```

[Federal Register Volume 89, Number 247 (Thursday, December 26, 2024)]
[Rules and Regulations]
[Pages 104859-104865]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2024-30274]

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DEPARTMENT OF ENERGY

10 CFR Part 431

[EERE-2024-BT-DET-0012]
RIN 1904-AE57

Energy Conservation Program: Commercial Warm Air Furnaces; 
Notification of Tentative Determination and Request for Comment

AGENCY: Office of Energy Efficiency and Renewable Energy, Department of 
Energy.

ACTION: Notification of tentative determination and request for 
comment.

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SUMMARY: On June 2, 2023, the U.S. Department of Energy (``DOE'' or the 
``Department'') published a test procedure final rule which established 
test procedures for commercial warm air furnaces (``CWAFs''). The Air-
Conditioning, Heating, and Refrigeration Institute (``AHRI'') filed a 
petition for review of the final rule in the United States Court of 
Appeals for the Fourth Circuit on August 1, 2023. In a February 6, 
2024, order, the Fourth Circuit granted a voluntary remand of the final 
rule to the Department of Energy (``DOE'') to determine whether 
establishment of the test procedure for the thermal efficiency two 
(``TE2'') metric is supported by the specific provisions applicable to 
CWAFs under the Energy Policy and Conservation Act (``EPCA''). More 
specifically, DOE agreed in this voluntary remand to only establish the 
TE2 test procedure if the Department makes a determination that the TE2 
test procedure is consistent with the amended industry test procedure, 
or a determination, supported by clear and convincing evidence, that 
the amended industry test procedure fails to satisfy the statutory 
requirements. This document provides DOE's tentative determination that 
the amended industry test procedure fails to satisfy EPCA's statutory 
requirements and requests comment on this topic.

DATES: DOE will accept comments, data, and information regarding this 
document no later than January 8, 2025. See section V, ``Public 
Participation,'' for details.

ADDRESSES: Interested persons are encouraged to submit comments using 
the Federal eRulemaking Portal at www.regulations.gov under docket 
number EERE-2024-BT-DET-0012. Follow the instructions for submitting 
comments. Alternatively, interested persons may submit comments, 
identified by docket numberEERE-2024-BT-DET-0012, by any of the 
following methods:
    (1) Email: [email protected]. Include the docket 
number EERE-2024-BT-DET-0012in the subject line of the message.
    (2) Postal Mail and Hand Delivery/Courier: Appliance and Equipment 
Standards Program, U.S. Department of Energy, Building Technologies 
Office, Mailstop EE-5B, 1000 Independence Avenue SW, Washington, DC 
20585-0121. Telephone: (202) 287-1445. If possible, please submit all 
items on a compact disc (``CD''), in which case it is not necessary to 
include printed copies.
    No telefacsimiles (``faxes'') will be accepted. For detailed 
instructions on submitting comments and additional information on this 
process, see section V of this document.
    Docket: The docket for this activity, which includes Federal 
Register notices, public meeting attendee lists and transcripts (if a 
public meeting is held), comments, and other supporting documents/
materials, is available for review at www.regulations.gov. All 
documents in the docket are listed in the www.regulations.gov index. 
However, not all documents listed in the index may be publicly 
available, such as information that is exempt from public disclosure.
    The docket web page can be found at www.regulations.gov/docket/EERE-2024-BT-DET-0012. The docket web page contains instructions on how 
to access all documents, including public comments, in the docket. See 
section V for information on how to submit comments through 
www.regulations.gov.

FOR FURTHER INFORMATION CONTACT: Ms. Julia Hegarty, U.S. Department of 
Energy, Office of Energy Efficiency and Renewable Energy, Building 
Technologies Office, EE-5B, 1000 Independence Avenue SW, Washington, DC 
20585-0121. Telephone: (240) 597-6737. Email: 
[email protected].
    Mr. Pete Cochran, U.S. Department of Energy, Office of the General 
Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC 20585-0121. 
Telephone: (240) 961-1189. Email: [email protected].
    For further information on how to submit a comment or review other 
public comments and the docket, contact the Appliance and Equipment 
Standards Program staff at (202) 287-1445 or by email: 
[email protected].

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Introduction
    A. Authority
    B. Energy Conservation Standards Rulemaking Process Under EPCA
    C. Background
II. Discussion
    A. ASHRAE Trigger
    B. Appendix B Test Procedure for TE2

[[Page 104860]]

    C. Industry Test Procedure (Appendix A Test Procedure for TE)
    1. Jacket Loss
III. Procedural Issues and Regulatory Review
IV. Public Participation
V. Approval of the Office of the Secretary

I. Introduction

A. Authority

    The Energy Policy and Conservation Act, Public Law 94-163, as 
amended (``EPCA''),\1\ authorizes DOE to regulate the energy efficiency 
of a number of consumer products and certain industrial equipment. (42 
U.S.C. 6291-6317, as codified) Title III, Part C of EPCA, added by 
Public Law 95-619, title IV, sec. 441(a), established the Energy 
Conservation Program for Certain Industrial Equipment, which sets forth 
a variety of provisions designed to improve energy efficiency. This 
equipment includes CWAFs, the subject of this document. (42 U.S.C. 
