Technical Support for Other 

Technical Issues Addressed in 

Revisions to Subpart I

Office of Air and Radiation, U.S. Environmental Protection Agency

August 2012
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1. Introduction

This document presents technical support for the following proposed changes in subpart I, Electronics 

Manufacturing, of the Greenhouse Gas Reporting Program (GHGRP):

 addressing situations where research and development (R&D) activities are integrated with 

regular facility production;

 revising the definition of maximum substrate starts;

 clarifying and revising the heel factor provisions; 

 revising the nitrous oxide(N2O) default emission factor and clarifying N2O regulatory language; 

and 

 revising the measurement equipment accuracy and precision requirements.

This document is based on information from Technical Support Document for Process Emissions from 

Electronics Manufacture (e.g., Micro-electro-mechanical systems, liquid crystal displays, photovoltaics, 

and semiconductors): Proposed Rule for Mandatory Reporting of Greenhouse Gases, Revised – November 

2010 (hereafter, the November 2010 TSD, available in docket EPA-HQ-OAR-2009-0927). It is also based 

on non-confidential materials submitted to the EPA by the Semiconductor Industry Association (SIA).

2. Integrated Production and Research and Development Processes

Per 40 CFR 98.2(a)(5), emissions resulting from research and development (R&D) activities are not 

considered to be part of any source category under the GHGRP.

1 However, in its petition for 

reconsideration of subpart I, SIA raised the issue that for some electronics manufacturing facilities

(particularly semiconductor facilities) R&D operations are integrated with regular manufacturing 

operations to better evaluate process manufacturability (SIA, 2011). Accordingly, SIA suggested that it 

would be burdensome on facilities that have integrated R&D activities to segregate R&D emissions from 

process emissions that are required to be reported. While the provisions in subpart A make it clear that 

reporting R&D emissions is not required, this does not preclude facilities that have integrated R&D 

activities to report those R&D emissions as part of regular facility manufacturing emissions. Since this is 

a important issue for subpart I, the EPA is proposing that subpart I facilities that include R&D emissions 

in their report (1) specify this in their report and (2) provide an estimated percent, on a carbon dioxide 

equivalent (CO2e) basis, of annual emissions that are attributable to R&D activities.2To provide flexibility 

and ease burden on reporters, the EPA is not specifying the methods facilities must use to estimate the 

percent of R&D emissions; however, the EPA is proposing that facilities maintain records of the 

calculation of the percent of total emissions of F-GHG and N2O attributable to R&D activities. These 

provisions would reduce burden on reporters with integrated R&D activities while still collecting 

information that will allow the EPA to compare non-R&D emissions across industries within the GHGRP.

3. Calculating Annual Manufacturing Capacity and Applicability Determinations

 

1

Research and development, as defined at 40 CFR 98.6, means those activities conducted in process units or at laboratory 

bench-scale settings whose purpose is to conduct research and development for new processes, technologies, or products and 

whose purpose is not for the manufacture of products for commercial sale, except in a de minimis manner.

2

Proposed amendments would allow facilities that have integrated R&D to indicate that their reported emissions include R&D 

with a simple “Yes/No” checkbox. Facilities that select “Yes” would also be required to report a range of R&D emissions in the 

form of <5%, 5 to <10%, 10 to <25%, 25 to <50%, ≥50%.
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In the December 2010 version of subpart I (75 FR 74774) EPA finalized a definition of maximum designed 

substrate starts that read as follows: 

Maximum designed substrate starts means the maximum quantity of substrates, expressed as 

surface area, that could be started each month during a reporting year if the facility were fully 

equipped as defined in the facility design specifications and if the equipment were fully utilized. It 

denotes 100 percent of annual manufacturing capacity of a facility.

Maximum designed substrate starts is used as the basis for determining a facility’s annual 

manufacturing capacity in Equation I-5, and annual manufacturing capacity is subsequently used in 

subpart I threshold applicability determinations.3

In its Petition for Reconsideration of subpart I, SIA noted however that, “The maximum capacity 

calculation, as set forth in the Final Subpart I, rests on two assumptions: (1) a facility has a full 

complement of equipment that corresponds to its design; and (2) this full complement of equipment is 

utilized to a maximum degree. Due to many factors, including ramping of production (both up and 

down) to meet market demand and retooling for new products, these assumptions do not reflect reality 

at most facilities most of the time.” (SIA, 2011) In some cases, this may result in a facility triggering the 

reporting threshold in subpart I even though the actual capacity of the facility would not reach the 

estimated annual manufacturing capacity of the facility based on maximum designed substrate starts 

and calculated per the provisions in subpart I.

