.1 |
| 502 – R–22/115 (48.8/51.2) | kg | 4785.92 |
| 436B – R–290/600 (52.0/48.0) | kg | 1.4712 |
| 404A – R–125/143a/134a (44.0/52.0/4.0) | kg | 3942.8 |
| 417A – R–125/134a/600 (46.6/50.0/3.4) | kg | 2127.322 |
| 413A – R–218/134a/600a (9.0/88.0/3.0) | kg | 1945.09 |
| 409B – R–22/124/142b (65.0/25.0/10.0) | kg | 1473.75 |
| Refrigerant blends: Azeotropes | ||
| 507A – R–125/143a (50.0/50.0) | kg | 3985 |
| Medical Gases (AR5 GWPs) | ||
| HFE–347mmz1 (Sevoflurane) – (CF₃)₂CHOCH₂F | kg | 216 |
| Entonox – N2O/O2 (57.9/42.1) (50.0/50.0 vol.) | kg | 153.435 |
| HCFE–235da2 (Isoflurane) – CHF₂OCHClCF₃ | kg | 491 |
| HFE–236ea2 (Desflurane) – CHF₂OCHFCF₃ | kg | 1790 |
| Entonox – N2O/O2 (57.9/42.1) (50.0/50.0 vol.) | kg | 153.435 |
| HCFE–235da2 (Isoflurane) – CHF₂OCHClCF₃ | kg | 491 |
| HFE–236ea2 (Desflurane) – CHF₂OCHFCF₃ | kg | 1790 |
| HFE–347mmz1 (Sevoflurane) – (CF₃)₂CHOCH₂F | kg | 216 |
4 Refrigerant and other gases
4.1 Overview of changes since previous update
| Domain | Emission factors | Size of change | Explanation for change |
|---|---|---|---|
| Refrigerant & other gases | Propane (R-290) | -98% | Last year's edition of the Measure Emissions Guide used the AR4 value for this emissions factor. It has since been corrected to reflect the AR5 value. |
| 436A | -55% | This refrigerant blend contains R-290 and is affected by the correction to Propane (R-290). This gas has a low GWP at 1.35 kg CO2-e. | |
| 436B | –51% | This refrigerant blend contains R-290 and is affected by the correction to Propane (R-290). This gas has a low GWP at 1.47 kg CO2-e. |
4.2 Refrigerant use
GHG emissions from hydrofluorocarbons (HFCs) are associated with unintentional leaks and spills from refrigeration units, HVAC systems, air conditioners and heat pumps. Quantities of HFCs in a GHG inventory may be small, but HFCs have very high GWPs so emissions from this source may be material. Also, emissions associated with this sector have grown significantly as they replace ozone depleting chemicals such as CFCs and HCFCs.
The list of refrigerant gases is continuously evolving with technology and scientific knowledge. We note that if a known gas is not listed in this guide, it does not imply there is no impact.
Emissions from HFCs are determined by estimating refrigerant equipment leakage and multiplying the leaked amount by the GWP of that refrigerant. There are three methods depending on the data available, see section Section 4.3.1, Section 4.3.2, and Section 4.3.3.
If you consider it likely that emissions from refrigerant equipment and leakage are a significant proportion of your total emissions (eg, greater than 5 per cent), include them in your GHG inventory. You may need to carry out a preliminary screening test to determine if this is a material source.
If the reporting entity owns or controls the refrigeration units, emissions from refrigeration are direct (Scope 1). If the entity leases the unit, associated emissions should be reported under indirect (Scope 3) emissions.
4.3 Global warming potentials (GWPs) of refrigerants and other GHGs
Table 4.2 details the GWPs (shown in kg CO2-e) of the refrigerants included in this section. The GWP is effectively the emission factor for each unit of refrigerant gas lost to the atmosphere. The guide uses the 100 year GWPs from the IPCC’s AR5 to ensure consistency with New Zealand’s Greenhouse Gas Inventory 1990–2023.
