[Federal Register Volume 88, Number 15 (Tuesday, January 24, 2023)]
[Proposed Rules]
[Pages 4091-4107]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-00942]


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 Proposed Rules
                                                 Federal Register
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
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  Federal Register / Vol. 88 , No. 15 / Tuesday, January 24, 2023 / 
Proposed Rules  

[[Page 4091]]



DEPARTMENT OF ENERGY

10 CFR Parts 429 and 430

[EERE-2022-BT-TP-0028]


Energy Conservation Program: Test Procedures for Central Air 
Conditioners and Heat Pumps

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

ACTION: Request for information.

-----------------------------------------------------------------------

SUMMARY: The U.S. Department of Energy (``DOE'') is undertaking the 
preliminary stages of a rulemaking to consider amendments to the test 
procedure for central air conditioners and heat pumps. Through this 
request for information (``RFI''), DOE seeks data and information 
regarding issues pertinent to whether amended test procedures would 
more accurately or fully comply with the requirement that the test 
procedure produces results that measure energy use during a 
representative average use cycle or period of use for the product 
without being unduly burdensome to conduct, or reduce testing burden. 
DOE welcomes written comments from the public on any subject within the 
scope of this document (including topics not raised in this RFI), as 
well as the submission of data and other relevant information.

DATES: Written comments and information are requested and will be 
accepted on or before February 23, 2023.

ADDRESSES: Interested persons are encouraged to submit comments using 
the Federal eRulemaking Portal at www.regulations.gov, under docket 
number EERE-2022-BT-TP-0028. Follow the instructions for submitting 
comments. Alternatively, interested persons may submit comments, 
identified by docket number EERE-2022-BT-TP-0028, by any of the 
following methods:
    Email: CACandHeatPump2022 [email protected]. Include the docket 
number EERE-2022-BT-TP-0028 in the subject line of the message.
    Postal Mail: 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.
    Hand Delivery/Courier: Appliance and Equipment Standards Program, 
U.S. Department of Energy, Building Technologies Office, 950 L'Enfant 
Plaza SW, 6th Floor, Washington, DC 20024. Telephone: (202) 287-1445. 
If possible, please submit all items on a 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 III of this 
document.
    Docket: The docket for this activity, which includes Federal 
Register notices, 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/#!docketDetail;D=EERE-2022-BT-TP-0028. The docket web page contains 
instructions on how to access all documents, including public comments, 
in the docket. See section III for information on how to submit 
comments through www.regulations.gov.

FOR FURTHER INFORMATION CONTACT: 
    Mr. Lucas Adin, U.S. Department of Energy, Office of Energy 
Efficiency and Renewable Energy, Building Technologies Office, EE-2J, 
1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone: 
(202) 287-5904. Email: [email protected]">ApplianceStandards[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: (202) 586-9496. 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]">ApplianceStandards[email protected].

SUPPLEMENTARY INFORMATION: 

Table of Contents

I. Introduction
    A. Authority and Background
    B. Rulemaking History
II. Request for Information
    A. Scope and Definitions
    B. Load-Based Testing
    1. Background
    2. Current DOE Test Procedures
    3. Categorization of Test Concepts
    4. Summaries of Selected Activities Investigating and Developing 
New Test Methods for Central Air Conditioners and Heat Pumps
    5. Request for Information
    C. Stakeholder Requests for Test Improvements in Appendix M1
    1. Shoulder-Season Fan Power Consumption
    2. Power Consumption of Auxiliary Components
    3. Low-Temperature Heating Performance
    D. Additional Improvements in Appendix M1
    1. Impact of Defrost on Performance
    2. Inlet Duct Design for Accurate Measurement With Minimal 
Length
    3. Heat Comfort Controllers
    4. Cut-Out and Cut-In Temperature Certification
    5. Extending the Definition of Low-Static Blower-Coil Systems to 
Single-Split Systems
    6. Hybrid Heat Pumps
III. Submission of Comments

I. Introduction

    Central air conditioners (``CACs'') and central air conditioning 
heat pumps (``HPs'') (collectively, ``CAC/HPs'') are included in the 
list of ``covered products'' for which DOE is authorized to establish 
and amend energy conservation standards and test procedures. (42 U.S.C. 
6292(a)(3)) DOE's energy conservation standards and test procedures for 
CAC/HPs are prescribed at title 10 of the Code of Federal Regulations 
(``CFR''), part 430 section 430.32(c), and 10 CFR part 430, subpart B, 
appendix M1 (``appendix M1'') (titled ``Uniform Test Method for 
Measuring the Energy Consumption of Central Air Conditioners and Heat 
Pumps''). The following sections discuss DOE's authority to establish 
and amend test

[[Page 4092]]

procedures for CAC/HPs as well as relevant background information 
regarding DOE's consideration of test procedures for this product.

A. Authority and Background

    The Energy Policy and Conservation Act, 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) Title III, Part B \2\ of EPCA established the Energy Conservation 
Program for Consumer Products Other Than Automobiles, which sets forth 
a variety of provisions designed to improve energy efficiency. These 
products include CAC/HPs,\3\ the subject of this RFI. (42 U.S.C. 
6292(a)(3))
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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.
    \2\ For editorial reasons, upon codification in the U.S. Code, 
Part B was redesignated Part A.
    \3\ This rulemaking uses the term ``CAC/HP'' to refer 
specifically to central air conditioners (which include heat pumps) 
as defined by EPCA. (42 U.S.C. 6291(21))
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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 specifically include definitions (42 U.S.C. 6291), 
test procedures (42 U.S.C. 6293), labeling provisions (42 U.S.C. 6294), 
energy conservation standards (42 U.S.C. 6295), and the authority to 
require information and reports from manufacturers (42 U.S.C. 6296).
    Federal energy efficiency requirements for covered products 
established under EPCA generally supersede State laws and regulations 
concerning energy conservation testing, labeling, and standards. (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. 6297(d))
    The Federal testing requirements consist of test procedures that 
manufacturers of covered products must use as the basis for: (1) 
certifying to DOE that their products comply with the applicable energy 
conservation standards adopted pursuant to EPCA (42 U.S.C. 6295(s)), 
and (2) making other representations about the efficiency of those 
consumer products (42 U.S.C. 6293(c)). Similarly, DOE must use these 
test procedures to determine whether the products comply with relevant 
standards promulgated under EPCA. (42 U.S.C. 6295(s))
    Under 42 U.S.C. 6293, EPCA sets forth the criteria and procedures 
DOE must follow when prescribing or amending test procedures for 
covered products. EPCA requires that any test procedures prescribed or 
amended under this section be reasonably designed to produce test 
results which measure energy efficiency, energy use or estimated annual 
operating cost of a covered product during a representative average use 
cycle or period of use and not be unduly burdensome to conduct. (42 
U.S.C. 6293(b)(3))
    EPCA also requires that, at least once every 7 years, DOE review 
test procedures for all type of covered products, including CAC/HPs, to 
determine whether amended test procedures would more accurately or 
fully comply with the requirements that the test procedures are (1) 
reasonably designed to produce test results which reflect energy 
efficiency, energy use, and estimated operating costs during a 
representative average use cycle or period of use and (2) not unduly 
burdensome to conduct. (42 U.S.C. 6293(b)(1)(A)) If the Secretary 
determines, on her own behalf or in response to a petition by any 
interested person, that a test procedure should be prescribed or 
amended, the Secretary shall promptly publish in the Federal Register 
proposed test procedures and afford interested persons an opportunity 
to present oral and written data, views, and arguments with respect to 
such procedures. The comment period on a proposed rule to amend a test 
procedure shall be at least 60 days and may not exceed 270 days. In 
prescribing or amending a test procedure, the Secretary shall take into 
account such information as the Secretary determines relevant to such 
procedure, including technological developments relating to energy use 
or energy efficiency of the type (or class) of covered products 
involved. (42 U.S.C. 6293(b)(2)) If DOE determines that test procedure 
revisions are not appropriate, DOE must publish its determination not 
to amend the test procedures.
    DOE is publishing this RFI to collect data and information to 
inform its decision in satisfaction of the 7-year review requirement 
specified in EPCA. (42 U.S.C. 6293(b)(1)(A))

B. Rulemaking History

    DOE's energy conservation standards for CAC/HPs are currently 
prescribed at 10 CFR 430.32(c), and test procedure at 10 CFR part 430, 
subpart B, appendix M1.
    On January 5, 2017, DOE published a final rule regarding the 
Federal test procedures for CAC/HPs. 82 FR 1426 (``January 2017 CAC TP 
final rule''). The January 2017 CAC TP final rule amended the current 
test procedure at that time, 10 CFR part 430, subpart B, appendix M 
(``appendix M'') and established appendix M1, use of which was required 
beginning January 1, 2023, for any representations, including 
compliance certifications, made with respect to the energy use or 
efficiency of CAC/HPs. Appendix M provides for the measurement of the 
cooling and heating performance of CAC/HPs using the seasonal energy 
efficiency ratio (``SEER'') metric and heating seasonal performance 
factor (``HSPF'') metric, respectively. Appendix M1 specifies a revised 
SEER metric (i.e., ``SEER2'') and a revised HSPF metric (i.e., 
``HSPF2'').
    On October 25, 2022, DOE published a final rule to address limited-
scope amendments to the existing test procedures for CAC/HPs in 
appendix M and appendix M1. 87 FR 64550 (``October 2022 CAC TP final 
rule''). The October 2022 CAC TP final rule provided changes to improve 
the functionality of appendix M1 to address the issues identified in 
test procedure waivers, improve representativeness, and correct 
typographical issues raised by commenters. Id. In the October 2022 CAC 
TP final rule, DOE noted that several commenters indicated the need for 
further test procedure amendments beyond the scope of the rulemaking. 
Id. at 87 FR 64554-64555. DOE received comments recommending 
consideration of load-based testing methods, controls validation 
(particularly for variable-speed systems), amended metrics, amended 
definitions, and expansion of test methods to capture low-temperature 
heating performance for heat pumps. Id. In its response to these 
comments, DOE noted that it had initiated the rulemaking not as a 
comprehensive revision that will satisfy the 7-year lookback 
requirements (see 42 U.S.C. 6293(b)(1)(A)), but to address a limited 
set of known issues, including those that have been raised through the 
test procedure waiver process. 87 FR 64554. However, DOE also responded 
that a future rulemaking may more comprehensively address the issues 
raised by the commenters. Id.
    DOE has considered the issues raised by stakeholders in two 
separate categories: (1) consideration of load-based testing 
methodologies that have been in development by multiple organizations 
and whether certain aspects of these methodologies might be adopted 
into the DOE test procedure (this is discussed in section II.B of this 
RFI) and (2) issues with the current appendix M1 test procedure that 
may or may not still be relevant when/if load-

[[Page 4093]]

based concepts are adopted in the DOE test procedure (these are 
discussed in sections II.C and II.D of this RFI).
    In summary, DOE is publishing this RFI to collect data and 
information regarding the need for amendments to the test procedures 
for CAC/HPs, including the issues raised by the commenters in the 
previous rulemaking, and in satisfaction of the 7-year review 
requirement specified in EPCA.

II. Request for Information

    In the following sections, DOE has identified a variety of issues 
on which it seeks input to determine whether, and if so how, an amended 
test procedure for CAC/HPs would (1) more accurately or fully comply 
with the requirements in EPCA that test procedures be reasonably 
designed to produce test results which reflect energy use during a 
representative average use cycle or period of use, without being unduly 
burdensome to conduct (42 U.S.C. 6293(b)(3)); or (2) reduce testing 
burden.
    Additionally, DOE welcomes comments on any aspect of the existing 
test procedures for CAC/HPs that may not specifically be identified in 
this document.

A. Scope and Definitions

    CAC/HPs are defined in 10 CFR 430.2. As laid out in section 1.1 of 
appendix M1, the test procedure applies to CAC/HPs including the 
following categories, all of which are defined either in 10 CFR 430.2 
or in section 1.2 of appendix M1:
    (a) Split-system air conditioners, including single-split, multi-
head mini-split, multi-split (including variable refrigerant flow 
(``VRF'')), and multi-circuit systems;
    (b) Split-system heat pumps, including single-split, multi-head 
mini-split, multi-split (including VRF), and multi-circuit systems;
    (c) Single-package air conditioners;
    (d) Single-package heat pumps;
    (e) Small-duct, high-velocity systems (including VRF);
    (f) Space-constrained products--air conditioners; and
    (g) Space-constrained products--heat pumps.
    The definition for central air conditioner or central air 
conditioning heat pump was last amended in the October 2022 CAC TP 
final rule. DOE revised the central air conditioner or central air 
conditioning heat pump definition so that it explicitly excluded 
certain equipment categories that met the CAC/HP definition based on 
their characteristics but are exclusively distributed in commerce for 
commercial and industrial applications. 87 FR 64550, 64573. DOE noted 
that there are certain types of equipment that meet the CAC/HP 
definition but are exclusively distributed in commerce for commercial 
and industrial applications, and that EPCA did not intend to regulate 
as consumer products. Id.
    Issue 1: DOE seeks information on whether the scope of CAC/HPs 
covered by appendices M and M1 needs to be limited, expanded, 
clarified, or revised in any way.
    Issue 2: DOE seeks information on whether the definition of central 
air conditioner or central air conditioning heat pump needs revision or 
further clarifications.

