# Energy Conservation Program: Test Procedure for Water-Source Heat Pumps

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URL: https://www.frixlaw.com/law-library/documents/fr%3A2022-17075

## Record

- **Collection:** Federal Register
- **Document type:** Proposed Rule
- **Published:** August 30, 2022
- **Citation:** 87 FR 53302

## Text

DEPARTMENT OF ENERGY
10 CFR Parts 429 and 431
[EERE-2017-BT-TP-0029]
RIN 1904-AE05
Energy Conservation Program: Test Procedure for Water-Source Heat Pumps

AGENCY:

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

ACTION:

Notice of proposed rulemaking and request for comment.

SUMMARY:

The U.S. Department of Energy (“DOE”) proposes to amend its test procedures for water-source heat pumps, with the main changes being ones to expand the scope of applicability of the test procedure, reference different industry standards than currently referenced, change to a seasonal cooling efficiency metric, and change the test conditions used for the heating metric. DOE has tentatively determined that the amended test procedure would produce results that are more representative of an average use cycle and more consistent with current industry practice without being unduly burdensome to conduct. DOE seeks comment from interested parties on this proposal.

DATES:

Comments:
DOE will accept comments, data, and information regarding this proposal no later than October 31, 2022. See section V, “Public Participation,” for details.

Public Meeting:
DOE will hold a public meeting via webinar on Wednesday, September 14, 2022, from 1:00 p.m. to 3:00 p.m. See section V, “Public Participation,” for webinar registration information, participant instructions, and information about the capabilities available to webinar participants.

ADDRESSES:

Interested persons are encouraged to submit comments using the Federal eRulemaking Portal at
www.regulations.gov,
under docket number EERE-2017-BT-TP-0029. Follow the instructions for submitting comments. Alternatively, interested persons may submit comments, identified by docket number EERE-2017-BT-TP-0029 and/or RIN 1904-AE05, by any of the following methods:

Email: WSHP2017TP0029@ee.doe.gov.
Include the docket number EERE-2017-BT-TP-0029 and/or RIN 1904-AE05 in the subject line of the message.

Postal Mail:
Appliance and Equipment Standards Program, U.S. Department of Energy, Building Technologies Office, Mailstop EE-5B, 1000 Independence Avenue SW, Washington, DC 20585-0121. If possible, please submit all items on a compact disc (“CD”), in which case it is not necessary to include printed copies.

Hand Delivery/Courier:
Appliance and Equipment Standards Program, U.S. Department of Energy, Building Technologies Office, 950 L'Enfant Plaza SW, 6th Floor, Washington, DC 20024. Telephone: (202) 287-1445. If possible, please submit all items on a CD, in which case it is not necessary to include printed copies.

No telefacsimiles (“faxes”) will be accepted. For detailed instructions on submitting comments and additional information on this process, see section V of this document (Public Participation).

Docket:
The docket, which includes
Federal Register
notices, public meeting/webinar attendee lists and transcripts, comments, and other supporting documents/materials, is available for review at
www.regulations.gov.
All documents in the docket are listed in the
www.regulations.gov
index. However, 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
www.regulations.gov/docket?D=EERE-2017-BT-TP-0029.
The docket web page contains instructions on how to access all documents, including public comments, in the docket. See section V (Public Participation) for information on how to submit comments through
www.regulations.gov.

FOR FURTHER INFORMATION CONTACT:

Ms. Catherine Rivest, 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) 586-7335. Email:
ApplianceStandardsQuestions@ee.doe.gov.

Mr. Eric Stas, U.S. Department of Energy, Office of the General Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone: (202) 586-5827. Email:
Eric.Stas@hq.doe.gov.

For further information on how to submit a comment, review other public comments and the docket, or participate in the public meeting webinar, contact the Appliance and Equipment Standards Program staff at (202) 287-1445 or by email:
ApplianceStandardsQuestions@ee.doe.gov.

SUPPLEMENTARY INFORMATION:

DOE proposes to incorporate by reference already-approved industry standards, an update to one of those standards, and a standard not previously-approved.

ANSI/ASHRAE Standard 37-2009, “Methods of Testing for Rating Electrically Driven Unitary Air-Conditioning and Heat Pump Equipment,” including errata sheet issued March 27, 2019, ASHRAE approved June 24, 2009.

Copies of the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (“ASHRAE”) ANSI/ASHRAE Standard 37-2009 are available from the American National Standards Institute (“ANSI”), 25 W. 43rd Street, 4th Floor, New York, NY 10036, (212) 642-4900, or online at:
https://webstore.ansi.org/.

ASHRAE errata sheet to ANSI/ASHRAE Standard 37-2009—Methods of Testing for Rating Electrically Driven Unitary Air-Conditioning and Heat Pump Equipment, ANSI/ASHRAE Approved March 27, 2019.

Copies of ASHRAE errata sheet to ANSI/ASHRAE Standard 37-2009 are available from ASHRAE, 180 Technology Parkway NW, Peachtree Corners, GA 30092, (404)-636-8400, or online at
https://ashrae.org/.

ISO Standard 13256-1:1998, “Water-source heat pumps—Testing and rating for performance—Part 1: Water-to-air and brine-to-air heat pumps,” ISO approved 1998.

Copies of ISO Standard 13256-1:1998 can be obtained from the International Organization for Standardization (“ISO”), Chemin de Blandonnet 8 CP 401, 1214 Vernier, Geneva, Switzerland, +41 22 749 01 11, or online at:
https://webstore.ansi.org/.

AHRI Standard 340/360-2022 (I-P), “2022 Standard for Performance Rating of Commercial and Industrial Unitary Air-conditioning and Heat Pump Equipment,” AHRI-approved January 26, 2022.

Copies of AHRI Standard 340/360-2022 (I-P) can be obtained from the Air-Conditioning, Heating, and Refrigeration Institute (“AHRI”), 2311 Wilson Blvd., Suite 400, Arlington, VA 22201, (703) 524-8800, or online at:
www.ahrinet.org/search-standards.aspx.

See section IV.M of this document for further discussion of these standards.

Table of Contents

I. Authority and Background

A. Authority

B. Background

II. Synopsis of the Notice of Proposed Rulemaking

III. Discussion

A. Scope of Applicability

B. Definition

C. Proposed Organization of the WSHP Test Procedure

D. Industry Standards

1. Applicable Industry Test Procedures

a. ISO Standard 13256-1

b. AHRI 340/360-2022 and ASHRAE 37-2009

c. AHRI 600

2. Comments Received on Industry Standards and DOE Responses

3. Proposal for DOE Test Procedure

E. Efficiency Metrics

1. IEER

a. General Discussion

b. Determination of IEER Via Interpolation and Extrapolation

2. COP

a. General Discussion

b. Determination of COP Via Interpolation

3. Entering Air Conditions

4. Operating Modes Other Than Mechanical Cooling and Heating

5. Dynamic Load-Based Test Procedure

F. Test Method

1. Airflow and External Static Pressure

a. Fan Power Adjustment and Required Air External Static Pressure

b. Setting Airflow and ESP

i. Ducted Units With Discrete-Step Fans

ii. Non-Ducted Units

2. Capacity Measurement

a. Primary and Secondary Methods

b. Compressor Heat

3. Cyclic Degradation

4. Pump Power Adjustment and Liquid External Static Pressure

5. Test Liquid and Specific Heat Capacity

6. Liquid Flow Rate

a. Full-Load Cooling Tests

b. Part-Load Cooling Tests

c. Heating Tests

d. Condition Tolerance

7. Refrigerant Line Losses

8. Airflow Measurement

9. Air Condition Measurements

10. Duct Losses

11. Refrigerant Charging

12. Voltage

G. Configuration of Unit Under Test

1. Specific Components

2. Non-Standard Indoor Fan Motors

H. Represented Values and Enforcement

1. Multiple Refrigerants

2. Cooling Capacity

3. Enforcement of IEER

I. Test Procedure Costs and Impact

J. Compliance Date

IV. Procedural Issues and Regulatory Review

A. Review Under Executive Orders 12866 and 13563

B. Review Under the Regulatory Flexibility Act

C. Review Under the Paperwork Reduction Act of 1995

D. Review Under the National Environmental Policy Act of 1969

E. Review Under Executive Order 13132

F. Review Under Executive Order 12988

G. Review Under the Unfunded Mandates Reform Act of 1995

H. Review Under the Treasury and General Government Appropriations Act, 1999

I. Review Under Executive Order 12630

J. Review Under Treasury and General Government Appropriations Act, 2001

K. Review Under Executive Order 13211

L. Review Under Section 32 of the Federal Energy Administration Act of 1974

M. Description of Materials Incorporated by Reference

V. Public Participation

A. Participation in the Public Meeting Webinar

B. Procedure for Submitting Prepared General Statements for Distribution

C. Conduct of the Public Meeting Webinar

D. Submission of Comments

E. Issues on Which DOE Seeks Comment

VI. Approval of the Office of the Secretary

I. Authority and Background

Water-source heat pumps (“WSHPs”) are a category of small, large, and very large commercial package air-conditioning and heating equipment,
1

which are included in the list of “covered equipment” for which DOE is authorized to establish and amend energy conservation standards and test procedures. (42 U.S.C. 6311(1)(B)-(D)) DOE's energy conservation standards and test procedures for WSHPs are currently prescribed in title 10 of the Code of Federal Regulations (“CFR”) at 10 CFR 431.97 and 10 CFR 431.96, respectively. The following sections discuss DOE's authority to establish and amend test procedures for WSHPs, as well as relevant background information regarding DOE's consideration of test procedures for this equipment.

1
The Energy Policy and Conservation Act, as amended (“EPCA”) defines “commercial package air conditioning and heating equipment” as air-cooled, water-cooled, evaporatively-cooled, or water-source (not including ground-water-source) electrically operated unitary central air conditioners and central air conditioning heat pumps for commercial application. (42 U.S.C. 6311(8)(A)) EPCA further defines “small commercial package air conditioning and heating equipment” as commercial package air conditioning and heating equipment that is rated below 135,000 Btu per hour (cooling capacity); “large commercial package air conditioning and heating equipment” as commercial package air conditioning and heating equipment that is rated at or above 135,000 Btu per hour and below 240,000 Btu per hour (cooling capacity); and “very large commercial package air conditioning and heating equipment” as commercial package air conditioning and heating equipment that is rated at or above 240,000 Btu per hour and below 760,000 Btu per hour (cooling capacity). (42 U.S.C. 6311(8)(B)-(D))

A. Authority

The Energy Policy and Conservation Act, as amended (“EPCA”),
2

Public Law 94-163 (42 U.S.C. 6291-6317, as codified), among other things, authorizes DOE to regulate the energy efficiency of a number of consumer products and certain industrial equipment. Title III, Part C
3

of EPCA, added by Public Law 95-619, Title IV, section 441(a), established the Energy Conservation Program for Certain Industrial Equipment, which sets forth a variety of provisions designed to improve energy efficiency. This equipment includes small, large, and very large commercial package air-conditioning and heating equipment, including WSHPs. (42 U.S.C. 6311(1)(B)-(D))

2
All references to EPCA in this document refer to the statute as amended through the Energy Act of 2020, Public Law 116-260 (Dec. 27, 2020), which reflects the last statutory amendments that impact Parts A and A-1 of EPCA.

3
For editorial reasons, upon codification in the U.S. Code, Part C was redesignated Part A-1.

The energy conservation program under EPCA consists essentially of four parts: (1) testing; (2) labeling; (3) Federal energy conservation standards, and (4) certification and enforcement procedures. Relevant provisions of EPCA specifically include definitions (42 U.S.C. 6311), energy conservation standards (42 U.S.C. 6313), test procedures (42 U.S.C. 6314), labeling provisions (42 U.S.C. 6315), and the authority to require information and reports from manufacturers (42 U.S.C. 6316; 42 U.S.C. 6296).

The Federal testing requirements consist of test procedures that manufacturers of covered equipment must use as the basis for: (1) certifying to DOE that their equipment complies with the applicable energy conservation standards adopted pursuant to EPCA (42 U.S.C. 6316(b); 42 U.S.C. 6296), and (2) making representations about the efficiency of that equipment (42 U.S.C. 6314(d)). Similarly, DOE uses these test procedures to determine whether the equipment complies with relevant standards promulgated under EPCA.