Some refrigerants are a mixture (or blend) of gases. If you know the blend composition, you can calculate the GWP based on the percentage mass of each gas. Alternatively, for the AR5 GWP of various refrigerant mixtures, see Section B.1.
These emission factors refer to direct emissions, not the indirect emissions associated with the production and supply of these refrigerants.
4.3.1 GHG inventory development
There are three approaches to estimate HFC leakage from refrigeration equipment, depending on the data available. The ideal method is the top-up method, Method A. Method B is the next best option. Method C is the least preferred because it has the most assumptions.
It is stressed that for all methods, users must individually identify the type of refrigerant because the GWPs vary widely.
Entities should indicate the method(s) used in their inventories to reflect the levels of accuracy and uncertainty.
4.3.2 Method A: Top-up
The best method to determine if emissions have occurred is through confirming if any top-ups were necessary during the measurement period. A piece of equipment is ‘charged’ with refrigerant gas, and any leaked gas must be replaced. Assuming that the system was at capacity before the leakage occurred and is full again after a top-up, the amount of top-up gas is equal to the gas leaked or lost to the atmosphere. The equipment maintenance service provider can typically provide information about the actual amount of refrigerant used to replace what has leaked.
\[ \begin{aligned} \text{Gas used (kg)} \times \text{GWP} &= \text{Emissions (kg CO}_{2}\text{-e)} \end{aligned} \]
Where:
- E = emissions from equipment in kg CO2-e
- GWP = the 100-year global warming potential of the refrigerant used in equipment Table 4.2, shown as kg CO2-e
4.3.3 Methods B and C: Screening
If top-up amounts are not available, we recommend using one of the following two methods for estimating leakage, depending on the equipment and available information. Section B.1 details both methods.
Method B is based on default leakage rates and known refrigerant type and volume. Use Method B when the type and amount of refrigerant held in a piece of equipment are known.
Method C is the same as Method B except that it allows default refrigerant quantities to be used as well as default leakage rates. Use Method C to estimate both volume of refrigerant and leakage rate when the amount of refrigerant held in a piece of equipment is not known.
Methods B and C are based on the screening approach outlined in the GHG Protocol HFC tool (WRI/WBCSD, 2005).
For most equipment, Method B is acceptable, especially for factory and office situations where refrigeration and air-conditioning equipment is incidental rather than central to operations. In some cases, Method C is only suitable for a screening estimate. Screening is a way of determining if the equipment should be included or excluded based on materiality of emissions from refrigerants. Entities should then try to source data based on the top-up-method.
We provide refrigerant emissions calculation examples below.
Company A performs a stocktake of refrigeration-related equipment and identifies the following units:
- one large commercial-sized chiller unit
- one commercial-sized office air conditioning unit.
Using the top-up approach, the calculation is as follows:
4.3.3.1 REFRIGERANT USE METHOD A: EXAMPLE CALCULATION
Method A: Top-up
Chiller unit: During the 2022 calendar year, a service technician confirmed a top-up of 6 kg of HFC-134a (AR5 GWP = 1,300) in December 2022. The technician also confirmed that when last serviced at the end of December 2021, no top-ups were needed. So, we assume all the 6 kg of gas was lost during calendar year 2022.
So, for the 2022 calendar,
6 kg HFC-134a x 1300 = 7,800 kg CO₂-e
Air conditioning unit: During the 2022 calendar year, a service technician confirmed a top-up of 6 kg of HFC-143a (AR5 = 4,800) in July 2022. The technician also confirmed that when last serviced at the end of July 2021, no top-ups were needed. So, we assume all the gas was lost at an even rate during the 12 months between service visits, and six of those months sit in the 2022 measurement period.
6 kg/12 months = 0.5 kg per month
So, for the 2022 calendar year inventory, 0.5 × 6 months = 3 kg. Emissions calculate as:
3 kg HFC-143a x 4800 = 14,400 kg CO₂-e
Note: Numbers may not add due to rounding.
