[Federal Register Volume 86, Number 115 (Thursday, June 17, 2021)]
[Proposed Rules]
[Pages 32332-32356]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-12081]



[[Page 32331]]

Vol. 86

Thursday,

No. 115

June 17, 2021

Part II





 Department of Energy





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10 CFR Part 431





Energy Conservation Program: Test Procedures for Certain Commercial and 
Industrial Equipment; Early Assessment Review: Walk-In Coolers and 
Freezers; Proposed Rule

  Federal Register / Vol. 86, No. 115 / Thursday, June 17, 2021 / 
Proposed Rules  

[[Page 32332]]


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DEPARTMENT OF ENERGY

10 CFR Part 431

[EERE-2017-BT-TP-0010]
RIN 1904-AD78


Energy Conservation Program: Test Procedures for Certain 
Commercial and Industrial Equipment; Early Assessment Review: Walk-In 
Coolers and Freezers

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

ACTION: Request for information.

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SUMMARY: The U.S. Department of Energy (``DOE'') is undertaking an 
early assessment review to determine whether amendments are warranted 
for the test procedures for walk-in coolers and walk-in freezers 
(``WICFs'' or ``walk-ins''). DOE has identified certain issues 
associated with the currently applicable test procedures on which DOE 
is interested in receiving comment. The issues outlined in this 
document address definitions and equipment classes of walk-in 
components, test procedure waivers received, and other test procedure 
issues related to walk-in doors, panels, and refrigeration systems. DOE 
welcomes written comments from the public on any subject within the 
scope of this document, including topics not raised in this request for 
information (``RFI'').

DATES: Written comments and information are requested and will be 
accepted on or before July 19, 2021.

ADDRESSES: Interested persons are encouraged to submit comments using 
the Federal eRulemaking Portal at https://www.regulations.gov. Follow 
the instructions for submitting comments. Alternatively, interested 
persons may submit comments by email to the following address: 
[email protected]. Include docket number EERE-2017-BT-TP-0010 
and/or RIN number 1904-AD78 in the subject line of the message. Submit 
electronic comments in WordPerfect, Microsoft Word, PDF, or ASCII file 
format, and avoid the use of special characters or any form of 
encryption. No telefacsimiles (faxes) will be accepted. For detailed 
instructions on submitting comments and additional information on the 
rulemaking process, see section III (Submission of Comments) of this 
document.
    Although DOE has routinely accepted public comment submissions 
through a variety of mechanisms, including postal mail and hand 
delivery/courier, the Department has found it necessary to make 
temporary modifications to the comment submission process in light of 
the ongoing Covid-19 pandemic. DOE is currently accepting only 
electronic submissions at this time. If a commenter finds that this 
change poses an undue hardship, please contact Appliance Standards 
Program staff at (202) 586-1445 to discuss the need for alternative 
arrangements. Once the Covid-19 pandemic health emergency is resolved, 
DOE anticipates resuming all of its regular options for public comment 
submission, including postal mail and hand delivery/courier.
    Docket: The docket for this activity, which includes Federal 
Register notices, comments, and other supporting documents/materials, 
is available for review at https://www.regulations.gov. All documents 
in the docket are listed in the https://www.regulations.gov index. 
However, some documents listed in the index, such as those containing 
information that is exempt from public disclosure, may not be publicly 
available.
    The docket web page can be found at: https://www.regulations.gov/#!docketDetail;D=EERE-2017-BT-TP-0010. The docket web page contains 
instructions on how to access all documents, including public comments, 
in the docket. See section III of this document for information on how 
to submit comments through https://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT: 

Dr. Stephanie Johnson, U.S. Department of Energy, Office of Energy 
Efficiency and Renewable Energy, Building Technologies Office, EE-5B, 
1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone: 
(202) 287-1943. Email: [email protected].
Mr. Michael Kido, U.S. Department of Energy, Office of the General 
Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC 20585-0121. 
Telephone: (202) 586-8145. Email: [email protected].

    For further information on how to submit a comment or review other 
public comments and the docket, contact the Appliance and Equipment 
Standards Program staff at (202) 287-1445 or by email: 
[email protected].

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Introduction
    A. Authority
    B. Rulemaking History
II. Request for Information
    A. Scope and Definitions
    1. Walk-In Refrigeration Systems
    2.Walk-In Doors
    B. Industry Test Standards
    1. NFRC 100 and NFRC 102
    2. ASTM C518
    3. AHRI 1250
    C. Test Procedure for Walk-In Doors
    1. Surface Area Used for Determining Compliance With Standards
    2. Thermal Transmittance Area
    3. Electrical Door Components
    4. EER Values To Convert Thermal Load to Energy Consumption
    5. Thermal Transmittance
    a. Calibration of Hot Box for Measuring U-Factor
    b. Tolerances of Surface Heat Transfer Coefficients
    6. Air Infiltration Reduction
    D. Test Procedure for Walk-In Panels
    1. Panel Thickness
    2. Parallelism and Flatness
    3. Specimen Conditioning
    4. Overall Thermal Transmittance
    5. Display Panels
    E. Test Procedure for Walk-In Refrigeration Systems
    1. Single-Package Systems
    a. Calorimeter Method
    2. Wine Cellar Refrigeration Systems
    3. CO2 Systems
    4. Defrost Test Method
    a. Moisture Addition
    b. Hot Gas Defrost
    c. Adaptive Defrost
    5. Off-Cycle Energy Use
    6. Multi-Capacity and Variable-Capacity Condensing Units
    7. Systems for High-Temperature Freezer Applications
    8. Consideration for Refrigerant Glide
III. Submission of Comments
IV. Issues on Which DOE Seeks Comment

I. Introduction

    DOE established an early assessment review process to conduct a 
more focused analysis that would allow DOE to determine, based on 
statutory criteria, whether an amended test procedure is warranted. 10 
CFR 431.4; 10 CFR part 430 subpart C appendix A section 8(a). This RFI 
requests information and data regarding whether an amended test 
procedure would more accurately and fully comply with the requirement 
that the test procedure produce results that measure energy use during 
a representative average use cycle for the equipment, and not be unduly 
burdensome to conduct. To inform interested parties and to facilitate 
this process, DOE has identified several issues associated with the 
currently applicable test procedures on which DOE is interested in 
receiving comment. Based on the information received in response to the 
RFI and DOE's own analysis, DOE will determine whether to proceed with 
a rulemaking for an amended test procedure.
    If DOE makes an initial determination that an amended test 
procedure would

[[Page 32333]]

more accurately or fully comply with statutory requirements, or DOE's 
analysis is inconclusive as to whether amendments are warranted, DOE 
would undertake a rulemaking to issue an amended test procedure. If DOE 
makes an initial determination based upon available evidence that an 
amended test procedure would not meet the applicable statutory 
criteria, DOE would engage in notice and comment rulemaking before 
issuing a final determination that an amended test procedure is not 
warranted.

A. Authority

    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 C \2\ of EPCA, added by Public Law 95-619, Title 
IV, section 441(a) (42 U.S.C. 6311-6317 as codified), established the 
Energy Conservation Program for Certain Industrial Equipment, which 
sets forth a variety of provisions designed to improve energy 
efficiency. This equipment includes walk-in coolers and freezers 
(collectively, ``walk-ins'' or ``WICFs''), the subject of this 
document. (42 U.S.C. 6311(1)(G))
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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).
    \2\ For editorial reasons, upon codification in the U.S. Code, 
Part C was redesignated Part A-1.
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    Under EPCA, DOE's energy conservation program consists essentially 
of four parts: (1) Testing, (2) labeling, (3) Federal energy 
conservation standards (``ECS''), and (4) certification and enforcement 
procedures. Relevant provisions of EPCA include definitions (42 U.S.C. 
6311), test procedures (42 U.S.C. 6314), labeling provisions (42 U.S.C. 
6315), energy conservation standards (42 U.S.C. 6313), and the 
authority to require information and reports from manufacturers (42 
U.S.C. 6316).
    Federal energy efficiency requirements for covered equipment 
established under EPCA generally supersede State laws and regulations 
concerning energy conservation testing, labeling, and standards. (42 
U.S.C. 6316(a) and (b); 42 U.S.C. 6297) DOE may, however, grant waivers 
of Federal preemption in limited instances for particular State laws or 
regulations, in accordance with the procedures and other provisions set 
forth under 42 U.S.C. 6316(b)(2)(D).
    EPCA also requires that, at least once every 7 years, DOE evaluate 
test procedures for each type of covered equipment, including walk-in 
coolers and freezers, to determine whether amended test procedures 
would more accurately or fully comply with the requirements for the 
test procedures to not be unduly burdensome to conduct and be 
reasonably designed to produce test results that reflect energy 
efficiency, energy use, and estimated operating costs during a 
representative average use cycle. (42 U.S.C. 6314(a)(1)) DOE is 
publishing this RFI to collect data and information to inform its 
decision to satisfy the 7-year-lookback review requirement.

B. Rulemaking History

    DOE has established test procedures to measure walk-in energy use, 
establishing separate test procedures for the principal components that 
make up a walk-in (i.e., doors, panels, and refrigeration systems) with 
separate test metrics for each component. 10 CFR 431.304(b). For walk-
in doors and display panels, the efficiency metric is daily energy 
consumption, measured in kilowatt-hours per day (``kWh/day''), which 
accounts for the thermal conduction through the door or display panel 
and the direct and indirect electricity use of any electrical 
components associated with the door. 10 CFR 431.304(b)(1)-(2) and 10 
CFR part 431, subpart R, appendix A, ``Uniform Test Method for the 
Measurement of Energy Consumption of the Components of Envelopes of 
Walk- In Coolers and Walk-In Freezers'' (``Appendix A'').
    For walk-in non-display panels and non-display doors, DOE codified 
in the Code of Federal Regulations (``CFR'') prescriptive standards 
established in EPCA based on R-value, expressed in units of (h-ft\2\-
[deg]F/Btu),\3\ which is calculated as 1/K multiplied by the thickness 
of the panel.\4\ 10 CFR 431.304(b)(3) and 10 CFR part 431 subpart R, 
appendix B, titled ``Uniform Test Method for the Measurement of R-Value 
for Envelope Components of Walk-In Coolers and Walk-In Freezers'' 
(``Appendix B''). (See also, 42 U.S.C. 6314(a)(9)(A)) The K factor is 
calculated based on American Society for Testing and Materials 
(``ASTM'') C518, ``Standard Test Method for Steady-State Thermal 
Transmission Properties by Means of the Heat Flow Meter Apparatus'' 
(``ASTM C518''), which is incorporated by reference. Id.
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    \3\ The R-value is the capacity of an insulated material to 
resist heat-flow. See 42 U.S.C. 6313(f)(1)(C) for the EPCA R-value 
requirements for non-display panels and doors.
    \4\ The K factor represents the thermal conductivity of a 
material, or its ability to conduct heat, in units of Btu-in/(h-
ft\2\-[deg]F).
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    For walk-in refrigeration systems, the efficiency metric is Annual 
Walk-in Energy Factor (``AWEF''), which is determined by conducting the 
test procedure set forth in American National Standards Institute 
(``ANSI'')/Air-Conditioning, Heating, and Refrigeration Institute 
(``AHRI'') Standard 1250P (I-P), ``2009 Standard for Performance Rating 
of Walk-In Coolers and Freezers,'' (``AHRI 1250-2009''), with certain 
adjustments specified in the CFR. 10 CFR 431.304(b)(4) and 10 CFR part 
431 subpart R, appendix C, ``Uniform Test Method for the Measurement of 
Net Capacity and AWEF of Walk-In Cooler and Walk-In Freezer 
Refrigeration Systems'' (``Appendix C''). A manufacturer may also 
determine AWEF using an alternative efficiency determination method 
(``AEDM''). 10 CFR 429.53(a)(2)(iii). An AEDM enables a manufacturer to 
utilize computer-based or mathematical models for purposes of 
determining an equipment's energy use or energy efficiency performance 
in lieu of testing, provided certain prerequisites have been met. 10 
CFR 429.70(f).
    On August 5, 2015, DOE published its intention to establish a 
Working Group under the Appliance Standards and Rulemaking Federal 
Advisory Committee (``ASRAC'') to negotiate energy conservation 
standards to replace the standards established in the final rule 
published on June 3, 2014 (``June 2014 ECS final rule''). 80 FR 46521 
(August 5, 2015). The Working Group assembled its recommendations into 
a Term Sheet \5\ (Docket EERE-2015-BT-STD-0016, No. 56) that was 
presented to, and approved by, ASRAC on December 18, 2015 (``Term 
Sheet'').
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    \5\ Appliance Standards and Rulemaking Federal Advisory 
Committee Refrigeration Systems Walk-in Coolers and Freezers Term 
Sheet, available at https://www.regulations.gov/document?D=EERE-2015-BT-STD-0016-0056.
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    The Term Sheet provided recommendations for energy conservation 
standards to replace standards that had been vacated by the United 
States Court of Appeals for the Fifth Circuit in a controlling order 
issued August 10, 2015. It also included recommendations regarding 
definitions for a number of terms related to the WICF regulations, as 
well as recommendations to amend the test procedure that the Working 
Group viewed as necessary to properly implement the energy conservation 
standards recommendations. Consequently, DOE initiated both an energy 
conservation standards rulemaking and a test procedure rulemaking in 
2016 to implement these

[[Page 32334]]

recommendations. The Term Sheet also included recommendations for 
future amendments to the test procedure intended to make DOE's test 
procedure more fully representative of walk-in energy use.
    On December 28, 2016, DOE published a final rule amending the test 
procedure (``December 2016 TP final rule''), consistent with the Term 
Sheet recommendations and provisions to facilitate implementation of 
energy conservation standards for walk-in components. 81 FR 95758. 
Subsequently, on July 10, 2017, DOE published a final rule amending the 
energy conservation standards for WICF refrigeration systems (``July 
2017 ECS final rule''). 82 FR 31808.
    To address Term Sheet recommendations regarding hot gas defrost, 
DOE published a final rule for hot gas defrost unit coolers on March 
26, 2021 (``March 2021 hot gas defrost TP final rule'') that amended 
the test procedure to rate hot gas defrost unit coolers using modified 
default values for energy use and heat load contributions that would 
make their ratings more consistent with those of electric defrost unit 
coolers. 86 FR 16027.

II. Request for Information

    DOE is publishing this RFI to collect data and information during 
the early assessment review to inform its decision, consistent with its 
obligations under EPCA, as to whether the Department should proceed 
with an amended test procedure rulemaking and if so, to assist in the 
development of proposed amendments. Accordingly, in the following 
sections, DOE has identified specific issues on which it seeks input to 
aid in its analysis of whether an amended test procedure for walk-in 
coolers and freezers 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 for the equipment, 
and not be unduly burdensome to conduct. DOE also welcomes comments on 
other issues relevant to its early assessment that may not specifically 
be identified in this document.

A. Scope and Definitions

    This RFI covers equipment meeting the ``walk-in cooler and walk-in 
freezer'' definition codified in 10 CFR 431.302: An enclosed storage 
space refrigerated to temperatures (1) above 32 [deg]F for walk-in 
coolers and (2) at or below 32 [deg]F for walk-in freezers, that can be 
walked into, and has a total chilled storage area of less than 3,000 
square feet, but excluding equipment designed and marketed exclusively 
for medical, scientific, or research purposes. 10 CFR 431.302. (See 
also 42 U.S.C. 6311(20)) In addition to the prescriptive requirements 
for walk-ins established by EPCA (42 U.S.C. 6313(f)(3)(A)-(D)) and 
codified at 10 CFR 431.306(a)-(b), DOE established performance-based 
energy conservation standards for doors and refrigeration systems. 10 
CFR 431.306(c)-(e).
1. Walk-In Refrigeration Systems
    DOE is aware of equipment that would appear to meet the walk-in 
definition and for which there is no current DOE test procedure or 
energy conservation standard. DOE indicated in a public meeting on 
October 22, 2014 that the WICF test procedures and standards did not 
apply to water-cooled condensing units or systems. (Docket EERE-2011-
BT-TP-0024, No. 109 \6\ at p. 11) DOE notes that the EPCA definition 
for walk-ins makes no distinction on how the condenser is cooled. (42 
U.S.C. 6311(20)(A))
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    \6\ Details of Executing the Test Procedures for Refrigeration 
Systems use in Walk-in Coolers and Freezers, available at https://www.regulations.gov/document?D=EERE-2011-BT-TP-0024-0109.
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    The current DOE test procedure for walk-in refrigeration systems, 
which incorporates by reference AHRI 1250-2009, does not address how to 
test liquid-cooled systems. Additionally, liquid-cooled condensing 
units are outside the scope of the most recent version of AHRI 1250, 
AHRI 1250-2020. Liquid-cooled condensing units for walk-ins are readily 
available for a wide range of capacities and refrigerants from major 
walk-in refrigeration system manufacturers. (See for example, Airdyne 
W-series indoor units (water-cooled), and Russell (water-cooled, 
glycol-cooled) (see Docket No. EERE-2017-BT-TP-0010-0001, Docket No. 
EERE-2017-BT-TP0010-0002, and Docket No. EERE-2017-BT-TP-0010-0003).
    Issue 1: DOE seeks comment on how liquid-cooled refrigeration 
systems are (or could be) used with respect to walk-in applications. 
DOE requests comment on whether it should consider establishing a test 
procedure for liquid-cooled refrigeration systems. If test procedures 
were considered for liquid-cooled refrigeration systems, DOE requests 
information on whether there is an industry standard or standards that 
should be considered.
    DOE is considering modifying the current equipment class 
definitions for refrigeration systems, which are based on walk-in 
application temperature. In the June 2014 ECS final rule, DOE 
established equipment classes for medium- and low- temperature walk-in 
refrigeration systems. 79 FR 32050, 32069-32070. While the terms 
``medium-temperature'' and ``low-temperature'' are not explicitly 
defined, the June 2014 ECS final rule, 2015 ASRAC negotiations, 
December 2016 TP final rule, and July 2017 ECS final rule all 
consistently used the term ``medium-temperature'' to refer to walk-in 
cooler refrigeration systems and the term ``low-temperature'' to refer 
to walk-in freezer refrigeration systems.
    Rating conditions are 35 [deg]F for cooler systems and -10 [deg]F 
for freezer systems. DOE acknowledges that there are ``medium-
temperature'' systems designed to operate between these two rating 
conditions, specifically between 10 [deg]F and 32 [deg]F. However, the 
EPCA definitions for walk-in freezers and walk-in coolers draws the 
line between them at 32 [deg]F, thus classifying such refrigeration 
systems as freezer refrigeration systems. DOE is considering whether 
equipment definitions and requirements should be amended to address 
these systems, which are discussed in detail in Section II.E.7.
    Finally, DOE is considering defining walk-in wine cellar 
refrigeration systems. These systems are typically designed to provide 
a cold environment at a temperature range between 45-65 [deg]F with 50-
70 percent relative humidity (``RH''), and typically are kept at 55 
[deg]F and 55 percent RH rather than the 35 [deg]F and less than 50 
percent RH test condition prescribed by the DOE test procedure. 
Operating a wine cellar at the 35 [deg]F condition would adversely 
mechanically alter the intended performance of the system, which would 
include icing of the evaporator coil that could potentially damage the 
compressor, and would not result in an accurate representation of the 
performance of the cooling unit. To distinguish walk-in wine-cellar 
refrigeration systems from other walk-in cooler systems, DOE is 
considering whether to specify 45 [deg]F as the minimum temperature at 
which a walk-in wine cellar refrigeration system can effectively 
operate. If DOE were to specify a minimum operating temperature, DOE 
would need to develop a definition specific for products that operate 
in this temperature region. Walk-in wine cellar refrigeration systems 
are discussed in more detail in Section II.E.2.
    Issue 2: DOE seeks comment on how wine cellar refrigeration systems 
should be defined to best represent the conditions under which these 
systems