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 for particular State laws or regulations, in accordance with the procedures and other provisions of EPCA. (42 U.S.C. 6316(b)(2)(D))

Under 42 U.S.C. 6314, EPCA sets forth the criteria and procedures DOE must follow when prescribing or amending test procedures for covered equipment. EPCA requires that any test procedures prescribed or amended under this section must be reasonably designed to produce test results which reflect energy efficiency, energy use, or estimated annual operating cost of covered equipment during a representative average use cycle and requires that test procedures not be unduly burdensome to conduct. (42 U.S.C. 6314(a)(2))

With respect to WSHPs, EPCA requires that the test procedures shall be those generally accepted industry testing procedures or rating procedures developed or recognized by the Air-Conditioning, Heating, and Refrigeration Institute (“AHRI”) or by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (“ASHRAE”), as referenced in ASHRAE Standard 90.1, “Energy Standard for Buildings Except Low-Rise Residential Buildings” (“ASHRAE Standard 90.1”). (42 U.S.C. 6314(a)(4)(A)) Further, if such an industry test procedure is amended, DOE must amend its test procedure to be consistent with the amended industry test procedure, unless DOE determines, by rule published in the
Federal Register
and supported by clear and convincing evidence, that the amended test procedure would not produce test results that reflect the energy efficiency, energy use, and estimated operating costs of that equipment during a representative average use cycle or would be unduly burdensome to conduct. (42 U.S.C. 6314(a)(4)(B))

EPCA also requires that, at least once every 7 years, DOE evaluate test procedures for each type of covered equipment, including WSHPs, 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))

In addition, if the Secretary determines that a test procedure amendment is warranted, DOE must publish proposed test procedures in the
Federal Register
and afford interested persons an opportunity (of not less than 45 days duration) to present oral and written data, views, and comments on the proposed test procedures. (42 U.S.C. 6314(b)) If DOE determines that test procedure revisions are not appropriate, DOE must publish in the
Federal Register
its determination not to amend the test procedures. (42 U.S.C. 6314(a)(1)(A)(ii))

In this notice of proposed rulemaking (“NOPR”), DOE is proposing amendments to the test procedures for WSHPs in satisfaction of the 7-year-lookback obligations under EPCA. (42 U.S.C. 6314(a)(1))

B. Background

DOE's existing test procedure for WSHPs is specified at 10 CFR 431.96 (“Uniform test method for the measurement of energy efficiency of commercial air conditioners and heat pumps”). The Federal test procedure currently incorporates by reference International Organization for Standardization (“ISO”) Standard 13256-1 (1998), “Water-source heat pumps—Testing and rating for performance—Part 1: Water-to-air and brine-to-air heat pumps,” (“ISO 13256-1:1998”). This is the test procedure specified by ASHRAE Standard 90.1 for water-source heat pumps.

DOE initially incorporated ISO 13256-1:1998 as the referenced test procedure for WSHPs on October 21, 2004 (69 FR 61962), and DOE last reviewed the test procedure for WSHPs as part of a final rule for commercial package air conditioners and heat pumps published in the
Federal Register
on May 16, 2012 (“May 2012 final rule”; 77 FR 28928). In the May 2012 final rule, DOE retained the reference to ISO 13256-1:1998 but adopted additional provisions for equipment set-up at 10 CFR 431.96(e), which provide specifications for addressing key information typically found in the installation and operation manuals.
Id
at 77 FR 28991.

On June 22, 2018, DOE published a request for information (“RFI”) in the
Federal Register
to collect information and data to consider amendments to DOE's test procedures for WSHPs. 83 FR 29048 (“June 2018 RFI”).
4

As part of the June 2018 RFI, DOE identified and requested comment on several issues associated with the currently applicable Federal test procedures, in particular concerning methods that are adopted through incorporation by reference of the applicable industry standard; efficiency metrics and calculations; additional specifications for the test methods; and any additional topics that may inform DOE's decisions in a future test procedure rulemaking, including methods to reduce regulatory burden while ensuring the test procedure's accuracy.
Id.

4
An extension of the comment period for the June 2018 RFI was published in the
Federal Register
on July 9, 2018. 83 FR 31704.

DOE received comments in response to the June 2018 RFI from the interested parties listed in Table I-1.

Table I-1—List of Commenters With Written Submissions in Response to the June 2018 RFI

Commenter(s)
Reference in this NOPR
Commenter type

Air-Conditioning, Heating, and Refrigeration Institute
AHRI
IR.

Appliance Standards Awareness Project, American Council for an Energy-Efficient Economy, Natural Resources Defense Council
Joint Advocates
EA.

Northwest Energy Efficiency Alliance
NEEA
EA.

Pacific Gas and Electric Company, San Diego Gas and Electric, and Southern California Edison; collectively referred to as the California Investor-Owned Utilities
CA IOUs
U.

Trane Technologies
Trane
M.

WaterFurnace International
WaterFurnace
M.

EA: Efficiency/Environmental Advocate; IR: Industry Representative; M: Manufacturer; U: Utility.

A parenthetical reference at the end of a comment quotation or paraphrase provides the location of the item in the public record.
5

5
The parenthetical reference provides a reference for information located in the docket of DOE's rulemaking to develop test procedures for WSHPs. (Docket No. EERE-2017-BT-TP-0029, which is maintained at
www.regulations.gov
). The references are arranged as follows: (commenter name, comment docket ID number, page of that document).

In May 2021, ISO published an updated version of Standard 13256-1, ISO Standard 13256-1 (2021), “Water-source heat pumps—Testing and rating for performance—Part 1: Water-to-air and brine-to-air heat pumps,” (“ISO 13256-1:2021”). ISO 13256-1:2021 is discussed further in section III.D of this NOPR.

II. Synopsis of the Notice of Proposed Rulemaking

In this NOPR, DOE is proposing to amend the Federal test procedures for WSHPs as follows: (1) expand the scope of the test procedure to include WSHPs

with capacities between 135,000 and 760,000 British thermal units per hour (“Btu/h”); (2) incorporate by reference AHRI Standard 340/360-2022 (I-P), “2022 Standard for Performance Rating of Commercial and Industrial Unitary Air-conditioning and Heat Pump Equipment” (“AHRI 340/360-2022”), and ANSI/ASHRAE Standard 37-2009, “Methods of Testing for Rating Electrically Driven Unitary Air-Conditioning and Heat Pump Equipment” (“ANSI/ASHRAE 37-2009”) as the applicable test procedures for WSHPs, instead of the currently referenced industry test procedure ISO 13256-1:1998; (3) establish provisions for a new cooling efficiency metric, integrated energy efficiency ratio (“IEER”), for WSHPs and provide an alternative method of calculating IEER using interpolation from test conditions commonly used for WSHPs; (4) modify the test conditions for measuring the heating coefficient of performance (“COP”) and provide an alternative method of calculating COP using interpolation from test conditions commonly used for WSHPs; (5) include additional specification of setting airflow and external static pressure (“ESP”) for non-ducted units and ducted units with discrete-step fans; (6) specify liquid ESP requirements for units with integral pumps and include a method to account for total pumping effect for units without integral pumps; (7) specify components that must be present for testing; and (8) amend certain provisions related to representations and enforcement in 10 CFR part 429.

DOE proposes to implement these changes by adding new appendices C and C1 to subpart F of part 431, with both to be titled “Uniform Test Method for Measuring the Energy Consumption of Water-Source Heat Pumps,” (“appendix C” and “appendix C1,” respectively). The current DOE test procedure for WSHPs would be relocated to appendix C without change, and the new test procedure adopting AHRI 340/360-2022 and ANSI/ASHRAE 37-2009 and any other amendments would be set forth in proposed appendix C1 for determining IEER. As discussed elsewhere in this NOPR, DOE has tentatively concluded, supported by clear and convincing evidence, that the proposed amended test procedure in appendix C1 (relying on AHRI 340/360-2022 and ASHRAE 37-2009) would provide more representative results and more fully comply with the requirements of 42 U.S.C. 6314(a)(2) than testing with the current Federal test procedure (relying on ISO 13256-1:1998). However, use of proposed appendix C1 would not be required until such time as compliance is required with amended energy conservation standards for WSHPs based on IEER, should DOE adopt such standards, although a manufacturer would need to make any voluntary early representations of IEER in accordance with appendix C1.

DOE's proposed actions are summarized in Table II-1 and addressed in detail in section III of this document.

Table II-1—Summary of Changes in the Proposed Test Procedure Relative to the Current Test Procedure for WSHPs

Current DOE test procedure
Proposed test procedure in Appendix C1
Attribution

Scope is limited to units with cooling capacity less than 135,000 Btu/h
Expands the scope of the test procedure to additionally include units with cooling capacity greater than or equal to 135,000 Btu/h and less than 760,000 Btu/h
Harmonize with scope of test procedure for water-cooled commercial unitary air conditioners.

Incorporates by reference ISO 13256-1:1998
Incorporates by reference AHRI 340/360-2022 and ANSI/ASHRAE 37-2009
Improve representativeness of test procedure.

Includes provisions for determining EER metric
Includes provisions for determining IEER, and specifies an alternative method of calculating IEER using interpolation and extrapolation from results of testing at ISO 13256-1:1998 temperatures
Improve representativeness of test procedure.

Specifies test condition of 68 °F for measuring COP
Changes the test condition for COP to 55 °F and provides an alternative method of calculating COP using interpolation from results of testing at ISO 13256-1:1998 temperatures
Improve representativeness of test procedure.

Does not include specification of setting airflow and ESP for non-ducted units or ducted units with discrete-step fans
Includes additional specification of setting airflow and ESP for non-ducted units and for ducted units with discrete-step fans
Improve representativeness of test procedure.

Allows for testing at any liquid ESP with an adjustment to include the pump power to overcome liquid internal static pressure
Specifies liquid ESP requirements for units with integral pumps, and includes a method for accounting for the total pumping effect for units without integral pumps
Improve representativeness of test procedure.

Does not include WSHP-specific provisions for determination of represented values in 10 CFR 429.43
Includes provisions in 10 CFR 429.43 specific to WSHPs to prevent cooling capacity over-rating and to determine represented values for models with specific components
Establish WSHP-specific provisions for determination of represented values.

Does not include WSHP-specific enforcement provisions in 10 CFR 429.134
Adopts product-specific enforcement provisions for WSHPs regarding verification of cooling capacity, testing of systems with specific components, and DOE IEER testing
Establish provisions for DOE testing of WSHPs.

DOE has tentatively determined that the proposed amendments described in section III of this NOPR regarding the establishment of appendix C would not alter the measured efficiency of WSHPs or require retesting solely as a result of DOE's adoption of the proposed amendments to the test procedure, if made final. DOE has tentatively determined that the proposed test procedure amendments in appendix C1 would, if adopted, alter the measured efficiency of WSHPs. DOE has tentatively determined that the proposed amendments would increase the cost of testing relative to the current Federal test procedure. Use of the proposed appendix C1 and the proposed

amendments to the representation requirements in 10 CFR 429.43 would not be required until the compliance date of amended standards denominated in terms of IEER, although manufacturers would need to use appendix C1 if they choose to make voluntary representations of IEER prior to the compliance date. DOE's proposed actions are discussed in further detail in section III of this NOPR.

III. Discussion

In the following sections, DOE proposes certain amendments to the Federal test procedure for WSHPs. For each proposed amendment, DOE provides relevant background information, explains why the amendment merits consideration, discusses any relevant public comments, and proposes a potential approach.

A. Scope of Applicability

This rulemaking applies to WSHPs, which are a category of small, large, and very large commercial package air-conditioning and heating equipment. (
See
42 U.S.C. 6311(1)(B)-(D)) In its regulations, DOE defines WSHP as “a single-phase or three-phase reverse-cycle heat pump that uses a circulating water loop as the heat source for heating and as the heat sink for cooling. The main components are a compressor, refrigerant-to-water heat exchanger, refrigerant-to-air heat exchanger, refrigerant expansion devices, refrigerant reversing valve, and indoor fan. Such equipment includes, but is not limited to, water-to-air water-loop heat pumps.” 10 CFR 431.92.

The current Federal test procedure and energy conservation standards apply to WSHPs with a rated cooling capacity below 135,000 Btu/h. 10 CFR 431.96, Table 1 and 431.97, Table 3. However, DOE has identified WSHPs on the market with cooling capacities equal to or greater than 135,000 Btu/h.
6

In the June 2018 RFI, DOE sought data and information on the size of the market for WSHPs with a cooling capacity over 135,000 Btu/h and any potential limitations to testing such units. 83 FR 29048, 29050 (June 22, 2018).

6
For simplicity in this NOPR, DOE refers to cooling capacity equal to or greater than 135,000 Btu/h as “over 135,000” Btu/h.

The Joint Advocates encouraged DOE to include WSHPs over 135,000 Btu/h within the scope of the test procedure. (Joint Advocates, No. 10 at p. 1)

AHRI, Trane, and WaterFurnace stated that the market for WSHPs over 135,000 Btu/h is very small—around 0.7 percent of the market—and that finding a lab to test these units would be difficult for the reasons that follow. AHRI commented that manufacturers have limitations on the size of units that can be tested in their own labs, so the proposed expanded scope of the WSHP test procedure to encompass units with higher rated capacities would necessitate the use of third-party labs, resulting in additional costs for testing. AHRI and WaterFurnace further commented that WSHPs in this capacity range are highly customized for their application and asserted that testing them would incur significant costs. Trane added that no independent test labs are currently certified to test WSHPs over 135,000 Btu/h. (Trane, No. 8 at p. 2; AHRI, No. 12 at pp. 3-4; WaterFurnace, No. 7 at pp. 2-3)

Furthermore, AHRI and WaterFurnace argued that units with capacity over 135,000 Btu/h are out of the scope of ISO 13256-1:1998. (AHRI, No. 12 at p. 4; WaterFurnace, No. 7 at p.2) WaterFurnace also commented that AHRI certification costs would be extreme for such a small market due to the need to test three larger and more expensive units for sampling selection of each basic model group, and the likely need to scrap the units after testing due the significant extent of customization of larger units. (WaterFurnace, No. 7 at pp. 2-3)

In response, DOE notes that contrary to the assertions of AHRI and WaterFurnace, no capacity limitation is expressed in ISO 13256-1:1998—the industry standard currently incorporated by reference—or ISO 13256-1:2021. Once again, DOE has identified numerous model lines of WSHPs with cooling capacity over 135,000 Btu/h from a wide variety of manufacturers. The manufacturer literature for all identified model lines includes efficiency representations that are explicitly based on ISO 13256-1:1998.