B. Load-Based Testing

1. Background
    As noted in section I.B of this RFI, several stakeholders in the 
previous rulemaking encouraged DOE to review ways to improve the 
representativeness of the test procedures for CAC/HPs. Specifically, 
the Pacific Gas and Electric Company, San Diego Gas and Electric, and 
Southern California Edison (collectively, the ``California Investor 
Owned Utilities'' or ``CA IOUs''); the Appliance Standards Awareness 
Project (``ASAP'') and American Council for an Energy-Efficient Economy 
(``ACEEE'') (collectively, the ``Joint Advocates''); and the Northwest 
Energy Efficiency Alliance (``NEEA'') all requested that DOE explore 
approaches that would capture the performance of variable-speed and 
multi-stage systems operating under native controls rather than under 
fixed compressor and fan speed controls as required under the current 
DOE test methods. (CA IOUs, No. 20 at pp. 2-3; Joint Advocates, No. 18 
at p. 1; NEEA, No. 23 at p. 1) \4\
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    \4\ The parenthetical reference provides a reference for 
information located in the docket of DOE's rulemaking to develop 
test procedures for central air conditioners and heat pumps (Docket 
No. EERE-2021-BT-TP-0030, which is maintained at 
www.regulations.gov). The references are arranged as follows: 
(commenter name, comment docket ID number, page of that document).
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    NEEA and the Joint Advocates recommended that DOE adopt a test 
procedure that evaluates performance for variable-speed systems with 
the heat pump operating using its native controls rather than using 
fixed-speed overrides of controls. (NEEA, No. 23 at p. 1; Joint 
Advocates, No. 18 at pp. 3-4) NEEA provided data to support their claim 
that seasonal efficiency performance is highly dependent on the 
installed firmware of the system. (Id. at pp. 3-4) NEEA compiled this 
information in a report \5\ that was also cited by the Joint Advocates 
in their comment. (Joint Advocates, No. 18 at p. 4)
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    \5\ The report titled ``Heat Pump and Air Conditioner Efficiency 
Ratings: Why Metrics Matter'' outlined how the built-in firmware of 
variable-speed CAC/HPs can have a significant impact on real-world 
performance, yet the firmware operation is explicitly excluded from 
current rating procedures. The report presented the case that a much 
better rating metric would utilize a load-based testing procedure 
that fully characterizes heat pump performance under realistic 
operating conditions, including the systems' built-in firmware. 
Available at https://neea.org/resources/heat-pump-and-air-conditioner-efficiency-ratings-why-metrics-matter.
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    NEEA also requested that DOE adopt a load-based test procedure with 
the tested system operating under native controls. (NEEA, No. 23 at p. 
2) NEEA again provided data concerning the representativeness of the 
existing DOE test procedure as compared to field data. Id. NEEA cited 
several ongoing projects related to the evaluation of load-based 
testing of CAC/HP and recommended that DOE leverage this work as a part 
of the next CAC/HP test procedure rulemaking. (Id. at pp. 5-7) NEEA 
additionally requested that DOE consider increasing the amount of data 
reported for heat pumps operating at part-load heating conditions, 
specifically advocating for required reporting of coefficient of 
performance (``COP'') for low-compressor-stage tests at 67 [deg]F and 
47 [deg]F. (Id. at p. 7)
    To address these comments, and in addition to the potential 
improvements in appendix M1 outlined in sections II.C and II.D of this 
RFI, DOE is exploring the potential of a load-based testing approach, 
primarily for variable-speed CAC/HPs, to evaluate performance 
characteristics that may not be captured by the existing steady-state 
test methods outlined in appendix M1. DOE has also considered load-
based test methods that are also applicable for single- and two-stage 
models. This section gives a brief introduction of the load-based 
testing methodologies and summarizes the various efforts and test 
programs that are investigating and developing new load-based test 
methods.
2. Current DOE Test Procedures
    As discussed, the current test procedures for CAC/HPs are given at 
title 10 CFR part 430, subpart B, appendix M1. Beginning January 1, 
2023, manufacturers must certify their systems under appendix M1 and 
meet energy conservation standards in terms of EER2, SEER2, HSPF2, and 
off-mode power.
a. Test Conditions
    Appendix M1 uses a steady-state test concept where test room 
conditions are kept within narrow operating tolerances for each test 
point, and the CAC/HP

[[Page 4094]]

system is manually controlled to operate at the specified compressor 
speed and airflow rate for each test point (i.e., the CAC/HP system's 
controls are overridden to ensure constant operation at the speed and 
airflow required by the DOE test procedure). While the DOE test 
procedures do include transient tests to examine the impact of defrost 
and compressor cycling, they do not incorporate any elements of load-
based testing \6\ in which the unit operates under its own native 
controls in responding to conditioning loads. Several research projects 
discussed in section II.B.4 have addressed development of load-based 
test approaches.
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    \6\ A load-based test method differs from the steady-state test 
method currently used in DOE test procedures for air conditioning 
and heat pump equipment. In a steady-state test method, the indoor 
room is maintained at a constant temperature throughout the test. In 
this type of test, any variable-speed or variable-position 
components of air conditioners and heat pumps are set in a fixed 
position, which is typically specified by the manufacturer. In 
contrast, a load-based test has the conditioning load applied to the 
indoor room using a load profile that approximates how the load 
varies for units installed in the field. In this type of test, an 
air conditioning system or heat pump is allowed to automatically 
determine and vary its control settings in response to the imposed 
conditioning loads, rather than relying on manufacturer-specified 
settings.
---------------------------------------------------------------------------

    Furthermore, there has been growing interest in cold climate heat 
pumps (``CCHPs''). A CCHP is a kind of central heat pump that could 
provide mechanical air heating utilizing a refrigerant vapor 
compression cycle, or a combination of mechanical air heating and 
electric resistance heating, at low outdoor ambient conditions (~5 
[deg]F) that could occur in generalized climate region V \7\ in the 
United States. On May 19, 2021, DOE, in conjunction with the U.S. 
Environmental Protection Agency (``EPA'') and National Resources Canada 
(``NRCan''), announced a Cold Climate Heat Pump Technology Challenge 
(``DOE CCHP Tech Challenge'') as part of the Energy, Emissions and 
Equity (``E3'') Initiative.\8\ In partnership with heat pump 
manufacturers, DOE developed a new technology specification for a high-
performance CCHP. Several CCHP prototypes meeting this technology 
specification will undergo field trials in the winters of 2022 and 2023 
to demonstrate performance in the field. In addition to the interest in 
CCHP development expressed by heat pump manufacturers, DOE is aware of 
growing interest from utilities and state governments to support the 
development of CCHPs to accelerate decarbonization efforts (e.g., 
replacing residential furnaces with heat pumps). Utility programs often 
offer rebates to consumers who purchase high-efficiency products, and 
high-performing CCHP are a growing component of several utility rebate 
programs.\9\
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    \7\ See ``Figure 1--Climatic Regions I through VI for the United 
States'' in appendix M1.
    \8\ As part of the E3 Initiative, DOE launched the DOE CCHP Tech 
Challenge. Currently, the challenge is focused on residential, 
centrally ducted, electric-only HPs. CCHP products that meet the 
challenge specification would offer high efficiency and heating 
capacity both seasonally and at very cold temperatures (5 [deg]F and 
below). The challenge builds upon the recent ENERGY STAR 
specification (v6.1). For further details, see www.energy.gov/sites/default/files/2022-02/bto-cchp-fact-sheet-021822.pdf.
    \9\ There currently is a database of CCHP products provided by 
the Northeast Energy Efficiency Partners (``NEEP''), and some 
utility providers are offering rebates if customers purchase and 
install a CCHP from the NEEP database. For example, the Vermont 
Public Power Supply Authority is offering one (vppsa.com/2021-cold-climate-heat-pump-instant-discount/).
---------------------------------------------------------------------------

    However, the validation of CCHP performance at colder outdoor 
ambient temperatures (i.e., 5 [deg]F and colder), is not a topic 
currently addressed by the DOE test procedures.
b. Control Inputs
    When testing for single-speed and two-speed CAC/HPs, the heating 
and cooling tests per the DOE test procedures are conducted using each 
of the discrete compressor speeds at which the system is capable of 
operating. However, when testing variable-speed CAC/HPs, appendix M1 
requires selection of appropriate compressor speeds that are intended 
to be representative of how the system would operate under its native 
controls.\10\ The DOE test procedures include some specification as to 
how compressor speeds should be selected for testing variable-speed 
CAC/HP. For example, appendix M1 specifies that for the H32 
heating test, the ``Heating Full'' compressor speed should be the 
maximum speed at which the system controls would operate the compressor 
in normal operation at 17 [deg]F ambient temperature. However, there is 
no process for verifying that the compressor speeds selected for 
testing agree with the compressor speed that would be observed if the 
system were operating at the same conditions under native controls.
---------------------------------------------------------------------------

    \10\ Native controls means configuring the unit under test with 
settings specified for field use and removing the unit from ``test 
mode'' used for steady-state tests. Native control settings are 
determined from manufacturer installation and operations manual 
shipped with the unit.
---------------------------------------------------------------------------

    Additionally, single-speed and two-speed CAC/HP systems rely on 
voltage signals from a thermostat to determine their operating state. 
When following DOE's test procedures for single-speed and two-speed 
CAC/HPs, it is common practice for the test lab to simulate a 
thermostat signal by sending the appropriate voltage signals directly 
to the unit under test instead of using a functional thermostat to 
induce the desired stage of heating or cooling mode. Conversely, 
variable-speed CAC/HPs installed in the field commonly utilize 
communicating thermostats where the control system communicates the 
difference in space temperature and space setpoint temperature to the 
control that sets compressor speed and indoor fan speed. Manufacturers 
involved in the development of the ENERGY STAR Central Air Conditioner 
and Air Source Heat Pump Specification Version 6.0 indicated that 
standard thermostats for their variable-speed units enable two-way 
communication control between the indoor and outdoor units.\11\ DOE is 
aware of concerns that two-way communication control may not be 
possible using a third-party smart thermostat or lab-simulated 
thermostat. Therefore, many variable-speed units would not operate 
without their proprietary communicating thermostat making it an 
inherent part of the native control. DOE is also aware of concerns that 
operation under native controls for variable-speed CAC/HP can result in 
dynamic operation that is inconsistent with the steady-state 
requirements in the current DOE test procedure.
---------------------------------------------------------------------------

    \11\ Lennox and Carrier comments on the Version 6.0 Limited 
Topic Proposal on Installation, dated February 23, 2021. Comments 
are accessible at https://www.energystar.gov/products/spec/central_air_conditioner_and_air_source_heat_pump_specification_version_6_0_pd.
---------------------------------------------------------------------------

3. Categorization of Test Concepts
    As explained in section II.B.1 of this document, the current DOE 
test procedure for CAC/HPs outlined in appendix M1 is a steady-state 
test, where the compressor speeds and airflow rates may be overridden 
for each test point.
    In contrast, a load-based test has the conditioning load applied to 
the indoor room using either a stable compensation load or a load 
profile that approximates how the load varies for units installed in 
the field. In this type of test, an air conditioning system or heat 
pump is allowed to automatically determine and vary its operation in 
response to the imposed conditioning loads, rather than operating at 
manually overridden speeds.
    Because of the different variations of load-based tests, it is 
important to define the method of inducing the conditioning load on the 
indoor psychrometric room. Broadly, there are two methods of inducing 
load, which

[[Page 4095]]

are detailed in the following sections II.B.3.a and II.B.3.b of this 
document.
a. Test Chamber Induced Load
    In this approach, the test chamber's reconditioning equipment, and/
or any alternative devices such as a fan coil or electric heater, add 
or remove heat to (or from) the chamber at a constant rate. An example 
of the test chamber induced load is the load-compensation method, which 
was first proposed by the German energy regulatory body, Bundesanstalt 
f[uuml]r Materialforschung und-Pr[uuml]fung (``BAM'').\12\ Like all 
load-based tests, the load-compensation method involves testing the 
CAC/HP equipment operating without any test unit native controls 
override (i.e., not in test mode). This approach minimizes the impact 
on test result variation caused by test chamber and measurement 
apparatus thermal mass due to the inherent steady-state nature of the 
testing.
---------------------------------------------------------------------------

    \12\ BAM (2019). Proposal for the revision of the harmonised 
test standard EN 14825:2016. Federal Institute for Materials 
Research and Testing (BAM).
---------------------------------------------------------------------------