To better reflect a facility’s actual potential to emit (on which threshold applicability calculations are 

based, see the November 2010 TSD), the EPA is proposing to amend the definition of “maximum 

designed substrate starts” so that it reflects the equipped capacity of the facility based on the 

equipment actually available for production and not on the designed capacity. The EPA is also proposing 

to revise the defined term to read “maximum substrate starts” to reflect the concept that annual 

capacity of a facility would no longer be based on the facility design, but actual installed capacity. The 

EPA is proposing to define “maximum substrate starts” as: 

The maximum quantity of substrates, expressed as surface area, that could be started each month 

during a reporting year based on the equipment installed in that facility and assuming that the 

installed equipment were fully utilized. Manufacturing equipment is considered installed when it is 

on the manufacturing floor and connected to required utilities.4

4. Facility-Wide Gas-Specific Heel Factor Provisions

The December 2010 subpart I required facilities to re-calculate a facility-wide gas-specific heel factor if 

they use a trigger point for change out for a gas and container type that differs by more than five 

 

3

Annual manufacturing capacity was also used to determine whether or not a semiconductor manufacturing facility was 

considered “large,” thereby requiring the use of a recipe-specific approach for estimating emissions from the etch process type. 

The EPA is proposing to remove from subpart I this method and the distinction between large and other semiconductor 

manufacturing facilities. See Technical Support for Modifications to the Fluorinated Greenhouse Gas Emission Estimation 

Method Option for Semiconductor Facilities under Subpart I for more information.

4

The proposed changes would not affect the applicability of subpart I to any facility that is already reporting GHG emissions 

under subpart I. If the proposed changes become final, facilities that are already reporting would not be able to re-calculate 

emissions using the procedures under 40 CFR 98.91 and cease reporting if they do not meet the revised applicability criteria. 

Facilities that are already reporting under subpart I may cease reporting only if they meet the criteria in 40 CFR 98.2(i).
August 2012 Subpart I Other Issues Technical Support 

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percent from the previously used trigger point for change out for that gas and container type. In its 

Petition for Reconsideration, SIA raised the following issue with regard to this requirement: “While this

requirement seems reasonable on its face, adhering to the technical specifications of this requirement in 

practice raises compliance difficulties. For example, under this requirement, if the trigger point used by 

a facility for a 20-pound container is two pounds, then any change in that trigger point of more than 0.1 

pounds would require a facility to ‘recalculate a facility-wide gas-specific heel factor,’...” (SIA, 2011) SIA

further noted that such a small change may represent process adjustments made to ensure that high 

yields of products are maintained, or may represent minor trigger point variations that are inherent 

when dealing with small quantities of gas. 

After considering this issue, the EPA has concluded that the intent of the provisions for recalculation of 

heel factors in subpart I in the December 2010 rule should be clarified. Therefore, the EPA is proposing 

an amendment to clarify the requirements in subpart I to state that a facility needs to recalculate a 

facility-wide gas-specific heel factor only if the facility executes a process change to modify the trigger 

point for a gas and container type that differs by more than five percent from the previously used trigger 

point for change out for that gas and container type. This amendment would clarify that variation in the 

actual heel left in gas containers would not result in a facility being required to recalculate heel factors. 

Recalculation of heel factors is needed only when there is an intentional change in the trigger point to 

reflect a process change at the facility.

SIA raised a similar measurement issue to the one described above for “small” gas containers with 

respect to the exceptional circumstance provisions in subpart I. The EPA included provisions in the 

December 2010 version of subpart I to account for situations or “exceptional circumstances” where gas 

containers are changed out at a point that deviates substantially from the a trigger point set for a given 

container. These exceptional circumstance provisions are intended to ensure that gas consumption is 

properly accounted for in these cases when estimating emissions. If an exceptional circumstance were 

to occur, subpart I requires that the amount of gas used for that container be manually measured (e.g., 

with a scale, pressure gauge, etc...) instead of relying on the heel factor for that gas and container type. 

EPA set the exceptional circumstance threshold at 20 percent or more than the set trigger point for 

change out for a container.

In its petition, SIA noted that the 20 percent limit presents difficulties when tracking exceptional 

circumstances for small containers because of the small quantities of gas that would be represented by 

an exceptional circumstance and that would have to be tracked. This comment prompted EPA to reevaluate the exceptional circumstances threshold. 