Additionally, DOE is aware of several independent test labs that have the capability to test WSHPs with cooling capacity over 135,000 Btu/h. DOE conducted investigative testing on multiple WSHP models with cooling capacity over 135,000 Btu/h at one such independent test lab and did not encounter any difficulties specific to units in this capacity range.

Further, AHRI 340/360-2022 and ANSI/ASHRAE 37-2009 include provisions for testing units with capacities over 135,000 Btu/h. Both ASHRAE Standard 90.1 and DOE regulations cover other categories of commercial air conditioning and heating equipment, including water-cooled commercial unitary air conditioners (“WCUACs”), with cooling capacity up to 760,000 Btu/h. DOE has tentatively determined that testing WSHPs with cooling capacity over 135,000 Btu/h would be of comparable burden to testing other commercial air conditioning and heating equipment of similar capacity.

Regarding WaterFurnace's comment that an expansion of test procedure scope would mean that many large units would need to be tested, DOE notes that expanding the scope of the test procedure would not necessitate certification unless DOE were to establish standards for such equipment. Until such a time, an expansion of scope for the test procedure would simplify require that if manufacturers choose to make optional representations of WSHPs with cooling capacity over 135,000 Btu/h, that such optional representations be made in accordance with the DOE test procedure. Further, representations for WSHPs can be made either based on testing (in accordance with 10 CFR 429.43(a)(1)) or based on alternative efficiency determination methods (“AEDMs”) (in accordance with 10 CFR 429.43(a)(2)). An AEDM is a computer modeling or mathematical tool that predicts the performance of non-tested basic models. These computer modeling and mathematical tools, when properly developed, can provide a means to predict the energy usage or efficiency characteristics of a basic model of a given covered product or equipment and reduce the burden and cost associated with testing. Whereas DOE requires at least two units to be tested per basic model when represented values are determined through testing, DOE requires each AEDM to be validated by tests of only two WSHP basic models of any capacity (in accordance with 10 CFR 429.70(c)(2)). Therefore, an expansion of scope for the DOE test procedure would not necessitate the testing of many large units.

For these reasons, DOE has tentatively concluded that testing units with cooling capacity over 135,000 Btu/h is feasible. Moreover, based on the presence on the market of units over 135,000 Btu/h with efficiency ratings and the identification of laboratories capable of testing such units, DOE has tentatively determined that such testing would not be unduly burdensome. Additionally, expanding the scope of DOE's test procedure for WSHPs to include equipment with cooling capacity between 135,000 Btu/h and 760,000 Btu/h would ensure that representations for all WSHPs are made using the same test procedure and that ratings for equipment in this cooling

capacity range are appropriately representative. Therefore, DOE proposes in this NOPR to expand the scope of applicability of the test procedure to include WSHPs with a cooling capacity between 135,000 and 760,000 Btu/h. Specifically, DOE proposes to update table 1 to 10 CFR 431.96 to include WSHPs with cooling capacity greater than or equal to 135,000 Btu/h and less than 240,000 Btu/h under Large Commercial Package Air-Conditioning and Heating Equipment; and to include WSHPs with cooling capacity greater than or equal to 240,000 Btu/h and less than 760,000 Btu/h under Very Large Commercial Package Air-Conditioning and Heating Equipment. For both capacity ranges, the specified test procedure would be the proposed appendix C, and DOE proposes that any voluntary representations with respect to the energy use or energy efficiency must be made in accordance with appendix C starting 360 days after a test procedure final rule is published in the
Federal Register
. DOE also proposes that, starting 360 days after a test procedure final rule is published in the
Federal Register
, any voluntary representations of IEER must be made in accordance with the proposed appendix C1.

DOE does not currently specify energy conservation standards for WSHPs with cooling capacity over 135,000 Btu/h. DOE would consider any future standards applicable to WSHPs over 135,000 Btu/h in a separate energy conservation standards rulemaking. Manufacturers of WSHPs with cooling capacity over 135,000 Btu/h would not be required to test WSHPs with a cooling capacity over 135,000 Btu/h until such time as compliance with standards for this equipment were required, should DOE adopt such standards, although any voluntary EER representations would need to be based on the test procedure in appendix C, and any voluntary IEER representations would need to be based on the test procedure in appendix C1 starting 360 days after the publication of a test procedure final rule. Additionally, if DOE were to adopt standards for WSHPs in terms of IEER, after the compliance date for those standards, any representations for WSHPs would be required to be made according to appendix C1.

Issue 1: DOE requests comments on the proposed expansion of the scope of applicability of the Federal test procedure to include WSHPs with cooling capacity between 135,000 and 760,000 Btu/h.

B. Definition

As discussed, WSHPs are a category of commercial package air-conditioning and heating equipment. The current definition for “water-source heat pump” does not explicitly state that it is “commercial package air-conditioning and heating equipment.” This is inconsistent with the definitions of most other categories of commercial package air-conditioning and heating equipment (
e.g.,
computer room air conditioner, single package vertical air conditioner, variable refrigerant flow multi-split air conditioner). 10 CFR 431.92. To provide consistency with other definitions of specific categories of commercial package air-conditioning and heating equipment, DOE proposes to amend the definition of “water-source heat pump” to explicitly indicate that WSHPs are a category of commercial package air-conditioning and heating equipment. This proposed clarification to the “water-source heat pump” definition would not change the scope of equipment covered by the definition.

In addition, DOE is proposing to amend the WSHP definition to clarify that an indoor fan is not an included component for coil-only WSHPs. The current definition lists the main components of a WSHP, and it includes “indoor fan” on that list. However, DOE has identified coil-only WSHPs on the market that rely on a separately installed furnace or modular blower for indoor air movement. To clarify that coil-only WSHPs are indeed covered under the WSHP definition, DOE is proposing to include the parenthesized statement “except that coil-only units do not include an indoor fan” in the sentence listing the main components in the WSHP definition.

In summary, DOE proposes to amend the definition of WSHP as follows:

“
Water-source heat pump
means commercial package air-conditioning and heating equipment that is a single-phase or three-phase reverse-cycle heat pump that uses a circulating water loop as the heat source for heating and as the heat sink for cooling. The main components are a compressor, refrigerant-to-water heat exchanger, refrigerant-to-air heat exchanger, refrigerant expansion devices, refrigerant reversing valve, and indoor fan (except that coil-only units do not include an indoor fan). Such equipment includes, but is not limited to, water-to-air water-loop heat pumps.”

Issue 2: DOE requests comments on the proposed change to the definition of WSHP to explicitly indicate that WSHP is a category of commercial package air-conditioning and heating equipment and to clarify that the presence of an indoor fan does not apply to coil-only units.

C. Proposed Organization of the WSHP Test Procedure

DOE is proposing to relocate and centralize the current test procedure for WSHPs to a new appendix C to subpart F of part 431. As proposed, appendix C would maintain the substance of the current test procedure. The test procedure as proposed in newly proposed appendix C would continue to reference ISO 13256-1:1998 and provide for determining energy efficiency ratio (“EER”) and COP. The proposed appendix C would centralize the additional test provisions currently applicable under 10 CFR 431.96,
i.e.,
additional provisions for equipment set-up (10 CFR 431.96(e)). As proposed, WSHPs would be required to be tested according to appendix C until such time as compliance is required with an amended energy conservation standard that relies on the IEER metric, should DOE adopt such a standard.

DOE is also proposing to establish a test procedure for WSHPs in a new appendix C1 to subpart F of part 431 that would incorporate by reference AHRI 340/360-2022 and ASHRAE 37-2009 along with additional provisions, as discussed in greater detail in the following sections. As proposed, WSHPs would not be required to test according to the test procedure in proposed appendix C1 until such time as compliance is required with an amended energy conservation standard that relies on the IEER metric, should DOE adopt such a standard, although any voluntary representations of IEER prior to the compliance date must be based on testing according to appendix C1.

D. Industry Standards

1. Applicable Industry Test Procedures

a. ISO Standard 13256-1

As noted in section I.B of this document, the DOE test procedure currently incorporates by reference ISO 13256-1:1998 and includes additional provisions for equipment set-up at 10 CFR 431.96(e), which provide specifications for addressing key information typically found in the installation and operation manuals.

ISO 13256-1:1998 specifies the cooling efficiency metric, EER,
7

which is the ratio of the net total cooling capacity to the effective power input at

a single set of operating conditions. Table 1 of ISO 13256-1:1998 specifies six sets of operating conditions for determining EER values based on variation in entering water temperature (“EWT”)
8

and, for models with capacity control (
i.e.,
multiple compressor stages), whether the test is a full-load or part-load test. The initial three sets, referred to as “standard rating test” conditions in Table 1 of ISO 13256-1:1998, are used to determine full-load EER values, which represent the cooling efficiency for a WSHP operating at its maximum capacity in the most demanding conditions (
i.e.,
highest EWT) that the WSHP would regularly encounter. The three standard rating test conditions in Table 1 of ISO 13256-1:1998 differ in terms of EWT, in that they represent the highest EWT that would be regularly encountered in different specific applications (
i.e.,
86 °F for water-loop, 59 °F for ground-water, and 77 °F for ground-loop heat pumps).
9

The standard rating test conditions specified for water-loop heat pumps are used in the current DOE test procedure.

7
DOE defines “EER” at 10 CFR 431.92 as the ratio of the produced cooling effect of an air conditioner or heat pump to its net work input, expressed in BTU/watt-hour.

8
“EWT” is used to describe the entering liquid temperature for WSHPs, which may be water or a brine solution, depending on the liquid temperature used for test.

9
EWTs are specified in degrees Celsius in ISO 13256-1:1998, but they are referred to by their equivalent values of degrees Fahrenheit in this NOPR to ease comparison with other temperatures discussed elsewhere in this document.

The next three sets of operating conditions for determining EER, referred to as “part-load rating test” conditions in Table 1 of ISO 13256-1:1998, are specified to determine EER values at less than full capacity for models with capacity control. As with the standard rating test conditions, Table 1 of ISO 13256-1:1998 specifies part-load rating test conditions for different specific applications (
i.e.,
86 °F for water-loop, 59 °F for ground-water, and 68 °F for ground-loop heat pumps). None of the part-load rating test conditions are used in the current DOE test procedure. Although Table 1 of ISO 13256-1:1998 specifies conditions for determining EER for multiple applications and (as applicable) capacity levels, ISO 13256-1:1998 does not include any seasonal cooling efficiency metrics.

Additionally, unlike the test methods for other categories of commercial package air conditioners and heat pumps (
e.g.,
AHRI 340/360-2022 for commercial unitary air conditioners and heat pumps (“CUAC/HPs”); AHRI Standard 1230-2021, “2021 Standard for Performance Rating of Variable Refrigerant Flow (VRF) Multi-Split Air-Conditioning and Heat Pump Equipment” (“AHRI 1230-2021”), for variable refrigerant flow air conditioners (“VRF multi-split systems”); AHRI Standard 390-2021, “2021 Standard for Performance Rating of Single Package Vertical Air-Conditioners and Heat Pumps” (“AHRI 390-2021”), for single package vertical units (“SPVUs”); and AHRI Standard 210/240-2023, “2023 Standard for Performance Rating of Unitary Air-conditioning & Air-source Heat Pump Equipment” (“AHRI 210/240-2023”), for central air conditioners and heat pumps (“CAC/HPs”)), for ducted units ISO 13256-1:1998 does not produce ratings that reflect indoor fan power needed to overcome ESP from ductwork. Instead, section 4.1.3 of ISO 13256-1:1998 includes a fan power adjustment (which assumes a fan efficiency of 0.3 for all units) to be applied such that only the fan power required to overcome the internal static pressure (“ISP”) of the unit is taken into account. The exclusion of fan power to overcome ESP from ductwork in ISO 13256-1:1998 ratings results in higher EER ratings than would be measured if ratings reflected fan power to overcome ESP, thereby being more representative of field applications.

Similar to the treatment of fan power, ISO 13256-1:1998 does not produce ratings that reflect the pump power needed to overcome liquid ESP from the water loop that pipes water to and from the WSHP. Instead, section 4.1.4 of ISO 13256-1:1998 includes a pump power adjustment (which assumes a pump efficiency of 0.3 for all units) to be applied such that only the pump power required to overcome the liquid ISP of the unit is taken into account. ISO 13256-1:1998 also does not specify any liquid ESP requirements for testing. The exclusion of pump power to overcome ESP from system water loop piping in ISO 13256-1:1998 ratings results in higher EER ratings than would be measured if ratings reflected pump power to overcome ESP, thereby being more representative of field applications.