    This testing methodology can be illustrated by explanation of its 
execution in the DOE CCHP Tech Challenge. Prior to conducting load-
compensation tests under native controls, appendix M1 tests are 
required to calculate HSPF2 and determine target compensation loads for 
a select sub-set of native control tests. During native control 
testing, the psychrometric chambers are operated with a fixed cooling 
load; this load should be equivalent in magnitude to the capacity from 
the corresponding appendix M1 regulatory test. Full-load tests are 
conducted with the thermostat set at the maximum available setpoint 
unless temporary over speeding is allowed by the system controls. In 
this case, the thermostat setpoint is reduced until temporary over 
speeding is no longer occurring. Minimum and intermediate speed tests 
are conducted with the thermostat set at the test condition target 
value (adjusted for thermostat offset). For example, if a heating 
capacity of 17,000 Btu/h was measured during the H11 test, 
the ``Min/Mild'' test would apply an equivalent 17,000 Btu/h cooling 
load to the indoor room's conditioning equipment. This results in the 
unit under test responding to the test chamber-induced load to maintain 
the desired temperature. If a similar capacity cannot be achieved 
without the unit cycling on and off, then the compensation load is 
incrementally increased until the unit is no longer cycling. Data is 
collected with the unit operating at a capacity as close as possible to 
the ratings test while running continuously (not cycling).
b. Virtual Building Load
    The Virtual Building Load (``VBL'') approach of load-based testing 
adds to the load-compensation approach by simulating the building 
response to the conditioning provided by the unit under test. 
Specifically, if the system capacity is lower than the average load in 
a heating test, the temperature of the air returned to the unit would 
be reduced (by the test chamber conditioning equipment) to reflect the 
transient reduction in temperature of the building while the load and 
unit capacity are not balanced. The main difference between the test 
chamber induced load test method and the VBL test method is that the 
former utilizes a stable load being imposed on the unit under test, 
whereas the latter varies the load to simulate the building response if 
the capacity of the unit under test does not match the imposed load. 
Several variations exist for implementation of the VBL for load-based 
testing of CAC/HPs, as detailed in section II.B.4 of this RFI. What all 
these variations have in common is that the indoor room temperature 
varies to mimic the response of the virtual building, which is a 
software loop continuously interacting with the indoor room's 
conditioning equipment.
4. Summaries of Selected Activities Investigating and Developing New 
Test Methods for Central Air Conditioners and Heat Pumps
    Several initiatives to investigate, research, and develop new test 
procedures have emerged in response to concerns that current regulatory 
test methods may have issues representing field performance. Some of 
these activities are described in the subsections below.
a. CSA EXP07
    In March 2019, The Canadian Standards Association (``CSA'') 
published a draft ``first edition'' of CSA EXP07:19, ``Load-based and 
climate-specific testing and rating procedures for heat pumps and air 
conditioners'' \13\ (``EXP07''). EXP07 is a load-based testing 
methodology applicable to single-split and packaged air-source CAC/HP 
with rated cooling or heating capacity below 65,000 Btu/h, including 
space-constrained and small-duct, high-velocity equipment. In contrast 
to conventional test methods, in which the indoor room conditions are 
held constant by the laboratory's indoor room conditioning equipment, 
EXP07 allows the unit under test to respond to a thermostat or 
temperature controller installed in the room or the return air, while 
the indoor room conditioning equipment is controlled to adjust that 
temperature to represent the conditioning (be it heating or cooling) 
provided by the unit as well as the response of a typical building. The 
test sequences through a set of representative outdoor room conditions. 
As the unit attempts to maintain a desired condition, all modulating 
components are free to perform under the unit's own native controls.
---------------------------------------------------------------------------

    \13\ CSA EXP07:19 is available for purchase in the CSA Group 
online store at www.csagroup.org/store/product/CSA%20EXP07%3A19. A 
total of 86 different comments were received by stakeholders 
regarding EXP07:19 during a technical review. A summary of the major 
comments is detailed in this article: Bruce Harley, Mark Alatorre, 
Christopher Dymond, Gary Hamer, ``CSA EXP07: Ongoing Progress, 
Lessons Learned, and Future Work in Load-based Testing of 
Residential Heat Pumps'' (2022). International Refrigeration and Air 
Conditioning Conference. Paper 2477.
---------------------------------------------------------------------------

    The load-based test concept that underpins the EXP07 procedure is 
heavily dependent on the interaction of the unit under test, the test 
chambers, and the thermostat. For CAC/HP systems equipped with a 
communicating control system, typical for variable-speed systems, the 
thermostat calculates the difference between the measured indoor room 
temperature and the unit setpoint for the indoor room, and continuously 
sends signals to the unit under test to control its operating state. 
CSA EXP07 also requires that the make and model of the thermostat be 
recorded and reported with test data.
b. AHRI 1230-2021 VRF CVP
    On May 18, 2021, the Air-Conditioning, Heating, and Refrigeration 
Institute (``AHRI'') published an updated test procedure (AHRI 1230-
2021) for Variable Refrigerant Flow Multi-Split Air Conditioners and 
Heat Pumps that incorporates a controls verification procedure 
(``CVP'') as appendix C \14\ (``VRF CVP''). AHRI 1230-2021 allows 
manufacturers to specify control settings for certain ``critical 
parameters'' (e.g., compressor speed, outdoor unit fan speed, and 
outdoor unit valve positions) in supplemental testing instructions; the 
VRF CVP is then used to verify whether these manufacturer-specified 
critical parameter settings are within the range of settings that would 
be used by the system during operation in the field. On October 20, 
2022, DOE published a Final Rule regarding Federal test procedures for 
VRFs. 87 FR 63860

[[Page 4096]]

(``October 2022 VRF TP final rule''). In the October 2022 VRF TP final 
rule, DOE incorporated the CVP (via reference to Appendix C of AHRI 
1230-2021) as part of DOE's product-specific enforcement provisions for 
VRF multi-split systems in the proposed Sec.  429.134(s). Id.
---------------------------------------------------------------------------

    \14\ See www.ahrinet.org/sites/default/files/2022-06/AHRI_Standard_1230-2021.pdf.
---------------------------------------------------------------------------

    The VRF CVP is performed in the cooling mode by using the test room 
conditioning apparatus to continuously reduce the indoor room 
temperature throughout the duration of the procedure. The VRF system 
responds as the temperature decreases and ``unloads'' as the demand 
diminishes for the system to provide cooling capacity. Throughout the 
CVP, the measured positions of each critical parameter are compared 
against the certified critical parameter values. The certified critical 
parameters are validated if a defined time exists from within the CVP 
where the measured values are within tolerance of the certified values. 
The VRF CVP is not used to measure capacity or efficiency; it is solely 
used for validating whether critical parameter control inputs are 
representative of behavior as observed under native control. 
Additionally, the VRF CVP is not a fully load-based method.
    The VRF CVP includes test provisions that are specific to the 
operation of VRF systems, such as requirements governing the number of 
thermally active indoor units and validation of critical parameters 
that are all variable-speed or modulating-position. Additional 
specification would be required to adapt the AHRI 1230-2021 CVP for VRF 
systems into a similar CVP applicable for CAC/CHP equipment intended to 
validate the operating states of variable-speed or modulating 
components. It is important to note that the VRF CVP utilizes a dynamic 
load that is neither constant nor simulates a virtual building load. 
The magnitude of the load is dynamically decreased by explicitly 
requiring the indoor temperature to be ramped down.
c. ENERGY STAR CCHP CVP
    On January 27, 2022, EPA published the ENERGY STAR Version 6.1 
Specification for CACs and Air-Source Heat Pumps (``ASHPs'').\15\ To 
certify as an ENERGY STAR CCHP, systems must also meet criteria at the 
5 [deg]F heating test condition and perform a controls verification 
procedure to confirm that the system achieves the same capacity and 
efficiency criteria at the 5 [deg]F test point when operating under 
native controls. The ENERGY STAR CCHP CVP is used as pass/fail 
verification criteria, rather than being used to develop a discrete 
performance rating, and the system must meet verification criteria in 
terms of capacity and efficiency.
---------------------------------------------------------------------------

    \15\ See www.energystar.gov/sites/default/files/asset/document/ENERGY%20STAR%20Version%206.1%20Central%20Air%20Conditioner%20and%20Heat%20Pump%20Final%20Specification%20%28Rev.%20January%20%202022%29.pdf.
---------------------------------------------------------------------------

    The ENERGY STAR CCHP CVP shares aspects of both load-based testing 
and controls verification procedures. The method is similar to other 
load-based test procedures in that the test unit operates under its 
native controls. During the ENERGY STAR CCHP CVP, the system thermostat 
is set to the highest achievable setpoint, while the indoor room 
conditioning apparatus is set to control to the standardized 70 [deg]F 
indoor room temperature used for heating tests.\16\ In cases in which 
the required capacity is exceeded but the COP is lower than the 
requirement, a modified test is allowed, in which the operating 
capacity is reduced, to attempt to shift both capacity and COP into 
compliance with the requirement. For this modified test, the thermostat 
setting is reduced to the standardized room temperature, and the load 
applied to the room is reduced. If the system can operate at a balance 
point where both the COP and heating capacity requirements are met, 
then the CCHP CVP is successful. This part of the ENERGY STAR CCHP CVP 
is a load-based method, since the chamber conditioning system applies a 
fixed load rather than maintaining chamber temperature.
---------------------------------------------------------------------------

    \16\ This is referred to as a ``buried thermostat'' test. The 
``buried'' term arose from use of the approach in cooling mode 
testing, for which the term is consistent with using the lowest 
setting.
---------------------------------------------------------------------------

d. BAM Dynamic Testing Method
    On May 29, 2019, BAM proposed a load-based (compensation method) 
test method (``Proposal for the revision of the harmonized test 
standard EN 14825, for the testing and rating of air conditioners and 
heat pumps at part load conditions and calculation of seasonal 
performance''), to be used as an alternative to EN 14825:2016 ``Air 
conditioners, liquid chilling packages and heat pumps, with 
electrically driven compressors, for space heating and cooling. Testing 
and rating at part load conditions and calculation of seasonal 
performance'' (``EN 14825''). The proposal outlined several issues \17\ 
with the fixed compressor speed standard, EN 14825.
---------------------------------------------------------------------------

    \17\ Section 2.3; May 29th BAM Proposal.
---------------------------------------------------------------------------

    After consultations with stakeholders, BAM released test guidelines 
based on their load-based test method on September 21st, 2020, for 
ducted and non-ducted, single-split and packaged air-source CAC/HPs 
with rated cooling or heating capacity below 41,000 Btu/h in a single 
or double calorimeter room (``Test guideline for a load-based 
performance testing and calculation of the seasonal performance (air 
conditioners, cooling only)'').\18\
---------------------------------------------------------------------------

    \18\ See: netzwerke.bam.de/Netzwerke/Content/DE/Downloads/Evpg/
Heizen-Kuehlen-Lueften/bam%20test%20guideline%20-%20load-
based%20testing%20of%20air%20conditioners%20cooling.pdf.pdf?__blob=pu
blicationFile.
---------------------------------------------------------------------------

    Through round-robin testing of CAC/HP units using the fixed 
compressor speed test procedure at seven different test labs, BAM found 
the standard deviation of reproducibility for EN 14825 to be 7.8% with 
a maximum deviation of 24% of Seasonal COP values. 19 20 BAM 
did undergo some limited investigation of the repeatability and 
reproducibility of the BAM Dynamic Testing method, and BAM claims that 
their test method is both repeatable and reproducible.\21\ They found 
the degree of repeatability using the BAM Dynamic Testing method to be 
comparable (~2%) to the repeatability of the current fixed compressor 
speed standard, EN 14825.\22\
---------------------------------------------------------------------------

    \19\ Figure 4a, 29th May 2019 BAM Proposal. BAM cites that many 
any labs were erroneously assuming various correction factors due to 
ambiguities in EN 14825, and without the need for these correction 
factors in a dynamic test procedure, BAM predicts that 
reproducibility will be higher.
    \20\ Table 2, 29th May 2019 BAM Proposal; BAM has not released 
substantial test data on the reproducibility of their test procedure 
in comparison to the European standard. Instead, they hypothesize 
that without the ambiguities found in EN 14825 or correction 
factors, the BAM Dynamic Test procedure will be more reproducible.
    \21\ Figure 10 in the May 29, 2019, proposal features a 
distribution of some of these results, but the document does not 
provide substantiating data to back up their claim of repeatability 
and reproducibility.
    \22\ ``Results'' section, 29th May 2019 BAM Proposal.
---------------------------------------------------------------------------

    BAM evaluated 15 CAC models during their preliminary testing for 
the BAM Dynamic Testing method and found that the unfixed compressor 
speed load compensation method results in, on average, an approximately 
20% lower SEER compared to declared values.\23\ The reason for this 
deviation was primarily due to varying behavior at part-load 
conditions, typically when the outdoor ambient temperature was between 
77 [deg]F and 86 [deg]F. Due to the different control strategies in 
each of the

[[Page 4097]]

CACs, the pattern of cycling on and off varied unit to unit, and hence 
affecting the SEER values. BAM observed that the compensation method 
allowed for a better comparison between units with well-designed 
control systems.
---------------------------------------------------------------------------

