Energy Conservation Program: Test Procedure for Room Air Conditioners

Federal RegisterJun 11, 2020

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DEPARTMENT OF ENERGY

10 CFR Parts 429 and 430

[EERE-2017-BT-TP-0012]

RIN 1904-AD47

Energy Conservation Program: Test Procedure for Room Air Conditioners

AGENCY:

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

ACTION:

Notice of proposed rulemaking.

SUMMARY:

The U.S. Department of Energy (DOE) proposes to amend the test procedure for room air conditioners (“room ACs”) to address updates to the industry standards that are incorporated by reference, provide for the testing of variable-speed room ACs to better reflect their relative efficiency gains at lower outdoor temperatures as compared to single-speed room ACs, and to provide specifications and minor corrections that would improve repeatability, reproducibility, and overall readability of the test procedure. Because there are no testing modifications proposed for single-speed room ACs, DOE expects that the proposed changes will not affect the measured energy use for these models. For variable-speed room ACs, the proposed changes will improve the representativeness of the measured energy use of these models. As part of this proposal, DOE is announcing a public meeting to collect comments and data on its proposal.

DATES:

Meeting:

DOE will hold a webinar on Wednesday, July 8, 2020, from 10:00 a.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. If no participants register for the webinar, then it will be cancelled. DOE will hold a public meeting on this proposed test procedure if one is requested by June 25, 2020.

Comments:

DOE will accept comments, data, and information regarding this proposal no later than August 10, 2020. See section V, “Public Participation,” for details.

ADDRESSES:

Interested persons are encouraged to submit comments using the Federal eRulemaking Portal at

http://www.regulations.gov.

Follow the instructions for submitting comments. Alternatively, interested persons may submit comments, identified by docket number EERE-2017-BT-TP-0012, by any of the following methods:

(1)

Federal eRulemaking Portal: http://www.regulations.gov.

Follow the instructions for submitting comments.

(2)

Email: RoomAC2017TP0012@ee.doe.gov.

Include the docket number EERE-2017-BT-TP-0012 or regulatory information number (RIN) 1904-AD47 in the subject line of the message.

(3)

Postal Mail:

Appliance and Equipment Standards Program, U.S. Department of Energy, Building Technologies Office, Mailstop EE-5B, 1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone: (202) 287-1445. If possible, please submit all items on a compact disc (CD), in which case it is not necessary to include printed copies.

(4)

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 telefacsimilies (faxes) will be accepted. For detailed instructions on submitting comments and additional information on the rulemaking process, see section V of this document.

Docket:

The docket, which includes

Federal Register

notices, public meeting attendee lists and transcripts (if a public meeting is held), comments, and other supporting documents/materials, is available for review at

http://www.regulations.gov.

All documents in the docket are listed in the

http://www.regulations.gov

index. However, some documents listed in the index, such as those containing information that is exempt from public disclosure, may not be publicly available.

The docket web page can be found at

https://www.regulations.gov/docket?D=EERE-2017-BT-TP-0012.

The docket web page will contain simple instructions on how to access all documents, including public comments, in the docket. See section V of this document for information on how to submit comments through

http://www.regulations.gov.

FOR FURTHER INFORMATION CONTACT:

Mr. Bryan Berringer, 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) 586-0371. Email:

ApplianceStandardsQuestions@ee.doe.gov.

Ms. Sarah Butler, U.S. Department of Energy, Office of the General Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone: (202) 586-1777. Email:

Sarah.Butler@hq.doe.gov.

For further information on how to submit a comment, review other public comments and the docket, or participate in the 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 the following industry standards into 10 CFR part 430:

(1) American National Standards Institute (ANSI)/Association of Home Appliance Manufacturers (AHAM) RAC-1-2015, (ANSI/AHAM RAC-1-2015), “Room Air Conditioners;” ANSI approved May 13, 2015.