[[Page 32335]]

are designed to operate and to fully distinguish these systems from 
systems designed to meet safe food storage requirements. Additionally, 
DOE requests comment on applications other than wine cellar storage for 
refrigeration systems that are designed to operate at temperatures 
warmer than typical for coolers and for which testing at 35 [deg]F 
would be representative of use. If there are such additional 
applications, DOE seeks information regarding the specific operating 
requirements (i.e., temperature and humidity) for these systems.
2. Walk-In Doors
    DOE is also reviewing the definitions applicable to WICF doors. DOE 
defines a ``door'' as an assembly installed in an opening on an 
interior or exterior wall that is used to allow access or close off the 
opening and that is movable in a sliding, pivoting, hinged, or 
revolving manner of movement. For walk-in coolers and walk-in freezers, 
a door includes the door panel, glass, framing materials, door plug, 
mullion, and any other elements that form the door or part of its 
connection to the wall. 10 CFR 431.302. DOE is interested in using 
language that is consistent across the walk-in door industry to define 
a door.
    Issue 3: DOE requests comment on the current definition of ``door'' 
in 10 CFR 431.302. DOE seeks feedback on the terminology of door 
components used and whether these are consistently interpreted. DOE 
seeks specific feedback from manufacturers on how they use the term 
``door plug'' and whether it is essential to the definition of a WICF 
``door''.
    DOE differentiates WICF doors by whether such doors are ``display 
doors'' or not display doors. A ``display door'' is defined as a door 
that: (1) Is designed for product display; or (2) has 75 percent or 
more of its surface area composed of glass or another transparent 
material. 10 CFR 431.302. WICF doors that are not display doors are 
differentiated according to whether they are ``freight doors'' or 
``passage doors.'' A ``freight door'' is a door that is not a display 
door and is equal to or larger than 4 feet wide and 8 feet tall. Id. A 
``passage door'' is a door that is not a freight or display door. Id.
    The use of dimensions in the definition of freight door conveys 
that these doors are intended for large machines (e.g., forklifts) to 
pass through carrying freight. However, the definition does not 
explicitly provide whether classification as a freight door occurs when 
one of the dimensions exceeds the dimension provided in the definition, 
but the other dimension is smaller than the dimension provided in the 
definition. For such doors, in some cases the surface area could be 
larger than 32 square feet, the area of a 4-foot by 8-foot door 
provided in the definition (e.g., a door 5 feet wide and 7 feet tall, 
with a surface area of 35 square feet); in other cases, the surface 
area could be smaller than 32 square feet (e.g., a door 5 feet wide and 
6 feet tall, with a surface area of 30 square feet). DOE reviewed the 
surface area of certified freight and passage doors in DOE's Compliance 
Certification Management System (``CCMS'') Database.\7\ Among 1,114 
unique individual models \8\ of freight doors, 44 unique individual 
models have a surface area less than 32 square feet. These models 
appear to have been classified on the understanding that a door is a 
freight door if just one dimension is larger than the dimensions 
specified in the freight door definition. Among 1,540 unique individual 
models of passage doors, 789 unique individual models have a surface 
area greater than or equal to 32 square feet.\9\ These models either 
are multi-door configurations, or they have been classified assuming 
that to be a freight door, both dimensions must be equal to or exceed 
the dimensions in the freight door definition. DOE further notes that 
the standards for each class of WICF doors are a function of surface 
area, and that different standards apply for freight doors and passage 
doors. DOE seeks information that would inform any potential revision 
of the door definitions, particularly ``freight door'' and ``passage 
door,'' to improve their clarity and ensure that there is no overlap 
between these definitions.
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    \7\ Data from the DOE CCMS database was accessed on March 6, 
2020. This database can be found at http://www.regulations.doe.gov/certification-data/.
    \8\ Unique individual models exclude any duplicate entries using 
the same individual model number.
    \9\ DOE understands that some certified passage doors may 
represent multi-door configurations in which the individual 
component doors each have a surface area of less than 32 square 
feet.
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    Issue 4: DOE requests comment on whether height and width or 
surface area are distinct attributes that effectively distinguish 
between passage and freight doors. DOE seeks information on any 
building codes, standards, or industry practices to support or refute 
maintaining the dimensions of a door as the defining characteristic 
which separates freight and passage doors.
    Issue 5: Regarding a door that meets the freight door definition 
but does so only because it has a multi-door configuration in which the 
individual component doors each would by themselves not meet the 
freight door definition, DOE seeks comment on how such doors should be 
classified, and whether such classification should depend on other 
factors, such as whether one or more frame members divides the door 
opening into smaller openings.
    Issue 6: DOE seeks comment on whether any attribute, or combination 
of attributes, other than size, would affect energy use and could be 
used to distinguish between freight doors and passage doors. If so, DOE 
requests data and comment on such attributes.

B. Industry Test Standards

    The current DOE test procedure for walk-in coolers and freezers 
incorporates the following industry test standards: NFRC 100 \10\ into 
Appendix A; ASTM C518-04 \11\ into Appendix B; and AHRI 1250-2009 \12\, 
AHRI 420-2008 \13\ and ASHRAE 23.1-2010 \14\ into Appendix C.
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    \10\ National Fenestration Rating Council (``NFRC'') 100-2010, 
``Procedure for Determining Fenestration U-factors'' (``NFRC 100'').
    \11\ American Society for Testing and Materials (``ASTM'') C518-
04, ``Standard Test Method for Steady-State Thermal Transmission 
Properties by Means of the Heat Flow Meter Apparatus'' (``ASTM C518-
04'').
    \12\ American National Standards Institute (``ANSI'')/Air-
Conditioning, Heating, and Refrigeration Institute (``AHRI'') 
Standard 1250P (I-P), ``2009 Standard for Performance Rating of 
Walk-In Coolers and Freezers'' (``AHRI 1250-2009'').
    \13\ AHRI 420-2008, ``Performance Rating of Forced-Circulation 
Free-Delivery Unit Coolers for Refrigeration'' (``AHRI 420-2008'').
    \14\ ANSI/ASHRAE 23.1-2010, ``Methods of Testing for Rating the 
Performance of Positive Displacement Refrigerant Compressors and 
Condensing Units that Operate at Subcritical Temperatures of the 
Refrigerant'' (``ASHRAE 23.1-2010'').
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1. NFRC 100 and NFRC 102
    Appendix A requires manufacturers to determine door thermal 
transmittance according to NFRC 100. See Appendix A, Section 5.3. NFRC 
100 includes a computational method to determine the thermal 
transmittance for a product line of doors if simulated results meet the 
validation requirements specified in NFRC 100. This approach may be 
less costly but generally may result in a higher, more conservative 
thermal transmittance value than the thermal transmittance value 
determined by testing each door. Section 4.3.2 of NFRC 100 provides a 
method for physically testing the thermal transmittance of walk-in 
doors by referencing NFRC 102, ``Procedure for Measuring the Steady-
State Thermal Transmittance of Fenestration Systems'' (``NFRC 102''). 
DOE is considering explicitly incorporating by reference NFRC 102 as

[[Page 32336]]

the test method for determining the thermal transmittance of walk-in 
doors in place of NFRC 100 and adopting AEDM provisions for walk-in 
display and non-display doors to replace the computational methodology 
in NFRC 100.
    Issue 7: DOE requests comment on the accuracy of the computational 
method in NFRC 100 to predict U-factor for display and non-display 
doors. DOE seeks feedback regarding the differences in results (if any) 
between those obtained using the NFRC 100 computational method and 
those obtained when conducting physical testing using NFRC 102 for 
display and non-display doors. DOE is also interested in the magnitude 
of these differences and whether the computational method can be 
modified to yield results that more closely match the results obtained 
from actual physical testing. If manufacturers are aware of other 
methods to predict U-factor for either display doors or non-display 
doors besides NFRC 100, DOE requests how the results from these methods 
compare to physical testing.
    Issue 8: DOE seeks information from manufacturers and other 
interested parties regarding how the industry currently rates 
individual door models, including the prevalence within the industry of 
using the computational method from NFRC 100. DOE also requests 
information on the costs associated with the computational method of 
NFRC 100 or an alternative computational method compared to physically 
testing the thermal transmittance of walk-in doors using NFRC 102.
2. ASTM C518
    Currently, section 4.2 of Appendix B references ASTM C518 to 
determine the thermal conductivity of panel insulation (the ``K 
factor''). EPCA requires that the measurement of the K factor used to 
calculate the R-value ``be based on ASTM test procedure C518-2004.'' 
(42 U.S.C. 6314(a)(9)(A)(ii)) In December 2015, ASTM published a 
revision of this standard (``ASTM C518-15''). ASTM C518-15 removed 
references to ASTM Standard C1363, ``Test Method for Thermal 
Performance of Building Materials and Envelope Assemblies by Means of a 
Hot Box Apparatus'' (``ASTM C1363''), and added references to ASTM 
Standard E456, ``Terminology Relating to Quality and Statistics''. 
Additionally, ASTM C518-15 relies solely on the International System of 
Units (``SI units''), with paragraph 1.13 clarifying that these SI unit 
values are to be regarded as standard.
    In July 2017, ASTM published another revision of ASTM C518 (``ASTM 
C518-17''). ASTM C518-17 added a summary of precision statistics from 
an interlaboratory study from 2002-2004 in section 10 ``Precision and 
Bias''. DOE has initially determined that the changes made in 2015 and 
2017 to ASTM C518 do not substantively change the test method and, 
therefore, DOE is considering specifying ASTM C518-17 as the referenced 
test procedure in Appendix B. If DOE makes this change as part of a 
test procedure rulemaking, it would also consider any changes necessary 
to ensure rounding consistency when converting the output of ASTM C518-
17 from SI units to English units.
    Issue 9: DOE requests comment on what issues, if any, would be 
present if ASTM C518-17 were to be referenced in the Appendix B test 
procedure for measuring panel K-factor, or average thermal 
conductivity. While not exhaustive, primary areas of interest to DOE 
include any differences between the currently referenced version of the 
industry standard (ASTM C518-04) and ASTM C518-17 that would result in 
a difference in the determined R-value and/or test burden (whether an 
increase or decrease), and if there are such differences, the magnitude 
of impact to the determined R-value and/or test burden.
3. AHRI 1250
    The current DOE test procedures for walk-in refrigeration systems 
incorporate by reference AHRI 1250-2009. 10 CFR 431.303(b)(2). AHRI 
1250-2009 provides test methods for determination of performance for 
matched pair refrigeration systems consisting of a unit cooler and a 
condensing unit, or for the individual unit cooler or condensing unit 
alone.\15\ In 2014, AHRI published a revision to this standard (``AHRI 
1250-2014''). AHRI 1250-2014 primarily aligned the test standard for 
consistency with the DOE test procedure, e.g. specifying that unit 
coolers be tested using 25 [deg]F saturated suction temperature for 
refrigerator unit coolers and -20 [deg]F for freezer unit coolers.
---------------------------------------------------------------------------

    \15\ A split-system refrigeration system consists of two 
separate components: A unit cooler that is installed inside a walk-
in enclosure, and a condensing unit, which is installed outside the 
enclosure, either inside a building in which the walk-in is 
constructed, or outdoors.
---------------------------------------------------------------------------

    AHRI again published a revision to the standard in April 2020 
(``AHRI 1250-2020''). AHRI 1250-2020 includes many updates, including 
(a) providing complete instructions for testing of unit coolers alone 
instead of incorporating by reference AHRI 420, (b) providing complete 
instructions for testing of condensing units alone instead of 
incorporating by reference ASHRAE 23.1-2010, (c) revision of instrument 
accuracy and test tolerances, (d) adding test methods for testing of 
single-package systems, (e) modified correlations for default 
evaporator fan power, defrost thermal load, and defrost energy use for 
use when testing condensing units alone, (f) correlations for defrost 
thermal load and energy use for use when testing hot gas defrost 
systems, (g) measurement of all relevant off-cycle energy use, 
including compressor crankcase heater energy use, and (h) methods to 
verify whether a refrigeration system has hot gas defrost and/or 
adaptive defrost capabilities.
    DOE may consider incorporating by reference AHRI 1250-2020 as the 
test method for walk-in refrigeration systems.
    Issue 10: DOE requests comment on what issues, if any, would be 
present if AHRI 1250-2020 were to be referenced in the Appendix C test 
procedure for measuring walk-in refrigeration system AWEF. While not 
exhaustive, primary areas of interest to DOE include any differences 
between the currently referenced version of the industry standard (AHRI 
1250-2009) and AHRI 1250-2020 that would result in a difference in the 
determined AWEF and/or test burden (whether an increase or decrease), 
and if there are such differences, the magnitude of impact to the 
determined AWEF and/or test burden.

C. Test Procedure for Walk-In Doors

    In the following subsections, DOE discusses several topics specific 
to walk-in doors that may affect the test procedure's ability to 
provide results that are more fully representative of walk-in door 
energy use during an average use cycle. In particular, the discussion 
focuses on: (a) The distinction between the surface area used for 
determining maximum energy consumption and the surface area used to 
calculate thermal transmittance; (b) walk-in door electrical 
components, such as motors, that may require specific consideration in 
the test procedure; (c) assumptions of refrigeration system energy 
efficiency ratio (``EER'') for calculating energy use associated with 
the thermal loads of walk-in doors; (d) calibrations of the hot box 
used for determining thermal transmittance (also referred to as ``U-
factor''); (e) maintaining tolerances on heat transfer coefficients for 
U-factor tests; and (f) measuring and accounting for air infiltration.

[[Page 32337]]

1. Surface Area Used for Determining Compliance With Standards
    The surface area of display doors and non-display doors (designated 
as Add and And, respectively) are used to determine maximum energy 
consumption in kWh/day of a walk-in door. 10 CFR 431.306(c)-(d). 
Surface area is defined in Appendix A as ``the area of the surface of 
the walk-in component that would be external to the walk-in cooler or 
walk-in freezer as appropriate.'' Appendix A, Section 3.4. DOE 
recognizes that this definition may benefit from additional detail. As 
currently written, the definition does not provide detail on how to 
determine the boundaries of the walk-in door from which height and 
width are determined to calculate surface area. Additionally, the 
definition does not specify if these measurements are to be strictly 
in-plane with the surface of the wall or panel that the walk-in door 
would be affixed to, or if troughs and other design features on the 
exterior surface of the walk-in door should be included in the surface 
area.
    Inconsistent determination of surface area, specifically with 
respect to the measurement boundaries, may result in unrepresentative 
maximum energy consumption. Display doors are fundamentally different 
from non-display doors in terms of their overall construction. For 
example, display door assemblies contain a larger frame encompassing 
multiple door openings; the entire assembly fits into an opening within 
a walk-in wall. Non-display doors differ in that they often are affixed 
to a panel-like structure that more closely resembles a walk-in wall 
rather than a traditional door frame. For the purposes of determining 
compliance with the standards, DOE interprets the surface area as the 
product of the height and width measurements of the door made external 
to the walk-in, where the height and width measurements are the maximum 
edge-to-edge dimensions of the door measured perpendicular to each 
other and parallel to the wall or panel of the walk-in to which the 
door is affixed. In applying this approach, DOE views the height and 
width measurements of display doors to include the frame and frame 
flange that overlaps the external edge of the WICF panel. For non-
display doors, DOE views the height and width measurements to include 
only the swinging or sliding portion of the door and not the door frame 
or any localized appendages such as hinges or hanging rails and 
brackets. DOE seeks feedback on its interpretation of surface area for 
both display and non-display doors. DOE is also interested in feedback 
on whether additional detail is needed regarding the surface area for 
both non-display doors and display doors, and if so, what further 
detail should be provided.
    Issue 11: DOE requests comment on how manufacturers determine 
surface area for the purpose of evaluating compliance with the 
standards for both display doors and non-display doors. DOE seeks input 
on any distinction between display doors and non-display doors, 
especially the door frames, which may warrant surface area for each to 
be determined differently.
    Additionally, walk-in doors with antisweat heaters are subject to 
prescriptive standards for power use of antisweat heaters per square 
foot of door opening. 10 CFR 431.306(b)(3)-(4). Although ``door 
opening'' is not defined, DOE considers the relevant area for 
determining ``power use per square foot of door opening'' to be 
consistent with the surface area used to determine maximum energy 
consumption.
    Issue 12: DOE seeks feedback on how manufacturers interpret and 
measure door opening as it relates to prescriptive standards for 
antisweat heaters, including whether or not manufacturers agree that 
the door opening considered for antisweat heat should be consistent 
with the surface area used to determine maximum energy consumption.
2. Thermal Transmittance Area
    Currently, equations 4-19 and 4-28 of Appendix A specify that 
surface area, as defined in section 3.4 of Appendix A, of display doors 
and non-display doors, respectively, are used to convert a door's U-
factor into a conduction load. This conduction load represents the 
amount of heat that transfers from the exterior to the interior of the 
walk-in. Based on recent review of the test procedure, DOE has 
identified that this defined surface area is inconsistent with the 
referenced industry test procedures for determining U-factor.
    As stated previously, Appendix A references NFRC 100 for the 
determination of U-factor. When conducting physical testing,\16\ U-
factor (Us) is calculated using projected surface area (As). ASTM 
C1199-09, Section 8.1.3. As is defined as ``the projected area of test 
specimen (same as test specimen aperture in surround panel)''. ASTM 
C1199-09, Section 3.3. This area differs from the currently defined 
areas (Add and And) in Appendix A. See Appendix A, Section 3.4. DOE is 
considering whether the surface area used in calculating the conduction 
load in Equations 4-19 and 4-28 of Appendix A should be the same 
surface area used to determine Us to provide greater consistency with 
the NFRC 100 definition of U-factor: ``The U-factor multiplied by the 
interior-exterior temperature difference and by the projected 
fenestration product area yields the total heat transfer through the 
fenestration product.''
---------------------------------------------------------------------------

    \16\ As mentioned previously, NFRC 100 references NFRC 102 for 
determining U-factor through physical testing. NFRC 102 is based on 
American Society for Testing and Materials (``ASTM'') C1199-09, 
``Standard Test Method for Measuring the Steady-State Thermal 
Transmittance of Fenestration Systems Using Hot Box Methods'' 
(``ASTM C1199-09'') with some modifications.
---------------------------------------------------------------------------

    Issue 13: DOE requests feedback on specifying the surface area used 
to determine thermal conduction through a walk-in door from the surface 
area used to determine the maximum energy consumption of a walk-in 
door.
3. Electrical Door Components
    Sections 4.4.2 and 4.5.2 of Appendix A include provisions for 
calculating the direct energy consumption of electrical components of 
display doors and non-display doors, respectively. For example, 
electrical components associated with doors could include, but are not 
limited to: Heater wire (for anti-sweat or anti-freeze application); 
lights (including display door lighting systems); control system units; 
and sensors. See Appendix A, Sections 4.4.2 and 4.5.2. For each 
electricity-consuming component, the calculation of energy consumption 
is based on the component's ``rated power'' rather than an actual 
measurement of its power draw. Section 3.5 of Appendix A defines 
``rated power'' as the electricity consuming device's power as 
specified on the device's nameplate, or from the device's product data 
sheet if the device does not have a nameplate or such nameplate does 
not list the device's power.
    DOE has observed that walk-in doors often provide a single 
nameplate for the door, rather than providing individual nameplates for 
each electricity-consuming device. In many cases, the nameplate does 
not provide separate power information for the different electrical 
components. Also, the nameplate often specifies voltage and amperage (a 
measure of current) ratings without providing wattage (a measure of 
power) ratings, as is referenced by the definition of ``rated power''. 
While the wattage is equal to voltage multiplied by the current for 
many components, this may not be true of all components that may be 
part of a walk-in door assembly. Furthermore, nameplate labels 
typically do not specify whether any listed values of rated power or 
amperage represent

[[Page 32338]]

the maximum operation conditions or continuous steady-state operating 
conditions, which could differ for components such as motors that 
experience an initial surge in power before leveling off at a lower 
power level. These issues make calculating a door's total energy 
consumption challenging when a test facility does not have in-depth 
knowledge of the electrical characteristics of the door components.
    DOE is considering whether there may be value in adding an option 
for direct measurement of door component electrical power, either as 
part of the test procedure for manufacturers wishing to make direct 
measurements, or for DOE testing, as an alternative to using the 
nameplate value. DOE seeks comment on issues that should be considered 
were DOE to develop requirements for such measurements, such as any 
additional instrumentation or test conditions that would be required.
    Issue 14: DOE seeks comment on whether, and if so how, an option 
for direct component power measurement could be included in the test 
procedure or compliance, certification, and enforcement (``CCE'') 
provisions to allow more accurate accounting for the direct electrical 
energy consumption of WICF doors. DOE also seeks input on whether 
specific provisions should be provided for determining power input from 
the information that is typically provided on nameplates, noting the 
limitations that were described above.
    As stated previously, Appendix A accounts for the energy 
consumption of various electrical components, including lights, 
sensors, anti-sweat heater wire, and other miscellaneous electrical 
devices. The test procedure assigns percent time off (``PTO'') values 
to various walk-in door components.\17\ Table II.1 lists the PTO values 
in the DOE test procedure for walk-in doors. This method provides a 
means to compare walk-in door performance while limiting the test 
burden on manufacturers.
---------------------------------------------------------------------------

    \17\ PTO values are applied in order to reflect the hours in a 
day that an electricity-consuming device operates at its full rated 
or certified power (i.e., daily component energy use is calculated 
assuming that the component operates at it rated power for a number 
of hours equal to 24 multiplied by (1-PTO)). PTO should not be 
incorporated into the rated or certified power of an electricity-
consuming device.

