# MEMORANDUM

To: Debbie Ottinger, EPA CC: Don Wuebbles, University of Illinois From: Mollie Averyt, Becky Ferenchiak, Mark Flugge, and Kasey Knoell, ICF Date: July 1 4 , 2014 Re: Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GHGRP (EPA Task Order EP - B14H - 00017 , ICF Task Order 022: Support for Implementing and Refining Mandatory GHG Reporting Requirements for Various Emitters of Fluorinated GHGs , Task 3 : Support for Evaluation of GWPs ) T his memorandum presents a summary of an ICF analysis to develop default Global Warming Potentials (GWPs) for fluorinated compounds without peer - reviewed GWPs . These default GWPs are being considered for inclusion in the proposed rule , Greenhouse Gas Reporting Program: Addition of Global Warming Potentials (EPA Docket No. 

### EPA - HQ - OAR - 2009 - 0927 , hereinafter referred to as “Proposed Rule to Add GWPs” ) . This memorandum also includes an ICF analysis to review comments received on the default GWPs that were included in the Proposed Amendments to Subpart L 

### . The purpose of the analysis is to: 1. Consider which sets of compounds should be used as the basis for default GWPs for the different groups of fluorinated GHGs whose GWPs do not appear on Table A - 1 , 2. Calculate the average and the standard deviation of the GWPs for these groups, and 3. Suggest possible default GWPs by rounding the average for each group to one or two significant figures . The remainder of this memorandum is organized i nto the following sections: I. Summary II . Analysis Method for Determining Default GWP Groups III. Comparison between Defaults and Estimated GWPs for Several F
- GHGs IV. Evaluation of Analysis Method by Dr. Wuebbles and Recommendations V. References Appen dix A: F - GHGs by Fluorinated GHG Group Appendix B: Default GWPs Based on AR5 GWPs Appendix C: Evaluation of Default GWPs Considering Numerical and Chemical Outliers Appendix D: Evaluation of the Comments Received on the Proposed Amendments to Subpart L The complete results of the analysis are contained in the spreadsheet “Subpart L Rule Default GWP Chemical G roup Analysis_Comment Analysis_ 7 - 9 - 2014.xlsx.” Please contact Mollie Averyt at 202 - 862 - 1569 ( mollie.averyt@icfi.com ) with any questions or comments.Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 1 

## I. Summary Through the Greenhouse Gas Reporting Program (GHGRP), the U.S. Environmental Protection Agency ( EPA ) receives reports of emissions of numerous fluorinated greenhouse gases (GHGs) and heat transfer fluids (HTFs) that do not have GWPs listed on Table A - 1, the GHGRP’s compendium of GWPs. EPA is proposing to add chemical - specific and default GWPs to Table A - 1 to address this situation . Specifically , EPA is proposing to add approximately 10 0 chemical - specific GWPs published by the Intergovernmental Panel on Climate Change (IPCC) in their Fifth Assessment Report (AR5) (Myhre et al. 2013) in the fall of 2013. For the fluorinated GHG s and HTF s reported under the GHGRP that do not have chemical - specific GWPs in either Table A - 1 or AR5 , EPA is proposing to add default GWPs . These default GWPs would be assigned based on the fluorinated GHG group to which the fluorinated GHG and HTF belonged, based on chemical structure . D efault GWPs would ensure th at the atmospheric impacts of all fluorinated GHGs and HTFs are reflected in facility calculations and carbon dioxide equivalent ( CO 2 

### e ) emissions totals. In developing the fluorinated GHG groups and associated default GWPs , the goal i s to model the GWPs of compounds that belong to each group (but whose GWPs are not on Table A
- 1) with as much accuracy and precision as possible. EPA is applying the following criteria to assess potential compound groups: (1) collectively, the compound gro ups should span the full range of atmospheric behavior (atmospheric lifetimes and GWPs) observed among fluorinated GHGs, (2) within each compound group, the compounds should be chemically similar and exhibit similar atmospheric behavior, and (3) compounds whose atmospheric behavior is likely to be different from that of any of the compounds whose GWPs are being modeled should be excluded from the calculation. However, numerical outliers should be included in the calculation when the possibility exists that such outliers may also occur among the fluorinated GHGs whose GWPs are being modeled. ICF previously performed an analysis based on these criteria to develop default GWPs that were proposed for purposes of reporti ng emissions under subpart L. 1 

### EPA proposed five fluorinated GHG groups and associated default GWPs in the P roposed A m endments to Subpart L 2 

### , as shown in Table 1 . Table 1 . Fluorinated GHG Groups and A s sociated Default GWPs in Proposed Amendments to Subpart L

Fluorinated GHG Group GWP in Proposed Amendments to Subpart L (100 - yr ) Average GWP Standard

Deviation of GWP Fully fluorinated GHGs 10,000 9,857 3,450 Saturated hydrofluorocarbons (HFCs) 2,200 2,187 3,346 Saturated hydrofluoroethers (HFEs) and saturated hydrochlorofluoroethers (HCFEs) a 1,600 1,5 36 2,5 36 Unsaturated perfluorocarbons ( PFCs ) , unsaturated HFCs, unsaturated hydrochlorofluorocarbons ( HCFCs ) , unsaturated HFEs, and fluorinated ketones 1 0.42 0.62 Other fluorinated GHGs b 100 1 12 1 77 a The average GWP and standard deviation for this group were revised from 1,559 and 2,551, respectively, after including 2 - Chloro - 1,1,2 - trifluoro
- 1 - methoxyethane , which was previously mis categorized in “Other fluorinated GHGs.” b The average GWP and standard deviation for this group were revised from 103 and 183, respectively, after removing fluorotelomer alcohols and fluorinated aldehyde s , which were previously categorized in “Other fluorinated GHGs , ” which at the time was the most appropriate category.

1 “Analysis of Potential Default GWPs for Fluorinated GHGs Reported Under the GHGRP,” available in docket EPA
- HQ - OAR 2009 - 0927. 2 Greenhouse Gas Reporting Program: Amendments and Confidentiality Determinations for Fluorinated Gas Production (78 FR 69337, November 19, 2013).Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 2 

### Three commenters, DuPont, 3M, and the American Chemistry Council (ACC) provided comments regarding the chemical groups and associated GWPs of fluorinated gases in the P roposed Amendments to Subpart L . The c ommenters requested that EPA split the third group (saturated HFEs and saturated HCFEs) into two , expand the fourth group ( unsaturated PFCs, unsaturated HFCs, unsaturated HCFCs, unsaturated HFEs, and fluorinated ketones ) , and add two additional groups, fluorotelomer alcohols and fluorinated GHGs with carbon
- iodine bonds, to increase the precision and accuracy of the default GWPs applied to the chemicals in these groups. The commenters stated that five types of che micals, including unsaturated fluorinated ethers, unsaturated halogenated esters, fluorinated aldehydes, fluorotelomer alcohols, and fluorinated GHGs with carbon iodine bonds, would have been assigned GWPs that were too high if they had remained in the “Ot her fluorinated GHGs ” category (group 5) as defined in the proposed rule . They further stated that two types of saturated HFEs and HCFEs would have been assigned GWPs that were, on average, either too high (for partially segregated saturated HFEs and HCFEs ) or too low (for non
- segregated saturated HFEs and HCFEs). These comments were reviewed and the fluorinated GHG groups and associated default GWPs were reevaluated for the P roposed R ule to Add GWPs . A brief summary and analysis of the GWP - related comments on the Proposed Amendments to Subpart L appears as Appendix D to this memorandum. A detailed summary and response to all the comments on the Proposed Amendments to Subpart L will be included in docket number EPA - HQ - OAR 2009 - 0927 when those amendments are finalized . E PA is now proposing eight default GWP values based on fluorinated GHG groups. These default GWPs would be added to Table A - 1 and would apply to fluorinated GHGs and HTFs not otherwise listed on Table A - 1. The propo sed fluorinated GHG groups are listed in Table 2, below. Table 2 . F luorinated GHG Groups and Associated Default GWPs for Proposed Rule to Add GWPs Fluorinated GHG Group GWP in Proposed Rule to Add GWPs (100 - year) Fully fluorinated GHGs 10,000 Saturated hydrofluorocarbons (HFCs) 2,200 Non - segregated saturated hydrofluoroethers (HFEs) Non - segregated saturated hydrochlorofluoroethers (HCFEs) 2, 4 00 Partially segregated saturated hydrofluoroethers (HFEs) Partially segregated saturated hydrochlorofluoroethers (HCFEs) 2 0 0 Unsaturated perfluorocarbons ( PFCs ) Unsaturated HFCs and HCFCs Unsaturated halogenated ethers Unsaturated halogenated esters Fluorinated ketones Fluorinated aldehydes 1
Fluorotelomer alcohols 1 Fluorinated GHGs with one or more carbon - iodine bond 1 Other fluorinated GHGs 110 

### For each fluorinated GHG group, EPA is basing the proposed default GWPs on the average of the chemical - specific GWPs of chemicals that belong to that group and that are either on Table A
- 1 or are proposed to be added to Table A - 1 under th e P roposed R ule to Add GWPs . The proposed fluorinated GH G groups and associated GWPs are listed in Appendix B. The fluorinated GHG groups are based primarily on chemical structure, which is correlated with atmospheric lifetime and GWP. Thus, within each group, GWPs fall into a relatively limited range, and amon g the groups, GWPs vary significantly.Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 3 

### This permits default GWPs to be established with more precision than is possible with larger or more diverse sets of fluorinated GHGs. 