6311(1)(J))
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    \1\ All references to EPCA in this document refer to the statute 
as amended through the Energy Act of 2020, Public Law 116-260 (Dec. 
27, 2020), which reflect the last statutory amendments that impact 
Parts A and A-1 of EPCA.
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    The energy conservation program under EPCA consists essentially of 
four parts: (1) testing, (2) labeling, (3) Federal energy conservation 
standards, and (4) certification and enforcement procedures. Relevant 
provisions of EPCA include definitions (42 U.S.C. 6311), test 
procedures (42 U.S.C. 6314), labeling provisions (42 U.S.C. 6315), 
energy conservation standards (42 U.S.C. 6313), and the authority to 
require information and reports from manufacturers (42 U.S.C. 6316; 42 
U.S.C. 6296).
    The Federal testing requirements consist of test procedures that 
manufacturers of covered equipment must use as the basis for: (1) 
certifying to DOE that their equipment complies with the applicable 
energy conservation standards adopted pursuant to EPCA (42 U.S.C. 
6316(b); 42 U.S.C. 6296), and (2) making other representations about 
the efficiency of that equipment (42 U.S.C. 6314(d)). Similarly, DOE 
uses these test procedures to determine whether the equipment complies 
with relevant standards promulgated under EPCA. DOE's test procedures 
for CWAFs are currently prescribed at subpart D of part 431 of title 10 
of the Code of Federal Regulations (``CFR'').
    Federal energy efficiency requirements for covered equipment 
established under EPCA generally supersede state laws and regulations 
concerning energy conservation testing, labeling, and standards. (42 
U.S.C. 6316(a) and 42 U.S.C. 6316(b); 42 U.S.C. 6297) DOE may, however, 
grant waivers of Federal preemption for particular state laws or 
regulations, in accordance with the procedures and other provisions of 
EPCA. (42 U.S.C. 6316(b)(2)(D))
    Under 42 U.S.C. 6314, EPCA sets forth the criteria and procedures 
DOE must follow when prescribing or amending test procedures for 
covered equipment. EPCA requires that any test procedures prescribed or 
amended under this section must be reasonably designed to produce test 
results that reflect energy efficiency, energy use, or estimated annual 
operating cost of a given type of covered equipment during a 
representative average use cycle (as determined by DOE) and requires 
that test procedures not be unduly burdensome to conduct. (42 U.S.C. 
6314(a)(2))
    EPCA generally requires that, at least once every seven years, DOE 
evaluate test procedures for each type of covered equipment, including 
CWAFs, to determine whether amended test procedures would more 
accurately or fully comply with the requirements for the test 
procedures to not be unduly burdensome to conduct and be reasonably 
designed to produce test results that reflect energy efficiency, energy 
use, and estimated operating costs during a representative average use 
cycle. (42 U.S.C. 6314(a)(1)-(3)) DOE refers to these provisions as the 
``lookback'' provisions and rulemakings conducted under these 
provisions as ``lookback'' rulemakings.
    Specific to certain commercial equipment, including CWAFs, EPCA 
required that the initial test procedures for this equipment be those 
generally accepted industry testing procedures or rating procedures 
developed or recognized by AHRI or ASHRAE, as referenced in ASHRAE 
Standard 90.1, ``Energy Standard for Buildings Except Low-Rise 
Residential Buildings'' (``ASHRAE Standard 90.1''), that were in effect 
on June 30, 1992. (42 U.S.C. 6314(a)(4)(A)) Further, if such an 
industry test procedure is amended, DOE must update its test procedure 
to be consistent with the amended industry test procedure unless DOE 
determines, by rule published in the Federal Register and supported by 
clear and convincing evidence, that the amended test procedure would 
not meet the requirements in 42 U.S.C. 6314(a)(2) and (3), in which 
case DOE may establish an amended test procedure that does satisfy 
those statutory provisions. (42 U.S.C. 6314(a)(4)(B) and (C)) DOE 
refers to these provisions as the ``ASHRAE trigger'' provisions and 
rulemakings conducted under these provisions as ``ASHRAE trigger'' 
rulemakings.