       Table II.1--Assigned PTO Values for Walk-In Door Components
------------------------------------------------------------------------
                                                           Percent time
                     Component type                        off  (PTO) %
------------------------------------------------------------------------
Lights without timers, control system or other demand-                25
 based control..........................................
Lights with timers, control system or other demand-based              50
 control................................................
Anti-sweat heaters without timers, control system or                   0
 other demand-based control.............................
Anti-sweat heaters on walk-in cooler doors with timers,               75
 control system or other demand-based control...........
Anti-sweat heaters on walk-in freezer doors with timers,              50
 control system or other demand-based control...........
All other electricity consuming devices without timers,                0
 control systems, or other auto-shut-off systems........
All other electricity consuming devices for which it can              25
 be demonstrated that the device is controlled by a
 preinstalled timer, control system or other auto- shut-
 off system.............................................
------------------------------------------------------------------------

    DOE has received several petitions for waivers and interim waivers 
with regard to the PTO used for doors with motorized door openers.\18\ 
These manufacturers stated that the test procedure for walk-in doors 
overstates the energy consumption of motorized doors because the 
applicable PTO value prescribed in the test procedure is not 
representative of the actual energy use of the motorized doors used in 
these applications. Under the current test procedure, motorized door 
openers would be considered ``other electricity-consuming devices,'' 
with PTO values of either 0 percent or 25 percent. See Appendix A, 
Sections 4.4.2(a)(3) and 4.5.2(a)(3). Based on the characteristics of 
its doors, each manufacturer requested a different PTO value (shown in 
Table II.2) to be applied to its basic models. After reviewing the 
performance data, equipment characteristics, and door-opening frequency 
assumptions presented by door manufacturers, and after soliciting and 
reviewing feedback from the public, DOE granted waivers to the 
manufacturers shown in Table II.2.
---------------------------------------------------------------------------

    \18\ By letters dated July 26, 2017, December 21, 2017, March 
13, 2020, and June 5, 2020, Jamison Door Company, HH Technologies, 
Senneca Holdings, and Hercules, respectively, submitted petitions 
for waivers and interim waivers for basic models of motorized walk-
in doors, requesting the use of alternate PTO values. (Jamison, 
EERE-2017-BT-WAV-0040, No. 2 at p. 2; HH Technologies, EERE-2018-BT-
WAV-0001, No. 1 at p. 2; Senneca Holdings, EERE-2020-BT-WAV-0009, 
No. 3 at p. 3; Hercules, EERE-2020-BT-WAV-0027, No. 2 at p. 3).

  Table II.2--PTO Values Granted in Decision and Orders for Manufacturers of Doors With Motorized Door Openers
----------------------------------------------------------------------------------------------------------------
                                               Percent time
                Manufacturer                   off  (PTO) %      Decision and order Federal Register citation
----------------------------------------------------------------------------------------------------------------
HH Technologies.............................              96  83 FR 53457. (Oct. 23, 2018).
Jamison Door Company........................            93.5  83 FR 53460. (Oct. 23, 2018).
Senneca Holdings............................              97  86 FR 75. (Jan. 4, 2021).
Hercules....................................              92  86 FR 17801. (Apr. 6, 2021).
----------------------------------------------------------------------------------------------------------------

    DOE is reviewing the test procedure's current PTO values and is 
interested in establishing standard PTO values for motorized door 
openers as well as any other electricity-consuming devices that would 
warrant PTOs different from those currently in Appendix A, also listed 
in Table II.1 of this document. DOE seeks information regarding how 
closely these values represent actual PTO values experienced in the 
field. In addition to motorized door openers,

[[Page 32339]]

DOE is also investigating whether any additional walk-in door 
electrical components, such as heated air vents and heated thresholds, 
would warrant the use of specific PTO values when calculating door 
energy use.
    Issue 15: DOE requests comment on the current PTO values and 
whether DOE should consider amending any of the current values or 
adding specific values for additional electrical components, 
specifically motorized door openers. DOE requests data from field 
studies or similar sources to support any proposed amendments (or 
additions) to these PTO values.
    DOE is aware that some manufacturers design and market walk-in 
cooler display doors for high humidity applications. Ratings from the 
CCMS database \19\ show these doors have more anti-sweat heater power 
per door opening area than standard cooler display doors. The average 
power use per door opening area for high humidity cooler doors is 1.66 
W/ft\2\, while the average power use for cooler doors not marketed for 
high humidity applications made by the same manufacturers who produce 
the high humidity doors is 1.01 W/ft\2\. Section 4.4.2(a)(2) of 
Appendix A requires a PTO value of 50 percent be used when determining 
the direct energy consumption for anti-sweat heaters with timers, 
control systems, or other demand-based controls situated within a walk-
in cooler door (which would include walk-in cooler doors marketed for 
high humidity applications). This approach assumes that the anti-sweat 
heaters are not operating for 50 percent of the time. DOE recognizes 
that anti-sweat heaters may be in operation for a different amount of 
time in high humidity installations than in standard installations.
---------------------------------------------------------------------------

    \19\ This data from the DOE CCMS database was accessed on March 
17, 2021. This database can be found at http://www.regulations.doe.gov/certification-data/.
---------------------------------------------------------------------------

    Issue 16: DOE seeks feedback on whether the current PTO of 50 
percent is appropriate for evaluating direct energy consumption of 
anti-sweat heaters with controls for walk-in cooler doors marketed for 
high humidity applications. DOE seeks feedback on the average amount of 
time per day or per year that anti-sweat heaters with controls are off 
for these high humidity doors and how this compares to standard (i.e., 
non-high humidity) walk-in cooler display doors.
4. EER Values To Convert Thermal Load to Energy Consumption
    To calculate the daily energy consumption associated with heat loss 
through a walk-in door, Appendix A requires dividing the calculated 
heat loss rate by specified EER values of 12.4 Btu per Watt-hour 
(``Btu/(W-h)'') for coolers and 6.3 Btu/(W-h) for freezers. Appendix A, 
Sections 4.4.4(a) and 4.5.4(a). DOE adopted these EER values in a final 
rule published April 15, 2011. 76 FR 21580, 21586, 21594 (``April 2011 
TP final rule''). As explained in a notice of proposed rulemaking 
(``NOPR'') leading to this final rule, DOE defined nominal EER values 
because an envelope component manufacturer cannot control what 
refrigeration equipment is installed, and the defined EER value is 
intended to provide a nominal means of comparison rather than reflect 
an actual walk-in installation. 75 FR 186, 197 (January 4, 2010) 
(``January 2010 TP NOPR''). DOE selected EER values of 12.4 Btu/(W-h) 
for coolers and 6.3 Btu/(W-h) for freezers because these are typical 
EER values of walk-in cooler and walk-in freezer refrigeration systems, 
respectively.\20\ 75 FR 186, 209.
---------------------------------------------------------------------------

    \20\ The difference in EER values between coolers and freezers 
reflects the relative efficiency of the refrigeration equipment for 
the associated application. 75 FR 186, 197. As the temperature of 
the air surrounding the evaporator coil drops (that is, when 
considering a freezer relative to a cooler), thermodynamics dictates 
that the system effectiveness at removing heat per unit of 
electrical input energy decreases. Id.
---------------------------------------------------------------------------

    The DOE test procedure also assigns nominal EER values when testing 
the refrigeration systems of walk-in unit coolers alone. When testing a 
unit cooler alone, the energy use attributed to the condensing unit is 
represented by a default value determined using the representative EER 
value specified for the appropriate ``adjusted'' dew point temperature 
in Table 17 of AHRI 1250-2009.\21\ The resulting EER values for unit 
coolers tested alone are 13.3 Btu/(W-h) for coolers and 6.6 Btu/(W-h) 
for freezers, which are different than the EER values of 12.4 and 6.3, 
respectively, applied to walk-in doors, as described above. DOE notes 
that based on Table 17 of AHRI 1250-2009, EER values of 12.4 and 6.3 
correspond to Adjusted Dewpoint Values of 19 [deg]F for a refrigerator 
and -26 [deg]F for a freezer (in contrast to Adjusted Dewpoint Values 
of 23 [deg]F and -22 [deg]F for unit cooler refrigerators and freezers, 
respectively, tested alone as defined in Table 15 and Table 16 of AHRI 
1250-2009 and subtracting 2 [deg]F as specified in section 7.9.1 of 
AHRI 1250-2009).
---------------------------------------------------------------------------

    \21\ The dewpoint temperature to be used for testing unit 
coolers alone is defined in section 3.3.1 of Appendix C to be the 
Suction A saturation condition provided in Tables 15 or 16 of 
Appendix C (for refrigerator unit coolers and freezer unit coolers, 
respectively). Table 15 for refrigerator unit coolers defines the 
Suction A saturation condition (i.e., dewpoint temperature) as 25 
[deg]F. Table 16 for freezer unit coolers defines the Suction A 
dewpoint temperature as -20 [deg]F. Furthermore, section 7.9.1 of 
AHRI 1250-2009 specifies that for unit coolers rated at a suction 
dewpoint other than 19 [deg]F for a refrigerator and -26 [deg]F for 
a freezer, the Adjusted Dewpoint Value shall be 2 [deg]F less than 
the unit cooler rating suction dewpoint--resulting in adjusted 
dewpoint values of 23 [deg]F and -22 [deg]F for refrigerator unit 
coolers and freezer unit coolers, respectively.
---------------------------------------------------------------------------

    DOE is considering whether to make the EER values used to calculate 
the energy consumption of walk-in doors consistent with the values used 
to calculate unit cooler energy consumption and whether such a change 
would provide a more accurate representation of the energy use of walk-
ins.
    Issue 17: DOE seeks feedback on the current EER values specified in 
Appendix A used to calculate daily energy consumption for walk-in doors 
and the values used in testing of unit coolers alone, as specified in 
Appendix C. Specifically, DOE requests comment on which of these sets 
of EER values is more representative, whether DOE should make the 
values used for door testing and unit cooler testing consistent with 
each other, and if so, which of the sets of values should be used.
5. Thermal Transmittance
a. Calibration of Hot Box for Measuring U-factor
    As stated previously, NFRC 100 references NFRC 102 as the physical 
test method for measuring U-factor, which in turn incorporates by 
reference ASTM C1199. ASTM C1199 references ASTM C1363-05, ``Standard 
Test Method for Thermal Performance of Building Materials and Envelope 
Assemblies by Means of a Hot Box Apparatus'' (``ASTM C1363''). Section 
6.1 of ASTM C1199 and Annexes 5 and 6 of ASTM C1363 include calibration 
requirements to characterize metering box wall loss and surround panel 
flanking loss, but the frequency at which these calibrations should 
occur is not specified in these test standards. DOE notes that ASHRAE 
Standard 16-2016, ``Method of Testing for Rating Room Air Conditioners 
and Packaged Terminal Air Conditioners'' (``ASHRAE 16-2016''), which is 
the test method incorporated by reference in the DOE test procedure for 
room air conditioners (10 CFR 430.3(g)(1)), uses in its determination 
of air conditioner capacity a value for heat loss through the partition 
wall based on prior calibration of the wall's heat loss. Conceptually, 
this use of a calibrated heat loss value is similar to the use of 
calibrated thermal losses in ASTM C1199 and ASTM C1363. DOE notes

[[Page 32340]]

further that section 6.1.2.2 of ASHRAE 16-2016 includes a requirement 
to calibrate the partition wall thermal loss at least every two years. 
DOE is interested in feedback on the frequency of calibration and how 
recalibrations are performed for test facilities using test standard 
ASTM C1199.
    Issue 18: DOE requests comment on how frequently test laboratories 
perform each of the calibration procedures referenced in ASTM C1199 and 
ASTM C1363, e.g., those used to determine calibration coefficients that 
are used to calculate metering box wall loss and surround panel 
flanking loss. DOE also requests comment on the magnitude of variation 
in the calibration coefficients measured during successive 
calibrations.
b. Tolerances of Surface Heat Transfer Coefficients
    Section 6 of ASTM C1199 specifies the standardized heat transfer 
coefficients and their tolerances as part of the procedure to set the 
surface heat transfer conditions of the test facility using the 
Calibration Transfer Standard (``CTS'') test. The warm-side surface 
heat transfer coefficient must be within  5 percent of the 
standardized warm-side value, and the cold-side surface heat transfer 
coefficient must be within  10 percent of the standardized 
cold-side value (ASTM C1199-09, sections 6.2.3 and 6.2.4). ASTM C1199 
does not require that the measured surface heat transfer coefficients 
match or be within a certain tolerance of standardized values during 
sample testing--although test facility operational (e.g., cold side fan 
settings) condition would remain identical to those set during the CTS 
test. On the other hand, Appendix A states in section 5.3(a)(1) that 
the average surface heat transfer coefficient on the cold-side of the 
apparatus shall be 30 Watts per square-meter-Kelvin  5 
percent and that the average surface heat transfer coefficient on the 
warm-side of the apparatus shall be 7.7 Watts per square-meter-Kelvin 
 5 percent.
    DOE originally proposed the heat transfer values and their 
associated tolerances in a supplemental notice of proposed rulemaking 
(``SNOPR'') published February 20, 2014 (``February 2014 AEDM TP 
SNOPR''). 79 FR 9818, 9837, 9847. DOE did not receive any comments from 
interested parties specific to the proposed tolerance of 5 
percent for both the cold-side and warm-side heat transfer 
coefficients, and finalized these values in a final rule published on 
May 13, 2014 (``May 2014 AEDM TP final rule''). 79 FR 27388, 27415.
    DOE has found that meeting the standardized heat transfer values 
within specified tolerances in section 5.3(a)(1) of Appendix A on the 
warm-side and cold-side may not be achievable depending on the thermal 
transmittance through the door. Specifically, the warm-side heat 
transfer is dominated by natural convection and radiation and the heat 
transfer coefficient varies as a function of surface temperature. When 
testing doors with higher thermal resistance, less heat is transferred 
across the door from the warm-side to the cold-side, so the warm-side 
surface temperature is closer to the warm-side air temperature. 
However, the CTS method in ASTM C1199 does not require measurement of 
the warm-side surface temperature of the door. Rather, this value is 
calculated based on the radiative and convective heat flows from the 
test specimen's surface to the surroundings, which are driven by values 
determined from the calibration of the hot box (e.g., the convection 
coefficient). See ASTM C1199, Section 9.2.1. When testing doors with 
extremely high- or low-thermal resistance, the resulting change in 
warm-side surface temperature can shift the warm-side heat transfer 
coefficient out of tolerance. The only way to adjust these coefficients 
to be within tolerance would be to recalibrate the hot box for a 
specific door, which would be burdensome and somewhat unpredictable.
    Issue 19: DOE requests feedback on whether the tolerances in 
section 5.3(a)(1) of Appendix A applied to the surface heat transfer 
coefficients used to measure thermal transmittance are achievable for 
all walk-in doors and if not, whether the tolerances should be 
increased or omitted. Specifically, DOE seeks data to support any 
changes to the tolerances on the surface heat transfer coefficients.
6. Air Infiltration Reduction
    EPCA includes prescriptive requirements for doors used in walk-in 
applications, which are intended to reduce air infiltration. 
Specifically, walk-ins must have (A) automatic door closers that firmly 
close all walk-in doors that have been closed to within 1 inch of full 
closure (excluding doors wider than 3 feet 9 inches or taller than 7 
feet), and (B) strip doors, spring-hinged doors, or other method of 
minimizing infiltration when doors are open. 42 U.S.C. 6313(f)(1)(A)-
(B). In the January 2010 TP NOPR and an SNOPR published on September 9, 
2010 (``September 2010 TP SNOPR''), DOE proposed methods for 
determining the thermal energy leakage due to steady-state infiltration 
through the seals of a closed door and door opening infiltration. 75 FR 
186, 214-216 and 75 FR 55068, 55107-55108. However, the April 2011 TP 
final rule did not include these methods because DOE concluded that 
steady-state infiltration was primarily influenced by on-site assembly 
practices rather than the performance of individual components. 76 FR 
21580, 21594-21595. Similarly, DOE stated that, based on its experience 
with the door manufacturing industry, door opening infiltration is 
primarily reduced by incorporating a separate infiltration reduction 
device at the assembly stage of the complete walk-in. Id.
    In this RFI, DOE is re-considering whether a method for measuring 
infiltration, specifically door opening infiltration, as well as a 
method to measure the impacts from technologies that reduce 
infiltration (e.g. fast-acting doors or air curtains), would improve on 
the current test procedure's accuracy and ability to produce results 
reflecting a given walk-in door's energy efficiency during a 
representative average use cycle, while not being unduly burdensome to 
conduct. Certain types of doors, like fast-acting doors, may have 
higher thermal transmittance, but may compensate for that factor by 
reducing infiltration from door openings--thereby, reducing a walk-in's 
overall energy use. DOE is considering how it may account for these 
types of doors in the walk-in test procedure.
    In the January 2010 TP NOPR, DOE proposed to require that the 
thermal load from air infiltration associated with each door opening 
event be calculated using an analytical method based on equations 
published in the ASHRAE Refrigeration Handbook in combination with 
assumed values for door-opening frequency and duration. That proposed 
method would have accounted for the presence of infiltration reduction 
devices by discounting the thermal load from door opening air 
infiltration by the effectiveness of the air infiltration device. 75 FR 
186, 196-197, 214-216. In order to determine the effectiveness of an 
infiltration reduction device, DOE proposed a two-part test that 
entailed measuring the concentration of tracer gas after a door opening 
event with and without the infiltration reduction device in place. Id. 
DOE proposed to use this effectiveness test for every unique door-
device combination offered by a manufacturer. Id.
    In the September 2010 TP SNOPR, DOE proposed a method for 
determining the thermal load associated with steady-state infiltration 
through walk-in doors. 75 FR 55068, 55084-55085, and 55107-

[[Page 32341]]

55108. For each door type with identical construction and only 
differences in dimensional size, DOE proposed to require calculating 
steady-state infiltration according to NFRC 400-2010-E0A1 (``Procedure 
for Determining Fenestration Product Air Leakage'') by testing three 
representative doors, one each of a ``small,'' ``medium,'' and 
``large'' size.\22\ Id. The steady-state infiltration from the 
representative doors would then be extrapolated or interpolated, as 
appropriate, to other doors that have the same construction. Id.
---------------------------------------------------------------------------

    \22\ DOE proposed a small size door as 48 inches 0.5 
inch wide and 84 inches 0.5 inch high, a medium size 
door as 96 inches 0.5 inch wide and 144 inches 0.5 inch high, and a large size door as 144 inches 0.5 inch wide and 180 inches 0.5 inch high. 75 FR 
55068, 55107.
---------------------------------------------------------------------------

    As noted, DOE is considering how to credit doors with infiltration-
reducing features that reduce overall walk-in energy use and that are 
in addition to the prescriptive requirements mandated by EPCA. In doing 
so, DOE may consider a revised version of one of its previous proposals 
related to door infiltration, or offer a new method for determining 
heat load associated with infiltration.
    DOE requests comment on whether it should account for steady-state 
and/or door opening infiltration in its test procedure--and if so, why; 
and if not, why not. With respect to suggestions for potential test 
methods, DOE is particularly interested in recommendations regarding 
test methods and calculation methods used by the industry to quantify 
heat load from infiltration. With respect to each of these methods, DOE 
seeks supporting information regarding the necessary costs in carrying 
them out. DOE seeks information and data on whether testing results 
obtained under any of the methods could be used to interpolate the load 
resulting from air infiltration of other door sizes in a product line. 
DOE also requests information on door usage patterns per door type 
(e.g., display doors, passage doors, motorized doors, and fast-acting 
doors), including any supporting data from research or field studies.