    \23\ Figure 6, 29th May 2019 BAM Proposal. This figure displays 
results from testing to the unfixed compressor, load compensation 
method defined in section 8.5.2 of EN 14825. This method is not 
exactly what the BAM Dynamic Testing method is, but the BAM Dynamic 
Testing method is largely based off this.
---------------------------------------------------------------------------

e. 4E IEA
    The Technology Collaboration Program on Energy Efficient End-use 
Equipment, International Energy Agency (``4E TCP'') studied various 
load-based testing techniques in order to see if it is possible to 
develop a test method that improves testing representativeness of 
variable-speed central air conditioners.\24\ 4E TCP conducted the 
testing series (titled ``Project 2.0'') where three different variable-
speed CAC/CHP units were tested by utilizing aspects of published load-
based test procedures (BAM Dynamic Testing, CSA EXP07 and AHRI 1230 
CVP).
---------------------------------------------------------------------------

    \24\ ``Load-based Testing for Variable Speed Air Conditioners & 
Heat Pumps Phase 1 Findings Webinar'' 4E IEA presentation (January 
29, 2021). See https://www.iea-4e.org/wp-content/uploads/2021/08/AC-HP-Test-Methods-Phase-1-Key-Findings_Revised.pdf.
---------------------------------------------------------------------------

    4E TCP presented their findings in a public webinar \25\ and 
solicited feedback from stakeholders on the preferred test concept to 
be used in a unified load-based test method. After investigative 
testing, 4E IEA recommended either a compensation target load-based 
method (if test condition/test operating tolerances, repeatability and 
burden increases are acceptable to stakeholders), or a CVP would be 
preferred if the tolerances and burden are not acceptable. They also 
found that the dynamic load response test method is not repeatable in a 
laboratory setting. Stakeholders indicated the projected 10%-15% 
repeatability increase for a compensation target load-based test was 
too large and that for regulatory purposes, the overridden steady-state 
test would be preferred.
---------------------------------------------------------------------------

    \25\ ``AC/HP Test Methods Investigative Testing: Phase 2 
Preliminary Findings'' 4E IEA presentation (May 7, 2021). See 
https://www.iea-4e.org/wp-content/uploads/2021/08/AC-HP-Test-Methods-Phase-2-key-Findings-2021-08-06-CLEAN.pdf.
---------------------------------------------------------------------------

    On December 1, 2021, 4E IEA published a test method in ``Controls 
Validation Method for Variable Speed Air Conditioners and Heat Pumps'' 
(``4E TCP AC/HP Controls Validation Method''). This test method 
utilized the compensation target load-based method as a CVP for 
confirmation against regulatory tests in which modulating component(s) 
are overridden. This methodology is applicable to variable-speed ducted 
and non-ducted single-split and packaged air-source CAC/CHP with rated 
cooling or heating capacity below 65,000 Btu/h, including through-the-
wall air conditioners (``ACs'') and heat pumps (``HPs'').
f. DOE Cold-Climate Heat Pump Investigative Testing
    To inform the development of test methods for Cold Climate Heat 
Pump Test methods, DOE conducted investigative testing on 7 non-ducted 
mini-split and 2 central-ducted split variable-speed heat pumps. All 
heating regulatory tests as per appendix M/M1 were conducted, in 
addition to the H42 test at 5 [deg]F (optional in appendix 
M1), H52 test at -5 [deg]F, and H62 test at -15 
[deg]F (not part of appendix M or M1). Load-based tests were conducted 
using the load-compensation method for select appendix M1 conditions, 
denoted by the ``x'' subscript, namely H1NX, 
H11X, and H42X. The testing showed that 
regulatory and load-based tests showed similar performance for ducted 
units at 47 [deg]F heating maximum air volume rate condition 
(H1N and H1NX). However, DOE found that 
regulatory tests did not capture ``real-world'' performance at ambient 
temperatures lower than 47 [deg]F. Specifically, DOE observed that the 
compressor speeds and indoor fan speeds for load-based and regulatory 
tests at ambient temperatures below 47 [deg]F differed by more than 11% 
for some of the tested units. Additionally, DOE observed that units in 
``test mode'' allowed operation below the point at which the native 
control tests cut out.
g. DOE CCHP Tech Challenge
    Performance of the CCHPs participating in the DOE CCHP Tech 
Challenge (see II.B.2 for further details) is evaluated by testing at 
the psychrometric chambers at Oak Ridge National Laboratory (``ORNL''). 
The test matrix comprises the regulatory heating mode tests outlined in 
appendix M1, with the H4/H42 test at outdoor ambient 
temperature of 5 [deg]F being mandatory. Additionally, after 
consultation with manufacturers, it was decided that a battery of CCHP-
Focused Dynamic Tests would be conducted based on the load-compensation 
method.\26\ For variable-speed CCHPs to pass the DOE CCHP Tech 
Challenge specifications, one of the requirements is that the minimum 
capacity at 47 [deg]F, validated using the ``Min/Mild'' load-based 
test, shall be at least 30% less than the nominal capacity at 47 [deg]F 
(i.e., capacity for test H1N of appendix M1). So far, 10 
manufacturers have committed to participate in the DOE CCHP Tech 
Challenge, with three of them having successfully achieved the 
challenge's standards to date.\27\
---------------------------------------------------------------------------

    \26\ See www.energy.gov/sites/default/files/2021-10/bto-cchp-tech-challenge-spec-102521.pdf.
    \27\ See www.energy.gov/articles/biden-harris-administration-announces-250-million-investment-inflation-reduction-act.
---------------------------------------------------------------------------

h. Emulator-Based Assessment Method for Dynamic Performance Evaluation 
of Air Conditioners by Waseda University
    Various groups at the Waseda University in Japan collaborated to 
develop an emulator-based method for load-based testing of ACs.\28\ The 
virtual room emulator simulates the return indoor air temperature based 
on the input assumptions for a VBL. Consequently, the AC responds to 
the simulated indoor air conditions by supplying cooling capacity 
according to the response guided by its control system. Testing was 
conducted, with and without the emulator enabled, on a 2-ton non-ducted 
CHP, as per the conditions outlined in the Japanese Industrial 
Standards annual performance tests (``JIS B 08615, 2013'') (i.e., 
indoor dry-bulb and wet-bulb temperatures of 80 [deg]F and 67 [deg]F, 
respectively, and outdoor dry-bulb and wet-bulb temperatures of 95 
[deg]F and 75 [deg]F, respectively, at a 25 percent loading condition). 
It was found that the COP of the unit with the emulator enabled was 22 
percent lower than the corresponding steady-state test (without the 
emulator).
---------------------------------------------------------------------------

    \28\ Niccolo Giannetti, Hifni Ariyadi, Yoichi Miyaoka, Jongsoo 
Jeong, Kiyoshi Saito, ``Development of an Emulator-Based Assessment 
Method for Representative Evaluation of the Dynamic Performance of 
Air Conditioners '' (2022). International Refrigeration and Air 
Conditioning Conference. Paper 2458. docs.lib.purdue.edu/iracc/2448/.
---------------------------------------------------------------------------

    As a result of testing, the team at Waseda University was able to 
identify several sources of errors and delays that affected the 
modulation of indoor air temperature and humidity, such as the 
emulator's calculation time delay, tracking of air flow rate, 
temperature and humidity by the condition generator, heat transfer and 
thermal capacity of the structure and instrumentation of the 
psychrometric chamber, time delay of the various signals, and the 
thermostat location.
i. The Advanced Heat Pump Coalition
    The Advanced Heat Pump Coalition is a group of utilities and energy 
efficiency advocates, namely NEEA, the Northeast Energy Efficiency 
Partners (``NEEP''), the Midwest Energy Efficiency Alliance (``MEEA''), 
NRCan, EPA, California Energy Commission, and the New York State Energy 
Research and Development Authority (``NYSERDA''), that share knowledge 
and resources to assist the market adoption of residential heat

[[Page 4098]]

pumps in the US.\29\ Workgroup 1 of this coalition aims to identify a 
load-based test procedure for ASHPs that is more representative of 
their performance in the field.
---------------------------------------------------------------------------

    \29\ See www.mwalliance.org/advanced-heat-pump-coalition.
---------------------------------------------------------------------------

    Initially, 13 heat pumps made by nine manufacturers were tested 
using CSA EXP07:19 and AHRI 210/240 \30\ (``Performance Rating of 
Unitary Air-conditioning & Air-source Heat Pump Equipment'') at the UL 
Plano laboratory in Texas. Two were initially tested only in the 
heating mode and 11 were tested in both heating and cooling modes to 
generate a complete set of seasonal COP ratings. As previously 
mentioned, EXP07 accounts for the on-board control algorithms of the 
units under test. A comparison of the relationship between HSPF and 
heating SCOP or SEER and cooling SCOP was not conducted due to the fact 
that these are two different metrics based on different measurement 
conditions and methodologies. However, comparing different models with 
similar SEER and HSPF ratings to the results using the CSA EXP07 method 
showed that the relative efficiencies of those models were 
significantly different. The Coalition stated that the on-board 
controls are a critical component of the heat pump's real performance 
and should be accounted for in future test standards.
---------------------------------------------------------------------------

    \30\ AHRI 210/240 establishes a method to rate residential 
central air conditioners and heat pumps consistent with the test 
procedure codified in 10 CFR part 430, subpart B, appendix M1.
---------------------------------------------------------------------------

j. ISO/TC 86/SC 6/TG 13
    TG 13 (``Next generation of performance standards'') is a working 
group of ISO/TC 86/SC 6 (``Testing and rating of air-conditioners and 
heat pumps'') that is responsible for gathering information on various 
activities pertaining to load-based testing methods for residential 
CAC/HPs. Recently, lab testing results of several CAC/HPs using the BAM 
Dynamic Testing Method (section II.B.4.d of this document), CSA-
EXP07:2019 (section II.B.4.a of this document), and the emulator-based 
assessment method (section II.B.4.h of this document), along with 
findings of the 4E IEA project (section II.B.4.e of this document), 
have been presented to members of ISO/TC 86/SC6/TG 13. The subcommittee 
has raised concerns about the repeatability and reproducibility of 
load-based tests on several occasions (e.g., the ``Load-based test 
method'' informal virtual meeting held on July 8th, 2022), and hence 
encourage all ongoing and future research projects to address both of 
these factors.
k. ASHRAE TC 8.11 Subcommittee Unitary Next Generation Test Procedure
    The American Society of Heating, Refrigerating and Air-Conditioning 
Engineers (``ASHRAE'') Technical Committee (``TC'') 8.11 \31\ is 
concerned with the following AC and HP systems: (1) ducted unitary ACs/
HPs, (2) room ACs such as window mounted units and non-ducted split 
systems, and (3) packaged terminal equipment. The TC 8.11 subcommittee 
titled ``Unitary Next Generation Test Procedure Subcommittee'' was 
developed with the aim of coordinating technical activities related to 
the development of the next generation load-based test procedure for 
unitary HVAC equipment. It is planning to develop a Research Topic 
Acceptance Request (``RTAR''), which will enable identification of 
ASHRAE Research Projects (``RPs'') to improve upon the reproducibility, 
repeatability, and representativeness of load-based test procedures for 
residential and commercial unitary AC/HP equipment.
---------------------------------------------------------------------------

    \31\ ASHRAE's technical committees are responsible for 
coordination of society-sponsored Research Projects (``RPs''), 
reviewing technical papers, evaluating the need for standards, and 
acting as the advisory board for the Society on all aspects of the 
technology for which it is in charge.
---------------------------------------------------------------------------

5. Request for Information
    As explained in section II.B.3, all load-based test methods are 
characterized by how the load is applied on the test chamber. Two 
primary testing procedures are used for capacity measuring, namely the 
calorimetric or air enthalpy method. The calorimetric room method 
measures the energy input to the equipment serving a known load added 
into the conditioned room. Test chambers are typically limited to a 
3.4-ton (12 kW) cooling capacity and are typically preferable for 
testing non-ducted CAC/HPs. In contrast, the air enthalpy method is 
typically employed in psychrometric chambers, and is geared towards 
ducted equipment, but can accommodate non-ducted if needed. Table II-1 
shows which of the two capacity measuring methods (i.e., calorimetric 
room or air enthalpy) are used for each load-based test method, and 
also show the load application scheme for each of them.