    Whether pursuant to the lookback provision or the trigger 
provision, if DOE determines that a test procedure amendment is 
warranted, EPCA requires that the Department publish proposed test 
procedures in the Federal Register and afford interested persons an 
opportunity (of not less than 45 days duration) to present oral and 
written data, views, and arguments on the proposed test procedures. (42 
U.S.C. 6314(b))

B. Energy Conservation Standards Rulemaking Process Under EPCA

    The purpose of energy conservation standards issued under EPCA is 
to reduce energy use by improving the energy efficiency of covered 
products and equipment. (See 42 U.S.C. 6312(a)) The first step in 
establishing new or amended energy conservation standards for any 
covered product or equipment is to determine what energy use by a 
covered product or equipment will be within the scope of the energy 
conservation standard, i.e., what is the representative average use 
cycle for the covered product or equipment. For example, prior to the 
Energy Independence and Security Act of 2007 (``EISA 2007''), the 
representative average use cycle for many covered products only 
included active mode energy use, i.e., energy used while the product 
was performing its main function. As such, the representative use cycle 
did not include any energy used while the product was in a standby or 
off mode. Thus, manufacturers had little incentive to reduce standby or 
off mode energy use as it had no effect on whether a covered product 
complied with the applicable energy conservation standards. But in EISA 
2007, Congress required DOE to include standby and off mode energy use 
as part of the representative average use cycle for any energy 
conservation standard adopted after July 1, 2010. (42 U.S.C. 
6295(gg)(3)).
    Representative average use cycles for covered products and 
equipment can also change over time as DOE's understanding of how the 
product or equipment is used in the field improves, consumer habits 
change, or technologies improve. For example, DOE recently issued an 
amended test procedure for air-cooled commercial package air 
conditioners and heat pumps that reflects how the representative 
average use cycle for this equipment has changed over time. 89 FR 43986 
(May 20, 2024). DOE adopted this new test procedure for air-cooled 
commercial air conditioners and heat pumps with the

[[Page 104861]]

support of a cross-section of stakeholders, including the heating and 
cooling industry, who recommended the details of the new test procedure 
to DOE as part of a negotiated consensus recommendation. Id. at 89 FR 
43991. The consensus recommendation recognized that the introduction of 
innovative technologies in the market, such as the ability for 
compressors to run at part-load values in response to different 
operating conditions in the field, has contributed to changes in the 
representative average use cycle for air-cooled commercial air 
conditioners and heat pumps. The consensus recommendation also 
recognized that air-cooled commercial air conditioners and heat pumps 
operate in additional heating and cooling modes not encompassed by the 
current representative average use cycle. As a result, the 
representative use cycle for air-cooled commercial air conditioners and 
heat pumps was updated to include, among other things, part-load 
operation at a variety of outdoor temperature points and additional 
modes of operation, e.g., integrated mechanical and economizer cooling, 
economizer-only cooling, cooling season ventilation, and unoccupied no-
load hours. Id. at 89 FR 43997-43998.
    Having determined a representative average use cycle for a covered 
product or equipment, the next step in EPCA's energy conservation 
standards rulemaking process is to prescribe a test procedure that is 
reasonably designed to produce test results that measure energy use of 
the covered product or equipment for that representative average use 
cycle and that is not unduly burdensome to conduct. (42 U.S.C. 
6293(b)(3); 42 U.S.C. 6314(a)(2)) For example, when Congress required 
DOE to include standby and off mode energy use in standards for covered 
products, it first directed DOE to amend test procedures for all 
covered products to include provisions for measuring standby and off 
mode energy use. (42 U.S.C. 6295(gg)(2)(A)) Congress then directed DOE 
to use these amended test procedures when prescribing new or amended 
standards that incorporate standby and off mode energy use. (42 U.S.C. 
6295(gg)(3)(A)) As the new standards would be based on a different 
representative use cycle, i.e., one that includes active mode, standby 
mode, and off mode, Congress clarified that the amended test procedures 
``shall not be used to determine compliance with product standards 
established prior to the adoption of the amended test procedures.'' (42 
U.S.C. 6295(gg)(2)(C)) It would have made little sense for Congress to 
require manufacturers to use test procedures that measure active, 
standby, and off mode energy when determining compliance with an energy 
conservation standard that is only based on active mode energy use. DOE 
takes the same approach when prescribing an amended test procedure for 
use in evaluating new or amended energy conservation standards that are 
based on an updated representative average use cycle. Use of the 
amended test procedure is only required upon the compliance date of the 
new or amended energy conservation standards. See sec. 8(f) of appendix 
A to subpart C of 10 CFR part 430.

C. Background

    Under EPCA's lookback provision, DOE initiated a test procedure 
rulemaking for CWAFs by publishing a request for information (``RFI'') 
in the Federal Register on May 5, 2020 (``May 2020 RFI''). 85 FR 26626. 
The current energy conservation standards for CWAFs are based on a 
representative average use cycle that assumes CWAFs always operate at 
100% capacity in the field and that the only energy losses are from 
flue exhaust gases. The May 2020 RFI solicited public comments, data, 
and information on aspects of the existing DOE test procedure for CWAFs 
at 10 CFR part 431, subpart D, appendix A (``appendix A''), which 
measures Thermal Efficiency (``TE'') and is used for determining 
compliance with the current energy conservation standards for CWAFs, 
including whether there were any issues with the existing test 
procedure at that time and whether it was in need of updates or 
revisions. Id.