D. Test Procedure for Walk-In Panels

    In the following subsections, DOE presents several topics specific 
to walk-in panels that, if adopted, may improve the current test 
procedure's ability to provide results that more accurately depict 
walk-in panel energy use during a representative average use cycle 
without causing the test procedure to become unduly burdensome to 
conduct. That test procedure, found in 10 CFR part 431, subpart R, 
appendix B, provides a detailed method by which to measure the energy 
efficiency of a given panel used in the construction of a walk-in. 
Since publication of the December 2016 TP final rule, DOE has 
identified the potential need to provide additional clarification to 
Appendix B regarding the measurement of the thickness of walk-in panels 
(see Section II.D.1 of this document) and the procedure for determining 
parallelism and flatness of test specimens (see Section II.D.2 of this 
document). DOE also has identified differences between Appendix B and 
the industry test standards referenced, specifically for specimen \23\ 
conditioning prior to testing (see Section II.D.3 of this document). In 
addition, DOE is examining the prospect of requiring a measurement for 
thermal transmittance for non-display panels (see Section II.D.4 of 
this document). While DOE previously adopted methods for measuring 
thermal transmittance in the April 2011 TP final rule, it later removed 
them. 79 FR 27387, 27405-27406. DOE remains interested in exploring the 
possibility of addressing this issue because of the potential variation 
in thermal transmittance of different panel designs with the same R-
value, and seeks additional information regarding market-related and 
industry test method-related changes that would inform DOE's potential 
reconsideration of adopting a test method for measuring thermal 
transmittance. Finally, DOE is seeking comment on the test procedure 
for display panels (Section II.D.5 of this document).
---------------------------------------------------------------------------

    \23\ ASTM C518 uses ``specimen'' to refer to the piece of 
insulation that is cut to size for testing, while the CFR uses 
``sample''. The discussion in this document is using ``specimen'' 
for consistency with the industry test standard.
---------------------------------------------------------------------------

1. Panel Thickness
    DOE's test procedure for walk-in panels requires manufacturers to 
determine the panel's R-value by measuring the thermal conductivity, 
referred to as the ``K factor'' of a 1  0.1-inch specimen 
of insulation according to ASTM C518-04. The R-value of the walk-in 
panel is determined by dividing the panel thickness by the K factor. 
See 10 CFR 431.304(b)(3) and Appendix B (detailing the test method used 
to measure the R-value for walk-in envelope components). DOE's current 
test procedure for determining a panel's R-value provides some 
direction for measuring panel thickness. However, because of the 
importance of this measurement in determining the panel's R-value, DOE 
is considering whether to include additional details regarding the 
thickness measurement.
    Issue 20: DOE requests comment on how panel thickness is currently 
measured for determining the panel's R-value per the DOE test 
procedure, including number of measurements, measurement location, and 
any steps that are routinely followed for the removal of the protective 
skins or facers to obtain the full panel thickness. DOE requests that 
commenters identify any specific guidelines, practices or standardized 
approaches that are followed, as well as their date of publication, if 
applicable.
2. Parallelism and Flatness
    The test procedure for determining R-value also requires that the 
two surfaces of the tested specimen that contact the hot plate 
assemblies (as defined in ASTM C518) maintain 0.03 inches 
flatness tolerance and also maintain parallelism with respect to one 
another within a tolerance of 0.03 inches.\24\ Section 4.5 
of Appendix B. The test procedure provides no direction on how flatness 
and parallelism should be measured or calculated. DOE is considering 
whether its test procedure should provide additional details indicating 
how to determine the flatness and parallelism of the tested specimen.
---------------------------------------------------------------------------

    \24\ Maintaining a flatness tolerance means that no part of a 
given surface is more distant than the tolerance from the ``best-fit 
perfectly flat plane'' representing the surface. Maintaining 
parallelism tolerance means that the range of distances between the 
best-fit perfectly flat planes representing the two surfaces is no 
more than twice the tolerance (e.g., for square surfaces, the 
distance between the most distant corners of the perfectly flat 
planes minus the distance between the closest corners is no more 
than twice the tolerance).
---------------------------------------------------------------------------

    Issue 21: DOE requests comment on how flatness and parallelism of 
the test specimen surfaces that contact the hot plate assemblies 
described in ASTM C518 are typically determined by test laboratories 
and whether the test procedure should be revised to clarify how to 
determine these parameters, e.g., what type of instruments are used to 
measure these values, how many measurements are made for a given 
specimen, and other details that could affect conclusions regarding 
compliance with the test procedure.
3. Specimen Conditioning
    ASTM C518 directs that a test specimen cut from a panel be 
conditioned prior to testing. See ASTM C518-04, section 7.3 (referring 
to panel conditioning as ``specimen conditioning''). However, ASTM C518 
does not specify the conditions at which specimen conditioning would be 
conducted, nor the duration. ASTM C518 states that specimen 
conditioning details should be provided in the

[[Page 32342]]

material specifications, and if not provided, conditions should be 
selected so as not to change the specimen in an irreversible manner. 
Id. ASTM C518 further states that material specifications typically 
call for specimen conditioning at 22 [deg]C (72 [deg]F) and 50 percent 
relative humidity until less than a 1 percent mass change is observed 
over a 24-hour period. Id. Calculations associated with conditioning 
are discussed in section 8.1 of ASTM C518, including calculation of the 
``density of the dry specimen as tested,'' which suggests that the 
purpose of conditioning is, at least in part, to dry the specimen, 
i.e., allow water to evaporate and/or diffuse out.
    DOE has not found specimen conditioning details to be provided by 
suppliers of insulation for any of the common insulation materials used 
in walk-ins. Given this lack of supplier-provided specimen conditioning 
details, it is DOE's understanding that ``material specifications'' in 
section 7.3 refers to ASTM specifications, e.g. ASTM C578-2019, 
``Standard Specification for Rigid, Cellular Polystyrene Thermal 
Insulation'' or ASTM C1029-2015, ``Standard Specification for Spray-
Applied Rigid Cellular Polyurethane Thermal Insulation''. However, 
there is no uniform set of ASTM conditioning specifications, and the 
material specifications identified in ASTM C518 as ``typical'' do not 
reflect what is provided in other ASTM standards. For example, ASTM 
C578-2019 calls for conditioning as specified in the applicable test 
procedure--this circular reference back to ASTM C518 means that ASTM 
C578-2019 effectively provides no explicit conditions. ASTM C1029-2015 
calls for conditioning at 73  2 [deg]F and 50  
5 percent relative humidity for 180  5 days from time of 
manufacture. In the context of the DOE WICF test procedures, the ASTM 
C1029-2015 specifications may be insufficient or inappropriate because 
the date of manufacture of the insulation in a walk-in panel or door 
may not be known, and the 180-day condition would likely represent a 
significant test burden.
    In the absence of clear instructions in ASTM C518, test 
laboratories may be using conditioning times, temperature, and humidity 
consistent with the conditions identified in ASTM C518-04 section 7.3 
as ``typical conditions.'' Additionally, the provision in section 4.5 
of Appendix B requires that testing per ASTM C518-04 must be completed 
within 24 hours of specimens being cut for the purpose of testing, 
eliminating use of the 180-day conditioning provided in ASTM C1029-2015 
or the example of typical specimen conditioning provided by ASTM C518.
    Issue 22: DOE requests comment on the extent to which manufacturers 
of insulation specify conditioning for insulation materials that differ 
from the typical conditioning approach described in ASTM C518. DOE also 
seeks feedback on whether more than one 24-hour conditioning period is 
ever needed to complete the conditioning (i.e., the change in specimen 
mass is less than 1 percent after the first 24 hours of conditioning) 
for a specimen extracted from a WICF panel or door. Finally, DOE 
requests information or data on how specimen conditioning times less 
than or equal to 24 hours impacts the accuracy, repeatability, and 
representativeness of the test.
4. Overall Thermal Transmittance
    In the April 2011 TP final rule, DOE adopted a test method for 
measuring the overall thermal transmittance of a walk-in panel, 
including the impacts of thermal bridges \25\ and edge effects (e.g., 
due to framing materials and fixtures used to mount cam locks). This 
method drew from an existing industry test method, incorporating by 
reference ASTM C1363-05. 76 FR 21580, 21605-21612. However, after 
receiving comments indicating that only two independent laboratories 
could conduct this test, DOE re-evaluated its earlier decision and 
removed this portion of the walk-in panel test procedure in the May 
2014 AEDM TP final rule. 79 FR 27388, 27405-27406. Despite this 
decision to remove its overall thermal transmittance measurement method 
from the walk-in test procedure, DOE remains concerned that elements 
like framing materials and fixtures used to mount cam locks can 
significantly affect walk-in panel energy efficiency performance. To 
address this issue, DOE is re-evaluating whether--and if so, how--to 
account for the overall thermal transmittance of walk-in panels in its 
test procedure.
---------------------------------------------------------------------------

    \25\ Thermal bridging occurs when a more conductive material 
allows an easy pathway for heat flow across a thermal barrier.
---------------------------------------------------------------------------

    Issue 23: DOE requests information about panel construction factors 
that would affect thermal transmission and the magnitude of the energy 
efficiency-related impacts of thermal bridges in the panel assembly. 
Additionally, DOE requests comment on alternative test methods that 
measure the overall thermal transmittance of walk-in panels and the 
relative advantages and disadvantages of each. DOE also seeks feedback 
on the number and location of labs that have the facilities and are 
qualified to run ASTM C1363-05.
5. Display Panels
    Display panels are defined in 10 CFR 431.302 as panels entirely or 
partially comprised of glass, a transparent material, or both that are 
used for display purposes. Display panels are subject to the test 
procedure in Appendix A for determining U-factor, conduction load, and 
energy use. 10 CFR 431.304(b)(1). Appendix A follows the procedure in 
NFRC 100 for determination of display panel U-factor. 10 CFR 431.303. 
Although DOE established a test procedure for display panels, DOE has 
not established energy conservation standards for them. DOE received no 
comments in response to the proposed test procedure outlined for 
display panels in the September 2010 TP SNOPR and DOE established 
Appendix A as the test procedure for display panels in the April 2011 
TP Final Rule. 76 FR 21580, 21606. DOE is interested in any feedback on 
amending the current test procedure for display panels.
    Issue 24: DOE seeks feedback on the current test procedure for 
display panels in Appendix A and what amendments should be made, if 
any, to it.

E. Test Procedure for Walk-In Refrigeration Systems

    DOE's test procedure for walk-in refrigeration systems can be found 
in Appendix C to Subpart R of 10 CFR part 431. The test procedure 
primarily incorporates by reference AHRI 1250-2009.
    DOE has also recently granted test procedure interim waivers and 
waivers to Appendix C specific to the testing of single-package 
systems, wine cellar refrigeration systems, and carbon dioxide 
(``CO2'') refrigerant based systems, summarized in Table 
II.3. Test procedure waivers provide alternate test provisions for 
units that DOE determines cannot be appropriately tested to its current 
test procedure. A waiver granted by DOE remains in effect until DOE 
amends its regulations so as to eliminate any need for it, pursuant to 
10 CFR 431.401(h) for commercial and industrial equipment. Sections 
II.E.1, II.E.2, and II.E.3, below discuss and request comment on 
addressing single-package systems, wine cellar

[[Page 32343]]

refrigeration systems, and CO2 systems in the test 
procedure.

        Table II.3--Interim Waivers and Waivers Granted to Manufacturers of Walk-In Refrigeration Systems
----------------------------------------------------------------------------------------------------------------
                                                                                            Waiver decision and
            Manufacturer                       Subject            Interim Waiver Federal      order  Federal
                                                                     Register citation       Register citation
----------------------------------------------------------------------------------------------------------------
Air Innovations....................  Wine Cellar Refrigeration    86 FR 2403 (Jan. 12,    86 FR 23702 (May 4,
                                      Systems.                     2021).                  2021).
Vinotheque.........................  Wine Cellar Refrigeration    86 FR 11961 (Mar. 1,    86 FR 26504 (May 14,
                                      Systems.                     2021).                  2021).
CellarPro..........................  Wine Cellar Refrigeration    86 FR 11972 (Mar. 1,    86 FR 26496 (May 14,
                                      Systems.                     2021).                  2021).
Vinotemp...........................  Wine Cellar Refrigeration    86 FR 23692 (May 4,     (*)
                                      Systems.                     2021).
HTPG...............................  CO2 Unit Coolers...........  85 FR 83927 (Dec. 23,   86 FR 14887 (Mar. 19,
                                                                   2020).                  2021).
Hussmann...........................  CO2 Unit Coolers...........  86 FR 10046 (Feb. 18,   86 FR 24606 (May 7,
                                                                   2021).                  2021).
Keeprite...........................  CO2 Unit Coolers...........  86 FR 12433 (Mar. 3,    86 FR 24603 (May 7,
                                                                   2021).                  2021).
Store It Cold......................  Single-Package Systems.....  84 FR 11944 (Mar. 29,   84 FR 39286 (Aug. 9,
                                                                   2019).                  2019).
----------------------------------------------------------------------------------------------------------------
* A decision and order granting the manufacturer a waiver has not yet been issued.

    As noted earlier, during DOE's previous rulemaking to develop 
standards for WICF refrigeration systems, the accompanying Term Sheet 
included a series of amendments to the test procedure that the Working 
Group viewed as necessary to properly implement its recommended energy 
conservation standards. Ultimately, DOE published final rules 
implementing the majority of both sets of recommendations. See 82 FR 
31808, 31808-31838 (July 10, 2017) (final rule amending the energy 
conservation standards for walk-ins) and 81 FR 95758 (December 28, 
2016) (final rule amending the walk-in test procedures).
    Three test procedure-related recommendations from the Term Sheet, 
however, were not part of DOE's December 2016 TP final rule. (Term 
Sheet Recommendation #6). The Working Group believed these 
recommendations merited consideration by DOE as part of future 
amendments to help make the test procedure more fully representative of 
walk-in energy use. (Id.) Specifically, the Working Group recommended 
that DOE amend its procedure to (a) measure the energy use associated 
with the defrost function, taking into account the potential savings 
associated with hot gas and adaptive defrost, (b) incorporate the 
measurement of off-cycle power consumption, including crankcase heater 
power consumption, and (c) allow for separate ratings of stand-alone 
variable-capacity condensing units. (Id.). Sections II.E.4 through 
II.E.6 of this document discuss these issues in more detail.
    Sections II.E.7 and II.E.8 discuss other issues that may also 
improve the test procedure's ability to provide results that are more 
representative of walk-in energy use. Specifically, these include 
consideration of amended test procedures and new equipment classes for 
so-called high-temperature freezer refrigeration systems used for walk-
ins at temperatures between 10 [deg]F and 32 [deg]F, and discussion of 
the impact of refrigerant temperature glide \26\ of zeotropic 
refrigerants such as R407A.
---------------------------------------------------------------------------

    \26\ ``Temperature glide'' for a refrigerant refers to the 
increase in temperature at a fixed pressure as liquid refrigerant 
vaporizes during its conversion from saturated liquid to saturated 
vapor.
---------------------------------------------------------------------------