## II. Analysis Method for Determining Default GWP Groups In order to establish differen t compound groups and evaluate potential default GWPs for each group, ICF analyzed the chemical structure, GWPs, and atmospheric lifetimes of the fluorinated GHGs with peer - reviewed GWPs. The F - GHGs with peer - reviewed GWPs include the compounds on Table A - 1 and the compounds in the IPCC Fifth Assessment Report (AR5) . As noted above, ICF also considered the comments on the Proposed Amendments to Subpart L. One hundred and two F - GHGs from AR5 and one F
- GHG from the IPCC Fourth Assessment Report (AR4) (Forster et al. 2007) (i.e., 103 F
- GHGs in total) that are not included in the current Table A
- 1 are included in this analysis. For compounds that are included in the current Table A - 1, ICF used the GWPs from Table A - 1 as they were updated in the “2013 Revisions t o the Greenhouse Gas Reporting Rule and Proposed Confidentiality Determinations for New or Substantially Revised Data Elements; Final Rule” (78 FR 71904; November 3, 2013), wit h the exception of sevoflurane, for which the AR5 GWP was used. For compounds th at are included only in AR5, ICF used the GWP from AR5 in the analysis, with the exception of several very short - lived compounds whose GWPs were listed in AR5 as “<1.” In order to increase the accuracy of the default GWP analysis, precise GWPs were calcula ted and used in this analysis for these compounds using the atmospheric lifetime and the corrected radiative efficiency provided in the AR5 . This analysis resulted in eight main model groups (Table 3 ) based on chemical structure. As was the case for the f luorinated GHG groups included in the Proposed Amendments to Subpart L, these groups exclude compounds that are chemically different (i.e., that are not fluorocarbons and are therefore chemical outliers ) from the compounds whose GWPs are being modeled, but they include compounds whose GWPs are unusually high or low (i.e., numerical outliers). ICF also analyzed variants of the groups that include chemical outliers and exclude numerical outliers; this analysis is available in Appendix C. Also like the fluor inated GHG groups included in the Proposed Amendments to Subpart L, t he groups include chemically similar chlorine - containing compounds that are defined as fluorinated GHGs (i.e., are not regulated as ozone - depleting compounds under 40 CFR part 82). T he average and standard deviation of the GWPs of the compounds within each model group were calculated. The suggested GWP for each model group is equal to the average GWP of the F
- GHGs within that model group, rounded to either one or two significant figur es. Table 3 presents the proposed fluorinated GHG groups with the corresponding average, standard deviation, and relative standard deviation of the GWPs for each gro up. As can be seen by comparing Table 3 to Table 1 , the additions and changes to the fluorinated GHG groups that were included i n the P roposed Amendments to Subpart L are likely to improve the accuracy and precision of the default GWPs. This improvement is driven by the relationship between the structural criteria used to break out the new groups ( and subgroups ) and atmospheric lifetime. As discussed further in Appendix D and in “Analysis of Atmospheric Lifetimes, Radiative Efficiencies, and Global Warming Potentials of Saturated Hydrofluoroethers by Number of Carbon
- Hydrogen and Carbon - Fluorine Bonds” ( available in DocketRevised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 4 

### EPA - HQ - OAR - 2009 - 0927 ), atmospheric lifetime is the key fac tor in determining the 100 - year GWPs of most fluorinated GHGs. 3 

### Table 3 . Average, Standard Deviation, and Relative Standard Deviation of GWPs of Fluorinated GHG Groups Fluorinated GHG Group Proposed GWP Average

GWP Standard Deviation Relative

Standard Deviation Number

of Chemicals in Group Fully fluorinated GHGs 10,000 9,857 3,450 35% 5 Saturated hydrofluorocarbons (HFCs) 2,200 2,187 3,346 153% 26 Partially segregated saturated HFEs and HCFEs 2 0 0 204 227 111% 2 5 Non - segregated saturated HFEs and HCFEs 2, 4 00 2,436 2,967 122% 37 Unsaturated PFCs 1 0.66 0.96 146% 6 Unsaturated HFCs and unsaturated HCFCs 1 0.38 0.51 134% 14 Unsaturated halogenated ethers 1 0.11 - - 2 Unsaturated halogenated esters 1 N / A N / A N / A 0 Fluorinated ketones 1 0.11 - - 1 Fluorinated aldehydes 1 0.01 - - 1 Fluorotelomer alcohols 1 0.32 0.10 31% 4 Fluorinated GHGs with one or more carbon - iodine bonds 1 0.4 - - 1 Other fluorinated compounds 1 1 0 112 177 159% 33 N / A = Not available 

### In addition, potential default GWPs for the fluorinated GHG groups were developed by also evaluating GWPs of the F
- GHGs from AR5 only. This analysis can be found in Appendix B.

3 The partial exception to this rule is the group of fully fluorinated GHGs. While the long atmospheric lifet imes of fully fluorinated GHGs give this group the highest average GWP of any group, those lifetimes are so long that differences between the lifetimes have relatively little impact on the differences between the 100
- year GWPs of the fully fluorinated GHGs . Whether a fully fluorinated GHG has an atmospheric lifetime of 1,000 years or 2,000 years, most emissions of that gas will still remain in the atmosphere after 100 years.Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 5 

### Figure 1 is a semi - log histogram that illustrates the number of chemicals in each F
- GHG group or subgroup whose GWPs fall within different orders of magnitude. The left
- most bar represents the number of compounds with GWPs between 0.001 and 0.01; the second bar represents compounds with GWPs between 0.01 and 0.1; etc.

Figure 1 . Histogram of F - GHG Group and Subgroup GWPs 0 5 10 15 20 25 30 35 40 45 50

0.001 to 0.01 0.01 to 0.1 0.1 to 1 1 to 10 10 to 100 100 to 1,000 1,000 to 10,000 10,000 and above 

### GWP Fully Fluorinated GHGs Saturated HFCs Partially segregated HFEs and HCFEs Non-segregated saturated HFEs and HCFEs Unsaturated PFCs Unsaturated HFCs and HCFCs Unsaturated Halogenated Ethers Unsaturated Halogenated Esters Fluorinated Ketones Fluorinated Aldehydes Fluorotelomer Alcohols Other Fluorinated GHGsRevised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 6 

## III. Comparison between Defaults and Estimated GWPs for Several F GHGs ICF tested the accuracy of the default GWPs based on chemical groups by comparing the default GWPs to ( 1) the GWPs of F
- GHGs with documented (but not peer
- reviewed) GWPs provided by 3M and m ade available for comment through the April 5, 2013 Notice of Data Av ailability (NODA) (78 FR 20632) (Table 4) and ( 2) the GWPs of F
- GHGs with documented (but not peer
- reviewed) GWPs in the Proposed 2013 Revisions rule (Table 5) . Chemical - specific GWPs fo r these fluorinated GHGs are not included in the Proposed Rule to Add GWPs . In Table 4, eight compounds with documented GWPs provided by 3M were categorized into the fluorinated GHG groups and assigned a default GWP:  T he first six compounds would be assigned t o the “fully f luorinated GHGs ” and have an average GWP of 9,452. This average GWP is similar to the s uggested default GWP for “fully fluorinated GHGs” , which is equal to 10,000.  The remaining two compounds provided by 3M, HFE - 7300 and HFE - 7500, have an average GWP of 205. Both HFE
- 7300 and HFE - 7500 are partially segregated saturated HFEs and have atmospheric lifetimes of 3.8 a nd 2.2 years, respectively. Therefore, these two compounds could be assigned to the partially segregated s aturated HFEs an d HCFEs, which ha s a suggested default GWP of 200 . Table 4 . 3M Company Fluorinated GHGs GWPs and Default GWP Comparison Potential Fluorinated GHG

Group Chemical Designation or Common Name Chemical Formula 3M

Submitted GWP Default

G WP Fully fluorinated GHGs Perfluorotripropyl amine (PTPA) C 9 F 21 N 8,690 10,000 Fully fluorinated GHGs Perfluorotributyl amine (PTBA) C 12 F 27 N 9,020 10,000 Fully fluorinated GHGs Perfluorotriamyl amine (PTAA) C 15 F 33 N 8,900 10,000 Fully fluorinated GHGs Perfluoromethyl morpholine (PMM) C 5 F 11 NO 9,500 10,000 Fully fluorinated GHGs Perfluoroisopropyl morpholine (PIPM) C 7 F 15 NO 11,000 10,000 Fully fluorinated GHGs 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9 - hexadecafluorooxonane C 8 F 16 O 9,600 10,000 Partially segregated saturated HFEs and HCFEs 1,1,1,2,2,3,4,5,5,5 - decafluoro
- 3 - methoxy - 4 - trifluoromethyl
- pentane ( HFE - 7300) C 7 H 3 F 13 O 310 200 Partially segregated saturated HFEs and HCFEs 3 - ethoxy - 1,1,1,2,3,4,4,5,5,6,6,6 - dodecafluoro
- 2 - trifluoromethyl
- hexane (HFE
- 7500) C 9 H 5 F 15 O 100 200


### As shown in Table 5 , eleven compounds with documented (but not peer
- reviewed) GWPs in the Proposed 2013 Revisions R ule that are not included in the Proposed Rule to Add GWPs were also categorized into the fluorinated GHG groups and assigned a default GWP:  Two of the compounds that would be categorized as “unsaturated halogenated ethers”, which both ha d estimated GWPs of 3, would be assigned a default GWP of 1.  S ix of the com pounds that would be categorized as “fluorinated GHGs with one or more carbon iodine bonds” , whose average estimated GWP wa s 2.3, would be assigned a default GWP of 1.Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 7 

###  The GWP for 1H,1H, 2H,2H - perfluorohexan
- 1 - ol (42 – AL) was listed as 2 in the Proposed 2013 Revisions Rule; this compound would be categorized as a “fluorotelomer alcohol” and assigned a default GWP of 1.  The GWP for FK – 6 – 1 – 12 was listed as 1 in the Proposed 2013 Revisions Rule and this compound would be cat egorized as a “fluorinated ketone” and assigned a default GWP of 1.  The GWP for carbonyl fluoride was listed as 2 in the 2013 Revisions Rule; this compound would be categorized as an “other fluorinated compound” and assigned a default GWP of 110. With the exception of the default GWP for carbonyl fluoride, the default GWPs assigned to these compounds are quite close to their previously estimated GWPs. T he defaults for the unsaturated compounds, fluorotelomer alcohols, and compounds with carbon
- iodine bond s are lower than the previously estimated GWPs for these compounds because the defaults reflect corrections made to the radiative efficiencies of these compounds in AR5. These corrections lower the radiative efficiencies to account for the fact that the co mpounds are very short - lived and are therefore not well - mixed in the atmosphere. Table 5 . Fluorinated GHG GWPs in Proposed 2013 Revisions Rule Not Included in Newly Proposed Rule Potential Fluorinated GHG

Group Chemical Designation or Common Name Chemical formula Proposed GWP Default

GWP Unsaturated halogenated ether s P erfluoropropyl vinyl ether C 5 F 10 O 3 1 Unsaturated halogenated ether s P erfluoroethyl vinyl ether C 4 F 8 O 3 1 Fluorinated GHGs with one or more carbon - iodine bonds P erfluorethyl iodide (2 – I) C 2 F 5 I 3 1 Fluorinated GHGs with one or more carbon - iodine bonds P erfluorbutyl iodide (PFBI, 42 – I) C 4 F 9 I 3 1 Fluorinated GHGs with one or more carbon - iodine bonds P erfluorhexyl iodide (6 – I) CF 3 CF 2 CF 2 CF 2 CF 2 CF 2 IC 6 F 13 I 2 1 Fluorinated GHGs with one or more carbon - iodine bonds P erfluoroctyl iodide (8 – I) C 8 F 17 I 2 1 Fluorinated GHGs with one or more carbon - iodine bonds 1,1,1,2,2 - pentafluoro
- 4 - iodo butane (22 – I) C 4 H 4 F 5 I 2 1 Fluorinated GHGs with one or more carbon - iodine bonds 1,1,1,2,2,3,3,4,4 - nonafluoro
- 6 - iodo hexane