An updated version of ISO Standard 13256-1 (
i.e.,
ISO 13256-1:2021) was published in 2021. While there are numerous changes in ISO 13256-1:2021 (discussed in detail in subsequent sections of this NOPR), the 2021 version maintains provisions for determining EER, and it does not include provisions for determining a seasonal metric that incorporates tests at multiple conditions. ISO 13256-1:2021 also maintains the same indoor fan power adjustment and pump power adjustment as in the 1998 version (see sections 5.1.3 and 5.1.4 of ISO 13256-1:2021), thus continuing to produce ratings that do not reflect fan power and pump power associated with overcoming ESP. As discussed in subsequent sections of this document, DOE is proposing provisions in its test procedures for WSHPs to address the identified shortcomings in ISO 13256-1:1998 and ISO 13256-1:2021.

b. AHRI 340/360-2022 and ASHRAE 37-2009

AHRI 340/360-2022 is the industry test procedure used for testing CUAC/HPs. AHRI 340/360-2022 includes the seasonal cooling metric IEER (see section 6.2 of AHRI 340/360-2022), which reflects cooling performance across a range of operating conditions and load levels. Specifically, IEER is a weighted average of the EER at full-load and several part-load conditions intended to represent the range of conditions that a unit would encounter over a full cooling season. The vast majority of operating hours for commercial air conditioners and heat pumps (including CUAC/HPs and WSHPs) occur when conditions are less demanding than full-load conditions. For example, the IEER metric in section 6.2.2 of AHRI 340/360-2022 specifies that full-load conditions account for only 2 percent of operation. AHRI 340/360-2022 also includes minimum ESP requirements that are intended to reflect ESPs in field installations and includes all indoor fan power needed to overcome the tested ESP in the calculation of IEER (see section 6.1.3.3 of AHRI 340/360-2022). AHRI 340/360-2022 also includes a power adder to account for the power of cooling tower fan motor(s) and circulating water pump(s). Similar to other industry test procedures for commercial package air-conditioning and heating equipment, AHRI 340/360-2022 references ANSI/ASHRAE 37-2009 (see section 5.1.1 of AHRI 340/360-2022), which provides a method of test applicable to many categories of air conditioning and heating equipment. In particular, sections 5 and 6 and appendices C, D, E, and I of AHRI 340/360-2022 reference methods of test in ANSI/ASHRAE 37-2009. As discussed in subsequent sections of this notice, DOE has tentatively concluded that AHRI 340/360-2022 addresses many of the identified shortcomings in ISO 13256-1:1998 and ISO 13256-1:2021.

c. AHRI 600

AHRI is in the process of developing a new industry test standard for WSHPs titled “AHRI Standard 600 IEER & SCHE Performance Rating of Water/Brine Source Heat Pumps” (“AHRI 600”). This was formerly designated as AHRI Standard 500P (“AHRI 500P”). DOE has

participated in AHRI committee meetings working to develop AHRI 600 since 2019. Based on its interactions with the AHRI committee, DOE understands that AHRI 600 would not include any provisions for testing, but rather would provide a method for calculation of a seasonal cooling efficiency metric for WSHPs (
i.e.,
IEER) based on testing conducted according to ISO 13256-1:1998. Specifically, DOE understands that AHRI 600 would provide for the calculation of IEER for WSHPs via interpolation and extrapolation of test results reflecting the testing temperatures specified in Table 1 of ISO 13256-1:1998, and the rating conditions for the IEER calculation would be based on the EWTs and weighting factors specified in Table 9 and section 6.2 of AHRI 340/360-2022 for determining IEER for water-cooled CUACs. AHRI 600 is still in development and has not yet published. As discussed in subsequent sections of this notice, DOE has tentatively concluded that the general methodology in AHRI 600 for determining IEER is appropriate, although DOE has identified several aspects of the methodology that warrant further modifications.

2. Comments Received on Industry Standards and DOE Responses

In the June 2018 RFI, DOE discussed how the test method used in ISO 13256-1:1998 is similar to ANSI/ASHRAE 37-2009 and that ANSI/ASHRAE 37-2009 is the method referenced by the 2015 version of AHRI 340/360 (the most current version at the time; “AHRI 340/360-2015”). 83 FR 29048, 29052 (June 22, 2018). DOE also discussed how AHRI 340/360-2015 is referenced by ASHRAE Standard 90.1 for testing WCUACs, and that DOE was considering whether using the same method of test for WSHPs and WCUACs would be appropriate, given the similarities in the design of WSHPs and WCUACs.
Id.
DOE requested comment on whether a single test method could be used for both WSHPs and WCUACs.
Id.
DOE also sought comment on any aspects of design, installation, and application of WSHPs that would make the use of ANSI/ASHRAE 37-2009 infeasible for WSHPs.
Id.

In response to the June 2018 RFI, AHRI and Trane stated that because ASHRAE Standard 90.1 reaffirmed the ISO 13256-1:1998 standard on October 26, 2018, the statutory trigger provisions of 42 U.S.C. 6314(a)(4)(B) do not provide a basis for DOE to review its WSHP test procedure at that time. (AHRI, No. 12 at p. 1, Trane, No. 8 at p. 1)

In response, DOE notes that in addition to the statutory trigger provisions of 42 U.S.C. 6314(a)(4)(B), the Department is statutorily required to review its test procedures every seven years per the 7-year-lookback requirements at 42 U.S.C. 6314(a)(1), as outlined in section I.A of this NOPR.

AHRI, WaterFurnace, and Trane recommended that DOE wait for the ISO revision process to be completed and adopt the revised version of ISO 13256-1:1998 following a second RFI. (AHRI, No. 12 at p. 6; WaterFurnace, No. 7 at p. 2; Trane, No. 8 at p. 3) AHRI and WaterFurnace further commented that the next version of ISO 13256-1 was expected to publish in early 2019, and these commenters recommended that DOE should support the development of the next version of ISO 13256-1:1998. (AHRI, No. 12 at pp. 3, 12-13; WaterFurnace, No. 7 at pp. 2, 10) AHRI and WaterFurnace also stated that many key authors of ANSI/ASHRAE 37-2009 are on the ISO working group, and that the working group was planning to add clarity to the test method with the next revision of ISO 13256-1:1998. The commenters also stated that minimum ESPs were being considered for inclusion in the revised version of ISO 13256-1:1998.
Id.

AHRI and WaterFurnace further stated that for international standards, each nation requires slight deviations from the written ISO standard and that the AHRI WSHP/Geothermal Operations Manual
10

provides the U.S. national deviations from ISO 13256-1:1998. (AHRI, No. 12 at p. 2; WaterFurnace, No. 7 at p. 2) They further stated that the AHRI WSHP/Geothermal Operations Manual addresses multiple issues raised by DOE in the June 2018 RFI.
Id.

10
DOE notes that the AHRI geothermal operations manual is available at:
https://www.ahrinet.org/App_Content/ahri/files/Certification/OM%20pdfs/WSHP_OM.pdf
(Last accessed July 29, 2022).

In response, DOE notes that ISO 13256-1:2021 also lacks a seasonal cooling efficiency metric and does not produce ratings that reflect fan power and pump power associated with overcoming ESP. As discussed, a seasonal cooling efficiency metric would account for the range of conditions that a unit would encounter over a full cooling season. In addition, the inclusion of fan and pump power associated with overcoming ESP would provide ratings that would be more representative of the power consumption in field applications needed to overcome pressure from ductwork and water piping. Section III.D.3 of this document provides further discussion of these considerations and DOE's preliminary conclusion that alternate test methods that address these key issues would provide a more representative measure of a WSHP's overall energy efficiency.

While an updated version of ISO Standard 13256-1 has published (
i.e.,
ISO 13256-1:2021), DOE is not aware of a deviation process being initiated for the U.S. (
i.e.,
development of the version designated with “AHRI/ASHRAE” that is intended for use for testing in the U.S.). DOE understands that the national deviation process will be initiated by a WSHP industry committee, but DOE does not know when that will begin or how long the national deviation process will take. DOE notes that in the past, the WSHP industry committees have taken years longer than expected to develop the revised version of ISO 13256-1, as well as AHRI 600. Specifically, in their RFI comments, AHRI and WaterFurnace stated that they expected the revised ISO 13256-1 to publish in “early 2019” and AHRI 600 to publish in 2019, whereas in reality, the revised ISO 13256-1 published in 2021 and AHRI 600 remains as yet unpublished. Therefore, DOE expects that the national deviation process will not be completed for several years, and the Department cannot speculate as to the substantive output of those efforts or a final completion date. Given EPCA's statutory requirement to review the appropriate test procedures for WSHPs every seven years, DOE has tentatively concluded that it would be neither appropriate nor permissible to delay the current rulemaking for the WSHP test procedure until after the completion of the national deviation process (which the Department understands has not yet even begun).

DOE further notes that the AHRI WSHP/Geothermal Operations Manual is not incorporated by reference into the DOE test procedure, nor is it referenced in ASHRAE Standard 90.1. Therefore, the deviations from the ISO standard included in the AHRI WSHP/Geothermal Operations Manual are not reflected in the current DOE test procedure. However, DOE has nonetheless reviewed the AHRI WSHP/Geothermal Operations Manual as part of its consideration of potential amended test procedure provisions in this NOPR.

With regards to use of a part-load efficiency metric, Trane, AHRI, and WaterFurnace commented that industry is currently developing an IEER metric for WSHPs. (Trane, No. 8 at p. 4; AHRI, No. 12 at p. 11; WaterFurnace, No. 7 at p. 9) AHRI and WaterFurnace commented further that the IEER metric

is included in the draft of AHRI 500P
11

and is calculated using performance data from ISO 13256-1:1998. In addition, AHRI and WaterFurnace stated that WSHPs in water-loop applications (
i.e.,
installed with cooling towers) operate with similar water-loop conditions to WCUACs. Therefore, the commenters argued that the provisions used for determining IEER for WSHPs in the draft of AHRI 500P are similar to those included in AHRI 340/360 and AHRI 1230; specifically, the commenters included a table showing that the IEER EWT conditions in the draft of AHRI 500P align with those specified in AHRI 340/360. Both AHRI and WaterFurnace commented that they anticipated AHRI 500P to be completed in 2019. (AHRI, No. 12 at pp. 11-12; WaterFurnace, No. 7 at p. 9)

11
As discussed, after DOE received comments in response to the June 2018 RFI, the draft AHRI Standard 500P was redesignated as the draft AHRI Standard 600.

Once again, DOE notes that AHRI 600
12

has not yet published, and the Department is unaware as to when that document will be completed. Accordingly, for this NOPR, in addition to proposing a method to determine IEER by testing at the IEER test points specified in Table 9 of AHRI 340/360-2022, DOE is proposing an alternate method of calculating IEER (based on interpolation and extrapolation from results of testing to EWTs specified in Table 1 of ISO 13256-1:1998, rather than testing directly at the EWTs specified for the IEER metric in Table 9 of AHRI 340/360-2022) that DOE understands to be consistent with the approach in the current draft version of AHRI 600. Section III.E.1.b of this NOPR includes further details on the proposed optional approach for calculation of IEER based on interpolation and extrapolation.

12
As discussed, after DOE received comments in response to the June 2018 RFI, the draft AHRI Standard 500P was redesignated as the draft AHRI Standard 600.

DOE also received comments from AHRI, Trane, and WaterFurnace that cautioned against using a different test standard, such as AHRI 340/360, for testing WSHPs instead of ISO 13256-1 as currently specified. (Trane, No. 8 at p. 4; AHRI, No. 12 at p. 12; WaterFurnace, No. 7 at p. 10) AHRI, Trane, and WaterFurnace argued that AHRI 340/360 does not include several important features that are included in ISO 13256-1:1998 such as: provisions for heating performance, performance mapping
13

across a wide temperature range, part-load ratings, application ratings for well water and geothermal, and provisions for testing units with variable-speed compressors. (Trane, No. 8 at p. 4; AHRI, No. 12 at p. 12; WaterFurnace, No. 7 at p. 10) Trane stated that AHRI 340/360 covers only cooling-mode operation of water-cooled units, and that WSHPs require a test procedure that includes both cooling and heating cycle operation. (Trane, No. 8 at p. 4) AHRI and WaterFurnace additionally stated that certain aspects of ISO 13256-1:1998, such as standard rating conditions, are not included in ANSI/ASHRAE 37-2009 because ANSI/ASHRAE 37-2009 is a method of test rather than a test standard. (AHRI, No. 12 at pp. 12-13; WaterFurnace, No. 7 at pp. 10-11) AHRI, Trane, and WaterFurnace further commented that that many aspects of ANSI/ASHRAE 37-2009 are accounted for in ISO 13256-1:1998. (AHRI, No. 12 at p. 13; Trane, No. 8 at p. 4; WaterFurnace, No. 7 at p. 10) AHRI and WaterFurnace also stated that several Environmental Protection Agency (“EPA”), State, utility, and building code requirements reference ISO 13256-1:1998, and they asserted that removing reference to it would have a significant negative impact on the industry and consumers who use efficiency programs and tax credits when selecting equipment. (AHRI, No. 12 at p. 12; WaterFurnace, No. 7 at p. 10)

13
DOE understands use of the term “performance mapping” as referring to making representations of performance across a range of temperature conditions, typically achieved by interpolating or extrapolating from test results obtained at specifically defined test conditions.

The following paragraphs provide DOE's responses to concerns expressed by commenters that AHRI 340/360 and ANSI/ASHRAE 37-2009 lack certain provisions that are present in ISO 13256-1 and that are needed for testing WSHPs.