In looking at Table 1, which presents gas container data provided by SIA, it can be seen that the range in 

sizes of gas containers used in the semiconductor manufacturing industry is quite broad. In deciding 

how to define a small container the EPA took into account an example from SIA examining containers of

20 pounds (approximately 9.08 kg) (SIA, 2011). The EPA also concluded there was a logical break in the 

gas container size data at 20 pounds (approximately 9.08 kg) (see gray highlighted row in Table 1). The 

EPA then evaluated how the 20 pounds or less small gas containers criteria would impact the minimum 

quantity of gas that would be required to be tracked manually in the case of exceptional circumstances. 
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The EPA evaluated three alternative exceptional circumstance thresholds (25 percent, 50 percent, and 

75 percent) to determine how an alternative threshold would translate into minimum gas quantities (kg)

that would have to be manually tracked. It can be seen in moving from the current 20 percent threshold 

to a 25 percent threshold does not change the quantity of gas for small containers that would have to be 

tracked manually significantly, or at all in some cases. In moving to a 50 percent from a 20 percent there 

are substantial changes in the quantity of gas associated with the exceptional circumstance threshold; in

many cases double the quantity of gas. The quantities seen under the 50 percent column for small gas 

containers (above the gray line) are also similar to many quantities seen for large gas containers under

the 20 percent column (under the gray line). Moving to a 75 percent exceptional circumstance threshold 

for small containers results in a much larger rise in the gas quantity associated with the exceptional 

circumstance threshold, mostly resulting in quantities that are bigger than those seen for some large gas 

containers at the 20 percent threshold (below the gray line). In light of this analysis the EPA is proposing 

to define an exceptional circumstance for small gas containers, defined as 9.08 kg (20 pounds) or less, as 

a 50 percent deviation from the trigger point for container change out. This proposed threshold would 

provide a balance between the feasibility and burden associated with tracking exceptional 

circumstances, taking into account normal variation in day-to-day container management that would be 

more likely to trigger an exceptional circumstance, while providing EPA with accurate gas usage 

information. For larger containers, the EPA is proposing to maintain the 20 percent exceptional 

circumstance threshold currently in subpart I.

Table 1. Analysis of Exceptional Circumstances (SIA, 2012a)

Gas

Full 

Weight 

of Gas 

(kg)

Heel 

Fraction

Heel 

Weight 

(kg)

Used 

Gas 

Weight 

(kg)

Mass of Gas (kg) Reflected at Different Exceptional Circumstance 

Thresholds

20 Percent 

Exceptional 

Circumstance 

Threshold

25 Percent

Exceptional 

Circumstance 

Threshold

50 Percent 

Exceptional 

Circumstance 

Threshold

75 Percent 

Exceptional 

Circumstance 

Threshold

CF4 0.82 5.00% 0.04 0.78 0.01 0.01 0.02 0.03

CH3F 1.36 21.00% 0.29 1.08 0.06 0.07 0.14 0.21

C4F6 2.72 7.00% 0.19 2.53 0.04 0.05 0.10 0.14

CH2F2 3.18 20.00% 0.64 2.54 0.13 0.16 0.32 0.48

CH2F2 4.54 20.00% 0.91 3.63 0.18 0.23 0.45 0.68

CH3F 4.54 21.00% 0.95 3.58 0.19 0.24 0.48 0.71

CH3F 6.80 13.00% 0.88 5.92 0.18 0.22 0.44 0.66

CHF3 6.80 5.00% 0.34 6.46 0.07 0.09 0.17 0.26

C4F8 6.94 10.00% 0.69 6.25 0.14 0.17 0.35 0.52

CH3F 8.62 10.00% 0.86 7.76 0.17 0.22 0.43 0.65

C5F8 8.98 10.00% 0.90 8.08 0.18 0.22 0.45 0.67

CF4 18.14 5.00% 0.91 17.24 0.18 0.23 0.45 0.68

SF6 18.14 6.00% 1.09 17.06 0.22 0.27 0.54 0.82

C4F8 19.96 10.00% 2.00 17.96 0.40 0.50 1.00 1.50

CHF3 21.32 11.10% 2.37 18.95 0.47 0.59 1.18 1.77

CHF3 21.32 11.10% 2.37 18.95 0.47 0.59 1.18 1.77

NF3 21.77 5.00% 1.09 20.68 0.22 0.27 0.54 0.82
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NF3 21.77 5.00% 1.09 20.68 0.22 0.27 0.54 0.82