(42 – I) C 6 H 4 F 9 I 2 1 Fluorotelomer alcohols 1H,1H, 2H,2H perfluorohexan
- 1 - ol (42 –

AL) C 6 H 5 F 9 O 5 1 Fluorinated k etone s FK – 6 – 1 – 12/NovecTM 774, C7 Fluoroketone C 7 F 14 O Chemical Blend 1 1 Other fluorinated compounds C arbonyl fluoride COF 2 2 110 

## IV. Evaluation of Analysis Method by Dr. Wuebbles and Recommendations Dr. Don Wuebbles evaluated the overall approach of assigning a default GWP to target compounds from certain compound groups based on the average GWP of similar “model” groups of compounds, and noted that although there are significant uncertainties associated with this approach due to the range of GWPs observed within each group of model compounds, this may be the most viable option for EPARevised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 8 

### based on the availabl e information and time constraints. Dr. Wuebbles recommend ed developing a technique for assigning default GWPs based on modeling, or by developing a default estimate based on the relative amounts of fluorine, chlorine, and hydrogen in each compound. Both techniques would require additional research, and the techniq ue based on modeling would be a major research effort. Dr. Wuebbles also suggested considering compounds with double carbon bonds (which are expected to all have short lifetimes) as a potential model group. Based on this suggestion, a model group consistin g of separate sub - groups for unsaturated PFCs, HFCs and HCFCs, halogenated ethers, and halogenated esters was developed. 4 

### Dr. Wuebbles also noted that the IP C C process for developing Assessment Reports (e.g., AR4) is not designed to be the sole arbiter of “official” GWP values, and other sources of published (i.e., peer
- reviewed) literature (e.g., WMO, 2010) should be considered when establishing default GWP estimates. In addition, as a result of this discussion, numerical outliers are not excluded when ca lculating the suggested (i.e., average) model group GWP, since the GWPs for unknown target compounds might equally be outliers themselves. Dr. Wuebbles also reviewed the comments that were received on the Proposed Amendments to Subpart L. Dr. Wueb bles agreed with the analyses conducted by DuPont because their suggestions are well defined from a physical chemistry standpoint and also because Hodnebrog et al. 2013 is the proper source to use for such analyses as is it the basis for the GWPs presented in AR5. Dr. Wuebbles also noted that 3M’s suggestion to use the median GWP of a group of compounds (i.e., saturated HFEs) to assign a default GWP for that particular group is in appropriate, as the compounds with very high GWPs would be assigned a much sma ller GWP value.

4 During a conference call on May 9, 2013 between ICF, EPA, and Dr. Don Wuebbles to have an intermediary discussion regarding the default GWP analysis, Dr. Wuebbles communicated that c ompounds with a lifetime greater than 1 year should be considered long - lived regardless of their corresponding GWP.Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 9 

## V. References Derwent, R.G. 1995 . Sources, Distributions, and Fates of VOCs in the Atmosphere. Issues in Environmental Science and Technology, 4. pp 1 - 16. Ellis, D.A. et al. 2003. Atmospheric Lifetime of Fluorotelomer Alcohols. Environmental Science & Technology. Vol 37. No. 17. pp 3816 - 3820. Forster, P., V. Ramaswamy, P. Artaxo, T. Berntsen, R. Betts, D.W. Fahey, J. Haywood, J. Lean, D.C. Lowe, G. Myhre, J. Nganga, R. Prinn, G. Raga, M. Schulz and R. Van Dorland. 2007. Changes in Atmospheric Constituents and in Radiative Forcing. In: Climate Change 2007:The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marqui s, K.B. Averyt, M.Tignor and H.L. Miller (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Hodnebrog, O. et al. 2013. Global Warming Potentials and Radiative Efficiencies of Halocarbons and Related Compounds: A Comprehen sive Review. Reviews of Geophysics, 51. Hurley, M.D. et al. 2004. Atmospheric Chemistry of Fluorinated Alcohols:  Reaction with Cl Atoms and OH Radicals and Atmospheric Lifetimes. Journal of Physical Chemistry. Vol 108. No 11. pp 1973
- 1979. IPCC/TEAP. 200 5. Special Report: Safeguarding the Ozone Layer and the Global Climate System: Issues Related to Hydrofluorocarbons and Perfluorocarbons. Chapter 10: Non
- Medical Aerosols, Solvents, and HFC - 23. Available online at: http://www.ipcc.ch/pdf/special

- reports/sroc/sroc10.pdf . Myhre, G., D. Shindell, F.A. Breon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J. - F. Lamarque, D. Lee, B. Mendoza, T. Nakajima, A. Robock, G. Stephens, T. Takemura and H. Zhang, 2013: Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013 : The Physical Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G. - K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (ed s.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Owens, J.G. 1999. “Segregated Hydrofluoroethers: Low GWP Alternatives to HFCs and PFCs,” Proceedings of the Joint Intergovernmental Panel on Climate Change/Technical and Economic Assessment Panel Expert Meeting on Options for the Limitation of Emissions of HFCs and PFCs: Petten, Netherlands. Weubbles, Don. 2014. Transcribed Correspondence with Don Weubbles on March 14, 2014. Youn, D. et al. 2010. Potential impact of iodin ated replacement compounds CF 3 

### I and CH 3 

### I on atmospheric ozone: a three - dimensional modeling study. Atmospheric Chemistry and Physics, 10. pp. 10129 - 10144. Young, C.J. et al. 2008. Atmospheric Chemistry of 4:2 Fluorotelomer Iodide (n
- C 4 

### F 9 

### CH 2 

### CH 2 

### I): Kinetics and Products of Photolysis and Reaction with OH Radicals and Cl Atoms. Journal of Physical Chemistry. Vol 112. No. 51. pp 13542 - 13548.Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 10 

## Appendix A: F - GHGs by Fluorinated GHG Group Trade Name Chemical Designation or Common Name CAS No. Chemical For mula Proposed GWP GWP Source Fully Fluorinated GHGs PFPMIE perfluoropolymethylisopropyl ether 69991 - 67 - 9 CF 3 OCF(CF 3 )CF 2 OCF 2 O CF 3 10 , 300 AR4/Table A

- 1 PFC – 14 Perfluoromethane 75 – 73 – 0 CF 4 7 , 390 AR4/Table A

- 1 PFC – 9 – 1 – 18 Perfluorodecalin (mixed) 306 – 94 – 5 C 10 F 18 7 , 500 AR4/Table A

- 1 PFC – 218 Perfluoropropane 76 – 19 – 7 C 3 F 8 8 , 830 AR4/Table A

- 1 PFC – 3 – 1 – 10 Perfluorobutane 355 – 25 – 9 C 4 F 10 8 , 860 AR4/Table A

- 1 PFC – 4 – 1 – 12 Perfluoropentane 678 – 26 – 2 C 5 F 12 9 , 160 AR4/Table A

- 1 PFC – 5 – 1 – 14 Tetradecafluorohexane 355 – 42 – 0 C 6 F 14 9 , 300 AR4/Table A

- 1 PFC - 6 - 1 - 12 Hexadecafluoroheptane 335 - 57 - 9 C 7 F 16 , CF 3 (CF 2 ) 5 CF 3 7 , 820 AR5 PFC - 7 - 1 - 18 Octadecafluorooctane 307 - 34 - 6 C 8 F 18 , CF 3 (CF 2 ) 6 CF 3 7 , 620 AR5 PFC - 318 Perfluorocyclobutane 115 – 25 – 3 c - C 4 F 8 10 , 300 AR4/Table A

- 1 PFC – 116 Perfluoroethane 76 – 16 – 4 C 2 F 6 12 , 200 AR4/Table A

- 1 PFC – c216 Perfluorocyclopropane 931 – 91 – 9 c - C 3 F 6 17 , 340 AR4/Table A

- 1 Perfluorodecalin (cis) 60433 - 11 - 6 cis - C 10 F 18 7 , 240 AR5 Perfluorodecalin (trans) 60433 - 12 - 7 trans - C 10 F 18 6 , 290 AR5 Trifluoromethyl sulphur pentafluoride 373 – 80 – 8 SF 5 CF 3 17 , 700 AR4/Table A

- 1 Saturated HFCs HFC – 161 353 – 36 – 6 CH 3 CH 2 F 12 AR4/Table A

- 1 HFC – 152 624 – 72 – 6 CH 2 FCH 2 F 53 AR4/Table A

- 1 HFC - 263fb 1,1,1 - Trifluoropropane 421 - 07 - 8 CH 3 CH 2 CF 3 76 AR5 HFC – 152a 75 – 37 – 6 CH 3 CHF 2 124 AR4/Table A

- 1 HFC – 41 593 – 53 – 3 CH 3 F 92 AR4/Table A

- 1 HFC - 272ca 2,2 - Difluoropropane 420 - 45 - 1 CH 3 CF 2 CH 3 144 AR5 HFC - 245eb 1,1,1,2,3 - Pentafluoropropane 431 - 31 - 2 CH 2 FCHFCF 3 290 AR5Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 11 Trade Name Chemical Designation or Common Name CAS No. Chemical For mula Proposed GWP GWP Source HFC - 245ea 1,1,2,3,3 - Pentafluoropropane 24270 - 66 - 4 CHF 2 CHFCHF 2 235 AR5 HFC – 143 430 – 66 – 0 C 2 H 3 F 3 353 AR4/Table A

- 1 HFC – 32 75 – 10 – 5 CH 2 F 2 675 AR4/Table A

- 1 HFC – 245ca 679 – 86 – 7 C 3 H 3 F 5 693 AR4/Table A

- 1 HFC – 245fa 460 – 73 – 1 CHF 2 CH 2 CF 3 1,030 AR4/Table A

- 1 HFC – 365mfc 406 – 58 – 6 CH 3 CF 2 CH 2 CF 3 794 AR4/Table A

- 1 HFC – 134 359 – 35 – 3 CHF 2 CHF 2 1,100 AR4/Table A

- 1 HFC – 236ea 431 – 63 – 0 CHF 2 CHFCF 3 1,370 AR4/Table A

- 1 HFC – 236cb 677 – 56 – 5 CH 2 FCF 2 CF 3 1,340 AR4/Table A

- 1 HFC – 134a 811 – 97 – 2 CH 2 FCF 3 1,430 AR4/Table A

- 1 HFC – 43 – 10mee 138495 – 42 – 8 CF 3 CFHCFHCF 2 CF 3 1,640 AR4/Table A

- 1 HFC - 227ca 1,1,1,2,2,3,3 - Heptafluoropropane 2252 - 84 - 8 CF 3 CF 2 CHF 2 2 , 640 AR5 HFC - 329p 1,1,1,2,2,3,3,4,4 - Nonafluorobutane 375 - 17 - 7 CHF 2 CF 2 CF 2 CF 3 2 , 360 AR5 HFC – 125 354 – 33 – 6 CHF 2 CF 3 3,500 AR4/Table A