(2) ANSI/American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) Standard 16-2016, (ANSI/ASHRAE Standard 16-2016), “Method of Testing for Rating Room Air Conditioners, Packaged Terminal Air Conditioners, and Packaged Terminal Heat Pumps for Cooling and Heating Capacity;” ANSI approved October 31, 2016.

(3) ANSI/ASHRAE Standard 41.1-2013, (ANSI/ASHRAE Standard 41.1), “Standard Method for Temperature Measurement;” ANSI approved January 30, 2013.

(4) ANSI/ASHRAE Standard 41.2-1987 (RA 1992), (ANSI/ASHRAE Standard 41.2-1987 (RA 1992)), “Standard Methods for Laboratory Airflow Measurement;” ANSI reaffirmed April 20, 1992.

(5) ANSI/ASHRAE Standard 41.3-2014 (“ANSI/ASHRAE Standard 41.3-2014”), “Standard Methods for Pressure Measurement;” ANSI approved July 3, 2014.

(6) ANSI/ASHRAE Standard 41.6-2014, (ANSI/ASHRAE Standard 41.6-2014), “Standard Method for Humidity Measurement;” ANSI approved July 3, 2014.

(7) ANSI/ASHRAE Standard 41.11-2014, (ANSI/ASHRAE Standard 41.11-2014), “Standard Methods for Power Measurement;” ANSI approved July 3, 2014.

(8) International Electrotechnical Commission (IEC) Standard 62301, (IEC Standard 62301 Second Edition), “Household electrical appliances—Measurement of standby power, (Edition 2.0);”.

Copies of ANSI/AHAM RAC-1-2015 can be obtained from the Association of Home Appliance Manufacturers at

https://www.aham.org/ht/d/Store/.

Copies of ANSI/ASHRAE Standard 16-

2016, ANSI/ASHRAE Standard 41.1-2013, ANSI/ASHRAE Standard 41.2-1987, ANSI/ASHRAE Standard 41.3-2014, ANSI/ASHRAE Standard 41.6-2014, and ANSI/ASHRAE Standard 41.11-2014 can be obtained from the American National Standards Institute at

https://webstore.ansi.org/.

Copies of IEC Standard 62301 can be obtained from

http://webstore.iec.ch.

See section IV.N for additional information on these standards.