    DOE subsequently published a notice of proposed rulemaking 
(``NOPR'') for the CWAFs test procedure in the Federal Register on 
February 25, 2022, which proposed amendments to the existing test 
procedure for TE as well as a new test procedure based on DOE's 
tentative determination that the representative average use cycle for 
CWAFs should include jacket losses and part-load operation. 87 FR 10726 
(``February 2022 NOPR''). DOE noted that CWAFs are typically installed 
outdoors and, as a result, jacket losses can be a significant source of 
energy loss. 87 FR 10726, 10735. DOE also noted that many CWAFs now 
have multiple heating stages and performance for these CWAFs can vary 
at different heating loads. id. As a result, DOE proposed that any new 
or amended energy conservation standards for CWAFs should be based on a 
representative average use cycle that includes jacket losses and part-
load operation, i.e., the TE2 metric. DOE proposed a new test procedure 
in 10 CFR part 431, subpart D, appendix B (``appendix B''), to measure 
energy efficiency under the TE2 metric. DOE tentatively determined that 
the appendix B test procedure met the statutory criteria in 42 U.S.C. 
6314(a)(2) and (3). 87 FR 10726, 10737-10738.
    The February 2022 NOPR had a 60-day comment period and DOE held a 
webinar public meeting on March 29, 2022. As directed by the remand 
order from the Fourth Circuit, this document considers whether the 
amended industry test procedure fails to satisfy the applicable 
statutory requirements. In this document, DOE focuses on two discrete 
issues related to whether the amended industry test procedure is 
reasonably designed to product test results that reflect energy use 
during a representative average use cyle: the lack of jacket loss and 
part-load testing provisions in the amended industry test procedure. 
DOE believes the comment period provided for in the DATES section is 
more than sufficient for interested parties to provide comments on 
these two issues and notes that DOE already satisfied the comment 
period required in 42 U.S.C. 6314(b) for prescribing the appendix A and 
appendix B test procedures with the 60-day comment period provided for 
in the February 2022 NOPR.
    Following publication of the February 2022 NOPR, the latest update 
to ASHRAE Standard 90.1 was released in January 2023 (``ASHRAE Standard 
90.1-2022''). ASHRAE Standard 90.1-2022 references CSA/ANSI Z21.47-
2021, Gas-fired central furnaces (``ANSI Z21.47-2021''), as the test 
method for gas-fired CWAFs and Underwriters Laboratories (``UL'') 
standard UL 727-2018, ``Standard for Safety Oil-Fired Central 
Furnaces'' (``UL 727-2018''), as the test method for oil-fired CWAFs.
    On June 2, 2023, DOE published a test procedure final rule for 
CWAFs. 88 FR 36217 (``June 2023 Final Rule''). In the June 2023 Final 
Rule, DOE amended the current test procedure for TE in appendix A and 
incorporated by reference the latest industry test procedures 
referenced in ASHRAE Standard 90.1-2022. The amendments to the industry 
test procedure were relatively minor and not based on any updates to 
the representative average use cycle for CWAFs. Rather, they were 
clarifications to the existing test procedure intended to improve 
clarity and help with the execution of the current test procedure. DOE 
also finalized the proposed appendix B test procedure that is based on 
an updated representative average use cycle that includes jacket losses 
and part-load operation. Similar to other rulemakings

[[Page 104862]]

where DOE has determined that the representative average use cycle 
should be updated, e.g., air-cooled commercial air conditioners and 
heat pumps, the June 2023 Final Rule states that use of the appendix B 
test procedure would not be required until such time as compliance is 
required with amended energy conservation standards based on the new 
metric, should DOE adopt such standards.
    Following publication of the June 2023 Final Rule, the Air-
Conditioning, Heating, and Refrigeration Institute (``AHRI'') filed a 
petition for review of the final rule in the United States Court of 
Appeals for the Fourth Circuit on August 1, 2023. In its opening brief, 
AHRI argued that DOE failed to provide notice and an opportunity for 
comment after being triggered by the ASHRAE Standard 90.1-2022 
publication prior to publishing the June 2023 Final Rule; DOE did not 
undertake the required analysis under 42 U.S.C. 6314(a)(4)(B); and that 
if DOE had conducted the correct analysis under 42 U.S.C. 
6314(a)(4)(B), it would necessarily have concluded that it lacked clear 
and convincing evidence that the industry test procedure did not meet 
the statutory requirements. See Air-Conditioning, Heating, and 
Refrigeration Institute v. United States Department of Energy, No. 23-
1793 (4th Cir. Oct. 23, 2023), 15-1.
    On February 6, 2024, the Fourth Circuit granted the Department's 
motion for voluntary remand. In its order, the Court granted DOE's 
motion for voluntary remand to clarify that, in this particular 
circumstance, where ASHRAE published an amended industry test procedure 
during the pendency of a rulemaking under the 7-year lookback 
provision, the Department will solicit public comment prior to making: 
(1) a final determination that the test procedure in appendix B for the 
TE2 metric is consistent with the amended industry test procedure; or 
(2) a final determination, supported by clear and convincing evidence, 
that the industry test procedure fails to satisfy the statutory 
requirements. See Air-Conditioning, Heating, and Refrigeration 
Institute v. United States Department of Energy, No. 23-1793 (4th Cir. 