                     Table II-1--Applicability of Load-Based Test Methods to Equipment Types, and Procedure for Capacity Measurement
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                       Test procedure for capacity    Type of equipment test method is       Load application scheme
                                                               measurement                      applicable to          ---------------------------------
              Load-based test method               --------------------------------------------------------------------
                                                      Calorimetric     Air enthalpy                                       Test chamber       Virtual
                                                          room            method           Ducted         Non-ducted      induced load    building load
--------------------------------------------------------------------------------------------------------------------------------------------------------
CSA EXP07.........................................  ...............         [check]          [check]          [check]   ...............         [check]
AHRI 1230-2021 VRF CVP............................  ...............         [check]          [check]          [check]          [check]   ...............
Energy Star CCHP CVP..............................  ...............         [check]          [check]          [check]          [check]   ...............
BAM Dynamic Testing Method........................         [check]   ...............         [check]          [check]          [check]   ...............
DOE CCHP Investigative Testing....................  ...............         [check]          [check]   ...............         [check]   ...............
DOE CCHP Tech Challenge...........................  ...............         [check]          [check]   ...............         [check]   ...............
Emulator-Based Assessment Method for Dynamic               [check]   ...............  ...............         [check]   ...............         [check]
 Performance Evaluation of ACs....................
4E TCP AC/HP Controls Validation Method...........         [check]          [check]          [check]          [check]          [check]   ...............
--------------------------------------------------------------------------------------------------------------------------------------------------------

    In the following sections, DOE has identified a variety of issues 
on which it seeks input to determine whether, and if so, how, an 
amended test procedure for CAC/HPs and CCHPs would more accurately or 
fully comply with the requirements in EPCA that test procedures be 
reasonably designed to produce test results that reflect energy use 
during a representative average use cycle or period of use without 
being unduly burdensome to conduct (42

[[Page 4099]]

U.S.C. 6293(b)(3)). DOE also seeks input on the most appropriate 
application of such an amended test procedure.
a. Repeatability and Reproducibility
    DOE is interested in information and data regarding the 
repeatability and reproducibility of known load-based test methods. 
Publicly available information on this topic for the load-based test 
method initiatives discussed in section II.B.4 is very limited. 
Presentations regarding the 4E IEA work on development of load-based 
test procedures (see section II.B.4.e of this document) include claims 
that the degree of repeatability and reproducibility of load-based test 
procedures is extremely important, and through testing three different 
units twice at different test labs, the COP was found to vary as much 
as 10.6 percent during the load compensation method.\32\ In addition, 
several units have been tested at two laboratories to assess the 
repeatability and reproducibility of CSA EXP07 and AHRI 210/240, but 
the information is only available to ISO/TC 86/SC 6/TG 13 and not to 
the public. DOE is aware of ongoing efforts where it has been pointed 
out during load-based testing that thermostat location within the 
indoor environmental chambers is very crucial for repeatability of 
load-based tests across different laboratories.\33\
---------------------------------------------------------------------------

    \32\ Slide 24 of ``AC/HP Test Methods Investigative Testing: 
Phase 2 Preliminary Findings'' 4E IEA presentation (May 7, 2021).
    \33\ Cheng, Li; Patil, Akash; Dhillon, Parveen; Braun, James E.; 
and Horton, W. Travis, ``Impact of Virtual Building Model and 
Thermostat Installation on Performance and Dynamics of Variable-
Speed Equipment during Load-based Tests'' (2018). International 
Refrigeration and Air Conditioning Conference. Paper 2078. 
docs.lib.purdue.edu/iracc/2078.
---------------------------------------------------------------------------

    Issue 3: DOE requests quantitative information regarding the 
repeatability and reproducibility of load-based test procedures (not 
limited to the developments discussed in section II.B.4 of this RFI). 
Specifically, which of the approaches presented in section II.B.4 are 
better in this regard, and what specific characteristics make them 
better? How do the repeatability and reproducibility of load-based test 
procedures compare to more conventional test methods that involve 
operating the system with one or more fixed control setting? To what 
extent do the differences in test facility characteristics lead to 
different settings of control system parameters as a result of control 
system learning (i.e., adaptation of control parameters in response to 
``conditioned system'' behavior) and how much does this affect 
different load-based test approaches? Please provide appropriate data 
to the extent possible to support the information.
b. Field Performance
    As described in sections II.B.1 and II.B.2 of this RFI, 
stakeholders have expressed greater interest in load-based test 
procedures based on the observation that variable-speed CAC/HPs may not 
always operate in the field in a manner that is represented by 
conventional testing using fixed speeds for the compressor and other 
key components. Developers of load-based testing methods claim these 
tests are more representative of an average use cycle than the fixed 
compressor speed methods found in appendix M1. However, comprehensive 
information comparing the results of different test methods with the 
results of field operation have not been made public. Currently, DOE is 
only aware of NEEP managing a field performance research study to 
directly compare the representativeness of both EXP07 and appendix M1, 
but the results of this research are expected in the 2nd quarter of 
2023.\34\
---------------------------------------------------------------------------

    \34\ See neep.org/request-proposals-heat-pump-rating-representativeness-project-0.
---------------------------------------------------------------------------

    Issue 4: DOE seeks data showing how the representativeness of load-
based test procedures compares to that of more conventional fixed-speed 
and fixed-setting test procedures. What are the key issues observed 
that cause field performance of CAC/HPs to deviate from the predictions 
of conventional testing, and has load-based testing provided more 
representative predictions? Additionally, DOE is interested in any data 
suggesting that CAC/HPs that were considered to be performing poorly in 
the lab when tested using load-based methods also performed poorly when 
installed in the field.
c. Test Burden
    In addition to considering repeatability, reproducibility, and 
representativeness when evaluating test procedures, DOE must also 
consider the relative burdens associated with conducting test 
procedures. One component of test burden is the total testing time, 
which includes setup/commissioning/decommissioning, official test 
points, and any time required to transition between test conditions. 
Test burden also accounts for difficulties in repeatably achieving test 
conditions (i.e., whether a test has a higher likelihood of needing to 
be conducted multiple times to achieve a valid result). Another key 
component of analyzing test burden is considering any upgrades to 
laboratory equipment or capital expenditures required to conduct 
testing. These upgrades may constitute considerable burden when large 
capital expenditures are required.
    Issue 5: DOE seeks information related to the test burden of load-
based test methods, including those discussed in this document and any 
other method that may not be considered here. What is the test duration 
and how does it compare with a regulatory test under the currently 
prescribed DOE test method? How much time is needed for control system 
learning (i.e., adaptation of control parameters in response to 
``conditioned system'' behavior) to take place prior to testing? What 
specific changes to the facility, including its control systems, are 
required to conduct load-based testing? Additionally, what are the 
costs associated with upgrading controls of environmental chambers and 
the time needed for training technicians to successfully conduct load-
based testing?
d. Thermostat Selection and Built-In Control Firmware
    A key aspect of system performance addressed by load-based test 
procedures is the way that the control system impacts the operation and 
performance of the system. Since thermostats can vary in their control 
algorithms and how they communicate with a system, the thermostat 
selection can potentially impact the results of the test (see section 
II.B.2.b of this RFI for further discussion). As noted in section 
II.B.4.a, CSA EXP07 requires the make and model of the thermostat to be 
recorded and reported with test data. The 4E IEA Project 2.0 round-
robin testing (described in section II.B.4.e of this RFI) is 
investigating the impact of different thermostat selections on system 
performance when subjected to the same test procedure using load-based 
test conditions. DOE is not aware of data showing the variability of 
test results when pairing the same CAC/CHP model with different 
thermostats. However, as explained in section II.B.1, in response to a 
notice of proposed rulemaking (``NOPR'') regarding CAC/HP test 
procedures published on March 24, 2022 (``March 2022 CAC TP NOPR''), 
NEEA provided data from a report \35\ that showed the seasonal 
efficiency performance of variable-speed CAC/HPs

[[Page 4100]]

was highly dependent on the internal firmware of the system. 87 FR 
16830.
---------------------------------------------------------------------------

    \35\ The report is titled ``Heat Pump and Air Conditioner 
Efficiency Ratings: Why Metrics Matter'', and can be downloaded for 
free from this link: neea.org/resources/heat-pump-and-air-conditioner-efficiency-ratings-why-metrics-matter.
---------------------------------------------------------------------------

    Issue 6: DOE requests comment on the impact of thermostat selection 
and the built-in firmware version when testing CAC/HP under their 
native controls. What range of performance could be measured using 
different thermostats when testing the same system? How does this vary 
for staged systems as compared with fully variable-speed systems? How 
should thermostat pairings and the built-in firmware be considered from 
a certification standpoint (i.e., should the thermostat used for 
testing be certified as part of the tested combination)? DOE is also 
interested in knowing how behavior of CAC/HPs in the field varies 
depending on the thermostats pairing (i.e., those shipped with the unit 
versus those obtained from third-party suppliers). DOE would like to 
know what percentage of thermostats can be updated remotely via 
firmware upgrades and what percentage can only be updated in the field 
via service technicians.
e. Use of Different Test Methods for Different Purposes
    It is DOE's understanding that some organizations seek to use load-
based testing as a tool to evaluate the performance of air conditioning 
and heat pump systems even as the current regulatory test procedures 
(e.g., appendix M1) are required for certification of compliance with 
minimum efficient standards. As noted in section II.B.4.a, CSA EXP07 
proposes to use test conditions that differ from the Federal test 
procedures, which will yield different test results, whether or not 
there might be inefficiencies that CSA EXP07 would capture that 
conventional test methods do not.
    Issue 7: DOE is interested in any existing examples of load-based 
testing for regulatory purposes or for use in voluntary incentive-based 
programs. Are there draft examples of how such regulation would be 
applied, with focus on differences as compared with more conventional 
test methods (e.g., appendix M1)?
f. Test Conditions for Load-Based Methods
    Load-based test procedures for CAC/HPs may sometimes have test 
conditions that do not align with the DOE test procedure outlined in 
appendix M1. For example, EXP07 includes more test conditions spanning 
a wider range of outdoor temperatures than appendix M1. Figure II-1 and 
Table II-2 show a comparison of the test room conditions used in EXP07 
versus the test conditions used in the DOE test procedure appendix M1.
[GRAPHIC] [TIFF OMITTED] TP24JA23.253


 Table II-2--Comparison of Outdoor Dry-Bulb Temperature Test Conditions
     Between EXP07 and DOE Test Procedure (Appendix M1) for CAC/HPs
------------------------------------------------------------------------
        Cooling test conditions \1\          Heating test conditions \2\
------------------------------------------------------------------------
Appendix M1:
  A2--95 [deg]F...........................  H01--62 [deg]F.
  Ev--87 [deg]F...........................  H11/H12*/H1N/H1C1*--47
                                             [deg]F.
  B1 & B2--82 [deg]F......................  H2V/H22*--35 [deg]F.
  F1/G1*/I1*--67 [deg]F...................  H32--17 [deg]F.
                                            H42*--5 [deg]F.
EXP07:
  CA*--113 [deg]F.........................  HA*--(-10 [deg]F).
  CB--104 [deg]F..........................  HB*--5 [deg]F.
  CC--95 [deg]F...........................  HC--17 [deg]F.
  CD--86 [deg]F...........................  HD--34 [deg]F.
  CE--77 [deg]F...........................  HE--47 [deg]F.
                                            HF--54 [deg]F.
------------------------------------------------------------------------
* Optional Test Condition.
\1\ Cooling-mode indoor room test condition temperatures are 80 [deg]F
  dry-bulb, 67 [deg]F wet-bulb for appendix M1. EXP07 utilizes different
  indoor room conditions based on humid climate (74 [deg]F dry-bulb, 63
  [deg]F wet-bulb) and dry climate (79 [deg]F dry-bulb, 56 [deg]F wet-
  bulb).
\2\ Heating-mode indoor room test condition temperatures are 70 [deg]F
  dry-bulb, 60 [deg]F wet-bulb for both appendix M1 and for EXP07.