1. Single-Package Systems
    As discussed in the December 2016 TP final rule, single-package 
systems are considered a type of dedicated condensing refrigeration 
system. 81 FR 95758, 95763-95764. The test methods in AHRI 1250-2009, 
which are incorporated by reference as DOE's test procedure for walk-
ins (10 CFR 431.303(b)), do not fully address or account for the 
features of single-package systems. As discussed in the December 2016 
TP final rule, commenters asserted that one practical challenge to 
testing single-package systems is the need to disassemble the unit 
under test in order to be able to install the refrigerant mass flow 
meters required for testing. Id. at 95763. Mass flow measurement is a 
key input in the calculation of capacity, as illustrated in equations 
C1 and C2 of AHRI 1250-2009.
    Regarding this class of equipment, DOE received a petition for 
waiver with regard to testing of single-package units. By letter dated 
May 9, 2020, Store It Cold submitted a petition for waiver and interim 
waiver from Appendix C for basic models of single-package systems. 
(EERE-2018-BT-WAV-0002, No. 2) Store It Cold stated that testing 
single-package systems with refrigerant mass flow meters installed 
produces results unrepresentative of their true energy consumption 
characteristics and would provide materially inaccurate comparative 
data. The petitioner requested that DOE permit the use of psychrometric 
`air-side' measurements to determine the Gross Total Refrigeration 
Capacity of such systems. DOE granted a test procedure waiver and 
interim waiver to Store It Cold for specified basic models in 2019. 84 
FR 39286 (August 9, 2019) (``Store It Cold Decision and Order'').
    AHRI 1250-2020 addresses testing of single-package systems in 
section C9 and incorporates by reference test standards developed for 
testing air-conditioning units that include alternative test methods 
that have been adapted for testing single-package systems. The air 
enthalpy methods in section C9 of AHRI 1250-2020 incorporate by 
reference ANSI/ASHRAE Standard 37-2009 (``ASHRAE 37-2009''), ``Methods 
of Testing for Rating Electrically Driven Unitary Air-Conditioning and 
Heat Pump Equipment'' and ANSI/ASHRAE 41.6-2014 (``ASHRAE 41.6''), 
``Standard Method for Humidity Measurement''. The calorimeter methods 
in section C9 of AHRI 1250-2020 incorporate by reference ANSI/ASHRAE 
Standard 16-2016 (``ASHRAE 16-2016''), ``Method of Testing for Rating 
Room Air Conditioners, Packaged Terminal Air Conditioners, and Packaged 
Terminal Heat Pumps for Cooling and Heating Capacity''. The compressor 
calibration methods in section C9 of AHRI 1250-2020 incorporate by 
reference ASHRAE 37 and ANSI/ASHRAE 23.1-2010. AWEF calculations for 
matched pair and single-package systems are detailed in section 7.1.1 
through 7.1.4 of AHRI 1250-2020.
    AHRI 1250-2020 requires two simultaneous measurements of system 
capacity (i.e., a primary and secondary method), and section C9.2.1 of 
Appendix C provides a requirement that the measurements agree within 6 
percent. Table C4 to Appendix C to AHRI 1250-2020 details which of the 
test methods (calorimeter, air enthalpy, and compressor calibration) 
qualify as primary and/or secondary methods.
    Issue 25: DOE requests comment on whether the single-package system 
test

[[Page 32344]]

and calculation methods described in AHRI 1250-2020 provide 
representative energy use. DOE also requests comment on whether DOE 
should incorporate by reference AHRI 1250-2020 as the test procedure 
for single-package systems.
    DOE also notes that, unlike split systems (i.e., matched-pair 
refrigeration systems), single-package systems may experience 
additional thermal losses because they circulate cold walk-in air 
through a cold section that has exterior surfaces exposed to warm air 
outside the walk-in enclosure. This exposure can contribute to 
additional infiltration losses, i.e., leakage of air between the 
interior and exterior of a walk-in. Accordingly, if these losses occur, 
they would reduce the net capacity of a single-package system without 
being fully captured by the refrigerant enthalpy methods established in 
AHRI 1250-2009.
    Issue 26: DOE requests any data or calculations quantifying the 
additional thermal losses associated with testing single-package 
systems due to the exposure of their cold sides to the exterior air 
(i.e., surface and infiltration losses). DOE additionally requests 
comment on whether the AHRI 1250-2020 test methodology for single-
package systems fully accounts for these additional losses.
a. Calorimeter Method
    As previously mentioned, AHRI 1250-2020 incorporates by reference 
ASHRAE 16-2016 as its indoor and outdoor room calorimeter method test 
procedure. ASHRAE 16-2016 includes a calorimeter test method with 
similarities to the calibrated box test method of AHRI 1250-2009, but 
with additional details and provisions. ASHRAE 16-2016 is used to 
measure the capacity and power input of single-package system products 
such as room air conditioners that have hot and cold sections, similar 
to single-package walk-in systems. The ASHRAE 16-2016 calorimeter test 
includes both outdoor- and indoor-based calorimetric measurements of 
the capacity--the indoor side measurement is similar to that of the 
calibrated box test method, while the outdoor side provides a 
determination of system cooling capacity by measuring the cooling 
required to maintain the outdoor room temperature and humidity 
conditions.
    DOE's work in evaluating single-package systems using the 
calorimeter methods referenced in AHRI 1250-2020 has highlighted the 
need to make very precise determination of the calorimeter chamber 
cooling fluid heat capacity. This fluid cannot be pure water, since it 
must be below water freezing temperature for testing WICF refrigeration 
systems. This makes precise determination of heat capacity more 
challenging, since an accurate determination of glycol concentration is 
required.
    Issue 27: DOE requests comment and data on the use of water, 
glycol, or other heat transfer liquid in maintaining test compartment 
temperature using the calorimeter methods referenced in AHRI 1250-2020 
for the testing of single-package refrigeration systems. DOE requests 
comment on whether the description and requirements for calorimetric 
testing as provided in AHRI 1250-2020 should be modified or enhanced in 
order to better ensure that measurements are accurate and repeatable.
    In addition, ASHRAE 16-2016 requires that a pressure-equalizing 
device be installed between the indoor and outdoor test compartments to 
maintain a balanced pressure between the compartments and to measure 
the air flow required to maintain equalization. Assuming the test 
facility is otherwise airtight, the air flow transferred and measured 
by the pressure-equalizing device represents air transferred in the 
opposite direction through leaks inside the equipment as a result of 
pressure differences between the warm and cold side of the system set 
up by its fans.
    Given that the related calibrated box test method has no 
requirements for pressure equalization, DOE is considering the need for 
pressure equalization for single-package testing. Alternatives include 
(a) no requirement addressing transfer air or pressure equalization, or 
(b) a requirement that the test facility chambers be leak-free with no 
equalization requirement. DOE expects that the use of a pressure 
equalization apparatus would incrementally increase test facility cost 
and test burden, and would ensure operation with losses consistent with 
the measured air leakage, but such equalized pressure conditions may 
not be representative of WICF refrigeration system use. The alternative 
options may reduce facility cost and test burden. Option (a) may reduce 
accuracy and repeatability, while both options may mask potential 
performance degradation associated with air leakage.
    Issue 28: DOE requests comment on whether calorimeter test methods 
for single-package systems should implement a pressure-equalizing 
device, as included in ASHRAE 16-2016. DOE requests information on any 
additional cost and resource burdens, if any, manufacturers would face 
when employing these methods to evaluate single-package systems.
    Issue 29: DOE seeks comment regarding any alternative test methods 
not mentioned in this document that could be used to measure single-
package system capacity. To the extent that any alternative test 
methods could be used for this purpose, DOE requests information on 
their advantages and disadvantages in measuring single-package system 
capacity.
2. Wine Cellar Refrigeration Systems
    DOE is aware of certain equipment within the walk-in definition 
that may be incapable of being tested in a manner that would yield 
results measuring the energy efficiency or energy use of that equipment 
during a representative average use cycle under the current version of 
the walk-in test procedure. Specifically, wine cellars that are 
installed in a variety of commercial settings are set to operate at a 
temperature range of 45 [deg]F to 65 [deg]F. They also meet the 
criteria established by Congress in the definition for a walk-in. See 
generally 42 U.S.C. 6311(20). Under the walk-in test procedure, walk-in 
coolers must be tested while operating at 35 [deg]F. Section 3.1.1 of 
Appendix C. Wines often suffer from damage when stored at temperatures 
below 45 [deg]F. To the extent that a wine cellar is not operated at 35 
[deg]F, applying the required 35 [deg]F testing temperature condition 
when evaluating the energy usage of this equipment would not produce 
results representative of an average use cycle.
    DOE has received requests for waiver and interim waiver from 
several manufacturers from the test procedure in Appendix C for basic 
models of wine cellar refrigeration systems.\27\( ). Manufacturers 
stated that wine cellars are intended to operate at a temperature range 
of 45 to 65 [deg]F and 50-70 percent relative humidity, rather than the 
35 [deg]F and less than 50 percent relative humidity test condition 
prescribed in Appendix C. Manufacturers asserted that testing at 35 
[deg]F would be unrepresentative of the true energy consumption 
characteristics of the specified units and that operation at this 
temperature may damage wine cellar refrigeration units. Given the 
number of waivers that DOE received, DOE

[[Page 32345]]

engaged with AHRI, the industry trade association, to discuss how to 
develop a consistent alternate test approach for wine cellars that 
would be applicable to all impacted manufacturers. Ultimately, AHRI 
submitted a memorandum on behalf of its wine cellar members supporting 
(1) a 45 [deg]F minimum operating temperature for wine cellar 
refrigeration systems, and (2) testing at 50 percent of maximum 
external static pressure, with manufacturers providing maximum external 
static pressure values to DOE.\28\ After reviewing manufacturer 
websites, product specification sheets, suggested alternate test 
approaches provided by each manufacturer and by AHRI, and after 
soliciting and reviewing feedback from the public, DOE has granted 
interim waivers or waivers as summarized in Table II.3.
---------------------------------------------------------------------------

    \27\ Air Innovations, Vinotheque Wine Cellars, Cellar Pro 
Cooling Systems, Vinotemp International Corp., and LRC Coil Company, 
respectively, submitted petitions for waivers and interim waivers 
for basic models of wine cellar walk-in refrigeration systems. (Air 
Innovations, EERE-2019-BT-WAV-0029, No. 6; Vinotheque, EERE-2019-BT-
WAV-0038, No. 6; CellarPro, EERE-2019-BT-WAV-0028, No. 6; Vinotemp, 
EERE-2020-BT-WAV-0022, No. 10; LRC Coil, EERE-2020-BT-WAV-0040, No. 
1).
    \28\ Memorandum from AHRI, ``Department of Energy (DOE) Wine 
Cellar Cooling Systems Test Procedure Waiver Industry Comments from 
AHRI Membership'', August 18, 2020. (EERE-2019-BT-WAV-0028, No. 5 
(CellarPro); EERE-2019-BT-WAV-0029, No. 5 (Air Innovations); EERE-
2019-BT-WAV-0038, No. 5 (Vinotheque); EERE-2019-BT-WAV-022, No. 2 
(Vinotemp))
---------------------------------------------------------------------------

    These waivers have addressed testing for single-package, matched-
pair, and unit-cooler-only wine cellar refrigeration systems. The 
alternative test procedures prescribed in these waivers address a 
number of differences in operation between wine cellar refrigeration 
systems and other walk-in refrigeration systems, including the 
following:
     Unit cooler air inlet condition of 55 [deg]F and 55 
percent RH, compared to 35 [deg]F and less than 50 percent RH for 
medium-temperature refrigeration systems in the DOE test procedure;
     For single-package wine cellar systems, capacity 
measurement is conducted using a primary and a secondary capacity 
measurement method as specified in AHRI 1250-2020, using two of the 
following: The indoor air enthalpy method; the outdoor air enthalpy 
method; the compressor calibration method; the indoor room calorimeter 
method; the outdoor room calorimeter method; or the balanced ambient 
room calorimeter method.
     Options for ducting on the condenser side, evaporator 
side, or both with specifications for setting the external static 
pressure.
     For calculating AWEF, the wine cellar box load level is 
set equal to half of the refrigeration system capacity at the 95 [deg]F 
test condition (for outdoor refrigeration systems) or 90 [deg]F (for 
indoor refrigeration systems), rather than using a two-tiered set of 
high- and low-load period box load levels, as prescribed in AHRI 1250-
2009. For calculating AWEF, the evaporator fan is assumed to operate 
for one-tenth of the compressor off-cycle period at the same wattage as 
applies for the compressor on-cycle. This contrasts with varying 
assumptions used for other WICF refrigeration systems, depending on the 
type of evaporator fan controls they use.
    Issue 30: DOE requests comment on the alternative test procedure 
for wine cellar walk-in refrigeration systems that it has granted in 
the interim waivers and waivers listed in Table II.3. DOE additionally 
seeks comment on whether the alternative test procedure prescribed for 
the specified basic models identified in the waivers would be 
appropriate for similar refrigeration equipment.
    As noted previously, wine cellar refrigeration systems are designed 
for both ducted and non-ducted air delivery; the DOE test procedure 
does not address the testing of ducted systems. For systems that can be 
installed with (1) ducted evaporator air, (2) with or without ducted 
evaporator air, (3) ducted condenser air, or (4) with or without ducted 
condenser air, the alternate test approach requires testing to be 
conducted at 50 percent of the maximum external static pressure 
(``ESP''), subject to a tolerance of -0.00/+0.05 in. DOE understands 
that maximum ESP is generally not published in available literature 
such as installation instructions, but manufacturers do generally 
specify the size and maximum length of ductwork that is acceptable for 
any given unit in such literature. The duct specifications determine 
what ESP would be imposed on the unit in field operation.\29\ The 
provision of allowable duct dimensions is more convenient for 
installers than maximum ESP, since it relieves the installer from 
having to perform duct pressure drop calculations to determine ESP. 
This approach differs from the approach used in related products/
equipment, e.g., air conditioners, where ESP is a function of 
capacity--ESP does not correlate well with capacity for wine cellar 
refrigeration systems.
---------------------------------------------------------------------------

    \29\ The duct material, length, diameter, shape, and 
configuration are used to calculate the ESP generated in the duct, 
along with the temperature and flow rate of the air passing through 
the duct. The conditions during normal operation that result in a 
maximum ESP are used to calculate the reported maximum ESP values, 
which are dependent on individual unit design and represent 
manufacturer-recommended installation and use.
---------------------------------------------------------------------------

    Issue 31: DOE requests feedback on its approach for testing ducted 
units in its alternate test procedure for wine cellar refrigeration 
systems. Specifically, DOE requests comment and supporting data on 
whether testing at 50 percent of maximum ESP provides representative 
performance values, or whether other fractions of maximum ESP may be 
more appropriate. Additionally, DOE seeks comment on other industry 
test methods that include the testing of ducted units. Finally, DOE is 
interested in other alternative approaches for testing ducted units 
that have been demonstrated to provide repeatable and representative 
results.
    The above discussion assumes that wine cellar refrigeration systems 
are either a single-package system or a matched-pair.\30\ However, DOE 
has also received a petition for waiver for unit coolers that are 
distributed into commerce without a paired condensing system.\31\ DOE 
recognizes that these unit cooler-only models will need to be tested 
according to the provisions in AHRI 1250-2020 for unit coolers tested 
alone, for which calculation of AWEF requires use of an appropriate EER 
based on the suction dew point temperature. Table 18 in AHRI 1250-2020 
provides EER values for medium and low temperature unit coolers tested 
alone. However, these values may not be appropriate for calculating 
AWEF for wine cellar unit coolers because this equipment likely 
operates with different suction dew point temperature and the 
counterpart condensing units likely use different compressor designs 
than those considered when developing the current EER values.
---------------------------------------------------------------------------

    \30\ A ``matched refrigeration system'' is also called a 
``matched pair'' and is a refrigeration system where the condensing 
system is distributed into commerce with a specific unit cooler(s). 
See 10 CFR 431.302.
    \31\ LRC Coil Company submitted a petition for waiver and 
interim waiver for specific basic models of unit cooler only walk-in 
wine cellar refrigeration systems. (LRC Coil, EERE-2020-BT-WAV-0040, 
No. 1) In reviewing another petition for waiver and interim waiver 
from Vinotheque for single-package system and matched-pair system 
basic models (Vinotheque, EERE-2019-BT-WAV-0038, No. 6), DOE noted 
that the manufacturer also offered unit cooler only systems 
distributed without a paired condensing system.
---------------------------------------------------------------------------

    Issue 32: DOE requests data and information on appropriate EER 
values for use in calculating AWEF for wine cellar unit coolers tested 
alone, and how these EER values might depend on refrigerant and/or 
capacity. DOE requests that commenters provide background explanation 
regarding how any such EER recommendations have been developed.
    Issue 33: Since unit coolers for wine cellar systems are sold 
alone, DOE seeks information on the characteristics of condensing units 
that would typically be paired with these unit coolers (e.g., make/
model, compressor style, capacity range, manufacturers).

[[Page 32346]]

    Additionally, DOE notes that its definitions for ``single-packaged 
system'' and ``unit cooler'' may not appropriately define ducted units. 
DOE currently defines a ``single-packaged dedicated system'' as ``a 
refrigeration system (as defined in this section) that is a single-
package system assembly that includes one or more compressors, a 
condenser, a means for forced circulation of refrigerated air, and 
elements by which heat is transferred from air to refrigerant, without 
any element external to the system imposing resistance to flow of the 
refrigerated air. 10 CFR 431.302. Similarly, DOE defines a ``unit 
cooler'' as ``an assembly, including means for forced air circulation 
and elements by which heat is transferred from air to refrigerant, thus 
cooling the air, without any element external to the cooler imposing 
air resistance. Id. Both definitions describe a single-package or unit 
cooler system, respectively, that is not ducted (i.e., there is no 
element external to the unit that imposes air resistance).
    Issue 34: DOE seeks comment on whether, and if so how, it should 
modify its definitions for ``single-packaged dedicated system'' and 
``unit cooler'' to address units that are designed to be installed with 
ducts.
    Issue 35: DOE requests comment on any other issues regarding 
testing of wine cellar refrigeration systems that may not be fully 
addressed by the current DOE test procedure.
3. CO2 Systems
    DOE has also become aware of WICF unit coolers that are being used 
in CO2 transcritical booster systems that cannot be tested 
using the current set of test conditions. DOE has received several test 
procedure waiver petitions regarding CO2 unit coolers used 
in transcritical booster systems.
    Heat Transfer Product Group (``HTPG''), Hussmann, and Keeprite 
submitted petitions for waivers and interim waivers from Appendix C for 
specific basic models of CO2 direct expansion unit 
coolers).\32\ The DOE test procedure for unit coolers requires testing 
with liquid inlet saturation temperature of 105 [deg]F and liquid inlet 
subcooling temperature of 9 [deg]F, as specified by Tables 15 and 16 of 
AHRI 1250-2009. However, CO2 has a critical temperature of 
87.8 [deg]F; therefore, it does not coexist as saturated liquid and gas 
above this temperature. The liquid inlet saturation temperature of 105 
[deg]F and the liquid inlet subcooling temperature of 9 [deg]F 
specified in Appendix C are not achievable by CO2 unit 
coolers. The three petitioners requested that DOE modify the test 
condition values to reflect typical operating conditions for a 
transcritical CO2 booster system (i.e., a liquid inlet 
saturation temperature of 38 [deg]F and a liquid inlet subcooling 
temperature of 5 [deg]F). After reviewing manufacturer websites, 
product specification sheets, and suggested alternate test approaches 
provided by each manufacturer, DOE has granted waivers or interim 
waivers to the manufacturers listed in Table II.3.
---------------------------------------------------------------------------

    \32\ Heat Transfer Products Group, Hussmann Corporation, and 
Keeprite Refrigeration, respectively, submitted petitions for 
waivers and interim waivers for basic models of CO2 unit 
coolers used in transcritical booster systems. (HTPG, EERE-2020-BT-
WAV-0025, No. 1; Hussmann, EERE-2020-BT-WAV-0026, No. 1; Keeprite, 
EERE-2020-BT-WAV-0028, No. 1).
---------------------------------------------------------------------------