Feb. 6, 2024), 22-1. The remand order did not vacate the June 2023 
Final Rule, nor did it require DOE to revisit its determination that 
the appendix B test procedure meets the statutory requirements at 42 
U.S.C. 6314(a)(2) and (3).
    DOE is publishing this document in accordance with the order from 
the Fourth Circuit. Specifically, DOE is presenting its tentative 
determination, supported by clear and convincing evidence, that the 
industry test procedure is not reasonably designed to produce test 
results that reflect energy efficiency during a representative average 
use cycle that, as determined by DOE, includes jacket losses and part-
load operation. DOE requests public comment on this tentative 
determination.

II. Discussion

A. ASHRAE Trigger

    As discussed, EPCA requires that if the industry test procedure for 
CWAFs is amended, DOE must update its test procedure to be consistent 
with the amended industry test procedure unless DOE determines, by rule 
published in the Federal Register and supported by clear and convincing 
evidence, that the amended test procedure would not meet the 
requirements in 42 U.S.C. 6314(a)(2) and (3), in which case DOE may 
establish an amended test procedure that does satisfy those statutory 
provisions. (42 U.S.C. 6314(a)(4)(B) and (C)) The publication of ASHRAE 
Standard 90.1-2022 represented an ASHRAE trigger for CWAFs. The test 
procedure established in appendix A for the TE metric references the 
industry test standards from the most recent version of ASHRAE Standard 
90.1 (2022), which satisfies DOE's obligations under the ASHRAE trigger 
provision with respect to the appendix A test procedure for the TE 
metric. See 42 U.S.C. 6314(a)(4)(B). In this document, DOE is applying 
the ASHRAE trigger provision to the appendix B test procedure for the 
TE2 metric. In the following section, DOE discusses its tentative 
determination, supported by clear and convincing evidence,\2\ that the 
industry test procedure is not reasonably designed to produce test 
results that reflect energy efficiency during a representative average 
use cycle that, as determined by DOE, includes jacket losses and part-
load operation.
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    \2\ ``[C]lear and convincing evidence requires a factfinder . . 
. to have an `abiding conviction' that her findings . . . are 
`highly probable' to be true.'' Am. Pub. Gas Ass'n v. United States 
Dep't of Energy, 22 F.4th 1018, 1025 (D.C. Cir. 2022) (quoting 
Colorado v. New Mexico, 467 U.S. 310, 316 (1984)).
---------------------------------------------------------------------------

B. Appendix B Test Procedure for TE2

    In the June 2023 Final Rule, DOE considered that the existing test 
procedure and standards were based on a representative average use 
cycle that did not include consideration of jacket losses or part-load 
performance. 88 FR 36217, 36223-36227. CWAFs lose energy to the 
environment through jacket losses and are capable of and do operate 
differently under part-load conditions. As a result, DOE determined in 
the June 2023 Final Rule that jacket losses and part-load performance 
can contribute significantly to overall equipment energy use and should 
be part of the representative average use cycle for CWAFs. Id. As such, 
DOE established a new test procedure (appendix B) based on a 
representative average use cycle that includes jacket losses and part-
load operation. The June 2023 Final Rule includes an extensive 
discussion supporting DOE's determination that the appendix B test 
procedure is reasonably designed to produce test results that reflect 
energy efficiency during a representative average use cycle that, as 
determined by DOE, includes jacket losses and part-load operation, and 
is not unduly burdensome to conduct. Id. In that discussion, DOE 
acknowledged that accounting for jacket losses and part-load operation 
would increase test burden. Id. at 88 FR 36224. But after a thorough 
analysis of the increased test costs, DOE concluded that the additional 
costs are not unduly burdensome and the inclusion of jacket losses and 
part-load operation provides for a more representative average use 
cycle. Id. at 88 FR 36230.

C. Industry Test Procedure (Appendix A Test Procedure for TE)

    As discussed previously, the industry test procedure, which is 
referenced in appendix A and is used for determining compliance with 
the current energy conservation standards, is based on a representative 
average use cycle that assumes CWAFs only operate at 100 percent 
capacity and that energy is only lost through flue exhaust gases. As 
discussed previously, these assumptions are an over-simplification of 
how CWAFs operate in the field. In this document, DOE evaluates the 
industry test procedure in the context of the ASHRAE trigger provisions 
and presents DOE's tentative determination, supported by clear and 
convincing evidence, that the industry test procedure does not satisfy 
all of the criteria in 42 U.S.C. 6314(a)(2) and (3). Specifically, DOE 
has tentatively determined that the industry test procedure is not 
reasonably designed to produce test results which reflect energy 
efficiency during a representative average use cycle that, as 
determined by DOE, includes jacket losses and part-load operation. As 
such, DOE's adoption of the appendix B test procedure, which DOE 
determined met the applicable statutory criteria in the June 2023 Final 
Rule, is consistent with the ASHRAE

[[Page 104863]]

trigger provisions in 42 U.S.C. 6314(a)(4)(B) and (C).