    Issue 8: Given the differences between the EXP07 and appendix M1 
test procedures for CAC/HPs, DOE requests information comparing how 
rankings/ratings of CAC/HPs would differ when tested using the EXP07 
test conditions (both outdoor and indoor) rather than the appendix M1 
test conditions, keeping other aspects of the test the same. Further, 
DOE requests comments on the relative benefits and drawbacks of 
revising the appendix M1 test conditions.
g. Communicating and Non-Communicating Variable-Speed CAC/HP Systems
    Controls used with CAC/HPs may transfer information between system 
components, or they may use more conventional low-voltage on-off 
signals to indicate ``calls'' for space conditioning and/or consumer 
selection of fan settings. In the October 2022 CAC TP Final Rule, DOE 
defined ``communicating control'' in the context of variable-speed 
coil-only CAC/HPs to differentiate the test procedure provisions 
applicable to communicating systems from those applicable to non-
communicating systems. 87 FR 16830, 16837. Section 1.2 of appendix M1 
defines ``Communicating Variable-Speed Coil-Only Central Air 
Conditioner or Heat Pump'' as follows:
    Variable-Speed Communicating Coil-Only Central Air Conditioner or 
Heat Pump means a variable-speed compressor system having a coil-only 
indoor unit that is installed with a control system that (a) 
communicates the difference in space temperature and space setpoint 
temperature (not a setpoint value inferred from on/off thermostat 
signals) to the control that sets compressor speed; (b) provides a 
signal to the indoor fan to set fan speed appropriate for compressor 
staging and air volume rate; and (c) has installation instructions 
indicating that the required control system meeting both (a) and (b) 
must be installed.
    Although the DOE test procedure explicitly addresses communicating 
vs. non-communicating operation only for coil-only variable-speed 
systems, DOE is aware that there may also be non-communicating blower 
coil variable-speed system installations. DOE understands that the 
fundamental differences in the control architecture will lead to 
performance differences. For example, a non-communicating

[[Page 4101]]

variable-speed system will not be able to apply classic proportional/
integral/differential control algorithms to minimizing space 
temperature offset from setpoint, since the space thermostat would 
generally only be able to indicate to the system whether there is a 
need for conditioning and/or whether a call for a first or a second 
level of conditioning should be engaged. Thus, it is unclear how such a 
system would determine the appropriate level of variable-speed 
compressor operation to engage to meet the conditioning load. It is 
expected that there would be more variation of the capacity level of 
such a system, operation which is known to affect efficiency. For 
communicating variable-speed systems, it is clearer how the control 
system would be able to set compressor operating level consistent and 
better optimized for the conditioning need.
    DOE is unaware if any of the load-based test methods have different 
test procedure provisions for communicating and non-communicating CAC/
HPs, regardless of whether they are coil-only or blower coil systems.
    Issue 9: DOE is interested in test data, if any, that shows how the 
performance of communicating and non-communicating variable-speed CAC/
HPs compares when tested using load-based methods. For systems equipped 
with non-communicating controls, DOE would like to know how load-based 
methods address modulation of compressor speed for changing load and 
outdoor conditions if the difference in indoor space temperature and 
space setpoint temperature is not communicated to the control setting 
compressor speed.
h. Load-Based Testing for Single-Stage and Two-Stage Variable-Speed 
CAC/HP Systems
    Much of the discussion about load-based testing has focused on 
potential performance differences of variable-speed CAC/HP systems in 
traditional fixed-setting testing as compared with load-based testing 
methodologies that may better reflect field performance. However, the 
potential application of load-based testing has also been discussed for 
single-stage and two-stage CAC/HP systems. Appendix M1 does include 
cyclic test procedures to capture the losses associated with compressor 
cycling when capacity is greater than the load.\36\ But there may be 
questions about whether this test is not sufficiently accurate or 
whether there are other factors that might cause traditional test 
methods to provide inaccurate indications of field performance.
---------------------------------------------------------------------------

    \36\ Sections 3.5 and 3.8 of appendix M1 contain provisions for 
conducting optional cooling and heating cyclic tests. These cyclic 
tests are used to determine the Coefficient of Degradation 
(CD), which is incorporated into the calculation of SEER2 
and HSPF2, to account for any compressor cycling losses. If the 
optional cyclic tests are not conducted, appendix M1 requires use of 
the default CD value of 0.25. However, for the majority 
of single- and two-stage systems, a lower CD can be 
achieved when completing the optional cyclic tests, which results in 
higher SEER2 and HSPF2.
---------------------------------------------------------------------------

    Issue 10: DOE requests comment on the application of load-based 
testing to single-stage and two-stage CAC/HP systems, specifically on 
the differences between conventional test approaches and load-based 
testing as indicators of system field performance. Additionally, DOE 
requests any available information indicating whether the cyclic test 
methods in appendix M1 may be unrepresentative in capturing cyclic 
losses. Finally, DOE requests comment on whether there are other 
aspects of single- and two-stage system operation that are not 
adequately captured by the test methods of appendix M1.
i. Other Factors That Affect System Energy Use
    The overall energy use of CAC/HP systems not only depends on how 
long they operate in the cooling and/or heating seasons, but also on 
aspects such as adaptive defrost systems, operation of electric 
resistance heating elements, operation of the fan when the compressor 
is not running (i.e., during the shoulder season) and operation of 
auxiliary components during off-mode, such as crank case heaters. In 
order to accurately capture the performance of CAC/HP systems while 
testing in a laboratory for regulatory purposes, it is imperative that 
a load-based test procedure should also account for the aforementioned 
aspects.
    Issue 11: DOE requests comment on the potential application of 
load-based test procedure to other aspects of CAC/HP operation 
affecting energy use, including but not limited to defrost systems, 
operation of electric resistance heating elements (if equipped), 
operation of fans when the compressor is not running during the 
shoulder season, and operation of crank case heaters during off-mode.

C. Stakeholder Requests for Test Improvements in Appendix M1

    As noted in section I.B, several stakeholder comments in the 
October 2022 CAC TP final rule encouraged DOE to review ways to improve 
the representativeness of the test procedures for CAC/HP in a future 
rulemaking under DOE's 7-year lookback authority. Stakeholder requests 
that relate to test procedure improvements in appendix M1 are discussed 
in the subsequent sections.
1. Shoulder-Season Fan Power Consumption
    In their written comments submitted during the rulemaking that 
culminated in the October 2022 CAC TP final rule, the CA IOUs contended 
that the current test procedure does not fully reflect energy use 
during the shoulder-season hours when outdoor temperatures are 
typically between 55 [deg]F and 64 [deg]F and the equipment is likely 
in fan-only mode (i.e., the compressor is not running). (CA IOUs, No. 
20 at pp. 2-3) CA IOUs further commented that the HSPF2 metric used for 
evaluating heating operation in appendix M1 no longer includes 
fractional bin hours when outdoor temperatures are between 55 [deg]F 
and 64 [deg]F and that these hours represent approximately 24 percent 
of the fractional bin hours relative to appendix M. Id.
    In the October 2022 CAC TP Final Rule, DOE acknowledged the CA 
IOUs' comment that shoulder-season fan energy consumption (i.e., fan 
operation when there is no heating or cooling load) is not captured by 
either the SEER/SEER2 or HSPF/HSPF2 metrics, which are constructed to 
represent cooling season efficiency and heating season efficiency, 
respectively.
    DOE notes that a majority of CAC/HPs are installed in the field 
with a furnace as the air mover (i.e., as coil-only CAC/HPs). Appendix 
M1 specifies a default fan power for the testing of coil-only CAC/HPs 
to represent the furnace fan use. The furnace fan test procedure (see 
10 CFR part 430, subpart B, appendix AA (``appendix AA'')) addresses 
fan energy use for cooling, heating, and constant circulation modes, 
including constant circulation operation during the shoulder season. 
Appendix AA uses an estimate of 400 hours as the national-average 
annual hours of constant circulation fan operation (see 10 CFR part 
430, subpart B, appendix AA, Table IV.2). The survey data used to 
develop this estimate value is described in a furnace fan NOPR, 
published on May 15, 2012. 77 FR 28674, 28682-28683. While the shoulder 
season may include many hours when heating or cooling is not required, 
the survey data and DOE's analysis suggest that only 9 percent of 
systems operate in fan-only mode when no heating or cooling is being 
provided, indicating that the shoulder-season fan energy consumption 
may not be as significant as the CA IOUs present. (See,

[[Page 4102]]

e.g., Table III.1 in the furnace fan NOPR, 77 FR 28674, 28682). While 
these hours are specifically associated with coil-only CAC/HP systems, 
they may also be representative of blower coil systems, which are 
excluded from the scope of appendix AA and covered in appendix M1. Key 
factors that would make this energy use significant and worth 
addressing include the constant circulation fan wattage of blower coil 
systems, the percentage of such systems that use constant fan when not 
in cooling and heating mode, and the average hours per year operating 
in this mode for such a system.
    Additionally, there is a potential of increased use of constant 
circulation in systems that employ new refrigerants to mitigate 
flammability risks. Currently, nearly all CAC/HP products are designed 
with R-410A as the refrigerant. The EPA Significant New Alternatives 
Policy (``SNAP'') Program evaluates and regulates substitutes for 
ozone-depleting chemicals (such as CAC/HP refrigerants) that are being 
phased out under the stratospheric ozone protection provisions of the 
Clean Air Act. (42 U.S.C. 7401 et seq.) \37\ Of interest in this RFI, 
the EPA SNAP Program's list of viable substitutes \38\ includes a group 
of refrigerants classified as A2L refrigerants. A2L refrigerants 
receive high attention for their low global warming potential in 
addition to their minimal to zero ozone depletion potential. However, 
A2L refrigerants also face stricter safety requirements than most due 
to the flammability concerns associated with their ``2L'' ASHRAE safety 
classification.\39\
---------------------------------------------------------------------------

    \37\ Additional information regarding EPA's SNAP Program is 
available online at: www.epa.gov/ozone/snap/.
    \38\ List of EPA SNAP program-approved refrigerant substitutes 
is available at: www.epa.gov/snap/substitutes-residential-and-light-commercial-air-conditioning-and-heat-pumps.
    \39\ ASHRAE assigns safety classification to refrigerants based 
on toxicity and flammability data. The capital letter designates a 
toxicity class based on allowable exposure and the numeral denotes 
flammability. For toxicity, Class A denotes refrigerants of lower 
toxicity, and Class B denotes refrigerants of higher toxicity. For 
flammability, class 1 denotes refrigerants that do not propagate a 
flame when tested as per the standard; class 2 and 2L denotes 
refrigerants of lower flammability; and class 3, for highly 
flammable refrigerants such as the hydrocarbons.
---------------------------------------------------------------------------

    Considering A2L flammability concerns and the large push towards 
their increased use in design, UL recently published updated safety 
standards \40\ for electrical heat pumps, air-conditioners, and 
dehumidifiers that include the CAC/HP products at issue in this 
document. One safety risk these standards address is refrigerant 
leakage, which can be especially hazardous with A2Ls involved. In 
satisfaction of new UL safety requirements, manufacturers may need to 
adjust CAC/HP product design to include refrigerant leak detection 
systems, which use sensors and control logic to detect a loss of 
pressure, activate the evaporator fan, and use circulated air to 
quickly disperse and dilute refrigerant in the event of a leakage. DOE 
acknowledges that a subsequent need may exist for the constant 
circulation of refrigerant or circulation based on leak detection to 
accommodate these refrigerant leak detection and mitigation strategies 
in CAC/HP product design.
---------------------------------------------------------------------------

    \40\ On November 1, 2019, UL published an updated 3rd edition of 
UL 60335-2-40 that includes safety requirements regarding the use 
A2L refrigerants in CAC/HP product design.
---------------------------------------------------------------------------

    Issue 12: DOE requests information on the typical fan power for 
constant circulation mode for blower coil systems (or as a fraction of 
cooling or heating fan power); whether constant circulation mode is a 
default or user configurable setting for these systems and whether 
manufacturers plan to modify this as part of their mitigation strategy 
for refrigerant leakage; and information on the percentage of people 
that use this mode and the associated hours per year on average the 
system would be in this mode.
    Issue 13: DOE requests comment on whether measurement of SEER2 and/
or HSPF2 should take into consideration that a certain fraction of 
systems will use constant circulation mode rather than turn off the fan 
during the compressor off mode.
    Issue 14: DOE requests comment on whether UL safety requirements 
for A2L refrigerants will require some level of circulation on a 
continuous basis, or whether circulation to disperse refrigerant will 
only be required when sensors detect a leak. DOE is interested to know 
of any other techniques that manufacturers will use for dispersing the 
A2L refrigerant in the event of a refrigerant leak.
2. Power Consumption of Auxiliary Components
    In comments submitted during the rulemaking that culminated in the 
October 2022 CAC TP final rule, the CA IOUs also commented that neither 
the HSPF2 nor the SEER2 metrics reflect the energy use of auxiliary 
components, including fans and crankcase heaters, when the compressor 
is off, and the SEER2 and HSPF2 metrics therefore do not fully 
represent any difference in the efficiency of auxiliary equipment 
between systems. (CA IOUs, No. 20 at pp. 2-3) They recommended that DOE 
consider methods to address these energy uses in a subsequent review of 
test procedure. Id.
    DOE notes that there are already test procedures and energy 
conservation standards governing the allowable off-mode power 
consumption for CAC/HPs, which encapsulates the off-mode and standby 
power consumed by auxiliary components such as crankcase heaters as 
suggested by the CA IOUs. These test procedures are enumerated in 
section 4.3 of appendix M and appendix M1, and standards are enumerated 
at 10 CFR 430.32(c)(4). DOE acknowledges the CA IOUs' comment that the 
energy use of crankcase heaters is not directly included \41\ in the 
SEER2 and HSPF2 metrics but notes that this energy use is accounted for 
in off-mode power. In a NOPR regarding CAC/HP test procedures published 
on June 2, 2010 (``June 2010 CAC TP NOPR''), DOE noted that integrating 
off-mode energy use, and hence crankcase heater energy use, into SEER 
and HSPF metrics, would not be technically feasible because they both 
are seasonal descriptors. 75 FR 31224, 31239. Using these two seasonal 
metrics to account for out-of-season off-mode energy consumption (i.e., 
the energy consumed during the shoulder season and during the heating 
season) would be inconsistent with the definitions of SEER and HSPF. 
Id. Hence, in order to maintain the technical integrity of SEER and 
HSPF and to account for off-mode energy consumption, DOE developed a 
separate algorithm to calculate the off-mode (off-season) energy 
consumption.\42\ Id. Nevertheless, to help DOE further assess whether 
its test procedure adequately addresses crankcase heater energy use, 
DOE is requesting information and data from stakeholders.
---------------------------------------------------------------------------

    \41\ Some energy use associated with crankcase heaters is 
inherently measured in the cyclic cooling (for non-temperature 
dependent crankcase heaters) and cyclic heating tests in appendix 
M1.
    \42\ The calculation of off-mode power consumption is explained 
in section 3.13 of appendix M, and section 4.3 of appendix M1.
---------------------------------------------------------------------------

    Issue 15: DOE requests information as to what percentage of units 
on the market (split separately between air-conditioners and heat 
pumps) are shipped from the factory with crank-case heaters; what 
percentage have crank-case heaters installed in the field (e.g., by 
contractors); and the percentage breakdown of controls used with units 
(both factory- and field-installed)--by those that are energized at 
full power during the compressor off cycle, those that also have an 
ambient thermostat to prevent use when temperature is high, and those 
that are self-regulating.