    DOE is seeking comment on how to address CO2 system 
testing in a way that is representative of the average use cycle for 
these units and is not unduly burdensome to conduct.
    Issue 36: DOE requests comment on test conditions that would be 
most appropriate for evaluating the energy use of CO2 unit 
coolers. Additionally, DOE requests feedback on any additional changes 
that would need to be made to the DOE test procedure to accurately 
evaluate energy use of these systems, while minimizing test burden.
    While all CO2 refrigerant waiver petitions DOE has thus 
far received address unit coolers for use in transcritical booster 
systems, it is possible that other CO2 refrigeration system 
configurations may be relevant in the future, e.g., dedicated 
condensing units (``DCUs''), matched pairs, or single-package systems. 
DOE reviewed product literature and other information for 
CO2 systems having some of these alternative configurations. 
Most of this information pertains to manufacturers operating in Europe.
    Issue 37: DOE requests comment on the present and future expected 
use of walk-in refrigeration systems using CO2. DOE requests 
specific information about these systems that would suggest a need to 
modify the DOE test procedure to address such equipment. Specifically, 
DOE requests information on whether such equipment is sold in the U.S., 
whether this equipment is sold as matched pairs or individual 
components, and to what extent dedicated condensing units are 
configured to supply subcritical liquid (rather than supercritical gas) 
to the unit coolers.
4. Defrost Test Method
    The April 2011 TP final rule incorporated AHRI 1250-2009 as DOE's 
WICF refrigeration system test procedure, including that standard's 
requirement that both frosted and dry coil defrost tests be conducted. 
Appendix C, Section 3. DOE later noted in the February 2014 AEDM TP 
SNOPR that this requirement may be overly burdensome for manufacturers 
to conduct, due to the difficulty of maintaining the moist air 
infiltration conditions for the frosted coil test in a repeatable 
manner. 79 FR 9818, 9831. Accordingly, in DOE's May 2014 AEDM TP final 
rule, DOE adopted a set of nominal values for calculating defrost 
energy use for a frosted coil, number of defrosts per day if the unit 
has an adaptive defrost system, and daily contribution of heat 
load.\33\ 79 FR 27388, 27401. To address testing low-temperature 
condensing units alone, the May 2014 AEDM TP final rule established 
nominal values for the defrost energy use and thermal load. In 
addressing refrigeration systems with hot gas defrost, the May 2014 
AEDM TP final rule established nominal values for calculating hot gas 
defrost energy use and heat load. Id.
---------------------------------------------------------------------------

    \33\ In a ``hot gas'' defrost system, high-temperature, high-
pressure hot refrigerant gas from the discharge side of the 
compressor is introduced into the evaporator, where it condenses, 
thereby releasing latent heat into the evaporator. This heat is used 
to melt the frost that has accumulated on the outside of the 
evaporator coil.
---------------------------------------------------------------------------

    The December 2016 TP final rule removed the method for calculating 
the defrost energy and defrost heat load of systems with hot gas 
defrost and established a new method to evaluate hot gas defrost 
refrigeration systems. That new method treated these hot gas defrost 
refrigeration systems as if they used electric defrost rather than hot 
gas defrost. This method relied on the same nominal values for defrost 
energy use and thermal load that the test procedure prescribes for 
electric-defrost condensing units that are tested alone. 81 FR 95758, 
95774-95777. This approach was modified in the March 2021 hot gas 
defrost TP final rule that amended the test procedure to rate hot gas 
defrost unit coolers using modified default values for energy use and 
heat load contributions that would make their ratings more consistent 
with those of electric defrost unit coolers. 86 FR 16027. The scope of 
the March 2021 hot gas defrost TP final rule is limited to unit coolers 
only. 86 FR 16027, 16030.
a. Moisture Addition
    DOE is considering whether using a test method--possibly similar to 
the one detailed in section C11.3 of AHRI 1250-2009--to measure the 
energy use associated with the defrosting of frosted coils would 
provide a reasonably accurate accounting of defrost energy

[[Page 32347]]

usage and savings associated with technologies such as adaptive defrost 
and hot gas defrost. DOE is also considering adopting a test method to 
assess and confirm defrost adequacy. Any test method used to measure 
defrost energy use and adequacy would have to provide consistent, 
repeatable methods for (1) delivering a frost load to the test coil and 
(2) measuring the thermal load released into the refrigerated space 
during the defrost cycle, regardless of the method of defrost (e.g., 
electric or hot gas defrost), all while ensuring that the procedure 
provides results reflecting energy usage during a representative 
average use cycle and not be unduly burdensome to conduct.
    In AHRI 1250-2009, the moisture to provide a frost load is 
introduced through the infiltration of air at 75.2 [deg]F dry-bulb 
temperature and 64.4 [deg]F wet-bulb temperature into the walk-in 
freezer at a constant airflow rate that depends on the refrigeration 
capacity of the tested freezer unit (equations C11 and C12 in section 
C11.1.1 of AHRI 1250-2009). A key issue with this approach is the 
difficulty in ensuring repeatable frost development on the unit under 
test, despite specifying the infiltration air dry-bulb and wet-bulb 
temperatures. For example, in addition to frost accumulating on the 
evaporator of the unit under test, frost may also accumulate on the 
evaporator of other cooling equipment used to condition the room, which 
could subsequently affect the rate of frost accumulation on the unit 
under test (by affecting the amount of moisture remaining in the air).
    ASHRAE-supported research--including a series of projects exploring 
frost loads and defrosting dynamics--suggest the possibility of 
alternative methods of creating a frost load. This work includes ASHRAE 
Project No. 622-RP ``A Study to Determine Heat Loads Due to Coil 
Defrosting'' \34\ (``622-RP'') and Project No. 1094-RP ``A Study to 
Determine Heat Loads Due to Coil Defrosting-Phase II'' \35\ (``1094-
RP''). For the experiments discussed in these reports, the researchers 
created a frost load by introducing steam directly into the 
refrigerated space. However, as discussed in 1094-RP, this approach can 
result in the suspension of ice crystals in the saturated room air and 
the formation of snow-like frost on the test coils. The researchers 
found that this snow-like frost degrades refrigeration system 
performance more, and is more difficult to defrost, than the ice-like 
frost that forms in sub-saturated air conditions. 622-RP and 1094-RP 
also observed that during the defrost cycle, a significant portion (a 
majority for some trials) of the coil frost was sublimated (converted 
to water vapor) rather than melted. This finding suggests that 
measuring the quantity of frost melt water mass may be a poor indicator 
of the frost load, since a significant portion of the frost would not 
be captured as melt water. DOE is interested in any viable alternate 
frost load delivery methods that could be used to apply a known and 
repeatable amount and type of frost.
---------------------------------------------------------------------------

    \34\ Sherif, S.A., P.J. Mago, and R.S. Theen. A Study to 
Determine Heat Loads Due to Coil Defrosting. 1997. University of 
Florida: Gainesville, FL. ASHRAE Project No. 622-RP. Report No. 
UFME/SEECL-9701.
    \35\ Sherif, S.A., P.J. Mago, and R.S. Theen. A Study to 
Determine Heat Loads Due to Coil Defrosting- Phase II. 2003. 
University of Florida: Gainesville, FL. ASHRAE Project No. 1094-RP. 
Report No. UFME/SEECL-200201.
---------------------------------------------------------------------------

    Issue 38: DOE requests information regarding potential methods of 
providing a measurable frost load and frost type for defrost testing, 
including data and information demonstrating the repeatability of such 
a test. Additionally, DOE requests data and information indicating what 
a typical frost load and frost type would be--for example, whether the 
moist air flow of section C11.1.1 of AHRI 1250-2009 provides the 
appropriate amount of moisture, and if so, whether any data are 
available to support the use of this quantity. If such data are 
available, DOE asks that interested parties share it with the agency 
for further consideration. If such data are currently unavailable, DOE 
is interested in what kind and amount of testing would be needed to 
sufficiently validate an appropriate method to evaluate frost loads and 
frost types during defrost testing.
b. Hot Gas Defrost
    Among its various recommendations, the Working Group recommended 
that DOE modify its current test procedure to account for hot gas 
defrost system performance. (Term Sheet Recommendation #6). As a result 
of this recommendation, DOE is interested in obtaining feedback on the 
most practicable method for measuring or otherwise accounting for hot 
gas defrost performance.\36\ DOE recognizes that in order to assess the 
energy performance of a defrost cycle, the test procedure must address 
both the energy consumed and the heat released into the refrigerated 
space by the defrost system. In general, for electric resistance 
heating systems, all the electrical energy consumed by the heater is 
transformed into heat, such that the energy consumed by the heater and 
the heat released into the space are equivalent. The procedure outlined 
in AHRI 1250-2009 is based on this principle and estimates the amount 
of heat released into the space by measuring energy consumption and 
subtracting the energy associated with frost melt that drains out of 
the chamber (section C11.1 of AHRI 1250-2009).
---------------------------------------------------------------------------

    \36\ As previously mentioned, the March 2021 hot gas defrost TP 
final rule updated the defrost energy use and thermal load equations 
for hot gas defrost unit coolers tested alone to provide a 
consistent performance evaluation between hot gas defrost and 
electric defrost unit coolers when tested alone. 86 FR 16027, 16030. 
However, this approach does not measure or account for actual hot 
gas defrost thermal load and energy use.
---------------------------------------------------------------------------

    Alternatively, for hot gas defrost systems, the heat energy 
released into the evaporator (in the form of latent heat), and 
ultimately into the refrigerated space, is greater than the electrical 
energy used by the compressor to drive the hot gas defrost system. The 
exact ratio of heat released to electrical energy consumed depends on 
the efficiency of the specific system design. Therefore, the amount of 
heat released into the room cannot be estimated by measuring the 
electrical energy consumption of the heating system. Because the 
procedure outlined in AHRI 1250-2009 relies on an assumption that the 
energy consumed by the heater equals the heat released into the space, 
it is not applicable to hot gas defrost systems. DOE is not aware of a 
test method that can reliably be used to directly measure the thermal 
impact of hot gas defrost without a substantial increase in test 
burden.
    Alternatively, DOE could consider the use of a calculation method. 
In such an approach, rather than measure the heat released into the 
refrigerated space for the unit-under-test, that heat load would be 
calculated as a function of the refrigeration system's steady-state 
capacity. The heat load-to-capacity relationship could be defined based 
on test data from actual hot gas defrost systems. Under this approach, 
the energy consumed by the hot gas defrost system could be quantified 
either by direct testing and measurement, or by using a calculation 
method, as described for heat load addition. DOE is aware that AHRI has 
developed a calculation method to represent hot gas defrost heat load 
and energy use contributions. This method is provided in Section C10.1 
of AHRI 1250-2020 and prescribes equations to represent energy use and 
heat addition associated with defrost for different system 
configurations (matched-pair, single-package, unit cooler, condensing 
unit) and with consideration of whether hot gas is used only to defrost 
the evaporator or

[[Page 32348]]

whether it also maintains warm temperatures in the drip pan.
    Finally, if DOE were to modify its walk-in test procedure to 
account for hot gas defrost energy consumption and heat load, DOE would 
need to determine the types of refrigeration system configurations 
(i.e., matched-pairs, stand-alone unit coolers, and stand-alone 
condensing units) to which a hot gas defrost-specific test procedure 
would apply. For each configuration, DOE would also need to consider 
which methods (i.e., testing, calculation, or both) would be most 
appropriate.
    Issue 39: DOE requests comment on the specific refrigeration system 
configurations (i.e., matched-pairs, stand-alone unit coolers, and 
stand-alone condensing units) to which a hot gas defrost-specific test 
procedure would apply. DOE requests comment on which methods for 
determining energy and heat load (i.e., testing, calculation, or both) 
would be most appropriate for each refrigeration system and why. DOE 
requests comment on the methods related to hot gas defrost systems in 
AHRI 1250-2020. Finally, DOE requests data to help quantify the 
relationship between hot gas defrost heat load addition and energy 
consumption versus capacity and/or to confirm the relationships 
provided in the AHRI 1250-2020 test methods for hot gas defrost.
c. Adaptive Defrost
    In the December 2016 TP final rule, DOE established a method to 
address systems with adaptive defrost. That approach requires that the 
feature be deactivated during compliance testing but allows a 
manufacturer to account for a unit's improved performance with adaptive 
defrost activated in its market representations. 81 FR 95758, 95767, 
95777, 95790. At the November 4, 2015 Working Group meeting, Southern 
California Edison expressed concern with the assumption that the 
overall energy use of traditional defrost systems significantly exceeds 
adaptive defrost system energy use. Southern California Edison 
presented data showing that, for a tested adaptive defrost system, the 
reduction in energy use resulting from reduced defrost frequency is 
largely offset by an increase in energy use during the refrigeration 
on-cycle, due to the thermal resistance of the increased frost 
accumulation (Docket EERE-2015-BT-STD-0016, No. 38 \37\). The data 
presented by Southern California Edison illustrates just one potential 
complication in properly addressing the energy use impact of adaptive 
defrost--specifically, that an adaptive system that waits too long 
(i.e., when too much frost builds up on the coils) to defrost may 
significantly affect the on-cycle performance of the refrigeration 
system. On the other hand, an adaptive system that defrosts too 
frequently could increase defrost energy use if the defrost frequency 
is higher than the four defrosts per day that is typical for a 
conventional timed defrost. The sensitivity of the adaptive defrost 
savings potential to the magnitude of the moisture load also suggests 
that a single adaptive defrost test using a constant moisture load may 
not properly represent this technology's benefits. The test procedure 
may have to account for the differences in daily and seasonal frosting 
patterns experienced by installed systems (e.g., frequent air 
infiltration during business hours and none during non-business hours--
or infiltration of warm, moist air in summer and cool, dry air in 
winter).
---------------------------------------------------------------------------

    \37\ Working Group Meeting Stakeholder Presentation: Walk-in 
Refrigeration ASRAC Meeting, available at https://www.regulations.gov/document?D=EERE-2015-BT-STD-0016-0038.
---------------------------------------------------------------------------

    Issue 40: DOE requests comment on how the performance of adaptive 
defrost systems should be accounted for in the walk-in test procedure 
and which refrigeration systems (i.e., matched-pairs, stand-alone unit 
coolers, and stand-alone condensing units) should be evaluated under a 
potential adaptive defrost test procedure. Specifically, DOE requests 
data showing the performance of adaptive defrost systems relative to 
non-controlled defrost systems, including impacts to on-cycle 
operation. DOE requests data demonstrating seasonal and daily frosting 
patterns for walk-in applications.
5. Off-Cycle Energy Use
    As discussed previously, the Working Group recommended that DOE 
amend its test procedure to address issues related to off-cycle power 
consumption (Term Sheet Recommendation #6). For walk-in refrigeration 
systems, the term ``off-cycle'' refers to the period when the 
compressor is not running and defrost (if applicable) is not active. 
During the off-cycle, unit cooler fans and other auxiliary equipment 
will typically run or cycle on and off, thereby consuming energy.
    While the current DOE test procedure accounts only for fan power 
consumption during the off-cycle period, AHRI 1250-2020 includes 
requirements specific to off-cycle fan power consumption in Section 
C3.5, which addresses power measurements for unit coolers (including 
total power to the fan motor(s), pan heaters, and controls) and DCUs, 
in addition to prescribing off-cycle measurement intervals, operating 
tolerances and data collection rates. Section C4.2 provides a method 
for determining off-cycle power consumption. DOE is considering the 
incorporation of this updated industry test method into its test 
procedures should a rulemaking be initiated.
    Issue 41: DOE requests information and data on whether the off-
cycle methods included in AHRI 1250-2020 provide a representative and 
repeatable measure of the off-cycle power use for matched pairs, 
single-package systems, and also for unit coolers and/or condensing 
units tested alone, and if not, what modifications are recommended. DOE 
also seeks information on other off-cycle mode energy-consuming 
components that are not currently addressed by AHRI 1250-2020. In 
addition to identifying all off-cycle mode energy-consuming components, 
DOE seeks information on the patterns and magnitudes of energy use by 
each of these components during the off-cycle.
6. Multi-Capacity and Variable-Capacity Condensing Units
    In the July 2017 ECS final rule, DOE noted that it expected the 
majority of refrigeration equipment within the dedicated condensing 
class to be certified as stand-alone condensing units, with a much 
smaller number of systems certified as matched-pairs. 82 FR 31808, 
31832. However, the current DOE test procedure does not include a 
method for assessing stand-alone multi- and variable-capacity systems. 
To address this gap, the Working Group recommended that DOE amend its 
test procedure to allow for separate ratings of stand-alone variable-
capacity condensing units. (Term Sheet Recommendation #6).
    Historically, refrigeration systems have been designed using a 
single-speed compressor, which operates at full cooling capacity while 
the compressor is on. To match the cooling load of the space, which in 
most cases is less than the full cooling capacity of the compressor, a 
single-speed compressor cycles on and off at a particular duty cycle. 
This cycling behavior introduces inefficiencies due to the surge in 
power draw experienced at the beginning of each ``on'' cycle, before 
the compressor reaches steady-state performance. In contrast, variable-
capacity systems employ an inverter compressor that can reduce its 
speed to match the observed cooling load. Accordingly, a variable-speed 
compressor runs continuously, adjusting its speed up or down as 
required, thereby avoiding compressor cycling when the full cooling 
capacity

[[Page 32349]]

of the compressor is not necessary to provide sufficient cooling to the 
space. Similarly, a multi-capacity compressor can ``unload'' individual 
cylinders within the compressor, which allows the compressor to remain 
on, but at a reduced capacity, to more closely match the required 
cooling load.
    The current DOE test procedure measures the performance of a walk-
in condensing unit while operating under a full cooling load at a fixed 
capacity; i.e., the compressor is operated continuously in its ``on'' 
state. See AHRI 1250-2009, Tables 11 through 14 and Appendix C, section 
3.0. While AHRI 1250-2009 and AHRI 1250-2020 both include test methods 
for multi- and variable-capacity matched pair refrigeration systems, 
there is no test method for multi- and variable-capacity condensing 
units when tested alone. As a result, any inefficiencies due to 
compressor cycling, and any performance benefit associated with part-
load operation, are not captured during the DOE test. Consequently, the 
current test procedure may underestimate the efficiency benefits of 
multi- and variable-capacity systems. DOE is aware of some multi- or 
variable- capacity condensing units that are currently available on the 
market.\38\
---------------------------------------------------------------------------

    \38\ Multi-capacity product information from one manufacturer 
can be found at http://www.regulations.gov Docket No. EERE-2017-BT-
TP-0010-0004.
---------------------------------------------------------------------------