Regarding provisions for heating tests, DOE acknowledges that AHRI 340/360-2022 does not include certain provisions needed for heating-mode testing of WSHPs because WCUACs, the water-cooled units for which AHRI 340/360-2022 is intended to apply, are not heat pumps. Specifically, AHRI 340/360-2022 does not specify the following provisions for a heating test: an EWT test condition, provisions for setting liquid flow rate, or how pump effects are accounted for. Therefore, DOE is proposing additional provisions that would address these aspects of heating-mode tests of WSHPs, as discussed further in sections III.E.2, III.F.4, III.F.5, and III.F.6 of this document. DOE notes that AHRI 340/360-2022 does include provisions appropriate for air-side measurements in heating tests because AHRI 340/360-2022 covers air-cooled commercial unitary heat pumps. Furthermore, ANSI/ASHRAE 37-2009 provides appropriate provisions for a method of test for WSHPs. DOE has tentatively concluded that its proposals for heating provisions for WSHPs would, when combined with the provisions in AHRI 340/360-2022, produce test results representative of an average use cycle.

Regarding performance mapping across a wide temperature range, part-load ratings, and ratings for ground-water and geothermal applications, DOE acknowledges that AHRI 340/360-2022 does not include EWTs specific to multiple applications of WSHPs. By contrast, Table 1 of ISO 13256-1:1998 provides separate EWTs for water-loop, ground-water, and ground-loop WSHP applications (see discussion in section III.D.1.a of this NOPR). AHRI 340/360-2022 includes full-load and part-load cooling EWTs for only water-loop applications of WCUACs, but the EWT for water-loop applications in Table 1 of ISO 13256-1:1998 is the only EWT test condition used in the current DOE test procedure. As discussed in sections III.D.3 and III.E.1 of this NOPR, DOE has tentatively concluded that the seasonal integrated cooling metric IEER specified in section 6.2 of AHRI 340/360-2022 would be more representative of field applications and provide consumers with a better understanding of year-round performance of WSHPs than the EER metric measured at a single temperature and load level. However, DOE recognizes the potential benefits to consumers of allowing manufacturers to continue to provide performance ratings at the temperatures and load levels specified in Table 1 of ISO 13256-1:1998, in addition to providing the proposed IEER ratings which are more representative of year-round performance. Therefore, as discussed in section III.E.1.a of this NOPR, DOE is proposing in section 5.2 of proposed appendix C1 to provide for optional representations of EER at the EWTs and load levels specified in Table 1 of ISO 13256-1:1998. Consequently, DOE has tentatively concluded that the proposals in this NOPR would continue to provide manufacturers the flexibility to offer full-load and part-load EER ratings at multiple temperatures that can be used for performance mapping, representations of part-load performance, and representations of performance for ground-water and geothermal applications.

Regarding variable-speed compressors, section 6.2 of AHRI 340/360-2022 includes appropriate provisions for testing and determining IEER for units with all compressor

types, including variable-speed compressors. Specifically, Section 6.2.6 of AHRI 340/360-2022 includes provisions addressing “proportionally capacity controlled units,” which is defined in section 3.22 of AHRI 340/360-2022 to include units incorporating one or more variable-capacity compressors where the compressor capacity can be modulated continuously or in steps not more than 5 percent of the full-load cooling capacity. Section 6.2.6 of AHRI 340/360-2022 includes steps for setting capacity of these units for each IEER test point.

With regards to EPA, State, utility, and building code requirements that reference ISO 13256-1:1998, DOE does not expect that an update to the DOE test procedure for WSHPs would create any particular challenges for any other agency or organization that references the performance ratings as measured by the DOE test procedure. EPCA directs DOE to establish and amend test procedures to be reasonably designed to produce test results which reflect energy efficiency, energy use, and estimated operating costs of covered equipment during a representative average use cycle (as determined by the Secretary), and not be unduly burdensome to conduct. (42 U.S.C. 6314(a)(2)) DOE test procedures are updated regularly, across many products and equipment types, and other agencies and organizations have historically updated their requirements as needed in response to those changes. With regard to EPA specifically, DOE has responsibility for developing and revising the test procedures that provide the basis for ratings under EPA's ENERGY STAR program. DOE and EPA work closely together to update ENERGY STAR specifications in response to any changes to the relevant DOE test procedure. Furthermore, DOE is proposing that the amended test procedure would not be required for use until the effective date of any future energy conservation standards based on the IEER metric, thereby providing sufficient advance notice for any agency or organization to adapt program requirements accordingly.

3. Proposal for DOE Test Procedure

As discussed, EPCA requires that test procedures for covered equipment, including WSHPs, be reasonably designed to produce test results which reflect energy efficiency, energy use, and estimated operating costs of a type of industrial equipment (or class thereof) during a representative average use cycle (as determined by the Secretary), and shall not be unduly burdensome to conduct. (42 U.S.C. 6314(a)(2))

For the reasons presented in the remainder of this section, DOE has tentatively determined that the test procedure for WSHPs as proposed would improve the representativeness of the current Federal test procedure for WSHPs and would not be unduly burdensome. Specifically, DOE has tentatively concluded, supported by clear and convincing evidence as discussed in the following paragraphs, that testing WSHPs in accordance with the industry test standards AHRI 340/360-2022 and ASHRAE 37-2009 would provide more representative results and more fully comply with the requirements of paragraph (2) of 42 U.S.C. 6314(a) than testing in accordance with the currently referenced standard ISO 13256-1:1998. Therefore, DOE is proposing to amend the test procedure for WSHPs so as to incorporate by reference in the proposed new appendix C1 the test provisions in AHRI 340/360-2022 and ASHRAE 37-2009, along with certain additional provisions.

Throughout the remainder of the discussion in section III of this NOPR, DOE presents the details and justifications for the proposed test procedure and deviation from the currently referenced industry test procedure, ISO 13256-1:1998 (
i.e.,
the industry test standard referenced in ASHRAE Standard 90.1). The following paragraphs summarize the key areas in which DOE has tentatively concluded, supported by clear and convincing evidence, that the proposal would improve the representativeness of the test procedure:

(1) Cooling efficiency metric: As discussed, the cooling metric specified in the current DOE test procedure (which references ISO 13256-1:1998) is EER, which reflects full-load performance only at a single operating condition. In contrast, IEER, the metric specified in section 6.2 of AHRI 340/360-2022, is a seasonal metric that is a weighted average of the full- and part-load performance at different outdoor conditions intended to represent average efficiency over a full cooling season. For the vast majority of operating hours for WSHPs and other commercial air conditioners and heat pumps installed in the field, loads are at less than full-load capacity. This is because units are sized to be able to provide sufficient air conditioning capacity at the hottest time on the hottest day of the year, but the vast majority of annual cooling hours are at significantly lower outdoor temperatures (and thus lower EWTs), with correspondingly lower cooling loads. This is demonstrated in the IEER metric specified in section 6.2.2 of AHRI 340/360-2022, which specifies a weighting factor for full-load conditions of only 2 percent of the hours included in the IEER metric, with the remaining 98 percent of hours assigned to lower load levels and lower outdoor temperatures. As discussed, from RFI comments and DOE's participation in AHRI 600 committee meetings, DOE understands that the AHRI 340/360-2022 IEER weighting factors are also included in the draft AHRI 600. Therefore, DOE has tentatively concluded that IEER would be more representative of an average use cycle than the EER metric. This topic is discussed further in section III.E.1 of this NOPR.

(2) Fan power and indoor air external static pressure: As discussed, for ducted units, ISO 13256-1:1998 does not produce ratings that reflect the fan power needed to overcome ESP. Further, that ISO standard does not specify ESP requirements for ducted units and instead uses a fan power adjustment, such that ratings reflect only the fan power needed to overcome internal static pressure within the unit and not the ESP from the ductwork that would be installed in the field. In contrast, Table 7 of AHRI 340/360-2022 specifies minimum ESP requirements at which performance is measured. Because ducted WSHPs are manufactured to be installed in the field with ductwork, DOE has tentatively concluded that a WSHP rating that reflects the indoor fan power needed to overcome ESP representative of typical installations (
i.e.,
the approach taken by AHRI 340/360-2022) would produce test results that are more representative of an average use cycle than testing in accordance with ISO 13256-1:1998, the standard currently incorporated by reference.

(3) Pump power and liquid external static pressure: ISO 13256-1:1998 does not produce ratings that reflect the pump power needed to overcome liquid ESP. Further, for units with integral pumps, ISO 13256-1:1998 does not specify ESP requirements and uses a pump power adjustment such that ratings reflect only the pump power needed to overcome internal static pressure within the unit. For units with integral pumps, DOE has tentatively concluded that ratings would be more representative if based on testing at a liquid ESP that is representative of the ESP from water piping in typical installations. For units without integral pumps, DOE has tentatively concluded that ratings would be more

representative if a pump power adder is included in the rating that reflects pump power needed to overcome a field-representative liquid ESP. More discussion on this topic is provided in section III.F.4 of this document.

DOE is proposing to adopt in its WSHP test procedure the following specific sections of AHRI 340/360-2022:

(1) Section 3: Definitions, excluding sections 3.2, 3.4, 3.5, 3.7, 3.8, 3.12, 3.14, 3.15, 3.17, 3.23, 3.26, 3.27, 3.29, 3.30, and 3.36;

(2) Section 5: Test Requirements;

(3) Section 6: Rating Requirements, excluding sections 6.1.1.7, 6.1.2.1, 6.1.3.4.5, 6.1.3.5.4, 6.1.3.5.5, 6.5, 6.6, and 6.7;

(4) Appendix A. References—Normative;

(5) Appendix C. Indoor and Outdoor Air Condition Measurement—Normative;

(6) Appendix E. Method of Testing Unitary Air Conditioning Products—Normative;

The key substantive changes that would result from DOE's proposal to adopt AHRI 340/360-2022 for testing WSHPs include the following:

(1) A new energy efficiency descriptor, IEER, which incorporates part-load cooling performance (see section 6.2 of AHRI 340/360-2022);

(2) Minimum ESP requirements, instructions for setting airflow and ESP, and tolerances for airflow and ESP (see sections 6.1.3.3, 6.1.3.4, and Table 6 of AHRI 340/360-2022);

(3) Fixed inlet and outlet water temperature conditions (see Table 5 of AHRI 340/360-2022);

(4) Operating tolerance for voltage (see Table 10 of AHRI 340/360-2022);

(5) Different indoor air conditions used for testing (see Table 5 of AHRI 340/360-2022);

(6) Refrigerant charging instructions for cases where they are not provided by the manufacturer (see section 5.8 of AHRI 340/360-2022), and

(7) Use of the primary capacity measurement (
i.e.,
indoor air enthalpy method) as the value for capacity, and different provisions for required agreement between primary and secondary capacity measurements (see section E6 of Appendix E to AHRI 340/360-2022).

Appendix E of AHRI 340/360-2022 specifies the method of test, including the use of specified provisions of ANSI/ASHRAE 37-2009. Consistent with AHRI 340/360-2022, DOE is proposing to incorporate by reference ANSI/ASHRAE 37-2009 in its test procedure for WSHPs. Specifically, in section 1 of the proposed test procedure for WSHPs in the proposed appendix C1, DOE is proposing to adopt all sections except sections 1, 2, and 4 of ANSI/ASHRAE 37-2009. The key substantive changes that would result from DOE's proposal to adopt ANSI/ASHRAE 37-2009 for testing WSHPs include the following:

(1) Provisions for split systems, such as accounting for compressor heat and refrigerant line losses (see sections 7.3.3.4, 7.3.4.4, and 7.6.1.2 of ASHRAE 37-2009);

(2) Measurement of duct losses for ducted units (see section 7.3.3.3 of ASHRAE 37-2009);

(3) Standardized heat capacity of water and brine (see section 12.2 of ASHRAE 37-2009), and

(4) A calculation for discharge coefficients (see section 6.3.2 of ASHRAE 37-2009).

Throughout the remainder of this NOPR, DOE discusses substantive differences between the proposed test procedure (including references to AHRI 340/360-2022 and ASHRAE 37-2009) and the current DOE test procedure (which incorporates by reference ISO 13256-1:1998). DOE also identified and considered provisions in the updated industry test procedure ISO 13256-1:2021 that substantively differ from ISO 13256-1:1998.

E. Efficiency Metrics

1. IEER

a. General Discussion

As discussed previously, DOE's current test procedure for WSHPs measures cooling-mode performance in terms of the EER metric, the current regulatory metric. 10 CFR 431.96. EER captures WSHP performance at a single, full-load operating point in cooling mode (
i.e.,
a single EWT) and does not provide a seasonal or load-weighted measure of energy efficiency. A seasonal metric is a weighted average of the performance of cooling or heating systems at different outdoor conditions intended to represent average efficiency over a full cooling or heating season. Several categories of commercial package air-conditioning and heating equipment are rated using a seasonal or part-load metric, such as IEER for CUACs specified in section 6.2 of AHRI 340/360-2022. IEER is a weighted average of efficiency at four load levels representing 100, 75, 50, and 25 percent of full-load capacity, each measured at a specified outdoor condition that is representative of field operation at the given load level. In general, the IEER metric provides a more representative measure of field performance than EER by weighting the full-load and part-load efficiencies by the average amount of time equipment spends operating at each load level. Table 1 of ISO 13256-1:1998, the industry test standard incorporated by reference into DOE's current WSHP test procedure, and Table 2 of ISO 13256-1:2021 both specify entering water temperature conditions to be used for developing part-load ratings of EER for WSHPs with capacity control (tested at minimum compressor speed). However, part-load EER ratings are not addressed in the current DOE test procedure. Further, each part-load rating captures operation only at a single compressor speed and entering water temperature, not operation across a range of temperatures and compressor speeds. Neither ISO 13256-1:1998 nor ISO 13256-1:2021 include seasonal metrics.