Table of Contents

I. Authority and Background

A. Authority

B. Background

1. The January 2011 Final Rule

2. The June 2015 Request for Information

3. The August 2017 RFI

4. The LG and Midea Waivers

II. Synopsis of the Notice of Proposed Rulemaking

III. Discussion

A. Room Air Conditioner Definition

B. Industry Test Standards

1. ANSI/AHAM RAC-1

2. ANSI/ASHRAE Standard 16

C. Variable-Speed Room Air Conditioner Test Procedure

1. Methodology

2. Test Conditions

3. Variable-Speed Compressor Operation

4. Capacity and Electrical Power Adjustment Factors

5. Cycling Loss Factors

6. Test Condition Weighting Factors

7. Performance Adjustment Factor

8. Air-Enthalpy Test Alternative

9. Product Specific Reporting Provisions

10. Estimated Annual Operating Cost Calculation

11. Potential Cost Impacts

D. Definitions

E. Active Mode Testing

1. Cooling Mode

2. Heating Mode

3. Off-Cycle Mode

F. Standby Modes and Off Mode

1. Referenced Standby Mode and Off Mode Test Standard

G. Network Functionality

H. Connected Test Procedure

I. Combined Energy Efficiency Ratio

J. Certification and Verification Requirements

K. Reorganization of Calculations Currently in 10 CFR 430.23

L. Test Procedure Costs, Harmonization, and Other Topics

1. Test Procedure Costs and Impact

2. Harmonization With Industry Standards

3. Other Test Procedure Topics

M. Compliance Date and Waivers

IV. Procedural Issues and Regulatory Review

A. Review Under Executive Order 12866

B. Review Under Executive Orders 13771 and 13777

C. Review Under the Regulatory Flexibility Act

D. Review Under the Paperwork Reduction Act of 1995

E. Review Under the National Environmental Policy Act of 1969

F. Review Under Executive Order 13132

G. Review Under Executive Order 12988

H. Review Under the Unfunded Mandates Reform Act of 1995

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

J. Review Under Executive Order 12630

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

L. Review Under Executive Order 13211

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

N. Description of Materials Incorporated by Reference

V. Public Participation

A. Participation in the Webinar

B. Submission of Comments

C. Issues on Which DOE Seeks Comment

VI. Approval of the Office of the Secretary

I. Authority and Background

Room ACs are included in the list of “covered products” for which DOE is authorized to establish and amend energy conservation standards and test procedures. (42 U.S.C. 6292(a)(2)) DOE's energy conservation standards and test procedure for room ACs are currently prescribed at 10 CFR 430.32(b) and 10 CFR 430.23(f), respectively. The following sections discuss DOE's authority to establish test procedures for room ACs and relevant background information regarding DOE's consideration of test procedures for this product.

A. Authority

The Energy Policy and Conservation Act, as amended, (EPCA or the Act),

authorizes DOE to regulate the energy efficiency of a number of consumer products and certain industrial equipment. (42 U.S.C. 6291-6317) Title III, Part B

of EPCA established the Energy Conservation Program for Consumer Products Other Than Automobiles, which sets forth a variety of provisions designed to improve energy efficiency. These products include room ACs, the subject of this document. (42 U.S.C. 6292(a)(2))

All references to EPCA in this document refer to the statute as amended through America's Water Infrastructure Act of 2018, Public Law 115-270 (Oct. 23, 2018).

For editorial reasons, upon codification in the U.S. Code, Part B was redesignated Part A.

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 the Act specifically include definitions (42 U.S.C. 6291), test procedures (42 U.S.C. 6293), energy conservation standards (42 U.S.C. 6295), labeling provisions (42 U.S.C. 6294), and the authority to require information and reports from manufacturers (42 U.S.C. 6296).

The Federal testing requirements consist of test procedures that manufacturers of covered products must use as the basis for: (1) Certifying to DOE that their products comply with the applicable energy conservation standards adopted pursuant to EPCA (42 U.S.C. 6295(s)), and (2) making other representations about the efficiency of those products (42 U.S.C. 6293(c)). Similarly, DOE must use these test procedures to determine whether the products comply with relevant standards promulgated under EPCA. (42 U.S.C. 6295(s))

Federal energy efficiency requirements for covered products established under EPCA generally supersede State laws and regulations concerning energy conservation testing, labeling, and standards. (See 42 U.S.C. 6297) DOE may, however, grant waivers of Federal preemption for particular State laws or regulations, in accordance with the procedures and other provisions of EPCA. (42 U.S.C. 6297(d))

Under 42 U.S.C. 6293, EPCA sets forth the criteria and procedures DOE must follow when prescribing or amending test procedures for covered products. EPCA requires that any test procedures prescribed or amended under this section be reasonably designed to produce test results which measure energy efficiency, energy use or estimated annual operating cost of a covered product during a representative average use cycle or period of use and not be unduly burdensome to conduct. (42 U.S.C. 6293(b)(3))

In addition, EPCA requires that DOE amend its test procedures for all covered products to integrate measures of standby mode and off mode energy consumption. (42 U.S.C. 6295(gg)(2)(A)) Standby mode and off mode energy consumption must be incorporated into the overall energy efficiency, energy consumption, or other energy descriptor for each covered product unless the current test procedures already account for and incorporate standby and off mode energy consumption or such integration is technically infeasible. If an integrated test procedure is technically infeasible, DOE must prescribe a separate standby mode and off mode energy use test procedure for the covered product, if technically feasible. (U.S.C. 6295(gg)(2)(A)(ii)) Any such amendment must consider the most current versions of the IEC Standard 62301

and IEC Standard

62087

as applicable. (42 U.S.C. 6295(gg)(2)(A))

IEC 62301, “Household electrical appliances—Measurement of standby power” (Edition 2.0, 2011-01).