    Issue 42: DOE requests input on the development of test methods 
that would more accurately measure the energy use performance--
including accounting for the potential efficiency benefits of multi- 
and variable-capacity systems--both for matched-pair and stand-alone 
condensing unit testing. DOE seeks data and information showing the 
potential magnitude of energy savings by reducing cycling losses in 
these multi and variable-capacity systems. DOE requests market 
information on whether there are multi- and variable-capacity 
condensing units available on the market (in addition to those already 
identified) and the brand name(s) and model numbers of those additional 
units.
7. Systems for High-Temperature Freezer Applications
    In the June 2014 ECS final rule, DOE established equipment classes 
for medium- and low-temperature walk-in refrigeration systems. 79 FR 
32050, 32069-32070. While the terms ``medium-temperature'' and ``low-
temperature'' are not explicitly defined, the June 2014 ECS final rule, 
2015 ASRAC negotiations, December 2016 TP final rule, and July 2017 ECS 
final rule all consistently used the term ``medium-temperature'' to 
refer to walk-in cooler/refrigerator refrigeration systems and the term 
``low-temperature'' to refer to walk-in freezer refrigeration systems.
    The current test procedure for walk-in refrigeration systems 
specifies rating conditions of 35 [deg]F for refrigerator systems and -
10 [deg]F for freezer systems (see section 5 of AHRI 1250-2009, 
incorporated by reference at 10 CFR 431.303(b)). The 35 [deg]F and -10 
[deg]F rating conditions produce a metric, AWEF, which is generally 
representative of the medium- and low-temperature refrigeration 
systems' energy use when installed in walk-in coolers and freezers, 
respectively. The AWEF metric forms the basis for energy conservation 
standards for medium- and low-temperature refrigeration systems. 
However, field usage data indicate that walk-in refrigeration systems 
operate at a broad range of application temperatures both above and 
below the respective 35 [deg]F and -10 [deg]F rating points.
    As discussed in the December 2016 TP final rule, stakeholders 
commented that so-called ``high-temperature'' freezer walk-ins, which 
have an enclosed storage (i.e. room) temperature range of 10 [deg]F to 
32 [deg]F, are refrigerated with medium-temperature condensing units. 
81 FR 95758, 95790. Under the statutory definitions of ``walk-in 
cooler'' and ``walk-in freezer,'' this equipment would be considered a 
walk-in freezer because its room temperature is less than or equal to 
32 [deg]F 42 U.S.C. 6311(20). Accordingly, these refrigeration systems 
would be tested using a room temperature of-10 [deg]F, as specified in 
Appendix C. However, stakeholders commented as to the difficulty these 
medium-temperature refrigeration systems have in meeting this 
temperature condition when using lower GWP refrigerants.\39\ 81 FR 
95758, 95790. Lennox offered data suggesting that medium-temperature 
units generally perform more efficiently at the 10 [deg]F operating 
condition (i.e., the low end of the cited ``high-temperature freezer'' 
temperature range) than low-temperature systems. (Docket EERE-2015-BT-
STD-0016, Lennox, No. 89 \40\ at pp. 2-5) Lennox suggested that this 
``high-temperature freezer'' application may justifiably represent a 
third class of walk-in refrigeration systems, but also noted the 
reporting and testing burden that establishing an additional set of 
classes would incur. In response, DOE noted that manufacturers of 
equipment that cannot be tested in a way that properly represents their 
performance characteristics may petition DOE for test procedure 
waivers, as detailed in 10 CFR 431.401. DOE also indicated that it may 
consider amending its regulations by establishing new equipment classes 
and applicable test methods. 81 FR 95758, 95790-95791.
---------------------------------------------------------------------------

    \39\ Lennox commented that the industry was moving to low-GWP 
refrigerants in response to the Environmental Protection Agency 
final rule under the Significant New Alternatives Policy (``SNAP'') 
program that prohibited the use of R-404A in certain retail food 
refrigeration applications, including WICF refrigeration systems 
starting July 20, 2016. (Docket EERE-2016-BT-TP-0030, Lennox, No. 13 
at p. 2) For further discussion of the SNAP rule, see section II.E.8 
of this document.
    \40\ Available at https://www.regulations.gov/document?D=EERE-2015-BT-STD-0016-0089.
---------------------------------------------------------------------------

    DOE is currently considering how, if at all, to address high-
temperature freezer walk-ins, including whether to establish test 
procedure provisions to specifically address the refrigeration systems 
serving such equipment. Multiple approaches are under consideration. 
One approach would allow walk-in manufacturers and contractors to 
install a medium temperature refrigeration system that is tested and 
certified based on the standardized 35 [deg]F walk-in cooler 
temperature (or corresponding refrigerant suction conditions) as a 
walk-in freezer, if the walk-in refrigeration system is marketed at or 
above 10 [deg]F. By extension, the approach would also allow 
representations of performance (e.g. capacity, power input) of such 
medium-temperature refrigeration systems for walk-in temperatures at 10 
[deg]F and higher without requiring them to be tested and certified 
based on the-10 [deg]F low-temperature walk-in test condition. This 
approach would alleviate the need for a new high-temperature freezer 
equipment class (thus avoiding the associated certification test 
burden), while still allowing the potentially more efficient medium 
temperature refrigeration systems to be used for high temperature 
freezer applications. (Docket EERE-2015-BT-STD-0016, Lennox, No. 89 at 
pp. 2-5 (offering data suggesting that medium temperature units 
generally perform more efficiently at the 10 [deg]F operating condition 
than low-temperature systems)).
    DOE could establish new definitions for the terms ``low-temperature 
refrigeration system'' and ``medium-temperature refrigeration system,'' 
that implement this potential structure. For example, ``low-temperature 
refrigeration system'' could be defined as ``a refrigeration system 
used to cool the interior of walk-in freezers and maintain a 
refrigerated room temperature of 10 [deg]F or less,'' while ``medium-
temperature refrigeration system'' could be defined

[[Page 32350]]

as ``a refrigeration system used to cool the interior of a walk-in 
cooler or a walk-in freezer operating above 10 [deg]F.''
    Alternatively, another approach would allow medium-temperature 
refrigeration systems used in high-temperature freezer walk-in 
applications to be tested and certified at their lowest application 
temperature conditions. This approach would be similar to that taken 
for commercial refrigerators, freezers, and refrigerator-freezers, for 
which manufacturers report the lowest application product temperature, 
i.e. the lowest average compartment temperature at which the equipment 
is capable of operating during testing (section 2.2 of appendix B to 10 
CFR part 431 subpart C). For walk-ins, this concept could be based on 
the lowest evaporator return air temperature for matched-pair 
refrigeration systems and the lowest saturated suction temperature (and 
a suitable corresponding return gas temperature) for condensing units 
tested separately. This approach would result in ratings for the units 
in high-temperature freezer applications that are directly 
representative of field performance, as the refrigeration system would 
be tested at a representative box temperature for such an application. 
Further, this approach would not presuppose what the optimal high-
temperature freezer operating condition would be, i.e., it avoids 
selecting a standardized condition that may be unachievable by some 
units. However, AWEF ratings obtained from the lowest application 
temperature for different units, which would be rated for different box 
temperatures, would not be directly comparable. The approach would also 
add testing and reporting burden associated with the additional test 
condition.
    DOE is also considering a third approach that would establish a 
single standardized test condition at which high-temperature freezer 
refrigeration equipment would be tested. This approach would result in 
AWEF ratings that are slightly less representative of field performance 
than the lowest application temperature approach, while still creating 
the potential need to establish a new equipment class (or classes) for 
low-temperature refrigeration systems. However, under a standardized 
test condition approach, all high-temperature freezer refrigeration 
systems would be rated at the same condition, providing directly 
comparable ratings for models that serve similar applications.
    DOE is investigating if and how the calculations used for 
determining the AWEF of WICF condensing units tested alone and with 
matched systems would need to be modified for products certified with 
the latter two approaches discussed previously--for example, whether 
any potential changes to the specified duty cycle at 95 [deg]F ambient 
temperature for an outdoor system would be necessary.
    Issue 43: DOE requests feedback on the three approaches discussed 
in this section to address high-temperature freezer walk-ins, as well 
as any other potential approaches not raised in this RFI.
    Issue 44: DOE also requests information that would help inform the 
development of test procedures for high-temperature freezer 
refrigeration systems, should such an approach be necessary. 
Additionally, DOE requests whether there are specific characteristics 
that distinguish a high-temperature freezer refrigeration system from a 
medium-temperature refrigeration system, in order to better define this 
category of equipment.
    Issue 45: DOE also requests comment on whether 10 [deg]F is the 
appropriate lowest end of the application range for equipment used in 
walk-in high-temperature freezers that cannot be tested using the -10 
[deg]F freezer test condition. Furthermore, DOE requests comment on 
whether all medium-temperature systems (matched-pair, condensing unit, 
evaporator) can be operated and tested at 10 [deg]F (or equivalent 
refrigerant suction conditions), or whether there is a wide range at 
the low-end of the operating range that depends on the design of the 
system.
    Issue 46: Regarding the testing of a medium-temperature 
refrigeration system in the high-temperature freezer range, DOE 
requests information on what specified test procedure parameters would 
need to be altered (and how) in order for the test to be representative 
of field operation. (In answering, DOE requests that commenters provide 
the supporting reasons for any suggested recommendations.) DOE requests 
information on whether a single standardized high-temperature freezer 
room condition could be appropriate for testing this group of walk-ins, 
and if so, what such an appropriate temperature would be.
    Issue 47: Finally, DOE requests comment on what, if any, changes 
would be needed in the calculation of AWEF for high-temperature freezer 
operation, and why.
    If DOE were to pursue the lowest application temperature approach 
or the standardized high-temperature freezer test condition approach, 
DOE would need to establish certain new default values to calculate the 
AWEF and net capacity of stand-alone high-temperature freezer dedicated 
condensing units. Currently, the test procedure provides equations for 
determining evaporator fan power, defrost energy, and defrost heat 
load, all of which are used in lieu of matched unit cooler test data 
(section 3.4.2 of Appendix C).
    The current test procedure offers two separate equations that 
relate the cooling capacity to the evaporator fan power for medium- and 
low-temperature unit coolers (section 3.4.2.2 of Appendix C). Based on 
the condensing unit capacity at the medium temperature test condition 
(35 [deg]F box temperature), using the medium-temperature equation 
seems to be the most appropriate approach since the condensing units in 
question would also be certified as medium-temperature condensing 
units. This approach also assumes that fan energy use at high-
temperature freezer conditions will be the same as fan energy use at 
medium-temperature conditions, since it makes no adjustment in the 
calculated fan power for the high-temperature freezer application.
    Issue 48: DOE requests comment on the appropriateness of using the 
current medium-temperature refrigeration system default fan input power 
equation (found at section 3.4.2.2 of Appendix C) to represent the fan 
input power of high- temperature freezer refrigeration systems. If the 
current medium-temperature refrigeration system default fan input power 
equation is not representative of the fan input power for high-
temperature freezer refrigeration systems, DOE requests suggestions for 
a more appropriate equation, or alternative relationships to consider, 
as well as any relevant data.
    In the current test procedure, defrost energy and defrost heat load 
for stand-alone dedicated condensing units are estimated based on the 
condenser capacity using an equation in section 3.4.2 of Appendix C. 
The calculations apply only to freezer models, since they assume that 
refrigeration systems serving walk-in coolers are not equipped for 
defrost capability and thus have no defrost energy or heat load. 
However, medium-temperature refrigeration systems designed for high-
temperature freezer applications require defrost capability because 
frost that collects on the evaporator during the compressor off-cycle 
will not melt in the sub-freezing walk-in temperature conditions. The 
energy and heat load of these high-temperature freezer defrost systems 
may differ significantly from

[[Page 32351]]

those of -10 [deg]F freezers. Therefore, proper accounting for defrost 
of high-temperature freezer refrigeration systems requires developing a 
modified calculation. The equation found in section 3.4.2.4 of Appendix 
C used to calculate freezer equipment daily defrost energy use (``DF'') 
uses as inputs the condenser capacity (``qmix,cd'') and the 
number of defrost cycles per day (``NDF''). The daily 
defrost heat load (``QDF'') is directly dependent on DF (see 
relevant equation in section 3.4.2.5 of Appendix C). DOE anticipates 
that a calculation of defrost impacts for high-temperature freezers, if 
adopted, would use similar equations with different magnitudes.
    Issue 49: DOE requests information or data that would indicate 
whether and how the equations used to calculate daily defrost energy 
use and heat addition in the test procedure should be modified for 
high-temperature freezer refrigeration systems rated as stand-alone 
condensing units (e.g., defrost heater wattage and daily energy use as 
a function of capacity for a 10 [deg]F walk-in temperature). If testing 
at the lowest application temperature is adopted, DOE requests comment 
on how the defrost equations should be modified to account for each 
model being tested at different conditions, and why. DOE requests 
information on whether frost loads and/or defrost frequency are 
different for high- temperature freezers than for -10 [deg]F freezers. 
(DOE requests that commenters include any available supporting 
information when responding.)
8. Consideration for Refrigerant Glide
    The analysis for the June 2014 ECS final rule assumed that the 
refrigerant R-404A would be used in all new refrigeration equipment 
meeting the standard. 79 FR 32050, 32074. In its subsequent negotiated 
rulemaking effort in 2015, WICF Working Group members suggested that 
DOE revise this approach by accounting for the use of a different 
refrigerant, R-407A, which was expected to become more commonly used 
for WICF applications. Consistent with that suggestion, DOE conducted 
the analysis for the July 2017 ECS final rule using R-407A as the 
refrigerant. 82 FR 31808, 31835-31836.
    On July 20, 2015, the U.S. Environmental Protection Agency 
(``EPA'') published a final rule under the Significant New Alternatives 
Policy (``SNAP'') program listing as unacceptable the use of certain 
hydrofluorocarbons (``HFCs''), including the use of R-404A in WICF 
refrigeration systems. 80 FR 42870 (``July 2015 EPA SNAP Rule''). In 
October 2016, the 28th Meeting of the Parties to the Montreal Protocol 
adopted the Kigali Amendment on HFCs, which, upon ratification, 
requires parties to the protocol to reduce consumption and production 
of HFCs.\41\ On December 1, 2016, EPA published a final rule 
(``December 2016 EPA SNAP Rule'') that listed a number of refrigerants 
for use in certain refrigerant applications as unacceptable, starting 
January 1, 2023 for cold storage warehouse application, and January 1, 
2021 for retail food refrigerant applications. 81 FR 86778. The list of 
unacceptable refrigerants included R-407A. The validity of the SNAP 
approach, however, has been the subject of a legal challenge regarding 
EPA's use of its SNAP authority to require manufacturers to replace 
HFCs with a substitute substance.
---------------------------------------------------------------------------

    \41\ http://www.unep.org/ozonaction/Portals/105/documents/7809-e-Factsheet_Kigali_Amendment_to_MP.pdf (last viewed February 3, 
2017).
---------------------------------------------------------------------------

    In August 2017, the U.S. Court of Appeals for the District of 
Columbia Circuit vacated and remanded the July 2015 EPA SNAP Rule to 
the extent that it required manufacturers to replace HFCs with a 
substitute substance.\42\ Mexichem Fluor, Inc. v. EPA, 866 F.3d 451 
(D.C. Cir. 2017). Subsequently, the December 2016 SNAP Rule was 
partially vacated by the court.\43\ While the United States has not 
ratified the Kigali Amendment, a significant portion of walk-in 
refrigeration systems currently use HFC- based refrigerants and may 
become affected by this Amendment to the Montreal Protocol. DOE plans 
to consider the potential impact (if any) of both the court's decision 
and remand as well as the Amendment to the Montreal Protocol on the 
test procedure issues addressed in this RFI.
---------------------------------------------------------------------------

    \42\ The vacatur and remand in Mexichem, Inc. v. EPA was of the 
July 2015 EPA SNAP Rule and did not directly address the December 
2016 EPA SNAP Rule. At issue was EPA's use of its SNAP authority as 
a means to remove HFCs from the agency's list of acceptable 
substitutes. On April 27, 2018, EPA published a notice stating that 
in the near-term it will not apply the HFC listings in the July 2015 
final rule pending a rulemaking and that it plans to begin a notice-
and-comment rulemaking process to address the remand. 83 FR 18431.
    \43\ Following the decision in the Mexichem case, the court 
vacated the December 2016 SNAP Rule to the extent it requires 
manufacturers to replace HFCs that were previously and lawfully 
installed as substitutes for ozone-depleting substances. Case No. 
17-1024 (D.C. Cir. April 5, 2019).
---------------------------------------------------------------------------

    Notwithstanding these legal developments, key differences between 
the refrigerants used in DOE's separate analyses of walk-in 
refrigeration systems merit discussion. Both R-404A and R-407A are 
blends of refrigerants that have different boiling points. This means 
that, unlike pure substances such as water, the temperature of the 
refrigerant changes as it boils or condenses, because one of the 
refrigerants in the blend, having a lower boiling point, boils off 
sooner than the other(s). This phenomenon is called ``glide.'' The 
refrigerants that make up R-404A have nearly identical boiling points, 
so this refrigerant has very little glide. In contrast, R-407A 
undergoes a much more significant temperature change when it boils--the 
temperature can rise as much as 8 degrees between the saturated liquid 
condition (the temperature at which a liquid begins to boil, also 
called the ``bubble point'') and the saturated vapor condition (the 
temperature at which a vapor begins to condense, also called the ``dew 
point''). The average of these two temperatures, bubble point and dew 
point, is called the mid-point temperature.
    The current DOE test procedure specifies that test conditions are 
based on dew point. DOE notes that if the refrigerant condition for a 
unit cooler is specified by dew point, the average refrigerant 
temperature would be significantly lower for a high-glide than for a 
low-glide refrigerant. As mentioned previously, DOE is considering 
changing its test procedure to be based on a refrigerant-neutral 
approach. One specific option would be to use the mid-point 
temperature. However, with walk-in refrigeration systems, the 
refrigerant entering the unit cooler is typically a two-phase 
refrigerant with a temperature higher than the bubble point. This 
scenario results in the average evaporator temperature being slightly 
greater than a mid-point equal to the average of bubble and dew point 
temperatures. To account for this difference, DOE could develop an 
approach to calculate and specify refrigerant temperatures in terms of 
a ``modified mid-point,'' which would be a calculated value slightly 
higher than the mid-point of the selected refrigerant.
    Issue 50: DOE requests comment on the appropriateness of specifying 
refrigerant temperatures in terms of mid-point or a modified mid-point, 
rather than dew point, which is currently used. DOE seeks feedback on 
potential definitions to use for a modified mid-point temperature as 
applied to WICF refrigeration system testing. In addition, DOE requests 
comments on what other factors should be considered when modifying the 
refrigeration system test conditions from dew point to mid-point or 
modified mid-point specifications.

III. Submission of Comments

    DOE invites all interested parties to submit in writing by the date 
specified

[[Page 32352]]

in the DATES heading, comments and information on matters addressed in 
this RFI and on other matters relevant to DOE's early assessment of 
whether an amended test procedure for walk-in coolers and freezers is 
warranted and if so, what such amendments should be.
    Submitting comments via https://www.regulations.gov. The https://www.regulations.gov web page requires 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. 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 https://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 https://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 https://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 https://www.regulations.gov provides after you have successfully uploaded your 
comment.
    Submitting comments via email. Comments and documents submitted via 
email also will be posted to https://www.regulations.gov. If you do not 
want your personal contact information to be publicly viewable, do not 
include it in your comment or any accompanying documents. Instead, 
provide your contact information in a cover letter. Include your first 
and last names, email address, telephone number, and optional mailing 
address. The cover letter will not be publicly viewable as long as it 
does not include any comments.
    Include contact information each time you submit comments, data, 
documents, and other information to DOE. No telefacsimiles (faxes) will 
be accepted.
    Comments, data, and other information submitted to DOE 
electronically should be provided in PDF (preferred), Microsoft Word or 
Excel, WordPerfect, or text (ASCII) file format. Provide documents that 
are not secured, written in English, and free of any defects or 
viruses. Documents should not contain special characters or any form of 
encryption and, if possible, they should carry the electronic signature 
of the author.
    Campaign form letters. Please submit campaign form letters by the 
originating organization in batches of between 50 to 500 form letters 
per PDF or as one form letter with a list of supporters' names compiled 
into one or more PDFs. This reduces comment processing and posting 
time.
    Confidential Business Information. Pursuant to 10 CFR 1004.11, any 
person submitting information that he or she believes to be 
confidential and exempt by law from public disclosure should submit via 
email two well-marked copies: One copy of the document marked 
``confidential'' including all the information believed to be 
confidential, and one copy of the document marked ``non-confidential'' 
with the information believed to be confidential deleted. Submit these 
documents via email. 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].