- 1 HFC – 227ea 431 – 89 – 0 C 3 HF 7 3,220 AR4/Table A

- 1 HFC - 245cb 1,1,1,2,2 - Pentafluoropropane 1814 - 88 - 6 CF 3 CF 2 CH 3 4 , 620 AR5 HFC – 143a 420 – 46 – 2 C 2 H 3 F 3 4,470 AR4/Table A

- 1 HFC – 236fa 690 – 39 – 1 C 3 H 2 F 6 9,810 AR4/Table A

- 1 HFC – 23 75 – 46 – 7 CHF 3 14,800 AR4/Table A

- 1 Partially Segregated Saturated HFE s and HCFEs R - E - 143a; HFE - 263m1 1,1,2,2 - Tetrafluoro
- 1 - (trifluoromethoxy)ethane 690 - 22 - 2 CF 3 OCH 2 CH 3 29 AR5 HFE – 356mmz1 1,1,1,3,3,3 - Hexafluoro
- 2 - methoxypropane 13171 - 18 - 1 C 4 H 4 F 6 O 27 Table A - 1Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 12 Trade Name Chemical Designation or Common Name CAS No. Chemical For mula Proposed GWP GWP Source HFE - 365mcf2 1 - Ethoxy - 1,1,2,2,2 - pentafluoroethane 22052 - 81 - 9 CF 3 CF 2 OCH 2 CH 3 58 AR5 HFE - 569sf2, (HFE
- 7200) Isomer blend 1 - Ethoxy - 1,1,2,2,3,3,4,4,4 - nonafluorobutane 163702 - 05 - 4 C 4 F 9 OC 2 H 5 59 AR4/Table A

- 1 HG'
- 01 1,1,2,2 - Tetrafluoro
- 1,2 - dimethoxyethane 73287 - 23 - 7 CH 3 OCF 2 CF 2 OCH 3 222 AR5 HG'
- 02 1,1,2,2 - Tetrafluoro
- 1 - methoxy - 2 - (1,1,2,2
- tetrafluoro
- 2 - methoxyethoxy)ethane 485399 - 46 - 0 CH 3 O(CF 2 CF 2 O) 2 CH 3 236 AR5 HG'
- 03 3,3,4,4,6,6,7,7,9,9,10,10 - Dodecafluoro
- 2,5,8,11 - tetraoxadodecane 485399 - 48 - 2 CH 3 O(CF 2 CF 2 O) 3 CH 3 221 AR5 HFE – 245cb2 1,1,1,2,2 - Pentafluoro
- 2 - methoxy - ethane 22410 - 44 - 2 CF 3 CF 2 OCH 3 708 AR4/Table A

- 1 HFE – 347mmy1 1,1,1,2,3,3,3 - Heptafluoro
- 2 - methoxypropane 22052 – 84 – 2 CH 3 OCF(CF 3 ) 2 343 Table A - 1 HFE - 449sl, (HFE
- 7100) Isomer blend 163702 – 07 – 6 C 4 F 9 OCH 3 297 AR4/Table A

- 1 HFE – 143a T rifluoromethoxymethane 421 – 14 – 7 CH 3 OCF 3 756 AR4/Table A

- 1 HFE – 347mcc3 Heptafluoropropyl methyl ether 375 - 03 - 128523 – 86 – 6 CH 3 OCF 2 CF 2 CF 3 575 AR4/Table A

- 1 1 - Ethoxy - 1,1,2,2,3,3,3 - heptafluoropropane 22052 - 86 - 4 CF 3 CF 2 CF 2 OCH 2 CH 3 61 AR5 2 - Ethoxy - 3,3,4,4,5 - pentafluorotetrahydro
- 2,5 - bis[1,2,2,2
- tetrafluoro
- 1 - (trifluoromethyl)ethyl]
- furan 920979 - 28 - 8 C 12 H 5 F 19 O 2 56 AR5 HFE – 356mec3 1,1,1,2,3,3 - Hexafluoro
- 3 - methoxypropane 382 - 34 - 3 CH 3 OCF 2 CHFCF 3 101 AR4/Table A

- 1 HFE – 263fb2 1,1,1 - Trifluoro
- 2 - methoxyethane 460 - 43 - 5 CF 3 CH 2 OCH 3 11 AR4/Table A

- 1 HFE – 365mcf3 1,1,1,2,2 - Pentafluoro
- 3 - methoxypropane 378 - 16 - 5 CF 3 CF 2 CH 2 OCH 3 11 AR4/Table A

- 1 HFE – 356pcc3 1,1,2,2,3,3 - Hexafluoro
- 1 - methoxypropane 160620 - 20 - 2 CH 3 OCF 2 CF 2 CHF 2 110 AR4/Table A - 1 HFE – 254cb1 1,1,2,2 - Tetrafluoro
- 1 - methoxyethane 425 - 88 - 7 CH 3 OCF 2 CHF 2 359 AR4/Table A

- 1Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 13 Trade Name Chemical Designation or Common Name CAS No. Chemical For mula Proposed GWP GWP Source HFE – 374pc2 1 - ethoxy - 1,1,2,2 - tetrafluoroethane 512 – 51 – 6 CH 3 CH 2 OCF 2 CHF 2 557 AR4/Table A

- 1

1,1,2,2 - Tetrafluoro
- 3 - methoxy - propane; Methyl 2,2,3,3 -

tetrafluoropropyl ether 60598 - 17 - 6 CHF 2 CF 2 CH 2 OCH 3 0 AR5 (Precise GWP Calculated) 1 - Ethoxy - 1,1,2,3,3,3 - hexafluoropropane 380 - 34 - 7 CF 3 CHFCF 2 OCH 2 CH 3 23 AR5 Fluoro(methoxy)methane 460 - 22 - 0 CH 3 OCH 2 F 13 AR5 Difluoro(methoxy)methane 359 - 15 - 9 CH 3 OCHF 2 144 AR5 2 - Chloro - 1,1,2 - trifluoro
- 1 - methoxyethane 425 - 87 - 6 CH 3 OCF 2 CHFCl 122 AR5 Non - segregated Saturated HFE s and HCFEs HFE – 356pcf2 1 - (2,2
- Difluoroethoxy)
- 1,1,2,2 - tetrafluoroethane 50807 - 77 - 7 CHF 2 CH 2 OCF 2 CHF 2 265 AR4/Table A

- 1 HFE – 245fa1 1,1 - Difluoro
- 2 - (trifluoromethoxy)ethane 84011 - 15 - 4 CHF 2 CH 2 OCF 3 286 AR4/Table A

- 1 Sevoflurane (HFE
347mmz1) 2 - (Difluoromethoxy)
- 1,1,1,3,3,3 - hexafluoropropane 28523 - 86 - 6 (CF 3 ) 2 CHOCHF 2 216 AR5 Isoflurane (HCFE – 235da2) 2 - chloro - 2 - (difluoromethoxy)
- 1,1,1 - trifluoro
- ethane 26675 - 46 - 7 C 3 H 2 ClF 5 O 350 AR4/Table A

- 1 HFE – 338mcf2 1,1,1,2,2 - Pentafluoro
- 2 - (2,2,2
- trifluoroethoxy)ethane 156053 - 88 - 2 CF 3 CH 2 OCF 2 CF 3 552 AR4/Table A

- 1 HFE – 347mcf2 1 - (2,2
- Difluoroethoxy)
- 1,1,2,2,2 - pentafluoroethane 171182 - 95 - 9 CHF 2 CH 2 OCF 2 CF 3 374 AR4/Table A

- 1 HFE – 356pcf3 3 - (difluoromethoxy)
- 1,1,2,2 - tetrafluoropropane 35042 – 99 – 0 CHF 2 OCH 2 CF 2 CHF 2 502 AR4/Table A

- 1 HFE – 236fa 1,1,1 - Trifluoro
- 2 - (trifluoromethoxy)ethane 20193 – 67 – 3 CF 3 CH 2 OCF 3 487 AR4/Table A

- 1 HFE - 356mff2 BIS(2,2,2
- TRIFLUOROETHYL) ETHER 333 - 36 - 8 CF 3 CH 2 OCH 2 CF 3 17 AR5 HFE – 245fa2 2 - (Difluoromethoxy)
- 1,1,1 - trifluoroethane 1885 - 48 - 9 CHF 2 OCH 2 CF 3 659 AR4/Table A

- 1 Desflurane (HFE – 236ea2) 2 - (Difluoromethoxy)
- 1,1,1,2 - tetrafluoroethane 57041 - 67 - 5 CHF 2 OCHFCF 3 989 AR4/Table A

- 1Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 14 Trade Name Chemical Designation or Common Name CAS No. Chemical For mula Proposed GWP GWP Source HFE – 338pcc13 (HG – 01) 1,2 - Bis(difluoromethoxy)
- 1,1,2,2 - tetrafluoroethane 188690 – 78 – 0 CHF 2 OCF 2 CF 2 OCHF 2 1,500 AR4/Table A

- 1 HFE – 43 – 10pccc (H – Galden 1040x) 1 - (Difluoromethoxy)
- 2 -

[(difluoromethoxy)(difluoro)methoxy]
- 1,1,2,2 -

tetrafluoroethane E1730133 CHF 2 OCF 2 OC 2 F 4 OCHF 2 1,870 AR4/Table A

- 1 HFE – 329mcc2 1,1,1,2,2 - Pentafluoro
- 2 - (1,1,2,2
- tetrafluoroethoxy)ethane 134769 - 21 - 4 CHF 2 CF 2 OCF 2 CF 3 919 AR4/Table A

- 1 HFE – 347pcf2 1,1,2,2 - Tetrafluoro
- 1 - (2,2,2
- trifluoroethoxy)ethane 406 - 78 - 0 CHF 2 CF 2 OCH 2 CF 3 580 AR4/Table A