In the June 2018 RFI, DOE requested comment on whether a seasonal metric that accounts for part-load performance would be appropriate for WSHPs, and the Department sought information on the specific details of a seasonal metric that would best represent average cooling efficiency for WSHPs. 83 FR 29048, 29051 (June 22, 2018).

NEEA encouraged DOE to consider adopting IEER for WSHPs and to improve the metric so as to make it more representative of an average use cycle by including changes to more accurately represent fan energy use in field applications, accounting for all modes of operation, and including ventilating and economizing. (NEEA, No. 11 at p. 2)

The Joint Advocates recommended that DOE should consider seasonal efficiency metrics for WSHPs to better reflect field energy consumption, including part-load operation. The Joint Advocates stated that it was their understanding that WSHPs operate most of the time at part-load, and that, therefore, full-load efficiency ratings do not provide sufficient information to consumers. The Joint Advocates also stated that the current metrics do not demonstrate the potential savings associated with technologies that improve part-load efficiency, such as variable-speed compressors. (Joint Advocates, No. 10 at p. 2)

The CA IOUs stated that while the IEER metric provides a valuable measure of annual efficiency, the EER metric is important for achieving reductions in peak loads. These commenters remarked that because the IEER metric uses a low weighting (
i.e.,
2 percent) for the full-load condition, a standard based only on the IEER metric would incentivize manufacturers to optimize equipment at the part-load conditions and could potentially result in equipment that is designed with lower full-load EERs than the current standards for this equipment. To prevent poor equipment performance at full-load conditions, the CA IOUs supported using the IEER metric that measures part-load efficiencies in conjunction with the currently regulated full-load EER metric. (CA IOUs, No. 9 at pp. 1-2) The CA IOUs further commented that the prevalence of economizers in buildings with WSHPs

should be investigated and that modifications to the IEER metric should be informed by the outcome of such research before the IEER metric is implemented as the efficiency metric for WSHPs. (CA IOUs, No. 9 at p. 1)

Trane, AHRI, and WaterFurnace commented that industry is currently developing an IEER metric for WSHPs (Trane, No. 8 at p. 4; AHRI, No. 12 at p. 11; WaterFurnace, No. 7 at p. 9). AHRI and WaterFurnace explained further that the IEER metric is included in the draft version of AHRI 500P,
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and as drafted, IEER is calculated using performance data from ISO 13256-1:1998. AHRI and WaterFurnace commented that the provisions used for determining IEER for WSHPs in the draft version of AHRI 500P are similar to those included in AHRI 340/360 and AHRI 1230. Both AHRI and WaterFurnace commented that they anticipated AHRI 500P to be completed in 2019. (AHRI, No. 12 at p. 11; WaterFurnace, No. 7 at p. 9)

14
As discussed, after DOE received comments in response to the June 2018 RFI, the draft AHRI Standard 500P was redesignated as the draft AHRI Standard 600.

As explained previously, DOE notes that the EER metric in DOE's current test procedure for WSHPs measures only full-load performance, and the revised industry test procedure ISO 13256-1:2021 does not include a seasonal metric. For the vast majority of operating hours of WSHPs installed in the field, loads are less than full-load capacity, thus causing single-stage WSHPs to cycle and multi-stage WSHPs to operate at part-load (
i.e.,
less than designed full capacity). Because a seasonal metric reflects operation at a range of conditions experienced over the period of a cooling season, DOE has tentatively concluded that a cooling metric that accounts for part-load performance across a range of temperatures (such as IEER specified in section 6.2 of AHRI 340/360-2022) would be more representative of an average use cycle than the full-load EER metric, which reflects operation at a single condition. Further, a seasonal metric that reflects varying load levels representative of a full cooling season would better incentivize use of modulating components (
e.g.,
multi-stage and variable-speed compressors) that can reduce annual energy consumption in field installations.

DOE has been participating in AHRI committee meetings to develop AHRI 600 with the goal of specifying an IEER metric for WSHPs. It is DOE's understanding that the committee's work is ongoing, and its completion date is uncertain. However, based on comments received on the June 2018 RFI, manufacturer feedback obtained via DOE's participation in AHRI 600 committee meetings, and DOE's own research, the Department has tentatively concluded that the EWTs and weighting factors specified in Table 9 and equation 3 of AHRI 340/360-2022 for water-cooled CUACs would be representative for WSHPs. DOE's understanding based on a review of market literature and available studies is that in the past, WSHP installations were more typically controlled such that water-loop temperatures were maintained at temperatures above 60 °F through heat provided by a system boiler. From manufacturer feedback provided in AHRI 600 committee meetings, DOE understands that in current practice, WSHP installations are typically controlled to allow water-loop temperatures to drop to temperatures closer to 50 °F. Manufacturers indicated that this change in how WSHP system loops are typically controlled in the field is because of multiple factors. One factor provided by manufacturers is that because commercial buildings with WSHP installations are typically cooling-dominated (
i.e.,
most WSHPs spend more time in cooling mode than heating mode), building engineers have increasingly optimized overall WSHP system performance by using the cooling tower to decrease EWTs below 60 °F even when some WSHPs in the loop are in heating mode, thereby improving efficiency for the WSHPs in cooling mode at the expense of reducing efficiency for the fewer WSHPs in heating mode. Additionally, manufacturers indicated that the market penetration of WSHPs with water-side economizers has significantly increased in recent years, largely related to requirements in ASHRAE Standard 90.1 regarding presence of economizers in HVAC systems. Water-side economizers provide compressor-free cooling when supplied with water of sufficiently low temperature; therefore, manufacturers have indicated that building engineers are increasingly maintaining WSHP loop temperatures below 60 °F to take advantage of water-side economizer cooling.
15

Given this feedback provided by manufacturers on the WSHP loop water temperatures typically used in the field, DOE has tentatively concluded that the IEER EWTs specified in Table 9 of AHRI 340/360-2022 (
i.e.,
85 °F, 73.5 °F, 62 °F, and 55 °F) are representative of current installations of WSHPs. Section III.E.4 of this NOPR includes discussion on other operating modes other than mechanical cooling and heating, such as ventilation and economizing.

15
In WSHPs with water-side economizers, if the EWT is sufficiently low in cooling mode, some or all of the entering water that would otherwise enter the water-to-refrigerant condenser coil instead enters the economizer coil, in which the cool water is used to directly cool indoor air, reducing the need for mechanical cooling from the compressor.

Based on the discussion in the preceding paragraphs, DOE has tentatively determined that use of a seasonal efficiency metric, specifically IEER based on AHRI 340/360-2022, would be more representative of the average use cycle of a unit as compared to the current EER metric. Once again, DOE notes that while it may have been expected that AHRI 600 was to publish in 2019, the draft standard has not yet been finalized. Accordingly, DOE is moving forward and proposing to adopt certain provisions of AHRI 340/360-2022 and use the IEER metric specified in section 6.2 of AHRI 340/360-2022 for WSHPs. DOE is proposing to specify the relevant test procedure requirements for WSHPs for measuring IEER in section 5.1 of proposed appendix C1.

As discussed, the proposed IEER test procedure for WSHPs would not be required until such a time as DOE adopts energy conservation standards for WSHPs denominated in terms of IEER, should DOE adopt such standards. If DOE were to adopt such standards, such shift to the IEER metric for WSHPs would require all WSHPs to be re-rated in terms of the IEER metric. Further, beginning 360 days after final rule publication, manufacturers would be required to use the proposed test procedure in appendix C1 to make optional representations of IEER for WSHPs. The cost and impacts to manufacturers of the proposed test procedure are discussed further in section III.I of this document. Additionally, adopting the IEER metric for WSHPs would increase the number of required cooling-mode tests from one to four. However, as discussed, DOE understands that AHRI 600 would provide for calculating IEER from test results measured at the EWTs specified in Table 1 of ISO 13256-1:1998. Consistent with this approach and as discussed in the following section, DOE is proposing to allow determination of IEER via interpolation and extrapolation from testing at the full-load and part-load EWT conditions specified in Table 1 of ISO 13256-1:1998.

In response to the CA IOUs' suggestion, although EPCA limits the agency to promulgation of a single performance standard (
see
42 U.S.C. 6311(18)), DOE is proposing to provide for optional representations of EER conducted per the proposed test procedure (sections 2 through 4 and 7 of proposed appendix C1) at the full-load and part-load EWT conditions specified in Table 1 of ISO 13256-1:1998 (
i.e.,
full load tests at 86 °F, 77 °F, and 59 °F and part-load tests at 86 °F, 68 °F, and 59 °F).

Issue 3: DOE requests comment on its proposal to adopt the test methods specified in AHRI 340/360-2022 for calculating the IEER of WSHPs. DOE also requests comment on its proposal that all EER tests at full-load and part-load conditions specified in Table 1 of ISO 13256-1:1998 (
i.e.,
full-load tests at 86 °F, 77 °F, and 59 °F and part-load tests at 86 °F, 68 °F, and 59 °F) are optional.

b. Determination of IEER Via Interpolation and Extrapolation

As discussed, DOE understands that the draft AHRI 600 would provide a mechanism for calculating IEER from test results measured at the EWTs specified in Table 1 of ISO 13256-1:1998. Specifically, interpolation and extrapolation
16

from ISO 13256-1:1998 test results would be used to calculate performance at the EWTs specified in Table 9 of AHRI 340/360-2022 for WCUACs, allowing calculation of IEER for WSHPs using the weighting factors specified in section 6.2.2 of AHRI 340/360-2022. Under this approach, AHRI 600 would not include any provisions for testing, but rather would provide a method for calculation of IEER based on results of testing under ISO 13256-1:1998. DOE recognizes that there may be a value for stakeholders in representations of full-load and part-load EER ratings at the temperatures specified in Table 1 of ISO 13256-1:1998. Specifically, these EWTs represent different applications, and manufacturers may prefer to provide representations of performance specific to different applications.

16
Per the draft AHRI 600 method, performance at IEER EWTs can be determined using test results at two different temperature conditions (specified in ISO 13256-1:1998). Interpolation is used if the IEER EWT is between the two tested EWTs, and extrapolation is used if the IEER EWT is outside the range of the two tested results.

The ability to determine EER ratings at the ISO 13256-1:1998 EWTs (in accordance with the proposed test procedure, at section 5.2 of the proposed appendix C1), and to determine IEER via interpolation and extrapolation from testing at the ISO 13256-1:1998 EWTs, rather than from additional testing at the IEER EWTs specified in AHRI 340/360-2022, may reduce overall testing burden for manufacturers. Consequently, DOE investigated the AHRI 600 method of calculating IEER.

To evaluate the draft AHRI 600 method of calculating IEER, DOE conducted investigative testing on a sample of WSHPs. DOE presents the results of testing 15 WSHPs in the following paragraphs. This testing compared the interpolation and extrapolation method of calculating IEER at the ISO 13256-1:1998 EWTs to testing at the IEER EWTs specified in AHRI 340/360-2022. In summary and for the reasons discussed in the following paragraphs, DOE has tentatively determined that an interpolation and extrapolation approach, similar to that in draft AHRI 600 with certain modifications, is appropriately representative to calculate IEER.

To determine if the interpolation and extrapolation method is appropriate for WSHPs, DOE evaluated whether the components needed to calculate IEER can be linearly interpolated across EWT. Specifically, the parameters necessary for the calculation of IEER are EER, capacity, total power, and all components of power (
i.e.,
compressor power, fan power, condenser section power, controls power). DOE tested 15 units at different EWTs to compare physical tested results and interpolated and extrapolated values. The method evaluated by DOE determines IEER ratings for WSHPs by interpolation and extrapolation from full-load tests at liquid inlet temperatures of 86 °F, 77 °F, and 59 °F and, for two-stage and variable-speed units, part-load tests at 86 °F, 68 °F, and 59 °F. DOE first evaluated the accuracy of interpolating to a different EWT for full-load tests. For each of the 15 units tested, DOE conducted full-load tests to measure EER at 86 °F, 77 °F, and 59 °F. DOE then used the results from the 86 °F and 59 °F tests to linearly interpolate to performance at 77 °F, and compared these interpolated results to the results of testing at 77 °F. Table 3 presents a summary of the percentage differences between the interpolated and measured values. Positive values in the average, minimum, and maximum columns of Table 3 indicate that the values interpolated to 77 °F from results measured at 86 °F and 59 °F were higher than the values measured at 77 °F, and negative values indicate the opposite.