IV. Issues on Which DOE Seeks Comment

    Although DOE welcomes comments on any aspect of this proposal, DOE 
is particularly interested in receiving comments and views of 
interested parties concerning the following issues:
    Issue 1: DOE seeks comment on how liquid-cooled refrigeration 
systems are (or could be) used with respect to walk-in applications. 
DOE requests comment on whether it should consider establishing a test 
procedure for liquid-cooled refrigeration systems. If test procedures 
were considered for liquid-cooled refrigeration systems, DOE requests 
information on whether there is an industry standard or standards that 
should be considered.
    Issue 2: DOE seeks comment on how wine cellar refrigeration systems 
should be defined to best represent the conditions under which these 
systems are designed to operate and to fully distinguish these systems 
from systems designed to meet safe food storage requirements. 
Additionally, DOE requests comment on applications other than wine 
cellar storage for refrigeration systems that are designed to operate 
at temperatures warmer than typical for coolers and for which testing 
at 35 [deg]F would be representative of use. If there are such 
additional applications, DOE seeks information regarding the specific 
operating requirements (i.e., temperature and humidity) for these 
systems.
    Issue 3: DOE requests comment on the current definition of ``door'' 
in 10 CFR 431.302. DOE seeks feedback on the terminology of door 
components used and whether these are consistently interpreted. DOE 
seeks specific feedback from manufacturers on how they use the term 
``door plug'' and whether it is essential to the definition of a WICF 
``door''.
    Issue 4: DOE requests comment on whether height and width or 
surface area are distinct attributes that effectively distinguish 
between passage and freight doors. DOE seeks information on any 
building codes, standards, or industry practices to support or refute 
maintaining the dimensions of a door as the defining

[[Page 32353]]

characteristic which separates freight and passage doors.
    Issue 5: Regarding a door that meets the freight door definition 
but does so only because it has a multi-door configuration in which the 
individual component doors each would by themselves not meet the 
freight door definition, DOE seeks comment on how such doors should be 
classified, and whether such classification should depend on other 
factors, such as whether one or more frame members divides the door 
opening into smaller openings.
    Issue 6: DOE seeks comment on whether any attribute, or combination 
of attributes, other than size, would affect energy use and could be 
used to distinguish between freight doors and passage doors. If so, DOE 
requests data and comment on such attributes.
    Issue 7: DOE requests comment on the accuracy of the computational 
method in NFRC 100 to predict U-factor for display and non-display 
doors. DOE seeks feedback regarding the differences in results (if any) 
between those obtained using the NFRC 100 computational method and 
those obtained when conducting physical testing using NFRC 102 for 
display and non-display doors. DOE is also interested in the magnitude 
of these differences and whether the computational method can be 
modified to yield results that more closely match the results obtained 
from actual physical testing. If manufacturers are aware of other 
methods to predict U-factor for either display doors or non-display 
doors besides NFRC 100, DOE requests how the results from these methods 
compare to physical testing.
    Issue 8: DOE seeks information from manufacturers and other 
interested parties regarding how the industry currently rates 
individual door models, including the prevalence within the industry of 
using the computational method from NFRC 100. DOE also requests 
information on the costs associated with the computational method of 
NFRC 100 or an alternative computational method compared to physically 
testing the thermal transmittance of walk-in doors using NFRC 102.
    Issue 9: DOE requests comment on what issues, if any, would be 
present if ASTM C518-17 were to be referenced in the Appendix B test 
procedure for measuring panel K-factor, or average thermal 
conductivity. While not exhaustive, primary areas of interest to DOE 
include any differences between the currently referenced version of the 
industry standard (ASTM C518-04) and ASTM C518-17 that would result in 
a difference in the determined R-value and/or test burden (whether an 
increase or decrease), and if there are such differences, the magnitude 
of impact to the determined R-value and/or test burden.
    Issue 10: DOE requests comment on what issues, if any, would be 
present if AHRI 1250-2020 were to be referenced in the Appendix C test 
procedure for measuring walk-in refrigeration system AWEF. While not 
exhaustive, primary areas of interest to DOE include any differences 
between the currently referenced version of the industry standard (AHRI 
1250-2009) and AHRI 1250-2020 that would result in a difference in the 
determined AWEF and/or test burden (whether an increase or decrease), 
and if there are such differences, the magnitude of impact to the 
determined AWEF and/or test burden.
    Issue 11: DOE requests comment on how manufacturers determine 
surface area for the purpose of evaluating compliance with the 
standards for both display doors and nondisplay doors. DOE seeks input 
on any distinction between display doors and nondisplay doors, 
especially the door frames, which may warrant surface area for each to 
be determined differently.
    Issue 12: DOE seeks feedback on how manufacturers interpret and 
measure door opening as it relates to prescriptive standards for 
antisweat heaters, including whether or not manufacturers agree that 
the door opening considered for antisweat heat should be consistent 
with the surface area used to determine maximum energy consumption.
    Issue 13: DOE requests feedback on specifying the surface area used 
to determine thermal conduction through a walk-in door from the surface 
area used to determine the maximum energy consumption of a walk-in 
door.
    Issue 14: DOE seeks comment on whether, and if so how, an option 
for direct component power measurement could be included in the test 
procedure or compliance, certification, and enforcement (``CCE'') 
provisions to allow more accurate accounting for the direct electrical 
energy consumption of WICF doors. DOE also seeks input on whether 
specific provisions should be provided for determining power input from 
the information that is typically provided on nameplates, noting the 
limitations that were described above.
    Issue 15: DOE requests comment on the current PTO values and 
whether DOE should consider amending any of the current values or 
adding specific values for additional electrical components, 
specifically motorized door openers. DOE requests data from field 
studies or similar sources to support any proposed amendments (or 
additions) to these PTO values.
    Issue 16: DOE seeks feedback on whether the current PTO of 50 
percent is appropriate for evaluating direct energy consumption of 
anti-sweat heaters with controls for walk- in cooler doors marketed for 
high humidity applications. DOE seeks feedback on the average amount of 
time per day or per year that anti-sweat heaters with controls are off 
for these high humidity doors and how this compares to standard (i.e., 
non-high humidity) walk-in cooler display doors.
    Issue 17: DOE seeks feedback on the current EER values specified in 
Appendix A used to calculate daily energy consumption for walk-in doors 
and the values used in testing of unit coolers alone, as specified in 
Appendix C. Specifically, DOE requests comment on which of these sets 
of EER values is more representative, whether DOE should make the 
values used for door testing and unit cooler testing consistent with 
each other, and if so, which of the sets of values should be used.
    Issue 18: DOE requests comment on how frequently test laboratories 
perform each of the calibration procedures referenced in ASTM C1199 and 
ASTM C1363, e.g., those used to determine calibration coefficients that 
are used to calculate metering box wall loss and surround panel 
flanking loss. DOE also requests comment on the magnitude of variation 
in the calibration coefficients measured during successive 
calibrations.
    Issue 19: DOE requests feedback on whether the tolerances in 
section 5.3(a)(1) of Appendix A applied to the surface heat transfer 
coefficients used to measure thermal transmittance are achievable for 
all walk-in doors and if not, whether the tolerances should be 
increased or omitted. Specifically, DOE seeks data to support any 
changes to the tolerances on the surface heat transfer coefficients.
    Issue 20: DOE requests comment on how panel thickness is currently 
measured for determining the panel's R-value per the DOE test 
procedure, including number of measurements, measurement location, and 
any steps that are routinely followed for the removal of the protective 
skins or facers to obtain the full panel thickness. DOE requests that 
commenters identify any specific guidelines, practices or standardized 
approaches that are followed, as well as their date of publication, if 
applicable.
    Issue 21: DOE requests comment on how flatness and parallelism of 
the test specimen surfaces that contact the hot

[[Page 32354]]

plate assemblies described in ASTM C518 are typically determined by 
test laboratories and whether the test procedure should be revised to 
clarify how to determine these parameters, e.g., what type of 
instruments are used to measure these values, how many measurements are 
made for a given specimen, and other details that could affect 
conclusions regarding compliance with the test procedure.
    Issue 22: DOE requests comment on the extent to which manufacturers 
of insulation specify conditioning for insulation materials that differ 
from the typical conditioning approach described in ASTM C518. DOE also 
seeks feedback on whether more than one 24-hour conditioning period is 
ever needed to complete the conditioning (i.e., the change in specimen 
mass is less than 1 percent after the first 24 hours of conditioning) 
for a specimen extracted from a WICF panel or door. Finally, DOE 
requests information or data on how specimen conditioning times less 
than or equal to 24 hours impacts the accuracy, repeatability, and 
representativeness of the test.
    Issue 23: DOE requests information about panel construction factors 
that would affect thermal transmission and the magnitude of the energy 
efficiency-related impacts of thermal bridges in the panel assembly. 
Additionally, DOE requests comment on alternative test methods that 
measure the overall thermal transmittance of walk-in panels and the 
relative advantages and disadvantages of each. DOE also seeks feedback 
on the number and location of labs that have the facilities and are 
qualified to run ASTM C1363-05.
    Issue 24: DOE seeks feedback on the current test procedure for 
display panels in Appendix A and what amendments should be made, if 
any, to it.
    Issue 25: DOE requests comment on whether the single-package system 
test and calculation methods described in AHRI 1250-2020 provide 
representative energy use. DOE also requests comment on whether DOE 
should incorporate by reference AHRI 1250-2020 as the test procedure 
for single-package systems.
    Issue 26: DOE requests any data or calculations quantifying the 
additional thermal losses associated with testing single-package 
systems due to the exposure of their cold sides to the exterior air 
(i.e., surface and infiltration losses). DOE additionally requests 
comment on whether the AHRI 1250-2020 test methodology for single- 
package systems fully accounts for these additional losses.
    Issue 27: DOE requests comment and data on the use of water, 
glycol, or other heat transfer liquid in maintaining test compartment 
temperature using the calorimeter methods referenced in AHRI 1250-2020 
for the testing of single-package refrigeration systems. DOE requests 
comment on whether the description and requirements for calorimetric 
testing as provided in AHRI 1250-2020 should be modified or enhanced in 
order to better ensure that measurements are accurate and repeatable.
    Issue 28: DOE requests comment on whether calorimeter test methods 
for single-package systems should implement a pressure-equalizing 
device, as included in ASHRAE 16-2016. DOE requests information on any 
additional cost and resource burdens, if any, manufacturers would face 
when employing these methods to evaluate single-package systems.
    Issue 29: DOE seeks comment regarding any alternative test methods 
not mentioned in this document that could be used to measure single-
package system capacity. To the extent that any alternative test 
methods could be used for this purpose, DOE requests information on 
their advantages and disadvantages in measuring single-package system 
capacity.
    Issue 30: DOE requests comment on the alternative test procedure 
for wine cellar walk-in refrigeration systems that it has granted in 
the interim waivers and waivers listed in Table II.3. DOE additionally 
seeks comment on whether the alternative test procedure prescribed for 
the specified basic models identified in the waivers would be 
appropriate for similar refrigeration equipment.
    Issue 31: DOE requests feedback on its approach for testing ducted 
units in its alternate test procedure for wine cellar refrigeration 
systems. Specifically, DOE requests comment and supporting data on 
whether testing at 50 percent of maximum ESP provides representative 
performance values, or whether other fractions of maximum ESP may be 
more appropriate. Additionally, DOE seeks comment on other industry 
test methods that include the testing of ducted units. Finally, DOE is 
interested in other alternative approaches for testing ducted units 
that have been demonstrated to provide repeatable and representative 
results.
    Issue 32: DOE requests data and information on appropriate EER 
values for use in calculating AWEF for wine cellar unit coolers tested 
alone, and how these EER values might depend on refrigerant and/or 
capacity. DOE requests that commenters provide background explanation 
regarding how any such EER recommendations have been developed.
    Issue 33: DOESince unit coolers for wine cellar systems are sold 
alone, DOE seeks information on the characteristics of condensing units 
that would typically be paired with these unit coolers (e.g., make/
model, compressor style, capacity range, manufacturers).
    Issue 34: DOE seeks comment on whether, and if so how, it should 
modify its definitions for ``single-packaged dedicated system'' and 
``unit cooler'' to address units that are designed to be installed with 
ducts.
    Issue 35: DOE requests comment on any other issues regarding 
testing of wine cellar refrigeration systems that may not be fully 
addressed by the current DOE test procedure.
    Issue 36: DOE requests comment on test conditions that would be 
most appropriate for evaluating the energy use of CO\2\ unit coolers. 
Additionally, DOE requests feedback on any additional changes that 
would need to be made to the DOE test procedure to accurately evaluate 
energy use of these systems, while minimizing test burden.
    Issue 37: DOE requests comment on the present and future expected 
use of walk-in refrigeration systems using CO2. DOE requests 
specific information about these systems that would suggest a need to 
modify the DOE test procedure to address such equipment. Specifically, 
DOE requests information on whether such equipment is sold in the U.S., 
whether this equipment is sold as matched pairs or individual 
components, and to what extent dedicated condensing units are 
configured to supply subcritical liquid (rather than supercritical gas) 
to the unit coolers.
    Issue 38: DOE requests information regarding potential methods of 
providing a measurable frost load and frost type for defrost testing, 
including data and information demonstrating the repeatability of such 
a test. Additionally, DOE requests data and information indicating what 
a typical frost load and frost type would be--for example, whether the 
moist air flow of section C11.1.1 of AHRI 1250-2009 provides the 
appropriate amount of moisture, and if so, whether any data are 
available to support the use of this quantity. If such data are 
available, DOE asks that interested parties share it with the agency 
for further consideration. If such data are currently unavailable, DOE 
is interested in what kind and amount of testing would be needed to 
sufficiently validate an appropriate method to evaluate frost loads and 
frost types during defrost testing.
    Issue 39: DOE requests comment on the specific refrigeration system 
configurations (i.e., matched-pairs,

[[Page 32355]]

stand-alone unit coolers, and stand-alone condensing units) to which a 
hot gas defrost-specific test procedure would apply. DOE requests 
comment on which methods for determining energy and heat load (i.e., 
testing, calculation, or both) would be most appropriate for each 
refrigeration system and why. DOE requests comment on the methods 
related to hot gas defrost systems in AHRI 1250- 2020. Finally, DOE 
requests data to help quantify the relationship between hot gas defrost 
heat load addition and energy consumption versus capacity and/or to 
confirm the relationships provided in the AHRI 1250-2020 test methods 
for hot gas defrost.
    Issue 40: DOE requests comment on how the performance of adaptive 
defrost systems should be accounted for in the walk-in test procedure 
and which refrigeration systems (i.e., matched-pairs, stand-alone unit 
coolers, and stand-alone condensing units) should be evaluated under a 
potential adaptive defrost test procedure. Specifically, DOE requests 
data showing the performance of adaptive defrost systems relative to 
non-controlled defrost systems, including impacts to on-cycle 
operation. DOE requests data demonstrating seasonal and daily frosting 
patterns for walk-in applications.
    Issue 41: DOE requests information and data on whether the off-
cycle methods included in AHRI 1250-2020 provide a representative and 
repeatable measure of the off-cycle power use for matched pairs, 
single-package systems, and also for unit coolers and/or condensing 
units tested alone, and if not, what modifications are recommended. DOE 
also seeks information on other off-cycle mode energy-consuming 
components that are not currently addressed by AHRI 1250-2020. In 
addition to identifying all off-cycle mode energy-consuming components, 
DOE seeks information on the patterns and magnitudes of energy use by 
each of these components during the off-cycle.
    Issue 42: DOE requests input on the development of test methods 
that would more accurately measure the energy use performance--
including accounting for the potential efficiency benefits of multi- 
and variable-capacity systems--both for matched-pair and stand-alone 
condensing unit testing. DOE seeks data and information showing the 
potential magnitude of energy savings by reducing cycling losses in 
these multi and variable-capacity systems. DOE requests market 
information on whether there are multi- and variable-capacity 
condensing units available on the market (in addition to those already 
identified) and the brand name(s) and model numbers of those additional 
units.
    Issue 43: DOE requests feedback on the three approaches discussed 
in this section to address high-temperature freezer walk-ins, as well 
as any other potential approaches not raised in this RFI.
    Issue 44: DOE also requests information that would help inform the 
development of test procedures for high-temperature freezer 
refrigeration systems, should such an approach be necessary. 
Additionally, DOE requests whether there are specific characteristics 
that distinguish a high-temperature freezer refrigeration system from a 
medium-temperature refrigeration system, in order to better define this 
category of equipment.
    Issue 45: DOE also requests comment on whether 10 [deg]F is the 
appropriate lowest end of the application range for equipment used in 
walk-in high-temperature freezers that cannot be tested using the -10 
[deg]F freezer test condition. Furthermore, DOE requests comment on 
whether all medium-temperature systems (matched-pair, condensing unit, 
evaporator) can be operated and tested at 10 [deg]F (or equivalent 
refrigerant suction conditions), or whether there is a wide range at 
the low-end of the operating range that depends on the design of the 
system.
    Issue 46: Regarding the testing of a medium-temperature 
refrigeration system in the high-temperature freezer range, DOE 
requests information on what specified test procedure parameters would 
need to be altered (and how) in order for the test to be representative 
of field operation. (In answering, DOE requests that commenters provide 
the supporting reasons for any suggested recommendations.) DOE requests 
information on whether a single standardized high-temperature freezer 
room condition could be appropriate for testing this group of walk-ins, 
and if so, what such an appropriate temperature would be.
    Issue 47: Finally, DOE requests comment on what, if any, changes 
would be needed in the calculation of AWEF for high-temperature freezer 
operation, and why.
    Issue 48: DOE requests comment on the appropriateness of using the 
current medium-temperature refrigeration system default fan input power 
equation (found at section 3.4.2.2 of Appendix C) to represent the fan 
input power of high-temperature freezer refrigeration systems. If the 
current medium-temperature refrigeration system default fan input power 
equation is not representative of the fan input power for high-
temperature freezer refrigeration systems, DOE requests suggestions for 
a more appropriate equation, or alternative relationships to consider, 
as well as any relevant data.
    Issue 49: DOE requests information or data that would indicate 
whether and how the equations used to calculate daily defrost energy 
use and heat addition in the test procedure should be modified for 
high-temperature freezer refrigeration systems rated as stand-alone 
condensing units (e.g., defrost heater wattage and daily energy use as 
a function of capacity for a 10 [deg]F walk-in temperature). If testing 
at the lowest application temperature is adopted, DOE requests comment 
on how the defrost equations should be modified to account for each 
model being tested at different conditions, and why. DOE requests 
information on whether frost loads and/or defrost frequency are 
different for high-temperature freezers than for -10 [deg]F freezers. 
(DOE requests that commenters include any available supporting 
information when responding.)
    Issue 50: DOE requests comment on the appropriateness of specifying 
refrigerant temperatures in terms of mid-point or a modified mid-point, 
rather than dew point, which is currently used. DOE seeks feedback on 
potential definitions to use for a modified mid-point temperature as 
applied to WICF refrigeration system testing. In addition, DOE requests 
comments on what other factors should be considered when modifying the 
refrigeration system test conditions from dew point to mid-point or 
modified mid-point specifications.

[[Page 32356]]

Signing Authority

    This document of the Department of Energy was signed on June 3, 
2021, by Kelly Speakes-Backman, Principal Deputy Assistant Secretary 
and 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 June 4, 2021.
Treena V. Garrett,
Federal Register Liaison Officer, U.S. Department of Energy.
[FR Doc. 2021-12081 Filed 6-16-21; 8:45 am]
BILLING CODE 6450-01-P