C4F8 22.68 10.00% 2.27 20.41 0.45 0.57 1.13 1.70

NF3 22.68 5.00% 1.13 21.55 0.23 0.28 0.57 0.85

NF3 22.68 4.00% 0.91 21.77 0.18 0.23 0.45 0.68

C4F8 23.13 10.00% 2.31 20.82 0.46 0.58 1.16 1.73

C4F8 31.75 7.00% 2.22 29.53 0.44 0.56 1.11 1.67

C4F8 31.75 5.00% 1.59 30.16 0.32 0.40 0.79 1.19

CF4 31.75 5.00% 1.59 30.16 0.32 0.40 0.79 1.19

CF4 31.75 5.00% 1.59 30.16 0.32 0.40 0.79 1.19

CH2F2 31.75 2.90% 0.92 30.83 0.18 0.23 0.46 0.69

CHF3 34.02 14.00% 4.76 29.26 0.95 1.19 2.38 3.57

C2F6 43.09 6.00% 2.59 40.51 0.52 0.65 1.29 1.94

SF6 43.09 6.00% 2.59 40.51 0.52 0.65 1.29 1.94

C2F6 45.36 5.00% 2.27 43.09 0.45 0.57 1.13 1.70

SF6 45.36 5.00% 2.27 43.09 0.45 0.57 1.13 1.70

SF6 45.36 10.00% 4.54 40.82 0.91 1.13 2.27 3.40

SF6 45.36 6.00% 2.72 42.64 0.54 0.68 1.36 2.04

SF6 45.36 5.00% 2.27 43.09 0.45 0.57 1.13 1.70

C3F8 47.63 9.50% 4.52 43.10 0.90 1.13 2.26 3.39

C4F8 49.58 2.00% 0.99 48.59 0.20 0.25 0.50 0.74

NF3 219.99 4.00% 8.80 211.19 1.76 2.20 4.40 6.60

CF4 260.82 5.00% 13.04 247.77 2.61 3.26 6.52 9.78

CF4 326.59 5.00% 16.33 310.26 3.27 4.08 8.16 12.25

CHF3 362.87 5.00% 18.14 344.73 3.63 4.54 9.07 13.61

NF3 362.87 1.90% 6.89 355.98 1.38 1.72 3.45 5.17

C2F6 430.91 6.00% 25.85 405.06 5.17 6.46 12.93 19.39

NF3 498.95 10.00% 49.90 449.06 9.98 12.47 24.95 37.42

C4F8 544.31 2.00% 10.89 533.42 2.18 2.72 5.44 8.16

5. Estimating N2O Emissions

The EPA is proposing two amendments to the provisions for estimating N2O emissions from electronics 

manufacturing. The first is to clarify the intent of the provisions, and the second is to revise the default 

emission factor (EF) for N2O emissions from all processes other than chemical vapor deposition (CVD).

The EPA is proposing to revise the language in subpart I to clarify that the intent of the December 2010 

final rule is to require facilities to estimate only two distinct types of N2O emissions (i.e., two N2O 

emissions numbers). These are (1) the aggregate of N2O emissions resulting from chemical vapor 

deposition (CVD) processes and (2) the aggregate of N2O emissions resulting from all other N2O-using 

processes at an electronics manufacturing facility. This clarification is being proposed in response to 

questions raised in SIA’s petition about EPA’s intent in the December 2010 final rule because of minor 

differences in wording in the rule sections for calculating and reporting emissions. These differences 

made the requirement ambiguous about whether reporting is for each kind of process or all processes 

combined.
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Second, the EPA is proposing to revise the default emission factor provided in Table I-8 to subpart I 

representing non-CVD N2O-using processes in light of new emission data and information submitted as a 

result of investigating and developing the proposed stack testing option. N2O stack test data indicated 

that the N2O emission factors for a fab may be above 1.0 (for all processes). Table 2 below presents the 

emission factor data collected through stack testing from two companies.

Table 2. N2O Emission Factors (SIA, 2012b)

Company/Fab Available N2O EFs Average Fab N2O EFs

Company F Fab1

0.87

1.15

1.7

1.89

0.77

1.15

0.54

Company F Fab 2 1.76 1.76

Company D

0.34

0.50

0.66

Average Across All Three Fabs 1.14

Note: N2O data from Company F, Fab 1 for the years 2003 to 2005 were not used because 

it was reported to EPA that these EFs were based on incorrectly recorded N2O usage data.