IEC 62087, “Methods of measurement for the power consumption of audio, video, and related equipment” (Edition 3.0, 2011-04).

If DOE determines that a test procedure amendment is warranted, it must publish proposed test procedures and offer the public an opportunity to present oral and written comments on them. (42 U.S.C. 6293(b)(2)) EPCA also requires that, at least once every 7 years, DOE evaluate test procedures for each type of covered product, including room ACs, 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 or period of use. (42 U.S.C. 6293(b)(1)(A) and (3)) If the Secretary determines, on his own behalf or in response to a petition by any interested person, that a test procedure should be prescribed or amended, the Secretary shall promptly publish in the

Federal Register

proposed test procedures and afford interested persons an opportunity to present oral and written data, views, and arguments with respect to such procedures. The comment period on a proposed rule to amend a test procedure shall be at least 60 days and may not exceed 270 days. In prescribing or amending a test procedure, the Secretary shall take into account such information as the Secretary determines relevant to such procedure, including technological developments relating to energy use or energy efficiency of the type (or class) of covered products involved. (42 U.S.C. 6293(b)(2)) If DOE determines that test procedure revisions are not appropriate, DOE must publish its determination not to amend the test procedures. DOE is publishing this notice of proposed rulemaking (NOPR) pursuant to the 7-year review requirement specified in EPCA. (42 U.S.C. 6293(b)(1)(A))

B. Background

DOE's existing test procedure for room ACs appears at Title 10 of the CFR part 430, subpart B, appendix F (“Uniform Test Method for Measuring the Energy Consumption of Room Air Conditioners” (“appendix F”)), and the room AC performance metric calculations are codified at 10 CFR 430.23(f). The test procedure for room ACs was established on June 1, 1977 (hereafter the “June 1977 final rule”) and was subsequently redesignated and editorially amended on June 29, 1979. 42 FR 27896 (June 1, 1977); 44 FR 37938 (June 29, 1979).

1. The January 2011 Final Rule

The Energy Independence and Security Act of 2007 (Public Law 110-140; EISA 2007) directed DOE to amend its energy efficiency test procedures for all covered products to include measures of standby mode and off mode energy consumption. (42 U.S.C. 6295(gg)(2)(A)) In compliance with these requirements, on January 6, 2011, DOE published a final rule (hereafter the “January 2011 Final Rule”), amending the room AC test procedure to include measurements of standby mode and off mode power and to introduce a new combined efficiency metric, Combined Energy Efficiency Ratio (CEER), that accounts for energy consumption in active mode, standby mode and off mode. 76 FR 971. DOE also incorporated into its regulations a new industry test method, International Electrotechnical Commission (IEC) Standard 62301, “Household electrical appliances—Measurement of standby power (first edition June 2005)” (“IEC Standard 62301 First Edition”), to measure the standby and off mode energy consumption. In addition to IEC Standard 62301 First Edition, the January 2011 Final Rule updated references to test methods developed by the American National Standards Institute (ANSI), the Association of Home Appliance Manufacturers (AHAM) and the American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE). The current room AC test procedure incorporates by reference three industry test methods: (1) ANSI/AHAM RAC-1-2008, “Room Air Conditioners” (ANSI/AHAM RAC-1-2008),

(2) ANSI/ASHRAE Standard 16-1983 (RA 2009), “Method of Testing for Rating Room Air Conditioners and Packaged Terminal Air Conditioners” (ANSI/ASHRAE Standard 16-2009),

and (3) IEC Standard 62301 First Edition.

Copies can be purchased from

http://webstore.ansi.org.

Copies can be purchased from

http://www.techstreet.com.

Copies can be purchased from

http://webstore.iec.ch.