[[Page 4103]]

    Issue 16: DOE requests information and available field data, on any 
other auxiliary components that come equipped with CAC/HPs that use 
energy or affect system energy use.
    In a supplemental notice of proposed rulemaking (``SNOPR'') 
regarding CAC/HP test procedures published on August 24, 2016, DOE 
revised the off-mode test procedure by imposing time delays to allow 
self-regulating crankcase heaters to approach equilibrium. 81 FR 58163, 
58173-58174 (``August 2016 CAC TP SNOPR''). Specifically, DOE proposed 
a 4-hour time delay for units without compressor sound blankets and an 
8-hour time delay for units with compressor sound blankets. Id. DOE 
proposed these time delays based on testing of a 5-ton residential 
condensing unit. Id. In response to stakeholder comments regarding the 
aforementioned time delays, DOE decided in the January 2017 CAC TP 
final rule to adopt the proposed time delays for measurements of off-
mode power for units with self-regulating crankcase heaters or heater 
systems in which the crankcase heater control is affected by the 
heater's heat, in appendix M1, but not appendix M. 82 FR 1426, 1438. 
Nevertheless, DOE acknowledges that with more test procedure 
development time, an approach could potentially be developed that would 
allow for accurate projections of self-regulating crankcase heater 
energy use to be determined in reduced time and requests comment on 
this possibility.
    Issue 17: DOE requests test data that would indicate if and how the 
4-hour time delay (for compressors without sound blankets) and 8-hour 
time delay (for compressors with sound blankets) may be reduced, for 
units with self-regulating crankcase heaters, without compromising the 
accuracy of the off-mode power consumption measurement.
3. Low-Temperature Heating Performance
    In the previous CAC/HP test procedure rulemaking, NYSERDA 
encouraged DOE to start immediately on foundational work needed to 
improve the standard and test procedure to better account for equipment 
performance in cold climates. (NYSERDA, No. 17 at pp. 2-3) NYSERDA 
requested that DOE make the H4, H42, or H43 
heating tests in appendix M1 mandatory in order to produce more 
representative ratings that account for system performance at 5 [deg]F. 
Id. NYSERDA also requested that DOE explore how to test and report 
relative capacity maintenance at temperatures lower than the heating 
mode test temperatures that are used to determine nominal capacity and 
suggested that DOE prescribe performance requirements of low-
temperature capacity maintenance for products advertised as cold-
climate heat pumps. Id. Further, NYSERDA requested that DOE evaluate 
how a variety of sizing approaches could be incorporated into the test 
procedure. Id. NYSERDA highlighted that DOE has previously established 
that the sizing assumptions inherent in the DOE test procedure are 
based on cooling capacity and provide an example of a sizing and 
selection guide that emphasizes heating function. Id.
    While the H4 heating tests provide meaningful information and more 
representative ratings for products designed specifically for low 
temperature operation, appendix M1 includes them as optional tests, as 
they may not be appropriate for all CHPs. Currently, appendix M1 allows 
the performance at 5 [deg]F to be extrapolated based on tests conducted 
at 17 [deg]F and 47 [deg]F (i.e. using the H32 and 
H12 tests, respectively) for CHPs that are not tested at the 
H4 heating condition. While the ENERGY STAR certification is a 
voluntary program, DOE notes that the latest ENERGY STAR specification 
for CAC/HPs \43\ already has cold-climate performance and capacity 
maintenance requirements as suggested by NYSERDA.
---------------------------------------------------------------------------

    \43\ Version 6.1 of the ENERGY STAR specification for CAC/HPs, 
revised in January 2022, can be found here: www.energystar.gov/products/spec/central_air_conditioner_and_air_source_heat_pump_specification_version_6_0_pd.
---------------------------------------------------------------------------

    In the August 2016 CAC TP SNOPR, DOE noted that most heat pump 
units in the field are sized based on cooling capacity as opposed to 
heat pump capacity, consistent with ACCA Manual S provisions. 81 FR 
58163, 58188. Subsequently, in the January 2017 CAC TP final rule, DOE 
revised appendix M1 such that the determination of the heating load 
line was based on cooling capacity rather than heating capacity. 82 FR 
1426,1453-1454. Part of DOE's motivation for this change was that the 
previous approach of heating load line determination based on the 
nominal heating capacity (H1N capacity) provided little incentive to 
design for good heat pump performance, since low H1N capacity resulted 
in a low load line and generally better HSPF. Sizing based on cooling 
capacity is consistent with trends for sales distributions of heat 
pumps, which have had greater adoption in milder climates than cold 
climates.\44\ However, DOE is aware that NRCan has proposed 
alternatives for sizing CAC/HPs, in its ``Air Source Heat Pump Sizing 
and Selection Guide'',\45\ which provides four different approaches 
with varying emphasis on heating vs. cooling, ranging from sizing based 
on cooling to sizing such that the heat pump can meet the design 
heating load without need for resistance auxiliary heat. DOE 
acknowledges that in cold climates, sizing a heat pump for heating may 
be more appropriate than sizing for cooling. Further, DOE acknowledges 
that accurate information regarding heat pump cold-weather performance 
is relevant for selection of the best heat pumps for cold climates. 
Nevertheless, it is not clear how a test procedure using a heating load 
line based on heating performance would incentivize good heating 
performance, particularly if it is based on heating performance at 47 
[deg]F, which is not a heating design temperature. As mentioned 
earlier, this is the same issue that led DOE to move to the cooling-
capacity-based load line in appendix M1. Further, given the greater 
market share in milder climates, it is unclear that requiring a 5 
[deg]F test is appropriate for all heat pump models.
---------------------------------------------------------------------------

    \44\ RECS 2020 data shows that electric heat pumps represent 29% 
of primary space heating equipment in homes in the South region, 
which is a higher number as compared to the 14% for US overall. See: 
www.eia.gov/consumption/residential/data/2020/hc/pdf/HC%206.8.pdf.
    \45\ The ``Air Source Heat Pump Sizing and Selection Guide'' was 
written by NRCan in response to stakeholder requests for consistent 
guidance for sizing ASHPs according to the design heating or cooling 
load and intended use as well as identifying the appropriate system 
according to the installation and application. The four methods of 
sizing in the Guide are Options 4A (Emphasis on Cooling), 4B 
(Balanced Heating and Cooling), 4C (Emphasis on Heating) and 4D 
(Sized on Design Heating Load). The ``Air Source Heat Pump Sizing 
and Selection Guide'' is available here: publications.gc.ca/collections/collection_2021/rncan-nrcan/M154-138-2020-eng.pdf.
---------------------------------------------------------------------------

    Issue 18: DOE requests comment on whether it would be appropriate 
to make the H4 heating tests mandatory for all CHPs. If not for all 
CHPs, DOE requests comment on whether it would be appropriate to make 
the tests mandatory for any subset of CHPs, e.g., cold climate heat 
pumps, and if so, what characteristics would represent a clear 
delineation to distinguish such models from others. DOE also seeks 
information on the prevalence of test chambers capable of testing CHPs 
at outdoor ambient temperature of 5 [deg]F.
    Issue 19: Further, DOE requests comment on whether the test 
procedure for such cold climate heat pumps should use a heating load 
line based on heating performance, and how such an approach could be 
implemented such that it does not weaken the incentive for good cold-
temperature heating performance.

[[Page 4104]]

D. Additional Improvements in Appendix M1

    In addition to the potential improvements in appendix M1 suggested 
by stakeholders in previous rulemakings, DOE is also considering 
potential improvements to address issues and questions that have come 
to light as part of DOE testing of CAC/HPs, industry technical 
committee discussions, and other discussions with stakeholders.
1. Impact of Defrost on Performance
    Defrost is required for heat pumps when operating in moderate to 
low outdoor temperatures when the outdoor coil surface temperature is 
sufficiently low to freeze moisture removed from the air or 
precipitation that can collect on the coil. For defrost, the system 
switches back to cooling mode operation in which heat is transferred 
from the indoor coil to the outdoor coil to provide the heat to warm 
the coil and melt the frost. During defrost, different control 
strategies are applied to maintain comfort level inside the house. For 
example, the indoor fan may or may not be operated during defrost, and 
(if the indoor fan is operated) the auxiliary resistance heater may or 
may not be energized to warm the indoor air while the system is 
temporarily in defrost mode. Defrost initiation can be based on time 
(clock time or time of compressor operation), or the need for defrost 
can be determined based on temperature and pressure or other 
measurements that provide an indication of the need for defrost.\46\ 
Appendix M1 defines a demand-defrost control system as a system that 
defrosts the heat pump outdoor coil only when measuring a predetermined 
degradation of performance. When frequent defrost occurrences are not 
needed, e.g. when there is insufficient moisture in the outdoor air to 
build up a significant frost layer on the outdoor coil, demand defrost 
can save energy by delaying defrost initiation. Defrost cycles are 
terminated when there is indication that defrost has been long enough 
for frost to be eliminated from the coil, e.g., when a coil temperature 
sensor indicates the coil is well above 32 [deg]F.
---------------------------------------------------------------------------

    \46\ Some examples of parameters monitored for demand-defrost 
control systems are coil to air differential temperature, coil 
differential air pressure, outdoor fan power or current, optical 
sensors. Note that systems that vary defrost intervals according to 
outdoor dry-bulb temperature are not demand-defrost systems.
---------------------------------------------------------------------------

    For CAC/HPs equipped with demand defrost, appendix M1 includes a 
term called the demand defrost credit (``Fdef'') in the 
HSPF2 calculation to provide nominal credit for heat pumps with a 
demand-defrost control system, reflecting the relative improvement in 
heating mode efficiency due to use of demand defrost rather than 
defrosts with fixed periodicity. The demand-defrost credit, first 
introduced in a March 14, 1988, rulemaking (53 FR 8304, 8319), is 
calculated by the following equation in section 3.9.2 of appendix
[GRAPHIC] [TIFF OMITTED] TP24JA23.254

where [Delta][tau]def = time between defrost terminations (in hours) or 
1.5, whichever is greater. [Delta][tau]def is assigned a value of 6 if 
this limit is reached during a frost accumulation test and the heat 
pump has not completed a defrost cycle, and [Delta][tau]max= maximum 
time between defrosts as allowed by the controls (in hours) or 12, 
whichever is less, as provided in the certification report.
    The credit equation has remained unchanged in its current form in 
the test procedure since at least January 22, 2001, when DOE published 
a NOPR. 66 FR 6767. Based on the test results of several CAC/HPs in 
various programs, DOE has noticed a range of defrost operation 
sequences and a range of approaches to defrost initiation for demand 
defrost. Based on these observations, DOE acknowledges that the demand 
defrost credit may no longer accurately reflect the benefits of demand 
defrost.
    Issue 20: DOE seeks information on the operation of demand-defrost 
control systems, specifically information that would indicate whether 
the demand-defrost credit outlined in the calculation in section 3.9.2 
of appendix M1 is representative of the improvement in seasonal heating 
efficiency in field operation. Further, DOE requests comment whether 
any specific change in the credit equation could improve its accuracy.
    Appendix M1 requires that CHPs undergo a test at 35 [deg]F dry-bulb 
temperature and 33 [deg]F wet-bulb temperature, a condition for which 
frost accumulation is rapid, generally affecting performance before a 
30-minute steady-state test can be completed. For this condition, the 
test procedure prescribes use of a transient test, including a frost 
accumulation period followed by defrost. Capacity and power input for 
the test are averaged for a full cycle of heating followed by defrost. 
At this condition, appendix M1 estimates the average capacity is 10 
percent lower (or more) than it would be if there were no frost 
accumulation, while average power may be just slightly lower, thus 
reducing efficiency. At temperatures between 17 [deg]F and 45 [deg]F, 
the performance calculations prescribed in the test procedure call for 
representing capacity as a linear function of temperature based on the 
tests conducted at 17 [deg]F and 35 [deg]F--likewise for power input. 
Hence, the frost/defrost impact is built into the HSPF2 calculation for 
temperatures in this range. The DOE test procedure requires use of the 
35 [deg]F test for single-stage and two-stage CHPs for all capacity 
levels. However, for variable-speed CHPs, the test procedure requires 
the defrost test be conducted only at intermediate compressor speed, 
and performance is estimated using default degradation factors at full 
capacity (see section 3.6.4.1.c of appendix M1).
    In testing, DOE has observed variations among CHP models in regard 
to defrost control (e.g., time durations of the defrost can vary 
significantly for different models, and the indoor unit fan shuts off 
during defrost for some units but not all). In addition, as part of the 
DOE CCHP Tech Challenge, DOE has tested systems with electric 
resistance heaters and noted that resistance heater operation during 
defrost can vary significantly for different models. This varying 
behavior clearly affects energy use, and while some aspects of which 
may be captured by the current appendix M1 test procedure, others may 
not be.
    Issue 21: DOE requests information regarding defrost impact on 
heating capacity and power input over a range of temperatures to inform 
evaluation of whether the approach used in the DOE test procedure to 
account for this impact is accurate or whether it could be improved by 
revision.