    As explained in more detail in the following sections, DOE 
estimates that the test procedure for TE2 could produce a result that 
is between 3.5 percent lower (in a model with high jacket loss and poor 
part-load performance) to 1 percent higher (in a model with negligible 
jacket loss and good part-load performance) than the industry test 
procedure because the TE2 metric includes jacket loss and part-load 
performance. This variation in efficiency is significant. For example, 
when DOE last amended the standards for gas-fired CWAFs, the minimum 
required efficiency went from 80 to 81 percent, which DOE determined 
would result in significant additional conservation of energy. 81 FR 
2420, 2430. Further, the average life-cycle cost savings to a consumer 
from that 1 percent increase in efficiency was $284. Id. at 81 FR 2423. 
Those already significant impacts are only magnified when larger 
differences in measured efficiency are considered. Therefore, DOE has 
tentatively determined, supported by clear and convincing evidence, 
that the industry test procedures referenced in ASHRAE Standard 90.1-
2022 are not reasonably designed to produce test results which reflect 
energy efficiency during a representative average use cycle that, as 
determined by DOE, includes jacket losses and part-load operation. The 
following sections discuss the significance of jacket loss and part-
load performance to overall energy use and efficiency during a 
representative average use cycle in more detail.
1. Jacket Loss
    As discussed, the current energy efficiency metric for CWAFs is TE. 
10 CFR 431.77. TE for a CWAF is defined in 10 CFR 431.72 as 100 percent 
minus the percent flue loss and is determined using the test procedure 
in appendix A. Appendix A and the industry test procedure produce 
results that are essentially a measure of combustion efficiency. 
However, the energy efficiency of CWAFs in the field is influenced by 
factors in addition to combustion efficiency (e.g., jacket loss). 
Jacket losses are losses from the commercial warm air furnace to the 
ambient environment that occur because heat is lost through the jacket, 
i.e., the cabinet surrounding the heating section, of the CWAF during 
operation. Jacket loss contributes to the overall energy use of a CWAF 
and is, therefore, one of the parameters that determines a CWAF's 
overall efficiency. In fact, table 6.8.1-5 of ASHRAE Standard 90.1-2022 
includes performance requirements for CWAFs and specifies that units 
must have jacket losses not exceeding 0.75 percent of the input rating, 
indicating that jacket loss is an important aspect of CWAF operation. 
Additionally, the test methods for similar products, such as consumer 
furnaces, account for jacket loss further demonstrating that jacket 
losses are an important factor in determining a furnace's efficiency. 
Heat loss through the cabinet (i.e., jacket loss) is generally 
proportional to the thickness of the insulation and/or insulative 
material used in the cabinet. CWAFs with the same TE, as determined 
under the current appendix A test procedure, could have different 
performance in the field if, for example, one unit has different 
insulation than the other (resulting in different levels of jacket 
loss). DOE also notes that the vast majority of CWAFs are installed 
within commercial unitary air conditioners (``CUACs'') located on 
rooftops,\3\ and that these outdoor installations will result in 
greater jacket loss than CWAFs installed indoors because of the colder 
ambient air. As such, DOE has tentatively determined that energy use of 
a CWAF will vary depending on installation location because of 
different levels of jacket loss. Differences in energy use based on 
differences in jacket loss are not captured by the industry test 
procedure. Incorporating jacket loss into the representative average 
use cycle and corresponding new metric, TE2, allows consumers to get a 
more accurate picture of CWAF energy use in the field by capturing 
differences in CWAF performance due to different levels of jacket loss 
(which as previously described could be caused by different levels of 
insulation, for example).
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    \3\ On January 15, 2016, DOE published a direct final rule 
amending energy conservation standards for various types of 
commercial air conditioning equipment and CWAFs. 81 FR 2420. As 
discussed in appendix 8D of the Direct Final Rule Technical Support 
Document, DOE found that 95% of gas-fired CWAFs are installed 
outdoors and packaged with a CUAC.
---------------------------------------------------------------------------

    While manufacturers currently complying with the ASHRAE Standard 
90.1 requirements would have to limit jacket losses so as not to exceed 
0.75 percent of the input rating, DOE notes that because the jacket 
loss percentage would be multiplied by the jacket loss factor for 
weatherized CWAFs designed to be installed outdoors (which represent 
the majority of CWAFs on the market and which have a jacket loss factor 
of 3.3), a jacket loss of 0.75 percent could result in a difference of 
nearly 2.5 percent as compared to a unit with negligible jacket losses. 
As discussed previously, even a 1 percent difference in efficiency is 
significant both in terms of the national benefits of energy 
conservation standards and benefits to individual consumers.
2. Part-Load Performance
    DOE has reviewed the current CWAF market and found that the vast 
majority of CWAFs have two or more stages of heating. DOE notes that 
CWAFs with two or more stages can operate at reduced firing rates to 
meet the building load. Part-load performance refers to the efficiency 
of the CWAF when operating at a reduced firing rate (as opposed to 
full-load performance which reflects the efficiency when operating at 
the maximum firing rate).