- 1 HFE – 227ea 2356 – 62 – 9 CF 3 CHFOCF 3 1,540 AR4/Table A

- 1 HFE – 236ca12 (HG – 10) Bis(difluoromethoxy)difluoromethane 78522 - 47 - 1 CHF 2 OCF 2 OCHF 2 2,800 AR4/Table A - 1 HG - 02 1 - (Difluoromethoxy)
- 2 - (2
- (difluoromethoxy)
- 1,1,2,2 -

tetrafluoroethoxy)
- 1,1,2,2 - tetrafluoroethane 205367 - 61 - 9 HF 2 C - (OCF 2 CF 2 ) 2 - OCF 2 H 2,730 AR5 HG - 03 1,1,3,3,4,4,6,6,7,7,9,9,10,10,12,12 - Hexadecafluoro
2,5,8,11 - tetraoxadodecane 173350 - 37 - 3 HF 2 C - (OCF 2 CF 2 ) 3 - OCF 2 H 2,850 AR5 HG - 21 1,1,3,3,5,5,7,7,8,8,10,10 - Dodecafluoro
- 2,4,6,9 - tetraoxadecane 249932 - 26 - 1 HF 2 C OCF 2 CF 2 OCF 2 OCF 2 O CF 2 H 3,890 AR5 1,1,2,2 - Tetrafluoro
- 1 - (fluoromethoxy)ethane 37031 - 31 - 5 CH 2 FOCF 2 CF 2 H 871 AR5 1,1,2 - Trifluoro
- 2 - (trifluoromethoxy)
- ethane 84011 - 06 - 3 CHF 2 CHFOCF 3 1,240 AR5 Fluoro(fluoromethoxy)methane 462 - 51 - 1 CH 2 FOCH 2 F 130 AR5 Difluoro(fluoromethoxy)methane 461 - 63 - 2 CH 2 FOCHF 2 617 AR5 Trifluoro(fluoromethoxy)methane 2261 - 01 - 0 CH 2 FOCF 3 751 AR5 HCFE - 235ca2 (enflurane) 2 - Chloro - 1 - (difluoromethoxy)
- 1,1,2 - trifluoroethane 13838 - 16 - 9 CHF 2 OCF 2 CHFCl 583 AR5 HFE – 338mmz1 2 - (Difluoromethoxy)
- 1,1,1,3,3,3 - hexafluoropropane 26103 - 08 - 2 (CF 3 ) 2 CHOCHF 2 380 AR4/Table A

- 1Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 15 Trade Name Chemical Designation or Common Name CAS No. Chemical For mula Proposed GWP GWP Source HFE - 236ca 1 - (Difluoromethoxy)
- 1,1,2,2 - tetrafluoroethane 32778 - 11 - 3 CHF 2 OCF 2 CHF 2 4,240 AR5 HFE – 134 1691 – 17 – 4 CHF 2 OCHF 2 6,320 AR4/Table A

- 1 HFE - 329me3 1,1,1,2,3,3 - Hexafluoro
- 3 - (trifluoromethoxy)propane 428454 - 68 - 6 CF 3 CFHCF 2 OCF 3 4,550 AR5 HFE – 125 (difluoromethoxy)(trifluoro)methane 3822 – 68 – 2 CHF 2 OCF 3 14,900 AR4/Table A

- 1 HG - 20 (Difluoromethoxy)((difluoromethoxy)difluoromethoxy)diflu oromethane 249932 - 25 - 0 HF 2 C - (OCF 2 ) 2 - OCF 2 H 5,300 AR5 HG - 30 1,1,3,3,5,5,7,7,9,9 - Decafluoro
- 2,4,6,8 - tetraoxanonane 188690 - 77 - 9 HF 2 C - (OCF 2 ) 3 - OCF 2 H 7,330 AR5

1,1,1,2,2,3,3 - Heptafluoro
- 3 - (1,2,2,2
- tetrafluoroethoxy)
-

propane 3330 - 15 - 2 CF 3 CF 2 CF 2 OCHFCF 3 6,490 AR5 1,1'
- Oxybis[2
- (difluoromethoxy)
- 1,1,2,2 - tetrafluoroethane 205367 - 61 - 9 HCF 2 O(CF 2 CF 2 O) 2 CF 2 H 4,920 AR5 1,1,3,3,4,4,6,6,7,7,9,9,10,10,12,12 - hexadecafluoro
2,5,8,11 - Tetraoxadodecane 173350 - 37 - 3 HCF 2 O(CF 2 CF 2 O)3CF 2 H 4,490 AR5 1,1,3,3,4,4,6,6,7,7,9,9,10,10,12,12,13,13,15,15 - eicosafluoro
- 2,5,8,11,14 - Pentaoxapentadecane 173350 - 38 - 4 HCF 2 O(CF 2 CF 2 O) 4 CF 2 H 3,630 AR5 Unsaturated PFC s PFC C - 1418 Perfluorocyclopentene; Octafluorocyclopentene 559 - 40 - 0 c - C 5 F 8 1.97 AR5 Dyneon HFP (3M) hexafluoropropylene (HFP); PFC
- 1216; Perfluoropropene 116 - 15 - 4 C 3 F 6 , CF 3 CF=CF 2 0.05 AR5 (Precise GWP Calculated) TFE tetrafluoroethylene (TFE); PFC
- 1114; Perfluoroethene 116 - 14 - 3 CF 2 =CF 2 , C 2 F 4; 0.004 AR5 (Precise GWP Calculated) Perfluorobuta
- 1,3 - diene 685 - 63 - 2 CF 2 =CFCF=CF 2 0.003 AR5 (Precise GWP Calculated) Perfluorobut
- 1 - ene 357 - 26 - 6 CF 3 CF 2 CF=CF 2 0.10 AR5 (Precise GWP Calculated) Perfluorobut
- 2 - ene 360 - 89 - 4 CF 3 CF=CFCF 3 1.82 AR5 (Precise GWP Calculated)Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 16 Trade Name Chemical Designation or Common Name CAS No. Chemical For mula Proposed GWP GWP Source Unsaturated HFC s HFC 1234ze(Z) (Z)
- 1,3,3,3 - Tetrafluoroprop
- 1 - ene 29118 - 25 - 0 C 3 H 2 F 4 trans - CF 3 CH=CHF, CF 3 CH=CHF(Z) 0.29 AR5 (Precise GWP Calculated) HFC 1234ze(E) (E)
- 1,3,3,3 - Tetrafluoroprop
- 1 - ene 1645 - 83 - 6 C 3 H 2 F 4 cis - CF 3 CH=CHF 0.97 AR5 (Precise GWP Calculated) TFP trifluoro propene (TFP); HFC
- 1243zf; 3,3,3
- Trifluoroprop
- 1 - ene 677 - 21 - 4 C 3 H 3 F 3 , CF 3 CH=CH 2 0.12 AR5 (Precise GWP Calculated) VF vinyl fluoride (VF); HFC - 1141 75 - 02 - 5 C 2 H 3 F, CH 2 =CHF 0.02 AR5 (Precise GWP Calculated) VF2 vinylidiene fluoride (VF2); HFC
- 1132a 75 - 38 - 7 C 2 H 2 F 2 , CF 2 =CH 2 0.04 AR5 (Precise GWP Calculated) HFC - 1234yf; HFO - 1234yf 2,3,3,3 - Tetrafluoroprop
- 1 - ene 754 - 12 - 1 C 3 H 2 F 4 CF 3 CF=CH 2 0.31 AR5 (Precise GWP Calculated) Capstone 42 - U perfluorobutyl ethene (42
- U); 3,3,4,4,5,5,6,6,6
- Nonafluorohex
- 1 - ene 19430 - 93 - 4 C 6 H 3 F 9, CF 3 (CF 2 ) 3 CH=CH 2 0.16 AR5 (Precise GWP Calculated) Capstone 62 - U perfluorohexyl ethene (62
- U); 3,3,4,4,5,5,6,6,7,7,8,8,8 - Tridecafluorooct
- 1 - ene 25291 - 17 - 2 C 8 H 3 F 13 , CF 3 (CF 2 ) 5 CH=CH 2 0.11 AR5 (Precise GWP Calculated) Capstone 82 - U perfluorooctyl ethene (82
- U);

3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10 - Heptadecafluorodec
- 1 - ene 21652 - 58 - 4 C 10 H 3 F 17 , CF 3 (CF 2 ) 7 CH=CH 2 0.09 AR5 (Precise GWP Calculated) Solstice 1233 zd(E) trans - 1 - chloro - 3,3,3 - trifluoroprop
- 1 - ene 102687 - 65 - 0 C 3 H 2 ClF 3 , CHCl=CHCF 3 1.34 AR5 (Precise GWP Calculated) (E)
- HFC 1225ye (E)
- 1,2,3,3,3 - Pentafluoroprop
- 1 - ene 5595 - 10 - 8 CF 3 CF=CHF(E) 0.06 AR5 (Precise GWP Calculated) (Z)
- HFC 1225ye (Z)
- 1,2,3,3,3 - Pentafluoroprop
- 1 - ene 5528 - 43 - 8 CF 3 CF=CHF(Z) 0.22 AR5 (Precise GWP Calculated) HFO - 1345zfc 3,3,4,4,4 - Pentafluorobut
- 1 - ene 374 - 27 - 6 C 2 F 5 CH=CH 2 0.09 AR5 (Precise GWP Calculated) (Z)
- HFC - 1336 (Z)
- 1,1,1,4,4,4 - Hexafluorobut
- 2 - ene 692 - 49 - 9 CF 3 CH=CHCF 3 (Z) 1.58 AR5 (Precise GWP Calculated)Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 17 Trade Name Chemical Designation or Common Name CAS No. Chemical For mula Proposed GWP GWP Source PMVE, HFE 216 perfluoromethyl vinyl ether (PMVE) 1187 - 93 - 5 CF 3 OCF=CF 2 0.17 AR5 (Precise GWP Calculated) Fluoroxene (2,2,2
- Trifluoroethoxy)ethene 406 - 90 - 6 CF 3 CH 2 OCH=CH 2 0.05 AR5 (Precise GWP Calculated) Fluorinated Aldehydes 3,3,3 - Trifluoro
- propanal 460 - 40 - 2 CF 3 CH 2 CHO 0.01 AR5 (Precise GWP Calculated) Fluorinated Ketone s Novec 1230 FK - 5 - 1 - 12 Perfluoroketone; FK
- 5 - 1 - 12myy2; PERFLUORO(2
- METHYL - 3 - PENTANONE) 756 - 13 - 8 CF 3 CF 2 C(O)CF (CF 3 ) 2 0.1 AR5 (Precise GWP Calculated) Fluorotelomer Alcohols 3,3,3 - Trifluoropropan
- 1 - ol 2240 - 88 - 2 CF 3 CH 2 CH 2 OH 0.35 AR5 (Precise GWP Calculated) 3,3,4,4,5,5,6,6,7,7,7 - Undecafluoroheptan
- 1 - ol 185689 - 57 - 0 CF 3 (CF 2 ) 4 CH 2 CH 2 OH 0.43 AR5 3,3,4,4,5,5,6,6,7,7,8,8,9,9,9 - Pentadecafluorononan
- 1 - ol 755 - 02 - 2 CF 3 (CF 2 ) 6 CH 2 CH 2 OH 0.33 AR5 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11 - Nonadecafluoroundecan
- 1 - ol 87017 - 97 - 8 CF 3 (CF 2 ) 8 CH 2 CH 2 OH 0.19 AR5