[[Page 4105]]

2. Inlet Duct Design for Accurate Measurement With Minimal Length
    In a final rule regarding CAC/HP test procedures published on June 
8, 2016 (``June 2016 CAC TP final rule''), DOE made clarifications on 
the indoor unit air inlet geometry and made a revision to ensure that 
the inlet plenum is not installed upstream of the airflow prevention 
device, and that the minimum lengths of inlet plenum, locations of 
static-pressure taps, and minimum cross-sectional dimensions are 
consistent with American National Standards Institute (``ANSI'')/ASHRAE 
Standard 37-2009 (``ANSI/ASHRAE 37-2009''), Methods of Testing for 
Rating Electrically Driven Unitary Air-Conditioning and Heat Pump 
Equipment. 81 FR 36991, 37037. DOE also clarified that when an inlet 
plenum is not used, then the length of straight duct upstream of the 
unit's inlet within the airflow prevention device must still adhere to 
the inlet plenum length requirements as illustrated in ANSI/ASHRAE 37-
2009, figures 7b, 7c, and 8. Id.
    In response, AHRI and Nortek commented that DOE's clarification of 
inlet plenum may result in the overall height of unit setup exceeding 
the current height limit of many existing psychrometric rooms. 82 FR 
1426, 1463. They proposed that DOE should consider allowing the 
approach included in ASHRAE's RP 1581, requesting DOE to approve the 
use of the 6'' skirt coupled with the 90[deg] square vane elbow, along 
with the appropriate leaving duct. Id. At the time of the January 2017 
CAC TP Final Rule, the ASHRAE Standards Policy Committee had not added 
the details of RP 1581 into ASHRAE Standard 37, and hence DOE did not 
modify its requirement laid out in the January 2016 CAC TP Final Rule. 
However, DOE is aware that these details may be part of the upcoming 
edition of ASHRAE Standard 37.
    Issue 22: DOE seeks test data that shows testing done using reduced 
overall height of the unit setup (similar to that proposed in ASHRAE RP 
1581) and compared against the baseline duct designs in ASHRAE 37-2009 
Figures 7(b) and 7(c) for blower coil indoor units, and Figure 8 for 
coil-only indoor units. DOE requests information that could help inform 
the existing CAC/HP test procedures to allow testing in smaller 
environmental chambers, or to incorporate adjustments to the test setup 
that might reduce test burden.
3. Heat Comfort Controllers
    A heat comfort controller enables a heat pump to regulate the 
operation of the electric resistance elements such that the air 
temperature leaving the indoor section does not fall below a specified 
temperature (see appendix M1). Appendix M1 notes that heat pumps that 
actively regulate the rate of electric resistance heating when the 
controls indicate heat pump capacity at the given outdoor temperature 
is insufficient to meet the load (e.g., through higher-stage calls from 
the thermostat), but do not operate to maintain a minimum delivery 
temperature, are not considered as having a heat comfort controller.
    Section 3.6.5 of appendix M1 includes test instructions for testing 
heat pumps having a heat comfort controller. However, DOE understands 
that the heat comfort controller option may no longer be prevalent in 
contemporary CHP systems.
    Issue 23: DOE requests information on the prevalence of CHP systems 
that include heat comfort controllers. DOE requests feedback on whether 
the heat comfort controller test approach in appendix M1 is utilized by 
manufacturers, and if yes, whether it needs to be updated.
4. Cut-Out and Cut-In Temperature Certification
    The calculation of HSPF2 in appendix M1 requires values for cut-out 
\47\ and cut-in \48\ temperatures (see, e.g., equation 4.2.1-3 in 
section 4.2 of appendix M1). For CAC/HPs that do not include the cut-
out and cut-in temperatures in their installation manuals, the 
manufacturer (or DOE, in case of compliance testing) must provide the 
test lab with this information. DOE's lab testing suggests that 
manufacturers often use cut-out and cut-in temperatures in their HSPF2 
calculations that are much lower than can be reasonably expected in the 
field--in some instances as low as -40 [deg]F. However, a review of 
product literature for scroll compressors with model numbers Copeland 
ZP*3KE and ZP*5KE R410A (typically used in CAC/HPs) shows that the 
lowest refrigerant evaporating temperature of these systems is no lower 
than -10 [deg]F.\49\
---------------------------------------------------------------------------

    \47\ Cut-out temperature refers to the outdoor temperature at 
which the unit compressor stops (cuts out) operation.
    \48\ Cut-out temperature refers to the outdoor temperature at 
which the unit compressor stops (cuts out) operation.
    \49\ Figure 7 in the operating bulletin of the Copeland ZP*3KE 
and ZP*5KE R410A scroll compressors shows their evaporating 
envelope, clearly indicating that they should not be used below 
saturated suction temperatures of -10 [deg]F, implying that this 
should be set as the cut-out temperature. The bulletin is available 
here climate.emerson.com/documents/ae-1331-zp16-to-zp44k3e-zp14-to-zp61k5e-r-410a-1-5-to-5-ton-copeland-scroll-compressors-en-us-1571048.pdf.
---------------------------------------------------------------------------

    DOE has also found in testing that the ambient temperatures at 
which the control cuts out and cuts in may be significantly different 
than the control's specified temperatures. This can be due to control 
component manufacturing variation. However, it can also be due to 
sensors being located where temperature deviates from that of the 
ambient air--this can occur downstream of the outdoor coil, which 
absorbs heat from the ambient air during heat pump operation.
    Issue 24: DOE requests information on the range of cut-out 
temperatures for compressor operation of CAC/HPs.
5. Extending the Definition of Low-Static Blower-Coil Systems to 
Single-Split Systems
    Section 3.1.4.1.1 of appendix M1 defines the minimum external 
static pressure (``ESP'') for ducted blower coil systems in Table 4. 
For conventional blower coil systems (i.e., all CAC/HPs that are not 
classified as ceiling-mount, wall-mount, mobile home, low-static, mid-
static, small-duct high-velocity (``SDHV''), or space-constrained), the 
minimum ESP is specified as 0.5 inches of water column (``w.c.''). The 
definition for low-static blower-coil systems includes only multi-split 
and multi-head mini-split systems--it does not include single-split 
systems. In response to the March 2022 CAC TP NOPR, DOE received 
multiple comments concerning the 0.5 inches w.c. minimum ESP. AHRI and 
Samsung commented that currently, appendix M1 does not allow testing of 
low-static single-zone \50\ units and requested that the low-static 
blower coil system definition be expanded to include products that 
cannot accommodate the 0.5 inches w.c. necessary for testing. (AHRI, 
No.25 at p. 7, Samsung, No.22 at pp. 2-3)
---------------------------------------------------------------------------

    \50\ The comments used the term ``single-zone'', which is 
addressed by the term ``single-split'' in appendix M1.
---------------------------------------------------------------------------

    In the October 2022 CAC TP final rule, DOE did not revise the 
definition for low-static blower coil systems, nor did it include any 
new test provisions to accommodate these system types. DOE presented 
evidence from the November 2015 SNOPR (80 FR 74020, 69355), 2016 CAC 
Term Sheet (see 2016 CAC Term Sheet: Docket No. EERE-2014-BT-STD-0048, 
No. 76), and the August 2016 CAC TP SNOPR (81 FR 58163) public meeting 
\51\ to indicate that stakeholders had rejected DOE's proposal to 
establish a ``short-ducted''

[[Page 4106]]

product class, and a majority of them expressed support for the new 
minimum ESP requirements that DOE had proposed, including the 0.5 
inches w.c. ESP requirement generally applicable to single-split 
systems. Thus, DOE believed that revising the definition of low-static 
blower coil systems, as suggested by Samsung and AHRI, would conflict 
with the intent of the stakeholders' comments when establishing 
appendix M1, and could potentially create an unfair competitive 
advantage for such systems by allowing more lenient testing conditions 
(and thus comparatively higher ratings) as compared to conventional 
centrally ducted systems tested at minimum ESPs exceeding 0.50 inches 
w.c. Rather than granting test procedure waivers to allow such models 
to test using lower ESP, DOE considers it more appropriate to revisit 
the issue in a test procedure rulemaking. Thus, DOE is soliciting 
feedback on this issue.
---------------------------------------------------------------------------

    \51\ See www.regulations.gov Docket No. EERE-2016-BT-TP-0029, 
No. 20 for the transcript of the August 2016 CAC TP SNOPR public 
meeting.
---------------------------------------------------------------------------

    Issue 25: DOE requests comment from stakeholders on whether the 
low-static blower-coil system definition should be extended to single-
split systems, and if extended, how these low-static blower-coil 
systems will be differentiated from conventional systems.
6. Hybrid Heat Pumps
    Heat pumps generally perform less efficiently at low ambient 
outdoor temperatures than they do at moderate ambient outdoor 
temperatures. DOE is aware of CHPs that combine the operation of a 
conventional electric CHP with a back-up heating source, such as a 
fuel-fired furnace or boiler. These are referred to as ``dual-fuel'' or 
hybrid heat pumps (``HHPs'') and provide an alternative to heat pumps 
specifically designed to perform in cold climates (i.e., cold climate 
heat pumps). HHPs rely on heat pump operation at milder ambient 
temperatures, but switch to the back-up heating source at low ambient 
temperatures, thereby optimizing for energy cost and comfort.
    Currently, the HSPF2 calculation at appendix M1 does not differ for 
a HHP and heat pumps that rely solely on vapor-compression or electric 
resistance auxiliary heating. However, this may not be representative 
of HHP field operation since the back-up heating source takes over for 
much of the coldest conditions when heat pump efficiency would be 
lower. While the focus of test procedures for cold climate heat pumps 
has been on evaluation of performance at colder temperatures (e.g. the 
optional 5 [deg]F test condition) to incentivize improved cold-
temperature performance, incentivizing efficiency improvement for HHPs 
might more appropriately focus on warmer conditions, potentially 
temperatures warmer than 17 [deg]F.
    Issue 26: DOE requests information on the prevalence of HHP systems 
(including shipment numbers and shipment breakdown among single-stage, 
two-stage and variable-capacity) and the climates they are most used 
in. DOE requests information on how the controls for HHPs are generally 
set up to provide dual functionality--specifically, whether the furnace 
is just set at a higher stage, or whether there is a crossover 
temperature below which the CHP isn't used, if so, the range of 
crossover temperatures; and whether these systems have electric 
resistance auxiliary heaters. DOE requests feedback on whether it is 
more appropriate to adjust the HSPF2 to address actual operation of the 
heat pump or just to emphasize performance only in heat pump mode 
(i.e., when the back-up source is not operating).

III. Submission of Comments

    DOE invites all interested parties to submit in writing by the date 
specified under the DATES heading, comments and information on matters 
addressed in this RFI and on other matters relevant to DOE's 
consideration of amended test procedures for CAC/HPs. These comments 
and information will aid in the development of a test procedure NOPR 
for CAC/HPs if DOE determines that amended test procedures may be 
appropriate for these products.
    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 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. Following this instruction, 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 on 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.
    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. 
Faxes will not 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 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

[[Page 4107]]

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. According 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).
    DOE considers public participation to be a very important part of 
the process for developing test procedures and energy conservation 
standards. DOE actively encourages the participation and interaction of 
the public during the comment period in each stage of this process. 
Interactions with and between members of the public provide a balanced 
discussion of the issues and assist DOE in the process. Anyone who 
wishes to be added to the DOE mailing list to receive future notices 
and information about this process should contact Appliance and 
Equipment Standards Program staff at (202) 287-1445 or via email at 
[email protected]">ApplianceStandards[email protected].

Signing Authority

    This document of the Department of Energy was signed on January 12, 
2023, by Francisco Alejandro Moreno, Acting 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 January 12, 2023.
Treena V. Garrett,
Federal Register Liaison Officer, U.S. Department of Energy.
[FR Doc. 2023-00942 Filed 1-23-23; 8:45 am]
BILLING CODE 6450-01-P