    Under the appendix A test procedure, TE reflects the efficiency of 
the CWAF when firing at the maximum input rate (i.e., at full load). 
When a CWAF burner operates at a reduced input rate (i.e., part load), 
the ratio of heat exchanger surface area to burner input rate is 
increased (in comparison to operation at the maximum input rate), which 
could increase the efficiency of the CWAF compared to operating at full 
load, if other aspects of operation are consistent. However, depending 
on the air-fuel ratio or other factors impacting combustion efficiency, 
the combustion efficiency could instead decrease when operating at a 
reduced firing rate, especially if the air-fuel ratio is not maintained 
at an optimal level. The change in performance, including whether 
efficiency is improved or reduced at part-load, would vary from model 
to model depending on the design and control strategies employed when 
operating at input rates below the maximum input rate. Therefore, CWAF 
part-load performance has the potential to be substantively different 
from full-load performance and including part-load performance in the 
measurement of CWAF efficiency would allow the efficiency metric to 
account for this potential.
    In previous testing of similar products, DOE has observed that the 
efficiency when operating at the reduced input rate can be as much as 2 
percent higher or lower than the efficiency when operating at the 
maximum input rate.\4\ In a CWAF that exhibits similar performance 
differences, the resulting difference in

[[Page 104864]]

TE2 would be 1 percent higher or lower than the TE of that unit 
(depending on whether part load operation is more or less efficient 
than at full load) when accounting for the weighting of 50 percent of 
time operating at the reduced input rate. As discussed previously, such 
a difference in efficiency is significant both in terms of the national 
benefits of energy conservation standards and benefits to individual 
consumers.
---------------------------------------------------------------------------

    \4\ In 2019, DOE conducted testing of consumer furnaces, which 
included 2-stage, non-condensing furnaces. The consumer furnace test 
method requires testing at both the maximum and minimum input rates 
for 2-stage models, so DOE was able to compare the steady-state 
efficiency at each input rate to determine the difference in 
performance when operating at a reduced input rate.
---------------------------------------------------------------------------

III. Conclusion

    The potential difference in CWAF efficiency measured under the 
industry test procedure and the appendix B test procedure is an 
excellent example of why Congress updated representative use cycles for 
covered products to include standby and off mode energy use in new or 
amended energy conservation standards and why stakeholders, including 
manufacturers, asked DOE to update the representative average use cycle 
for air-cooled commercial air conditioners and heat pumps--consumers 
and manufacturers are both better off when DOE test procedures and 
energy conservation standards capture more energy use in the field. For 
example, as discussed previously, a CWAF with a TE of 81 percent as 
measured by the industry test procedure could, depending on jacket 
losses and part-load operation, have an actual range of efficiencies 
from 77.5 to 82 percent using the appendix B test procedure for TE2. 
That is a significant difference in efficiency and corresponds to a 
significant difference in fuel costs over the lifetime of the CWAF, 
which is important information for consumers. The industry test 
procedure also does not allow manufacturers to fully differentiate 
their products in the market. For example, under the industry test 
procedure, a manufacturer with a line of CWAF models with well-
insulated jackets has no way to advertise their improved efficiency in 
the market. Under the industry test procedure, these models will have 
the same advertised efficiency as similar models that lack insulation 
and have higher jacket losses.
    Having determined that any future, amended standards for CWAFs 
should be based on a representative average use cycle that includes 
jacket losses and part-load operation, DOE adopted the appendix B test 
procedure in the June 2023 Final Rule. The appendix B test procedure 
contains specific provisions for measuring jacket losses and energy use 
during part-load operation and will be used by DOE to evaluate 
potential amended standards for CWAFs. Use of the appendix B test 
procedure by manufacturers would not be required until such time as 
compliance is required with amended energy conservation standards based 
on the new representative average use cycle, should DOE adopt such 
standards.
    In this document, DOE evaluated whether the industry test procedure 
is reasonably designed to produce test results which reflect energy use 
during a representative average use cycle that, as determined by DOE, 
includes jacket losses and part-load operation. Unlike the appendix B 
test procedure, the industry test procedure does not have provisions 
for calculating jacket losses and changes in energy efficiency due to 
part-load operation. As discussed previously, this results in the 
industry test procedure producing test results that do not account for 
significant variations in energy use across different CWAF models. As a 
result, DOE has tentatively determined, supported by clear and 
convincing evidence, that the industry test procedure is not reasonably 
designed to produce test results which reflect energy efficiency during 
a representative average use cycle. DOE requests comment on this 
tentative determination.

III. Procedural Issues and Regulatory Review

    DOE has concluded that the determinations made pursuant to the 
various procedural requirements applicable to the June 2023 Final Rule 
remain unchanged for this notification of tentative determination. 