Fluorinated GHGs with one or more carbon - iodine bonds Trifluoroiodomethane 2314 - 97 - 8 CF 3 I 0.4 AR4 Other Fluorinated Compounds Perfluorobutyl acetate 209597 - 28 - 4 CH 3 COOCF 2 CF 2 CF 2 CF 3 1.6 AR5 (Precise GWP Calculated) Perfluoropropyl acetate 1344118 - 10 - 0 CH 3 COOCF 2 CF 2 CF 3 1.8 AR5 (Precise GWP Calculated) Perfluoroethyl acetate 343269 - 97 - 6 CH 3 COOCF 2 CF 3 2.1 AR5 (Precise GWP Calculated) Trifluoromethyl acetate 74123 - 20 - 9 CH 3 COOCF 3 2.0 AR5 (Precise GWP Calculated) 1,1 - Difluoroethyl 2,2,2
- trifluoroacetate 1344118 - 13 - 3 CF 3 COOCF 2 CH 3 31 AR5Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 18 Trade Name Chemical Designation or Common Name CAS No. Chemical For mula Proposed GWP GWP Source Ethyl 2,2,2 - trifluoroacetate 383 - 63 - 1 CF 3 COOCH 2 CH 3 1.30 AR5 2,2,2 - Trifluoroethyl 2,2,2
- trifluoroacetate 407 - 38 - 5 CF 3 COOCH 2 CF 3 7 AR5 Methyl 2,2 - difluoroacetate 433 - 53 - 4 HCF 2 COOCH 3 3 AR5 Difluoromethyl 2,2,2
- trifluoroacetate 2024 - 86 - 4 CF 3 COOCHF 2 27 AR5 Methyl 2,2,2 - trifluoroacetate 431 - 47 - 0 CF 3 COOCH 3 52 AR5 2,2,3,3,4,4,5,5 - Octafluorocyclopentanol 16621 - 87 - 7 - (CF 2 ) 4 CH(OH)
- 73 AR4/Table A

- 1 1,1,1,3,3,3 - Hexafluoropropan
- 2 - ol 920 - 66 - 1 (CF 3 ) 2 CHOH 182 AR5 2,2,3,3,3 - Pentafluoropropan
- 1 - ol 422 - 05 - 9 CF 3 CF 2 CH 2 OH 19 AR5 4,4,4 - Trifluorobutan
- 1 - ol 461 - 18 - 7 CF 3 (CH 2 ) 2 CH 2 OH 0.05 AR5 (Precise GWP Calculated) 2,2,3,3,4,4,4 - Heptafluorobutan
- 1 - ol 375 - 01 - 9 C 3 F 7 CH 2 OH 34 AR5 2,2,3,3 - Tetrafluoro
- 1 - propanol 76 - 37 - 9 CHF 2 CF 2 CH 2 OH 13 AR5 2,2,3,4,4,4 - Hexafluoro
- 1 - butanol 382 - 31 - 0 CF 3 CHFCF 2 CH 2 OH 17 AR5 2,2,3,3,4,4,4 - Heptafluoro
- 1 - butanol 375 - 01 - 9 CF 3 CF 2 CF 2 CH 2 OH 16 AR5

2 - Fluoroethanol 371 - 62 - 0 CH 2 FCH 2 OH 1.07 AR5 (Precise GWP Calculated) 2,2 - Difluoroethanol 359 - 13 - 7 CHF 2 CH 2 OH 3 AR5 2,2,2 - Trifluoroethanol 75 - 89 - 8 CF 3 CH 2 OH 20 AR5 Methyl carbonofluoridate 1538 - 06 - 3 FCOOCH 3 95 AR5 1,1 - Difluoroethyl carbonofluoridate 1344118 - 11 - 1 FCOOCF 2 CH 3 27 AR5 Trifluoromethyl formate 85358 - 65 - 2 HCOOCF 3 588 AR5 Perfluoroethyl formate 313064 - 40 - 3 HCOOCF 2 CF 3 580 AR5 Perfluoropropyl formate 271257 - 42 - 2 HCOOCF 2 CF 2 CF 3 376 AR5 Perfluorobutyl formate 197218 - 56 - 7 HCOOCF 2 CF 2 CF 2 CF 3 392 AR5 2,2,2 - Trifluoroethyl formate 32042 - 38 - 9 HCOOCH 2 CF 3 33 AR5Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GH GRP Page 19 Trade Name Chemical Designation or Common Name CAS No. Chemical For mula Proposed GWP GWP Source 3,3,3 - Trifluoropropyl formate 1344118 - 09 - 7 HCOOCH 2 CH 2 CF 3 17 AR5 1,2,2,2 - Tetrafluoroethyl formate 481631 - 19 - 0 HCOOCHFCF 3 470 AR5 1,1,1,3,3,3 - Hexafluoropropan
- 2 - yl formate 856766 - 70 - 6 HCOOCH(CF 3 ) 2 333 AR5 Halon - 1202 Dibromodifluoromethane 75 - 61 - 6 CBR 2 F 2 231 AR5 Halon - 2311 / Halothane 2 - Bromo - 2 - chloro - 1,1,1 - trifluoroethane 151 - 67 - 7 CHBrClCF 3 41 AR5Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GHGRP Page 20 

## Appendix B: Default GWPs Based on AR5 GWPs As indicated in Section II, potential default GWPs for the fluorinated GHG groups were developed using the GWPs of the F
- GHGs from AR5 only. Table 6 , below, presents the new fluorinated GHG groups with the corresponding average, standard deviation, and relative standard dev iation of the GWPs for each group. Table 6 . Average, Standard Deviation, and Relative Standard Deviation of GWPs from AR5 Only of

Fluorinated GHG Groups for Newly Proposed Rule Fluorinated GHG Group Average GWP Standard Deviation Relative

Standard Deviation Possible

Default GWP Fully fluorinated GHGs 8,953 2,671 30% 9,000 Saturated hydrofluorocarbons (HFCs) 2,016 2,848 141% 2,000 Partially segregated saturated HFEs and HCFEs 2 07 2 0 4 9 9 % 2 10 Non - segregated saturated HFEs and HCFEs 2,728 2,619 96% 2 , 700 Unsaturated PFCs 0.66 0.96 146% 1 Unsaturated HFCs and unsaturated HCFCs 0.38 0.51 134% 1 Unsaturated halogenated ethers 0.11 - - 1 Unsaturated halogenated esters N / A N / A N / A 1 Fluorinated ketones 0.11 - - 1 Fluorinated aldehydes 0.01 - - 1 Fluorotelomer alcohols 0.32 0.10 31% 1 Fluorinated GHGs with one or more carbon - iodine bonds 0.4 - - 1 Other fluorinated compounds 11 1 178 162% 110Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GHGRP Page 21 

## Appendix C: Evaluation of Default GWPs Considering Numerical and Chemical Outliers The eight main model groups were further evaluated without numerical outliers and the fully fluorinated GHGs were further evaluated including chemical outliers . For the purpose of this analysis, numerical outliers were defin ed as compounds with a GWP greater than or less than two standard deviations from the average mod el group GWP . Table 7 presents the proposed fluorinated GHG groups excluding outliers with the corresponding average, standard deviation, and relative standard deviation of the GWPs for each group. As expected, ex clusion of numerical outliers moves the average GWP away from the GWPs of the outliers and reduces the absolute and relative standard deviations of the GWPs within the model groups . Table 7 . Average, Standard Deviation, and Relativ e Standard Deviation of GWPs of Fluorinated GHG Groups Excluding Numerical Outliers Fluorinated GHG Group Excluding Outliers Proposed GWP Average

GWP Standard

Deviation Relative

Standard Deviation Number

of Chemicals in Group Fully fluorinated GHGs 10,000 8,678 1,608 19% 13 Saturated HFCs 2,200 1,344 1,409 105% 24 Part ially segregated HFEs and HCFEs 2 0 0 158 227 144% 23 Non - segr egated saturated HFEs and HCFEs 2, 4 00 2,089 488 23% 36 Unsaturated PFCs 1 0.66 0.96 146% 6 Unsaturated HFCs 1 0 .29 0.40 136% 13 Unsaturated halogenated ethers 1 0.11 0.09 79% 2 Unsaturated halogenated esters 1 N/A N/A N/A 0 Fluorinated ketones 1 N/A N/A N/A 0 Fluorinated aldehydes 1 N/A N/A N/A 0 Fluorotelomer alcohols 1 0.32 0.10 31% 4 Fluorinated GHGs with one or more carbon iodine bonds 1 N/A N/A N/A 0 Ot her fluorinated GHGs 1 1 0 68 114 167% 30 

### Only one model group, fully fluorinated GHGs, has the potential to include compounds that are chemically different from the compounds whose GWPs are being modeled by that group . These compounds, SF 6 

### and NF 3 

### , are excluded from fully fluorinated GHGs in the main analysis. Table 8 shows how the average GWP for this group would increase if SF 6 

### and NF 3 

### were included in the group. Table 8 . Average, Standard Deviation, and Relative Standard Deviation of GWPs of Fully Fluorinated GHG Group, Including SF 6 

### and NF 3 Fluorinated GHG Group Proposed GWP Average

GWP Standard

Deviation Relative

Standard Deviation Number

of Chemicals in Group Fully fluorinated GHGs , Including SF 6 and NF 3 10,000 11,050 4,769 43% 17Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GHGRP Page 22 

## Appendix D : Evaluation of the Comments Received on the Proposed Amendments to Subpart L Comments related to the construction of the F
- GHG groups were received from three entities: DuPont, 3M Company, and ACC. These commenters provide d suggestions to improve the default GWPs presented in the Proposed Amendments to Subpart L. ICF evaluated whether the suggestions provided by DuPont, 3M, and ACC 5 

### — to add compounds to the existing g roups and to create new groups — we re likely to improve the accuracy and precision of the default GWPs proposed for subpart L . To do this evaluation, ICF incorporated these suggestions into the analysis used to develop the default GWPs for the Proposed Amendments to Subpart L. Specifically, ICF analyzed the “other fluorinated compounds” and “s aturated HFEs and HCFEs” groups from the Proposed Amendments to Subpart L and assigned each compound a more specific group designation. By disaggregating the “other fluorinated compounds” into these groups (e.g., unsaturated halogenated esters, fluorinated aldehydes, fluorotelomer alcohols, fluorinated alcohols, formates, etc.), it was possible to evaluate the GWPs of each group and compare them to the previously proposed GWP of 100 (see Table 1 ). A similar approach was adopted for the compounds in the proposed group “saturated HFEs and HCFEs.” Table 9 presents a comparison of the Proposed Amendments to Subpart L’s F
- GHG groups and the commenters’ suggested F
- GHG groups . I n most cases, the F - GHG compounds in the suggested new groups were or iginally part of the “other fluorinated compounds” group in the Proposed Amendments to Subpart L ; the exceptions were the compounds in the suggested new groups, “partially segregated saturated HFEs” and “non
- segregated saturated HFEs,” which were originall y part of the “saturated HFEs and HCFEs” group. Table 9 . Comparison of Proposed Amendments to Subpart L and Commenter Suggested F - GHG Groups a Source Fluorinated GHG Group GWP Suggested by Source (100 - year) Number

of Chemicals in Group Average

GWP (100 - year) Average

Lifetime (years)