2. The June 2015 Request for Information

On June 18, 2015, DOE published a request for information (RFI) (hereafter the “June 2015 RFI”) regarding the energy conservation standards and test procedure for room ACs. 80 FR 34843. In addition to soliciting information regarding the energy conservations standards, the June 2015 RFI discussed and sought comment on the following aspects of the room AC test procedure: (1) Potential updates to the energy efficiency metric that would address performance in additional operating modes; (2) alternate methods for measuring cooling mode performance; (3) measuring heating mode performance and any relevant test methods, temperature conditions, or test burden; (4) methods for measuring performance at reduced cooling loads and the prevalence of units on the market with components optimized for efficient operation at reduced cooling loads; (5) testing and certification of units that can operate on multiple voltages; and (6) the energy usage associated with connected functionality. 80 FR at 34846-34848 (June 18, 2015). In response to the June 2015 RFI, DOE received comments from interested parties pertaining to the room AC test procedure, which are summarized throughout this NOPR.

All public comments are located in the room AC energy conservation standards rulemaking docket:

http://www.regulations.gov/#!docketDetail;D=EERE-2014-BT-STD-0059.

3. The August 2017 RFI

On August 4, 2017, DOE published another RFI (hereafter the “August 2017 RFI”) regarding the test procedure for room ACs. 82 FR 36349. Following publication of the June 2015 RFI, DOE identified additional topics and questions for which it sought feedback, specifically regarding amendments to the room AC test procedure to harmonize with the recently established portable air conditioner (“portable AC”) test procedure, to clarify test setup and temperature conditions, to reference updated industry test procedures for room ACs, and on any additional topics that might inform DOE's decisions in a future test procedure rulemaking. DOE also welcomed further comments on the topics raised in the June 2015 RFI and on other issues relevant to the conduct of such a rulemaking that were not specifically identified in that document.

AHAM opposed harmonizing the room AC test procedure with the portable AC test procedure, claiming that harmonization would not assist consumers in making purchasing decisions, mainly because the two products have different consumers and are used for significantly different applications, based on recent consumer survey data. (AHAM, No. 3 at pp. 1-4)

According to AHAM, the survey suggested that room ACs are purchased for homes without central air conditioning (“central AC”), where cost is a key factor, and where portability is not. AHAM also stated that room ACs are typically used for primary cooling, whereas portable ACs are used for supplemental cooling (

i.e.,

in addition to a central AC). AHAM claimed that the significant design difference between room ACs and portable ACs (specifically, that room ACs are installed in the barrier between the conditioned and unconditioned space, whereas portable ACs are installed entirely within the conditioned space) leads to drastically different design decisions on the size, weight, and shape of the product, impacting available design options for improving efficiency as well as the physical limitations on testing the products. Therefore, according to AHAM, harmonizing the test procedures for room ACs and portable ACs would result in consumer confusion and increased burden for manufacturers.

Id.

DOE notes that the proposals in this document regarding test procedure updates for room ACs were not considered on the basis of similarities or differences between room ACs and portable ACs. However, in development of the portable AC test procedure, DOE relied on data for room ACs in instances in which data specific to portable ACs were lacking. In the current rulemaking, DOE considered such data for room ACs during development of the proposed amendments to the room AC test procedure.

A notation in the form “AHAM, No. 3 at pp. 1-4” identifies a written comment: (1) Made by the Association of Home Appliance Manufacturers; (2) recorded in document number 3 that is filed in the docket of the current room AC test procedure

rulemaking (Docket No. EERE-2017-BT-TP-0012) and available for review at

https://www.regulations.gov;

and (3) which appears on pages 1 through 4 of document number 3.

The Appliance Standards Awareness Project, Alliance to Save Energy, American Council for an Energy-Efficient Economy, Consumer Federation of America, Natural Resources Defense Council, Northeast Energy Efficiency Partnerships, Northwest Energy Efficiency Alliance, and Northwest Power and Conservation Council (hereafter the “Joint Advocates”) and the Pacific Gas and Electric Company, Southern California Gas Company, San Diego Gas and Electric, and Southern California Edison (hereafter the “California IOUs”) both noted that harmonizing the room AC and portable AC test procedures would allow for a comparison between the two products, which they agreed provide a similar function and consumer utility. (Joint Advocates, No. 6 at p. 1; California IOUs, No. 5 at p. 2) Nonetheless, neither supported aligning the room AC test procedure with the current portable AC test procedure.