Table 3—Percentage Differences of Interpolated Results From Measured Results for Capacity, Power, and EER

Parameter
Average
Minimum
Maximum

Average
absolute
value

Cooling Capacity
−0.2
−1.4
2.2
0.9

Total Power
−0.4
−2.6
1.5
0.8

Interpolated EER
2.3
0.3
4.8
2.3

EER calculated from interpolated capacity and power
0.2
−1.7
2.9
1.0

Note:
Positive values in the average, minimum, and maximum columns indicate that the values interpolated to 77 °F from results measured at 86 °F and 59 °F were higher than the values measured at 77 °F. Negative values in the average, minimum, and maximum columns indicate that the values interpolated to 77 °F from results measured at 86 °F and 59 °F were lower than the values measured at 77 °F.

As shown in Table 3, the interpolated values for cooling capacity and total power differed from the corresponding tested values by an average of less than 1 percent. Therefore, DOE has determined that interpolating capacity and total power results in representative values of capacity and total power, respectively. However, the interpolated EER value at 77 °F was higher than the tested EER value at 77 °F for all tested units, with an average difference of 2.3 percent (ranging from 0.3 percent to 4.8 percent higher). Because of the consistent bias in the results showing interpolated EER higher than tested

EER,
17

DOE considered an alternate approach of calculating EER based on interpolated values of cooling capacity and total power rather than interpolating EER directly. The bottom row of Table 3 shows the results of calculating EER at 77 °F using the interpolated values of cooling capacity and total power. As shown in in the bottom row of Table 3, calculating EER at 77 °F using interpolated values of cooling capacity and total power resulted in EER values that were on average 0.2 percent higher than the tested EER value at 77 °F (ranging from 1.7 percent lower to 2.9 percent higher). Because determining EER by interpolating cooling capacity and total power results in closer agreement to tested values than directly interpolating EER (and does not consistently bias results toward higher interpolated EER values), DOE used the former approach in the calculation of IEER values discussed in the following paragraphs.

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As presented in Table 3, the results from DOE's testing show that that linear interpolation across EWT results in close agreement for cooling capacity and total power. Because EER = Cooling Capacity/Total Power, if linear equations are used to represent the relationship between cooling capacity and EWT, as well as between total power and EWT, the resulting equation for EER has equations linearly dependent on EWT in the numerator and denominator. Such an equation simplifies to an inverse function (
i.e.,
the variable (EWT) is in the denominator), which is concave up (
i.e.,
the slope of the EER vs EWT curve increases with increasing EWT), such that between any two points on the curve, the curve is always below a line drawn between the two points. Therefore, calculating EER by linearly interpolating EER values across EWT consistently results in an interpolated EER value that is higher than the EER value measured by testing or determined by linearly interpolating cooling capacity and total power.

For determining IEER for single-stage units, this interpolation and extrapolation approach would be used to determine EER at the EWTs for all 4 IEER points, and the EER results for the part-load points (
i.e.,
test points designated as B, C, and D in AHRI 340/360-2022) would also be adjusted for cyclic degradation (see discussion in section III.F.2.b of this document).

For two-stage and variable-speed WSHPs, DOE evaluated a method that tests at the minimum compressor speed at the EWTs specified in Table 1 of ISO 13256-1:1998 for part-load tests (
i.e.,
at 86 °F, 68 °F, and 59 °F). As with the draft AHRI 600 method, the method evaluated by DOE then provides for interpolating to the IEER liquid inlet temperatures from these part-load tests, and IEER is determined using interpolated results for the IEER EWTs for both full-load and part-load tests.
18

To evaluate the accuracy of this methodology for calculating IEER for staged WSHPs, DOE conducted additional investigative testing on 10 of the 15 tested WSHPs (6 two-stage WSHPs and 4 variable-speed WSHPs). Specifically, these 10 units were tested to calculate IEER via the interpolation and extrapolation method (by conducting full-load and part-load tests at the EWTs specified in Table 1 of ISO 13256-1:1998 and using interpolation and extrapolation to calculate IEER) and were tested to determine IEER per section 6.2 of AHRI 340/360-2022 by testing at the IEER EWTs and target load levels specified in Table 9 of AHRI 340/360-2022. Consistent with the discussion in the previous paragraphs, when interpolating to determine performance at a different EWT for a given compressor stage for staged units, DOE calculated the EER values by interpolating and extrapolating values of cooling capacity and total power, rather than directly interpolating and extrapolating values of EER. Table 4 presents a summary of the results. Positive values in the average, minimum, and maximum columns of Table 4 indicate that the IEER values determined via the interpolation and extrapolation method were higher than the IEER values determined through testing at the EWTs and load levels specified in section 6.2 of AHRI 340/360-2022, and negative values indicate the opposite.

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After interpolating the full-load and part-load interpolated across EWT, the AHRI 340/360-2022 IEER calculation methodology is then used. The interpolated results would either need cyclic degradation (see discussion in section III.F.2.b of this NOPR) or interpolation across compressor staging to determine the specific load EER values to be used in the IEER calculation, unless the EWT interpolation yields a calculated percent load that meets the 3 percent tolerance for the respective IEER load point.

Table 4—Percentage Differences of Interpolated IEER From Measured IEER for Two-Stage and Variable-Speed Units

Capacity
control type

Average
Minimum
Maximum

Average
absolute
value

Two-Stage
−0.9
−2.7
−0.0
0.9

Variable-Speed
−6.3
−13.6
0.2
6.4

Note:
Positive values in the average, minimum, and maximum columns indicate that the IEER values determined via the interpolation and extrapolation method were higher than the IEER values determined through testing at the EWTs and load levels specified in section 6.2 of AHRI 340/360-2022. Negative values in the average, minimum, and maximum columns indicate that the IEER values determined via the interpolation and extrapolation method were lower than the IEER values determined through testing at the EWTs and load levels specified in section 6.2 of AHRI 340/360-2022.

As shown in Table 4, for the six tested two-stage WSHPs, the IEER values calculated using the described interpolation and extrapolation method were on average 0.9 percent lower than the IEER value measured from testing per AHRI 340/360-2022 (ranging from 0.0 percent to 2.7 percent lower).

For the four variable-speed units, the IEER values calculated using the described interpolation and extrapolation method were on average 6.3 percent lower than the IEER value measured from testing per AHRI 340/360-2022 (ranging from 0.2 percent higher to 13.6 percent lower). These results demonstrate a wider discrepancy from AHRI 340/360-2022 results than for single-stage or two-stage WSHPs. This discrepancy is likely because the interpolation and extrapolation method described only includes testing at maximum and minimum compressor speed, whereas the AHRI 340/360-2022 approach includes testing at compressor speeds to operate at each of the part-load test points (
i.e.,
75 percent, 50 percent, and 25 percent load). Therefore, for variable-speed WSHPs with higher EER at intermediate compressor speeds than at maximum or minimum compressor speeds, the interpolation and extrapolation method described results in a lower calculated IEER than testing at the IEER conditions specified in AHRI 340/360-2022, which was the case for three of the four tested units. While for certain tested variable-speed units calculating IEER via interpolation and extrapolation resulted in a lower IEER value, from participation in AHRI 600 committee

meetings, DOE understands that many manufacturers would prefer the option to use the interpolation and extrapolation method for variable-speed WSHPs even if it results in lower IEER ratings, because it would result in less overall testing burden than testing at each of the AHRI 340/360-2022 conditions.

Based on the investigative testing conducted, DOE has tentatively concluded that determining IEER via interpolation and extrapolation from testing at the ISO 13256-1:1998 EWTs (in accordance with DOE's proposed test procedure), similar to the method in the draft AHRI 600, provides appropriately representative results that are comparable to testing at the EWTs (and for staged units, load levels) specified in Table 9 of AHRI 340/360-2022. Therefore, DOE is proposing in section 5 of the proposed appendix C1 to allow that IEER for WSHPs can be calculated from either of two methods: (1) “option 1”—testing in accordance with AHRI 340/360-2022 (at EWTs of 85 °F, 73.5 °F, 62 °F, and 55 °F); or (2) “option 2”—interpolation and extrapolation of cooling capacity and power values based on testing in accordance with the proposed test procedure at EWTs of 86 °F, 77 °F, and 59 °F for full-load tests and (for staged units) EWTs of 86 °F, 68 °F, and 59 °F for part-load tests. For single speed units, option 2 would require three full-load tests at entering liquid temperatures of 86 °F, 77 °F, and 59 °F. For two-stage and variable-speed units, three additional tests at the minimum compressor speed would be required, at entering liquid temperature of 86 °F, 68 °F, and 59 °F.

Specifically for option 2, aside from the EWTs, the tests for option 2 would be performed using the same test provisions from AHRI 340/360-2022, ANSI/ASHRAE 37-2009, and sections 2 through 4 and 7 of proposed appendix C1 as the tests for option 1. As discussed, DOE has tentatively determined that results from the interpolation and extrapolation method have greater agreement with, and, therefore, are comparably representative to, the tested results by interpolating values of cooling capacity and total power rather than interpolating values of EER; therefore, DOE is proposing that the alternative method specify interpolation using the cooling capacity and total power. The proposed provisions for option 2 in section 5.1.2 of proposed appendix C1 are otherwise generally consistent with the draft AHRI 600 method, except for the cyclic degradation approach, which is discussed in section III.F.2.b of this NOPR.

DOE notes that representations for WSHPs can be made either based on testing (in accordance with 10 CFR 429.43(a)(1)) or AEDMs (in accordance with 10 CFR 429.43(a)(2)). If represented values for a basic model are determined with an AEDM, the AEDM could use either option 1 or option 2 for determining IEER per the proposed test procedure in appendix C1.

Issue 4: DOE requests comment on the proposal to allow determination of IEER using two different methods: (1) testing in accordance with AHRI 340/360-2022; or (2) interpolation and extrapolation of cooling capacity and power values based on testing in accordance with the proposed test procedure at the EWTs specified in Table 1 of ISO 13256-1:1998. Specifically, DOE seeks feedback on the proposed method for calculating IEER via interpolation and extrapolation, and on whether this approach would serve as a potential burden-reducing option as compared to testing at the AHRI 340/360-2022 conditions.

Issue 5: DOE requests comment on whether the proposed methodology to determine IEER based on interpolation and extrapolation is appropriate for variable-speed units. DOE would consider requiring variable-speed equipment be tested only according to AHRI 340/360-2022 and, thus, testing physically at the IEER EWTs, if suggested by commenters.

DOE is aware that ISO 13256-1:2021 includes changes from ISO 13256-1:1998 with respect to the EWTs specified for cooling tests. Specifically, Table 2 of ISO 13256-1:2021 specifies full-load cooling temperatures of 86 °F, 68 °F, and 50 °F, and part-load cooling temperatures of 77 °F, 59 °F, and 41 °F. Consistent with the draft AHRI 600 method, DOE is proposing to use the temperatures specified in Table 1 of ISO 13256-1:1998 for option 2 tests; however, it is expected that the results under the proposed interpolation and extrapolation method would provide comparable results using the EWTs specified in Table 2 of ISO 13256-1:2021.

Issue 6: DOE seeks feedback on whether the proposed interpolation and extrapolation method should be based on testing at the ISO 13256-1:2021 EWTs.

2. COP

a. General Discussion

DOE's current test procedure for WSHPs measures heating-mode performance in terms of the COP metric, based on testing with a 68 °F EWT. 10 CFR 431.96. For the reasons explained in the following paragraphs, DOE is proposing in section 6.2 of proposed appendix C1 to use an EWT of 55 °F for the COP metric because DOE has tentatively concluded that 55 °F is more representative of field operation than the current EWT of 68 °F.

COP is a full-load heating efficiency metric for WSHP water-loop applications, meaning that it represents the heating efficiency for a WSHP operating at its maximum capacity at an EWT that is typical of heating operation in water-loop applications. Because commercial buildings served by WSHPs in water-loop applications are typically cooling-dominated, DOE understands that the majority of heating hours in these applications occur in simultaneous cooling and heating operation—in which certain WSHPs (
e.g.,
servicing zones around the perimeter of the building) are in heating mode while other WSHPs (
e.g.,
servicing interior zones closer to the center of the building) are in cooling mode. Because all WSHPs in the system loop are provided water with the same EWT, at any given time, WSHPs that are in heating mode operate at the same EWT as WSHPs in cooling mode. As discussed in section III.E.1.a of this NOPR, from manufacturer feedback provided in AHRI 600 committee meetings, DOE understands that while in the past water-loop temperatures were maintained at temperatures above 60 °F via heat provided by a system boiler, in current practice, WSHP installations are typically controlled to allow water-loop temperatures to drop to temperatures closer to 50 °F. Correspondingly, DOE is proposing part-load IEER EWTs that align with AHRI 340/360-2022 and the draft AHRI 600, including 62 °F for the 50-percent load point and 55 °F for the 25-percent load point.

Because DOE understands that WSHP water-loop temperatures are typically controlled to drop closer to 50 °F (as represented by the 55 °F EWT for the 25-percent load point), the Department understands that most hours of heating mode operation for WSHPs in water-loop applications occur with EWTs closer to 50 °F. Therefore, while the current 68 °F EWT for the COP metric may have been more representative of how WSHP systems were controlled in the past (
i.e.,
with a boiler maintaining water-loop temperatures above 60 °F), DOE has tentatively determined that the COP EWT should be no higher than the lowest EWT used in the IEER metric, which is 55 °F (for the 25-percent load point), because most heating hours occur when outdoor air temperatures are lower and, thus, cooling loads are

lower. Therefore, DOE has tentatively concluded that the COP metric would be more representative of water-loop WSHP applications if based on an EWT of 55 °F.