These data are not reflected in table above. (SIA, 2012c)

The EPA and SIA could not identify the cause of the N2O emission factors reported in Table 2 that are

greater than 1.0 (SIA, 2012c). N2O is not generally known to be a by-product from processes used in 

electronics manufacturing; however, the data presented in Table 2 indicate that there may be a physical

or chemical process that results in N2O being formed. Therefore, the EPA is proposing to revise the 

default N2O emission factor for the aggregate of other N2O-using processes to be 1.14, based on the 

average of the data in Table 2. The EPA is not proposing to revise the default N2O EF for CVD processes 

because EPA has historical data supporting this EF (see the November 2010 TSD for a discussion of this 

data and setting the N2O CVD default EF) and no new data are available indicating this EF should be 

revised. 

6. Accuracy and Precision of Measurement Equipment

The EPA is proposing to revise the accuracy and precision requirements for measurement equipment at 

40 CFR 98.94(i). The December 2010 version of subpart I has a requirement that all measurement 

equipment (e.g., flow meters, weigh scales, pressure gauges, and thermometers) have an accuracy and 
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precision of one percent of full scale or better.5In light of new information submitted by SIA in its 

petition (SIA, 2011) and in response to questions from the EPA, the EPA is proposing to revise the 

accuracy and precision requirements of subpart I to 1) remove the subpart-specific requirements and 2)

reference the general calibration and accuracy requirements in subpart A (see 40 CFR 98.3(i)). The EPA is 

proposing this modification because although the majority of new facilities and new equipment will be 

able to meet the one percent of full scale accuracy requirement, many older facilities have accuracies of 

two to four percent (SIA, 2011). Modifying the requirements would reduce the burden for facilities that 

would otherwise have to make capital investments to upgrade measurement equipment to meet the 

one percent of full scale provision. This provision modification is not expected to impact the accuracy of 

facility GHG emission estimates at facilities that are using measurement equipment that met the one 

percent of full scale standard. It may impact the accuracy of F-GHG emission estimates, particularly at 

older facilities that have less accurate measurement equipment. The accuracy requirements in subpart 

A that EPA is proposing to apply to subpart I are a minimum requirement. Facilities that are currently 

meeting the higher accuracy standard in subpart I would be expected to continue to use the same 

monitoring equipment and achieve the same level of accuracy, and would not be expected to “fall back” 

to the minimum accuracy requirement in subpart A by, for example, replacing current equipment with 

less accurate monitoring equipment. Additionally, as older facilities and equipment are replaced and 

newer facilities come online, the industry is expected to trend towards using more accurate and precise 

measurement equipment.

7. References

SIA (2011). Semiconductor Industry Associated Petition for Reconsideration and Request for Stay Pending 

Reconsideration of Subpart I of the Final Rule for Mandatory Reporting of Greenhouse Gases. January 31, 

2011. Available in docket EPA–HQ–OAR–2011-0028.

SIA (2012a). Appendix 4 - Gas Cylinder Heel Triggers Industry. February 6, 2012. Available in docket EPA–

HQ–OAR–2011-0028.

SIA (2012b). Response to EPA’s Stack Test Question 1. March 7, 2012. Available in docket EPA–HQ–OAR–

2011-0028.

SIA (2012c). Outstanding Questions / Topics from SIA / EPA Discussions as of April 24, 2012 Response as 

of April 26, 2012. April 26, 2012. Available in docket EPA–HQ–OAR–2011-0028.

 

5

Some entities provided comment on the April 2010 proposed subpart I that a one percent of full scale accuracy and precision 

requirement was not feasible for all facilities. The commenters stated that 74 percent of respondents (where respondents 

represent 58 percent of total U.S. silicon area production capacity) to an industry survey have measurements devices that meet 

the 1 percent accuracy requirement, but 24 percent do not. The commenters also stated that no respondents to the industry 

survey utilized flow meters with an accuracy of 1 percent for tracking gas consumption. However, the EPA elected to not modify 

this requirement in the final subpart I because it was not clear that the commenters understood the requirements of subpart I 

as they were intended, and research indicated that equipment at that level of accuracy and precisions was available (although

in some cases, as the commenters noted, the more accurate equipment may not have been installed at all facilities). Please see 

the Subpart I Response to Comments Document (dated November 2010) for more information.