The California IOUs expressed concern that the benefit of harmonization might not outweigh the negative impacts of an additional cooling mode test condition for room ACs; namely, that adding a second test condition would obscure the determination of peak load energy consumption and would be detrimental for the effective determination of room AC energy demand impact during peak usage times, which is of significant importance to the California IOUs. (California IOUs, No. 5 at p. 2) The Joint Advocates noted that the portable AC test procedure does not capture part-load performance and thus would not capture the benefits of technologies that improve part-load performance, such as variable-speed compressors. In light of this, rather than aligning the room AC test procedure with the portable AC test procedure, the Joint Advocates urged DOE to incorporate part-load performance into the room AC test procedure and the portable AC test procedure. (Joint Advocates, No. 6 at pp. 1-3) As discussed in sections III.E through III.K of this document, DOE is not proposing any significant changes to the room AC test procedure at this time for single-speed room ACs, which represent the majority of room AC configurations on the market today. Specifically, as discussed in section III.E.1.e of this document, DOE considered multiple test conditions as well as constant-cooling-load-based

or dynamic-cooling-load-based tests

as an alternative to the existing constant-temperature single outdoor condition room AC test procedure and has initially determined that such amendments would not be warranted for single-speed room ACs. However, DOE proposes in this document to adopt specific testing requirements for room ACs that use variable-speed compressors (“variable-speed room ACs”) to better represent their relative efficiency compared to single-speed room ACs, as described further in section III.C of this document.

Constant-cooling-load-based tests fix the amount of heat to the indoor test room by the reconditioning equipment, generally less than the test unit's nominal cooling capacity, while the indoor test room temperature is permitted to change and is controlled by the test unit according to its thermostat setting, which is fixed throughout testing.

Dynamic-cooling-load-based tests vary the amount of heat added to the indoor test room by the chamber reconditioning equipment, while the indoor test room temperature is permitted to change and is controlled by the test unit and fixed thermostat setting, thereby measuring how a unit reacts to changing load conditions.

4. The LG and Midea Waivers

On June 29, 2018, DOE announced receipt of a petition for waiver and application of an interim waiver from LG Electronic USA, Inc. (“LG”), in which LG sought an exemption from the DOE test procedure for room ACs, which appears in appendix F for certain room AC models with variable-speed capabilities (hereafter the “LG Petition for Waiver”).

83 FR 30717 (June 29, 2018). According to LG, the current DOE test procedure for room ACs, which provides for testing at full-load performance only, does not take into account the benefits of variable-speed room ACs at part-load conditions, and misrepresents their actual energy consumption. LG suggested an alternate test procedure for its variable-speed room ACs, which provided for testing each unit at four different outdoor temperatures instead of a single outdoor temperature, with the unit compressor speed fixed at each temperature. LG's approach for the alternate test procedure was derived from the current DOE test procedure for central ACs (10 CFR part 430, subpart B, appendix M (“appendix M”)). As discussed in a notice of petition for waiver and notice of grant of interim waiver (hereafter the “Grant of LG Interim Waiver”), DOE initially agreed with LG's claim that the DOE test procedure evaluates the variable-speed models listed in the LG Petition for Waiver in a manner that is unrepresentative of their energy use. 83 FR 30717, 30719. DOE also reviewed the alternate procedure proposed by LG and based on that review determined that LG's suggested procedure would allow for the accurate measurement of the energy use for the listed variable-speed room ACs. Therefore, DOE granted an interim waiver to LG to use LG's suggested alternate test procedure for LG's listed variable-speed room AC models, with an additional specification of how to determine the intermediate compressor speed. On May, 8, 2019, DOE published a Decision and Order (hereafter the “LG Waiver”), granting a waiver for four variable-speed basic models with the condition that LG must test and rate these models according to an alternate test procedure that was substantively consistent with that suggested by LG, and report product-specific information that reflects the alternate test procedure. 84 FR 2011.