Proposed Amendments to Subpart L Fully fluorinated GHGs 10,000 15 9,857 5,953

Saturated hydrofluorocarbons (HFCs) 2,200 26 2,187 32 Saturated hydrofluoroethers (HFEs) and saturated hydrochlorofluoroethers (HCFEs) 1,600 61 1,536 10 Unsaturated PFCs, unsaturated HFCs, unsaturated HCFCs, unsaturated HFEs, and fluorinated ketones 1 23 <1 «1 b Other fluorinated compounds 100 32 94 <1 Recommended by DuPont Unsaturated PFCs, unsaturated HFCs,

unsaturated HCFCs, unsaturated halogenated ethers, unsaturated halogenated esters, fluorinated ketones , and fluorinated aldehydes 1 25 <1 «1 b

5 ICF did not specifically address com ments provided by ACC because their suggested groups were covered by DuPont’s recommendations, and because the groups suggested by DuPont were more specific.Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GHGRP Page 23 Source Fluorinated GHG Group GWP Suggested by Source (100 - year) Number

of Chemicals in Group Average

GWP (100 - year) Average

Lifetime (years) Fluorinated and Fluorotelomer Alcohols c 1 1 5 25 <1 Fluorotelomer Alcohols d 1 4 <1 «1 Fluorinated GHGs with one or more carbon iodine bonds 1 0 N/A N/A Recommended by 3M Partially segregated saturated HFEs 230 25 204 2

Non - segregated saturated HFEs 2,800 37 2,436 15 Evaluated by ICF Other fluorinated compounds without fully

fluorinated unsaturated halogenated ethers, fluorinated aldehydes, fluorotelomer alcohols , or fluorinated GHGs with carbon
iodine bonds 110 33 112 1 Evaluated by ICF Formates 350 8 349 3 Evaluated by ICF Other fluorinated compounds without fully

fluorinated unsaturated halogenated ethers, fluorinated aldehydes, fluorotelomer alcohols, fluorinated GHGs with carbon
iodine bonds, or formates 20 21 19 <1

a DuPont a lso recommended grouping 4,4,4 - t rifluorobutanal (a fluorinated aldehyde) wi th the fluorinated ketones and v inyl 2,2,2 - trifluoroacetate (a n unsaturated ester) with the unsaturated halogenated ethe rs. 4,4,4 - trifluorobutanal and v inyl 2,2,2 - trifluoroacetate are included in the AR5 Comprehensive Review, but were ultimately not publ ished in AR5 because they do not have GWPs and are therefore not included in this analysis. b An average lifetime of «1 denotes a value less than or equal to 1 x 10 - 2 . c Includes four fluorotelomer alcohols. d Fluorotelomer alcohols, a subset of fluorinat ed alcohols, were evaluated separately. 

## a. Unsaturated Halogenated Ethers DuPont suggested broadening “unsaturated HFEs” to “unsaturated halogenated ethers” to account for the carbon - carbon double bond in unsaturated ethers that result s in a short atmospheri c lifetime and low GWP for these compounds . A s explained by DuPont, the degree of fluorination of the compound has a small effect on the lifetime and GWP. For example, HFE
- 216 (CF 3 

### OCF=CF 2 

### ), an unsaturated fully fluorinated ether, has a 100
- year GWP of 0 .17 6 

### and lifetime of 8.4 days in IPCC AR5 . Additionally, fluoroxene (CF 3 

### CH 2 

### OCH=CH 2 

### ), an unsaturated ether that is not fully fluorinated, has a 100
- year GWP of and lifetime of 3.6 days according to IPCC AR5. This suggestion revises the classification of all un saturated fully fluorinated ethers, which were previously assigned as “other fluorinated compounds , ” instead of unsaturated HFEs, because they do not contain a carbon
- hydrogen bond. In the revised fluorinated GHG group, all “unsaturated halogenated ethers” must contain one or more carbon - carbon multiple bonds , but can have any degree of fluorine or chlorine substitution in the alkyl groups . ICF expects this categorization to be accurate and to appropriately categorize all unsaturated fluorinated ethers, reg ardless of the degree of fluorination and/or chlorination in the alkyl groups.

6 This precise GWP was calculated using the atmospheric lifetime and the corrected radiative effic iency provided in the AR5.Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GHGRP Page 24 

## b. Fluorinated Ketones and Aldehydes DuPont suggested expanding fluorinated ketones to include fluorinated aldehydes , which were previously categorized as “other fluorinated compounds ; ” this would assign fluorinated aldehydes a GWP of 1. This approach is accurate and well defined from a physical chemistry viewpoint. As noted by DuPont, peer - reviewed literature suggests similarities between the behavior of fluorinated ketones a nd aldehydes as they photodissociate readily in hours or days. Photolysis lifetimes of aldehydes and ketones in the sunlit troposphere are approximately several days (Derwent, 1995). This behavior indicates that these compounds have short atmospheric lifet ime and therefore low GWPs. For example, 3,3,3 – trifluoro
- propanal has a 100 - year GWP of 0.01 7 

### and lifetime of 2.0 days according to IPCC AR5. ICF’s evaluation shows that this group could be added to the previously existing group of compounds assigned a G WP of 1 (see Table 9 ). ICF expects this categorization to be accurate for the fluorinated aldehydes whose atmospheric behavior has not yet been studied . 

## c. Fluorinated Alcohols (including Fluorotelomer Alcohols ) DuPont suggested that all fluorinated alcohols be assigned a GWP of 1 based on their analysis of the GWPs of a subset of fluorinated alcohols, fluorotelomer alcohols. DuPont noted that all fluorotelomer alcohols are likely to have short atmospheric lifetimes and therefore low GWPs. A study of the kinetics of the reactions of fluorotelomer alcohols with OH radicals indicates that the atmospheric lifetime of fluorotelomer alcohols, regardless of the length of the mo lecule, is approximately 20 days, or 0.05 years (Ellis et al., 2003). Additionally, IPCC AR5 assigns GWPs of less than one to all four of the fluoro telomer alcohols included in AR5 . For example , 3,3,3 - t rifluoropropan
- 1 - ol has a GWP of 0.35 7 

### and an atmospheric lifetime of 12.0 days and 3,3,4,4,5,5,6,6,7,7,7 - Undecafluoroheptan
- 1 - ol has a GWP of 0.43 7 

### and an atmospheric lifetime of 20.0 days; both of these compounds are fluorotelomer alcohols. DuPont’s comments recommend combining fluorotelom er alcohols and fluorinated alcohols into a single group with an assigned GWP of 1. However, as shown in Table 9 above, the average GWP of fluorinated alcohols , inclu ding the four fluorotelomer alcohols, is greater than 1 (i.e., 25 ), and therefore assigning all fluorinated alcohols a GWP of 1 is not accurate. Additionally, a study of the kinetics of the reactions of a series of fluorinated alcohols with OH radicals ind icates that the atmospheric lifetime of fluorinated alcohols is approximately 164 days, or 0.45 years (Hurley et al., 2004). ICF’s analysis suggests assigning fluorotelomer alcohols a GWP of 1 and adding them to the previously existing group of compounds a ssigned a GWP of 1, while other fluorinated alcohols would remain in the “other fluorinated compounds” group. 

## d. Unsaturated Halogenated Esters DuPont suggested assigning unsaturated halogenated esters, which were previously categorized as “other fluorinated compounds,” a GWP of 1. This approach is accurate and well defined from a physical chemistry viewpoint. As described by DuPont, unsaturated halogenated esters have a double carbon carbon bond whose reactivity results in a short atmospheric lifetime and th erefore low GWP. A search of the peer
- reviewed literature, including AR5 and Hodnebrog et al. (2013), did not yield GWPs for any unsaturated halogenated esters. Hodnebrog et al. (2013) includes a radiative efficiency, but not an atmospheric lifetime, for one unsaturated halogenated ester, vinyl, 2,2,2 - trifluoroacetate. This radiative efficiency, 0.387 Wm - 2 

### ppb - 1 

### , is an overestimate because it has not been corrected to reflect the

7 This precise GWP was calculated using the atmospheric lifetime and the corrected radiative efficiency provided in the AR5.Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GHGRP Page 25 

### (probably very short) atmospheric lifetime of vinyl, 2,2,2
- trifluoroacetate. 8 

### Nevertheless, when this uncorrected radiative efficiency is considered in conjunction with the atmospheric behavior of a saturated near - relative of vinyl, 2,2,2
- trifluoroacetate, ethyl 2,2,2
- trifluoroacetate, some conclusions may be drawn regarding the GWP of the former. According to AR5, ethyl 2,2,2 - trifluoroacetate has a lifetime of 21.9 days, a corrected radiative efficiency of 0.05 3 , and a GWP of 1 .3 . 9 

### Hodnebrog et al. (2013) provides an uncorrected radiative efficiency of 0. 28 Wm - 2 

### ppb - 1 

### for ethyl 2,2,2, - trifluoroacetate, indicating that the correction factor for this compound (and compounds with similar atmospheric lifetimes) is about 0.19 . Assuming vinyl 2,2,2 - trifluoroacetate has a lifetime of no more than 21.9 days and that the same correction factor should be applied to its radiative efficiency, the GWP for vinyl 2,2,2
- trifluoroacetate is estimated to be 1.8. Because vinyl 2,2,2 - trifluoroacetate is unsaturated, it is likely to be more short
- lived than ethyl 2,2,2 - trifluoroacetate and therefore to have a lower GWP than what was calculated using a lifetime of 21.9 days. For this compound to have a GWP of around 1 (applying the same corrected radiative efficiency) , it s atmospheric lifetime would have to be a pproximately 1 2 days . This is comparable to the average atmospheric lifetimes of the un saturated HFCs and PFCs (10 and 1 3 days, respectively). Looking beyond vinyl 2,2,2 - trifluoroacetate, the atmospheric behavior of the saturated and unsaturated HFCs and PFCs implies t hat the atmospheric lifetimes and GWPs of unsaturated fluorinated esters are likely to be low. Specifically, the saturated HFCs and PFCs have average GWPs of 2,187 and 9,857 respectively, considerably higher than the average GWP of the saturated fluorinate d esters, 162 . This difference is largely driven by the difference in atmospheric lifetimes, with HFCs and PFCs having average lifetimes of 32 and 5,953 years, respectively, and saturated fluorinated esters having an average lifetime of 1.2 years. At the s ame time, the unsaturated HFCs and PFCs have average GWPs of 0.4 and 0.7 respectively, reflecting atmospheric lifetimes of days or weeks. Because unsaturated fluorinated esters are expected to have lifetimes as brief (or briefer) than those of HFCs and PF Cs, the unsaturated fluorinated esters are also likely to have GWPs below 1. This conclusion is expected to be valid as long as the other compound - dependent term in the GWP calculation, specifically, the ratio of radiative efficiency to molecular weight , is also similar for unsaturated esters and unsaturated HFCs and PFCs. To further investigate the latter assumption, ICF calculated the ratio of the uncorrected radiative efficiency (RE) to the molecular weight (MW) (i.e., RE/MW) for all of the saturated and unsaturated fluorinated esters, HFCs, and PFCs that are included in the default GWP analysis. 10 