DOE also considered whether an EWT below 55 °F, specifically 50 °F, might be more representative for determining COP, depending upon typical heating conditions for water-loop WSHPs. However, DOE currently lacks data or evidence indicating that 50 °F would be a more representative heating EWT than 55 °F for WSHPs. Therefore, in the absence of any data suggesting a lower EWT would be more representative of heating operation of WSHPs, DOE is proposing an EWT of 55 °F, which aligns with the lowest IEER EWT as proposed.

Issue 7: DOE seeks comment and data on the representativeness of 55 °F as the EWT condition for determining COP. Specifically, DOE requests feedback and data on whether a lower EWT, such as 50 °F, would be more representative of heating operation of WSHPs. DOE will further consider any alternate EWT suggested by comments in developing any final rule.

Additionally, DOE is proposing provisions in section 6.3 of proposed appendix C1 to provide for optional representations of COP based on testing conducted per the proposed test procedure (sections 2 through 4 and 7 of proposed appendix C1) at the full-load and part-load EWT conditions specified in Table 2 of ISO 13256-1:1998 (
i.e.,
68 °F, 50 °F, 41 °F, and 32 °F).

b. Determination of COP Via Interpolation

As discussed in section III.E.1.b of this NOPR, DOE is proposing to include an alternate method for determining IEER that allows manufacturers to perform tests at the EWTs in Table 1 of ISO 13256-1:1998 and interpolate efficiency metrics to the EWTs specified in Table 9 of AHRI 340/360-2022. This method would reduce overall testing burden for manufacturers who choose to make optional EER representations at the EWTs specified in Table 1 of ISO 13256-1:1998, by allowing them to avoid additional testing at the IEER EWTs.

In order to provide comparable flexibility for measuring COP, DOE is proposing a similar alternative test method in section 6.2.2 of appendix C1 for determining COP by interpolation from results of testing at the EWTs specified in Table 2 of ISO 13256-1:1998. To evaluate the interpolation method for COP, DOE conducted investigative testing on five WSHPs at the three heating EWTs specified in Table 1 of ISO 13256-1:1998: 68 °F, 50 °F and 32 °F. DOE interpolated the cooling capacity and total power results from 68 °F and 32 °F to 50 °F, and then calculated COP at 50 °F using the interpolated values of cooling capacity and total power.
19

Finally, DOE compared these interpolated values to the results of testing at 50 °F. Table 5 presents a summary of the percentage differences between the interpolated and measured values. Positive values in the average, minimum, and maximum columns of Table 5 indicate that the values interpolated to 50 °F from results measured at 68 °F and 32 °F were higher than the values measured at 50 °F, and negative values indicate the opposite.

19
As discussed in section III.E.1.b of this NOPR, DOE tentatively determined that interpolation of EER directly results in a consistent bias, and that more representative results are obtained by calculating EER using interpolated values of cooling capacity and total power. Similarly, for COP, DOE is proposing that COP can be determined using interpolated values of heating capacity and total power, rather than interpolating COP values directly.

Table 5—Percentage Differences of Interpolated Results From Measured Results for Capacity, Power, and COP

Parameter
Average
Minimum
Maximum

Average
absolute
value

Cooling Capacity
−0.4
−1.9
0.6
0.9

Total Power
0.3
−1.2
2.1
0.9

COP calculated from interpolated capacity and power
−0.7
−3.9
0.9
1.1

Note:
Positive values in the average, minimum, and maximum columns indicate that the values interpolated to 50 °F from results measured at 68 °F and 32 °F were higher than the values measured at 50 °F. Negative values in the average, minimum, and maximum columns indicate that the values interpolated to 50 °F from results measured at 68 °F and 32 °F were lower than the values measured at 50 °F.

As shown in Table 4, the COP calculated from interpolated values of cooling capacity and total power differed from measured COP by an average of less than 1 percent. Therefore, DOE has tentatively concluded that determining COP via interpolation in this temperature range from testing at the ISO 13256-1:1998 EWTs (in accordance with DOE's proposed test procedure) provides appropriately representative results that are comparable to testing at 55 °F. Therefore, DOE is proposing in section 6.2 of the proposed appendix C1 to allow that COP for WSHPs can be calculated from either of two methods: (1) “option A”—testing at 55 °F; or (2) “option B”—interpolation of heating capacity and power values based on testing in accordance with the proposed test procedure at EWTs of 50 °F and 68 °F. Aside from the EWTs, the tests for option B would be performed using the same test provisions from AHRI 340/360-2022, ANSI/ASHRAE 37-2009, and sections 2 through 4 and 7 of proposed appendix C1 as the tests for option A.

Issue 8: DOE requests comment on the proposal to allow determination of COP using two different methods: (1) testing at 55 °F; or (2) interpolation of heating capacity and power values based on testing in accordance with the proposed test procedure at EWTs specified for heating tests in Table 2 of ISO 13256-1:1998 (
i.e.,
50 °F and 68 °F). Specifically, DOE seeks feedback on the proposed method for calculating COP via interpolation, and on whether this approach would serve as a potential burden-reducing option as compared to testing at 55 °F.

3. Entering Air Conditions

The current DOE test procedure references ISO 13256-1:1998, which specifies in Table 1 that EER is measured with entering air at 27 °C (80.6 °F) dry-bulb temperature and 19 °C (66.2 °F) wet-bulb temperature and in Table 2 that COP is measured with entering air at 20 °C (68 °F) dry-bulb temperature and 15 °C (59 °F) wet-bulb temperature. Table 2 and Table 3 of ISO 13256-1:2021 specify the same entering air conditions as ISO 13256-1:1998. As

discussed in section III.D.3 of this NOPR, DOE proposes to adopt AHRI 340/360-2022 as the test procedure for WSHPs. Table 6 of AHRI 340/360-2022 specifies entering indoor air conditions for standard rating cooling tests to be 80 °F dry-bulb temperature and a maximum of 67 °F wet-bulb temperature and standard rating heating tests to be 70 °F dry-bulb temperature and a maximum of 60 °F wet-bulb temperature.

The entering air conditions specified in AHRI 340/360-2022 are similar to the conditions specified in ISO 13256-1:1998 and ISO 13256-1:2021, differing for cooling by 0.6 °F for dry-bulb temperature and 0.8 °F for wet-bulb temperature and for heating by 2 °F for dry-bulb temperature and 1 °F for wet-bulb temperature. DOE surmises that these differences are likely due to the conditions in ISO 13256-1 (1998 and 2021 versions) being specified in terms of degrees Celsius, whereas the conditions in AHRI 340/360-2022 are specified in degrees Fahrenheit. The entering air conditions specified in AHRI 340/360-2022 are the same as in previous versions of AHRI 340/360, including AHRI 340/360-2007, which is referenced in the current DOE test procedure for CUAC/HPs. Further, the most common application for WSHPs (and the application DOE understands that the WSHP industry is intending to represent via use of the IEER metric in AHRI 600) is commercial buildings, similar to CUAC/HPs. Therefore, DOE has tentatively determined that the entering air conditions in AHRI 340/360-2022 are appropriately representative of the average conditions in which WSHPs operate in the field. DOE is proposing in sections 5 and 6 of proposed appendix C1 to use entering air conditions from Table 6 of AHRI 340/360-2022 for both cooling (IEER) and heating (COP) tests.

Issue 9: DOE requests comment on its proposal to specify in proposed appendix C1 use of the cooling entering air conditions from AHRI 340/360-2022 (
i.e.,
80 °F dry-bulb temperature and 67 °F wet-bulb temperature) and the heating entering air conditions from AHRI 340/360-2022 (
i.e.,
70 °F dry-bulb temperature and a maximum of 60 °F wet-bulb temperature).

4. Operating Modes Other Than Mechanical Cooling and Heating

On April 1, 2015, DOE published in the
Federal Register
a notification of its intent to establish a working group under the Appliance Standards and Rulemaking Federal Advisory Committee (“ASRAC”) Commercial and Industrial Fans and Blowers Working Group (“ASRAC Working Group”) to discuss and, if possible, reach consensus on the scope of the rulemaking, certain key aspects of a proposed test procedure, and proposed energy conservation standard for fans and blowers. 80 FR 17359. The ASRAC Working Group term sheet for commercial and industrial fans and blowers was approved (Docket No. EERE-2013-BT-STD-0006-0179).
20

Recommendation #3 of the term sheet addressed supply and condenser fans that are embedded in certain covered equipment. (
Id.
at p. 3) The ASRAC Working Group recommended that DOE consider revising efficiency metrics that include energy use of supply fans in order to include the energy consumption during all relevant operating modes (
e.g.,
auxiliary heating mode, ventilation mode, and part-load operation) in the next round of test procedure rulemakings. (
Id.
at p. 4) The ASRAC Working Group included WSHPs in its list of regulated equipment for which fan energy use should be considered. (
Id.
at p. 16)

20
Available at:
www.regulations.gov/document/EERE-2013-BT-STD-0006-0179.

As part of the June 2018 RFI, DOE stated that it was investigating whether changes to the WSHP test procedure are needed to properly characterize a representative average use cycle, including changes to more accurately represent fan energy use in field applications. 83 FR 29048, 29050 (June 22, 2018). DOE requested information as to the extent that accounting for the energy use of fans in commercial equipment such as WSHPs would be additive of other existing accountings of fan energy use.
Id.

In the June 2018 RFI, DOE also sought comment on whether accounting for the energy use of fan operation in WSHPs would alter measured efficiency, and if so, to what extent.
Id.
DOE also requested data and information regarding what forms of auxiliary heating are installed in WSHPs, how frequently they operate, and whether they operate independently of the WSHP.
Id.
Additionally, DOE requested data and information on how frequently WSHP supply fans are operated when there is no demand for heating or cooling, such as for fresh air ventilation or air circulation or filtration.
Id.

The Joint Advocates and NEEA commented that DOE should amend the test procedure to account for fan energy use outside of mechanical cooling and heating for fans in regulated equipment to more fully capture fan energy use. (Joint Advocates, No. 10 at p. 1; NEEA, No. 11 at p. 1) The Joint Advocates asserted that by failing to capture fan operation for economizing, ventilation, and other functions outside of cooling mode, the test procedure may be significantly underestimating fan energy consumption. (Joint Advocates, No. 10 at p. 1)

NEEA commented that the commercial prototype building models used by Pacific Northwest National Laboratory in the analysis in support of ASHRAE Standard 90.1 include information on the operation of fans in ventilation mode and economizer mode and could be used to develop national average fan operating hours outside of heating and cooling. (NEEA, No. 11 at pp. 3) Furthermore, NEEA stated that the vast majority of WSHPs are installed in commercial buildings, thereby subjecting them to ASHRAE Standard 90.1 code requirements such as the requirement of water side economizers in many U.S. climate zones.
Id.
NEEA added that details of requirements for certain control and component features are provided in ASHRAE Standard 90.1 and should be an indicator of prevalence of these features in WSHPs on the market.
Id.

NEEA further stated that ANSI and the Air Movement Control Association (“AMCA”) developed ANSI/AMCA 208-18, “Calculation of the Fan Energy Index,” which provides a potential way to measure embedded fan performance in WSHPs using the fan energy index (“FEI”). According to NEEA, DOE could develop a revised IEER-type metric that weighs together cooling performance (using the IEER test) and fan efficiency (using an FEI-based metric). NEEA argued that accounting for the energy use of fan operation in WSHPs does not need to alter measured efficiency, and that to reduce burden on manufacturers, DOE could combine the FEI and IEER metrics such that manufacturers would have multiple viable design option pathways to achieve the minimum IEER efficiency standard without improving the embedded fan efficiency above the minimum FEI efficiency standard. (NEEA, No. 11 at p. 2)

Trane commented that there are some applications in which a WSHP would be used for ventilation, but that ventilation is not the main use, and that using a WSHP for purposes other than heating and cooling is rare. Trane stated further that typical practice is for ventilation air to be provided by a dedicated outdoor air system (“DOAS”) using a separate ductwork system, whereas the WSHP system provides the heating and cooling. Finally, Trane commented that for installations in which the DOAS and WSHPs supply to common ductwork, WSHP fans would operate when

ventilation is needed, but rarely would this be needed without heating or cooling. (Trane, No. 8 at pp. 2, 5)

AHRI and WaterFurnace both stated that a high percentage of WSHP systems offer a continuous fan mode to circulate fresh air but did not have data on how often. (AHRI, No. 12 at pp. 4-5; WaterFurnace, No. 7 at p. 3) However, both estimated that a typical WSHP would operate in continuous fan mode (
i.e.,
without cooling or heating) for approximately 1,300 hours per year. The commenters estimated total cooling and heating mode operation of 3,300 hours per year. (AHRI, No. 12 at pp. 9; WaterFurnace, No. 7 at p. 9)

Further, AHRI and WaterFurnace commented that fan power is largely dependent on motor type and typically represents 13 to 18 percent of total power. (AHRI, No. 12 at pp. 4, 8-9; WaterFurnace, No. 7 at pp. 3, 8-9) AHRI asserted

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2022-17075. Public record. Not legal advice.