If information was not available from the technician, Company A could use the following approach:
4.3.3.2 REFRIGERANT USE METHOD B: EXAMPLE CALCULATION
Method B: Screening method with default annual leakage rate
Chiller unit: Compliance plates on the equipment confirm the refrigerant is HFC-134a (AR5 GWP = 1,300) and the volume held is 12 kg. For the chiller unit size, the default leakage rate is 8%.
So, for the 2022 calendar year,
12 kg HFC-134a x 1300 * 8% = 1,250 kg CO₂-e
Air conditioning unit: A service technician confirms the refrigerant is HFC-143a (AR5 GWP = 4,800) and the volume held is 12 kg. For the size of the unit, the default leakage rate is 3%.
So, for the 2022 calendar year,
12 kg HFC-143a x 4800 * 3% = 1,730 kg CO₂-e
Note: Numbers may not add due to rounding.
The difference between Method A and Method B suggests that the leakage of refrigerant exceeds the default leakage rate, so improved maintenance of the refrigeration systems could help reduce leakage.
4.4 Medical gases use
This section covers emissions from medical gases. Anaesthetic medical gases can be a significant source of direct (Scope 1) emissions in hospitals. The most accurate way to calculate emissions from medical gases is based on consumption data.
4.4.1 Global warming potentials of medical gases
Table 4.3 details the GWPs of the medical gases included in this section (shown in kg CO2-e). The GWP is effectively the emission factor for each unit of medical gas lost to the atmosphere. The guide uses IPCC AR5 GWPs.
Some medical gases consist of a mixture (or blend) of gases. If you know the blend composition, you can calculate the GWP based on the percentage of each gas.
| Emissions Source | Unit | kg CO₂–e/unit |
|---|---|---|
| Medical Gases (AR5 GWPs) | ||
| Entonox – N2O/O2 (57.9/42.1) (50.0/50.0 vol.) | kg | 153.435 |
| HCFE–235da2 (Isoflurane) – CHF₂OCHClCF₃ | kg | 491 |
| HFE–236ea2 (Desflurane) – CHF₂OCHFCF₃ | kg | 1790 |
| HFE–347mmz1 (Sevoflurane) – (CF₃)₂CHOCH₂F | kg | 216 |
4.4.2 GHG inventory development
To calculate medical gas emissions, collect consumption data for each medical gas used by the entity, and multiply this by the GWP for each gas.
\[ \begin{aligned} \text{Gas used (kg)} \times \text{GWP} &= \text{Emissions (kg CO}_{2}\text{-e)} \end{aligned} \]
Medical gases are supplied in bottles or cylinders. If only the volume of the gas is known, an additional calculation to calculate the mass of the gas is required to estimate emissions. This should be done by multiplying the volume (L) of gas by its density (g/mL or kg/L).
4.4.2.1 MEDICAL GAS USE: EXAMPLE CALCULATION
An entity uses 5 bottles of Isoflurane (HCFE-235da2, AR5 GWP = 491) in the reporting period. Each bottle holds 0.3 kg of Isoflurane. Its direct (Scope 1) emissions are:
5 bottles x 0.3 kg = 1.5 kg
Total CO2-e emissions = 1.5 x 491 = 736 kg CO₂-e
An entity uses 5 250 mL bottles of Isoflurane (HCFE-235da2, AR5 GWP = 491) in the reporting period. The density of Isoflurane is 1.49 g/mL. Its direct (Scope 1) emissions are:
5 bottles x 250 mL x 1.49/1,000 = 1.86 kg
Total CO2-e emissions = 1.86 x 491 = 913 kg CO₂-e
Note: Numbers may not add due to rounding.
4.4.3 Assumptions
This approach assumes that all anaesthetic gases used are eventually emitted, including the gases inhaled by patients.