The alternate test procedure required under the LG Waiver differs from that required in the Grant of LG Interim Waiver as follows: (1) Removing the allowance to use a psychrometric chamber (which would be consistent with an air-enthalpy testing approach) instead of a calorimeter chamber, (2) adding definitions for each fixed compressor speed, (3) adjusting the annual energy consumption and operating cost calculations that provide the basis for the information presented to consumers on the EnergyGuide Label, and (4) requiring that compressor speeds be set in accordance with instructions submitted by LG on April 2, 2019.

DOE determined that those changes were necessary to ensure better repeatability and reproducibility of the LG Waiver test procedure, as well as representativeness of the results. 84 FR 20111.

All published documents directly related to the waiver are available in docket EERE-2018-BT-WAV-0006. (

https://www.regulations.gov/document?D=EERE-2018-BT-WAV-0006.

)

The instructions provided by LG on April 2, 2019 were marked as confidential and, as such, were treated as confidential. The document is located in the docket at

https://www.regulations.gov/document?D=EERE-2018-BT-WAV-0006-0010.

On March 25, 2019, GD Midea Air Conditioning Equipment Co. LTD. (“Midea”) submitted a petition for waiver and application for interim waiver from the room AC test procedure for six room AC models with variable-speed capabilities.

Midea sought a test procedure exemption consistent with the approach DOE allowed in the Grant of LG Interim Waiver. DOE reviewed Midea's petition and, based on that review, initially agreed that Midea's suggested procedure, with the same modifications DOE included in the LG Waiver, would allow for the accurate measurement of the energy use for the listed variable-speed room AC models. Therefore, on December 13, 2019, DOE granted Midea an interim waiver from the room AC test procedure (hereafter the “Grant of Midea Interim Waiver”) for the models listed in Midea's petition, using the alternate test procedure required in the LG Waiver, which published subsequent to Midea's petition for waiver. 84 FR 68159.

All published documents directly related to the interim waiver are available in docket EERE-2019-BT-WAV-0009 (

https://www.regulations.gov/docket?D=EERE-2019-BT-WAV-0009.

)

Pursuant to 10 CFR 430.27(l), following the grant of any waiver, DOE must publish in the

Federal Register

a notice of proposed rulemaking to amend its regulations so as to eliminate the need for continuation of the waiver. As soon thereafter as practicable, DOE must publish in the

Federal Register

a final rule.

Id.

The waiver would then terminate on the effective date of the final rule. 10 CFR 430.27(h)(2).

II. Synopsis of the Notice of Proposed Rulemaking

In this NOPR, DOE proposes amendments to the existing test procedures for room ACs to: (1) Update to the latest versions of industry test methods that are incorporated by reference; (2) adopt new testing provisions for variable-speed room ACs that reflect the relative efficiency gains at reduced cooling loads compared to single-speed room ACs; (3) adopt new definitions consistent with these two proposed amendments; and (4) provide specifications and minor corrections to improve the test procedure repeatability, reproducibility, and overall readability.

DOE has tentatively determined that the proposed amendments would both provide more representative efficiency measurements for variable-speed room ACs and not alter the measured efficiency of single-speed room ACs, which constitute the large majority of units on the market. DOE has also tentatively determined that the proposed test procedure would not be unduly burdensome to conduct. 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 Proposed Test Procedure Relative to Current Test Procedure

Current DOE test procedure

Proposed test procedure

Attribution

References industry standards—

Updates references to applicable sections of:

Industry test procedure updates.