### This exercise evaluated the possibility that the fluorinated esters have significantly higher RE/MW ratios than the HFCs and PFCs, which would indicate that even if the unsaturated esters are as short - lived as the unsaturated HFCs and PFCs, they could have significantly higher GWPs. Based on the ratios s hown in Table 10 b elow, the average RE/ MW ratios for the saturated fluorinated esters (fluorinated acetates and formates) are higher than the average RE/MW ratios for the saturated HFCs and PFCs, but are still within a factor of two. Similarly, the RE/MW ratio for vinyl 2, 2,2 -

8 Many estimates of GHGs’ radiative efficiencies are based on the assumption that the GHGs are well
- mixe d in the atmosphere. For GHGs with lifetimes of a few months or less, this assumption is not realistic and leads to overestimates of the radiative efficiencies (and GWPs) of the GHGs. The GWPs and radiative efficiencies included in Hodnebrog et al. (2013) and AR5 reflect corrections to the radiative efficiencies of short
- lived GHGs to mitigate this overestimate. 9 This precise GWP was calculated using the atmospheric lifetime and the corrected radiative efficiency provided in the AR5. 10 Saturated fluorinated esters were included because radiative efficiency information was available for only one unsaturated fluorinated ester, vinyl 2,2,2
- trifluoroacetate, and because their inherent radiative properties were expected to be similar to thos e of unsaturated fluorinated esters. Uncorrected radiative efficiencies were used in order to permit a comparison between the saturated and unsaturated compounds in the absence of atmospheric lifetime.Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GHGRP Page 26 

### trifluo roacetate (unsaturated ester) is higher than the RE/MW ratios of the unsaturated HFCs and PFCs, but is still within a factor of two. Based on this analysis, it appears likely that the average GWPs for the unsaturated fluorinated esters are likel y to be near 1, and that it is appropriate to assign these compounds a default GWP of 1. Table 10 . Comparison of Radiative Efficiency to Molecular Weight Ratios of Saturated and Unsaturated HFCs and PFCs Fluorinated GHG Group RE/ MW Ratio Saturated PFC 0.0014 Saturated HFC 0.0015 Unsaturated PFC 0.0015 Unsaturated HFC 0.0018 Fluorinated Acetates 0.00 25 Formate 0.002 5 Unsaturated Ester 0.0027 

### Therefore, the default GWP of 1 is expected to be accurate for the unsaturated halogenated esters whose atmospheric behavior has not yet been studied . ICF’s analysis suggests that this group be could added to the previously existing group of compounds assi gned a GWP of 1. 

## e. Partially Segregated and Non - Segregated Saturated HFEs and HCFEs 3M suggest ed disaggregating “saturated HFEs and HCFEs ” into ‘partially segregated’ and ‘non
segregated’ HFEs and HCFEs to more accurately reflect the GWPs of this group. 3M noted that partially segregated HFEs display significantly shorter atmospheric lifetimes and lower GWPs than non
segregated HFEs. ICF evaluated this suggestion by disaggregating saturated HFEs and HCFEs into two groups using the following classifications:  Partially segregated compounds contain a fully hydrogenated alkyl group on one side of the oxygen with no fluorine substitutes and a partially or fully fluorinated alkyl group on the other side.  Non - segregated compounds contain fluorine substitutes on all alkyl groups, but are not necessarily fully fluorinated. For example, HFE - 449s1 (C 4 

### F 9 

### OC 2 

### H 5 

### ) and HFE
- 569sf2 (C 4 

### F 9 

### OC 2 

### H 5 

### ) are segregated HFEs with the ether oxygen separating a fully fluorinated and a fully hydr ogenated alkyl group, while HFE - 347pcf (CF 2 

### HCF 2 

### OCH 2 

### CF 3 

### ) is a non
- segregated HFE with oxygen separating two partially fluorinated alkyl groups (IPCC/TEAP, 2005 ). In its comments, 3M did not explain the mechanism through which the segregation of fluorine a toms in HFE molecules leads to shorter lifetimes . However, Owens (1999) notes that the “segregated structure maximizes the effect of the ether oxygen in reducing the atmospheric lifetimes.” Owens further notes that fluorine can decrease the activating ef fect of the ether and states , “although there can be a deactivating effect from fluorine atoms across the ether bond, it is much less pronounced than that produced by fluorine atoms on the same alkyl group. This segregated structure appears to buffer the hydrogen atoms from the very electronegative fluorine atoms taking full advantage of the activating effect of the ether oxygen. ”Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GHGRP Page 27 

### The histogram below shows the GWPs of the saturated HFEs and HCFEs sorted into partially segregated and non - segregated HFEs an d HCFEs in order to evaluate whether th is separation of saturated HFEs and HCFEs is an indicator of whether a compound is likely to have a low or high GWP, and whether this separation would therefore be a valuable distinction to make when establishing F
- GH G groups.

Figure 2 . Histogram comparing GWPs of partially segregated and non - segregated saturated HFEs and HCFEs . The table below shows the average GWP s, standard deviation s, and proposed default GWPs of each sub - group based on ICF’s evaluation , as well as the same values for the aggregated group of saturated HFEs and HCFEs.

Table 11 . Comparison of Average GWPs of Saturated HFE and HCFE Groups Saturated HFE Group Proposed GWP (100 - year ) Average

GWP (100 - year ) Standard

Deviation Average

Atmospheric Lifetime Saturated HFEs and HCFEs 1,600 a 1,5 36 2,5 36 10.0 Partially segregated saturated HFEs and HCFEs 2 0 0 2 04 227 1.8 Non - segregated saturated HFEs and HCFEs 2, 4 00 2, 436 2,967 15.5 a Default proposed in Proposed Amendments to Subpart L based on previously calculated average GWP (see footnote “ a ” to Table 1). 

### As shown by Figure 2 and Table 11 , the distinction between the partially segregated and non - segregated saturated HFEs and HCFEs captures pervasive (though not universal) differences in GWPs among the saturated HFEs and HCFEs . Most partially segregated HFEs and HCFEs have GWPs below 500, while most non - segregated HFEs and HCFEs have GWPs great er than 500. However, th ere are outliers in both groups. For example, the (lower
- GWP) partially segregated HFE group with a default GWP of 200 would include HFE - 143a ( CH 3 

### OCF 3 

### ), which has a lifetime of 4.3 years and GWP of 756. 0 2 4 6 8 10 12

0 to 100 100 to 250 250 to 500 500 to 750 750 to 1,000 1,000 to

2,500 2,500 to

5,000 5,000 to

7,500 7,500 to

10,000 Over

10,000 Frequency



### GWP Range Partially Segregated Non-SegregatedRevised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GHGRP Page 28 

### Despite these known outlier s, the two sub - groups of saturated HFEs and HCFEs are based on chemical structure, which could more accurately categorize the HFEs, and potentially assign the saturated HFE s and HCFEs more representative GWPs. Therefore, these new groupings are likely to a pply to HFEs and HCFEs whose atmospheric behavior has not yet been studied . Additional analysis of the GWPs of saturated HFEs and HCFEs , including an analysis of the relationship between these GWPs and the numbers of carbon - hydrogen (C
- H) and carbon - fluorine (C
- F) bonds in the molecule, can be found in “ Revised Analysis of Atmospheric Lifetimes, Radiative Efficiencies, and Global Warming Potentials of Saturated Hydrofluoroethers by Number of Carbon
- Hydrogen and Carbon Fluorine Bonds .” 

## f. Fluorinated GHGs with One or More Carbon - iodine Bond DuPont suggested forming an additional group for fluorinated compounds containing one or more carbon - iodine bonds, because any fluorinated compound with a carbon - iodine bond is expected to photodissociat e readily, resulting in an atmospheric lifetime of a few hours and an approximate GWP of 1. ICF found the following evidence to support this suggestion:  A three - dimensional global chemistry - transport model (CTM) of the troposphere and stratosphere was used to evaluate the potential effects of CF 3 

### I, a very short - lived iodinated compound. The model indicated that this compound has a lifetime of 5.03 days and 1.13 days for emissions assumed to be evenly distributed over land surfaces at mid
- latitudes and the t ropics, respectively (Youn et al., 2010). Furthermore, according to IPCC AR4, CF 3 

### I has a direct 100 - year GWP of 0.4 and lifetime of 0.005 years. This direct GWP does not account for any stratospheric ozone depletion by CF 3 

### I, which is likely to be negligib le and would be expected to decrease the GWP.  A study on the reactions of fluorotelomer i odide (n
- C 4 

### F 9 

### CH 2 

### CH 2 

### I) calculated t hat the atmospheric lifetime of this iodinated compound is determined by photolysis and is a few days (Young et al., 2008).  Approxim ately ten fluorinated iodine compounds have been examined by scientists, and all have very short lifetimes (i.e. 5 days or less) because they photolyze rapidly resulting in GWP values less than 1 (Wuebbles, 2014). Based on the results of these studies and DuPont’s supporting information, any fluorinated compound with a carbon - iodine bond is expected to have a very short atmospheric lifetime and could therefore be assigned a GWP of 1. 

## g. Formates During this analysis, ICF noticed that the eight formates categ orized as “other fluorinated compounds” have an average GWP of 350 and an average lifetime of 2.5 years. For example, according to IPCC AR5, t rifluoromethyl formate has a 100 - year GWP of 588 and a lifetime of 3.5 years while 2,2,2
- t rifluoroethyl formate ha s a 100 - year GWP of 33 and a lifetime of 0.4 years. Removing these eight compounds from the list of “other fluorinated compounds” results in an average GWP for the “other fluorinated compounds” of 20 and an average lifetime of 0.3 years. To improve the acc uracy and precision of the proposed GHG groups, one potential action is to remove formates from “other fluorinated compounds” and create a new “formates” group with a default GWP of 350. 11

11 Note: Dr. Weubbles did not provide feedback on this observation.Revised Analysis of Default GWPs for Fluorinated GHGs Reported Under the GHGRP Page 29 

### However, revising the GWP of “other fluorinated compounds” to 20 m ay not be appropriate as a new compound with an inherently higher GWP than 20 could be reported in the future and fall into this group. Therefore, it may be preferable to retain the more conservative GWP of 100 for “other fluorinated compounds” in the even t a high - GWP compound is assigned to this group.