These determinations are set forth in the June 2023 Final Rule. 88 FR 
36217, 36230-36233. DOE is publishing this document to present its 
tentative determination, supported by clear and convincing evidence, 
that the industry test procedure would not provide test results that 
are representative of an average use cycle for the TE2 metric, and to 
seek comment from interested parties.

IV. Public Participation

    DOE will accept comments, data, and information regarding this 
document no later than the date provided in the DATES section at the 
beginning of this document. Interested parties may submit comments, 
data, and other information using any of the methods described in the 
ADDRESSES section at the beginning of this document.
    Submitting comments via www.regulations.gov. The 
www.regulations.gov web page will require you to provide your name and 
contact information. Your contact information will be viewable to DOE 
Building Technologies staff only. Your contact information will not be 
publicly viewable except for your first and last names, organization 
name (if any), and submitter representative name (if any). If your 
comment is not processed properly because of technical difficulties, 
DOE will use this information to contact you. If DOE cannot read your 
comment due to technical difficulties and cannot contact you for 
clarification, DOE may not be able to consider your comment.
    However, your contact information will be publicly viewable if you 
include it in the comment itself or in any documents attached to your 
comment. Any information that you do not want to be publicly viewable 
should not be included in your comment, nor in any document attached to 
your comment. Otherwise, persons viewing comments will see only first 
and last names, organization names, correspondence containing comments, 
and any documents submitted with the comments.
    Do not submit to www.regulations.gov information for which 
disclosure is restricted by statute, such as trade secrets and 
commercial or financial information (hereinafter referred to as 
Confidential Business Information (``CBI'')). Comments submitted 
through www.regulations.gov cannot be claimed as CBI. Comments received 
through the website will waive any CBI claims for the information 
submitted. For information on submitting CBI, see the Confidential 
Business Information section.
    DOE processes submissions made through www.regulations.gov before 
posting. Normally, comments will be posted within a few days of being 
submitted. However, if large volumes of comments are being processed 
simultaneously, your comment may not be viewable for up to several 
weeks. Please keep the comment tracking number that www.regulations.gov 
provides after you have successfully uploaded your comment.
    Submitting comments via email, hand delivery/courier, or postal 
mail. Comments and documents submitted via email, hand delivery/
courier, or postal mail also will be posted to www.regulations.gov. If 
you do not want your personal contact information to be publicly 
viewable, do not include it in your comment or any accompanying 
documents. Instead, provide your contact information in a cover letter. 
Include your first and last names, email address, telephone number, and 
optional mailing address. The cover letter will not be publicly 
viewable as long as it does not include any comments.

[[Page 104865]]

    Include contact information each time you submit comments, data, 
documents, and other information to DOE. If you submit via postal mail 
or hand delivery/courier, please provide all items on a CD, if 
feasible, in which case it is not necessary to submit printed copies. 
No telefacsimiles (``faxes'') will be accepted.
    Comments, data, and other information submitted to DOE 
electronically should be provided in PDF (preferred), Microsoft Word or 
Excel, WordPerfect, or text (ASCII) file format. Provide documents that 
are not secured, written in English, and that are free of any defects 
or viruses. Documents should not contain special characters or any form 
of encryption and, if possible, they should carry the electronic 
signature of the author.
    Campaign form letters. Please submit campaign form letters by the 
originating organization in batches of between 50 to 500 form letters 
per PDF or as one form letter with a list of supporters' names compiled 
into one or more PDFs. This reduces comment processing and posting 
time.
    Confidential Business Information. Pursuant to 10 CFR 1004.11, any 
person submitting information that he or she believes to be 
confidential and exempt by law from public disclosure should submit via 
email two well-marked copies: one copy of the document marked 
``confidential'' including all the information believed to be 
confidential, and one copy of the document marked ``non-confidential'' 
with the information believed to be confidential deleted. DOE will make 
its own determination about the confidential status of the information 
and treat it according to its determination.
    It is DOE's policy that all comments may be included in the public 
docket, without change and as received, including any personal 
information provided in the comments (except information deemed to be 
exempt from public disclosure).

V. Approval of the Office of the Secretary

    The Secretary of Energy has approved publication of this 
notification of tentative determination and request for comment.

Signing Authority

    This document of the Department of Energy was signed on December 
13, 2024, by Jeffrey Marootian, Principal Deputy Assistant Secretary 
for Energy Efficiency and Renewable Energy, pursuant to delegated 
authority from the Secretary of Energy. That document with the original 
signature and date is maintained by DOE. For administrative purposes 
only, and in compliance with requirements of the Office of the Federal 
Register, the undersigned DOE Federal Register Liaison Officer has been 
authorized to sign and submit the document in electronic format for 
publication, as an official document of the Department of Energy. This 
administrative process in no way alters the legal effect of this 
document upon publication in the Federal Register.

    Signed in Washington, DC, on December 16, 2024.
Treena V. Garrett,
Federal Register Liaison Officer, U.S. Department of Energy.
[FR Doc. 2024-30274 Filed 12-23-24; 8:45 am]
BILLING CODE 6450-01-P
```