• ANSI/AHAM RAC-1-2008,

• ANSI/AHAM RAC-1-2015,

• ANSI/ASHRAE Standard 16-2009, and

• ANSI/ASHRAE Standard 16-2016 (including relevant cross-referenced industry standards), and

• IEC Standard 62301 First Edition.

• IEC Standard 62301 Second Edition.

Testing, calculation of CEER metric, and certification for all room ACs based on single temperature rating condition

Testing, calculation of CEER metric, and certification for variable-speed room ACs based on additional reduced outdoor temperature test conditions

In response to the LG Waiver.

—Definition of “room air conditioner” does not explicitly include function of providing cool conditioned air to an enclosed space, and references “prime,” an undefined term, to describe the source of refrigeration

—“Cooling mode” is an undefined term.

Definitions—

—Adds the word “cooled” in the definition of “room air conditioner” to describe the conditioned air a room AC provides and removes “prime” from the definition

—Adds definition for “cooling mode”.

Added by DOE (clarification).

Appendix F does not explicitly identify the scope of the test procedure

Creates new section indicating the appendix applies to the energy performance of room ACs

Added by DOE (specifies the applicability of the test procedure).

Provides that test unit be installed in a manner similar to consumer installation

—References ANSI/ASHRAE Standard-2016, specifying that the perimeter of louvered room ACs be sealed to the separating partition, consistent with common testing practice

—Specifies that non-louvered room ACs be installed inside a compatible wall sleeve, with the manufacturer-provided installation materials

Industry test procedure update and added by DOE (additional installation specifications).

Calculations for average annual energy consumption, combined annual energy consumption, energy efficiency ratio (EER), and CEER are located in 10 CFR 430.23(f)

—Moves calculations for CEER and annual energy consumption for each operating mode into appendix F

—Removes EER calculation and references entirely, as it is obsolete.

Added by DOE (improve readability).

III. Discussion

A. Room Air Conditioner Definition

DOE defines a “room air conditioner” as a consumer product, other than a packaged terminal air conditioner, which is powered by a single-phase electric current and which is an encased assembly designed as a unit for mounting in a window or through the wall for the purpose of providing delivery of conditioned air to an enclosed space. It includes a prime source of refrigeration and may include a means for ventilating and heating. 10 CFR 430.2.

DOE does not propose any changes to the room AC definition in this NOPR that would modify the current scope of covered products. However, as described further below, DOE proposes minor adjustments to the room AC definition to ensure the definition does not inadvertently apply to new products introduced on the market. The proposed revised definition would harmonize with the wording of definitions for other DOE covered products, which DOE believes will help avoid any potential confusion or unintentional overlap in scope of coverage between room ACs and any other products.

In the June 2015 RFI, DOE noted that other consumer products, including portable ACs and dehumidifiers, are also self-encased, powered by a single-phase electric current, refrigeration-based, and deliver conditioned air to an enclosed space, thereby meeting many of the criteria in the room AC definition. DOE also noted, however, that the definition of a room AC specifies that the unit is designed to be mounted in a window or through a wall, which excludes portable ACs and dehumidifiers. DOE suggested in the June 2015 RFI that explicitly excluding other products was unnecessary because of the distinction based on mounting. 80 FR 34843, 34845 (June 18, 2015). AHAM agreed that the room AC definition need not be updated to explicitly exclude other products and further suggested that adding these exclusions would be confusing. (AHAM, June 2015 RFI, No. 5 at p. 2) General Electric Appliances (GE) supported AHAM's comments. (GE, June 2015 RFI, No. 6 at p. 1)

GE stated that it supports the comments submitted by AHAM in response to the June 2015 RFI in their entirety and adopted them by reference.

Based on DOE's considerations in the June 2015 RFI, and given that no commenters objected to DOE's suggestion, DOE does not propose to add exclusions for other consumer products in the room AC definition.

In the June 2015 RFI, DOE also noted that some room ACs may have other functions beyond the cooling, heating, and ventilation functions currently specified in the room AC definition. These additional functions could include air circulation, where air from within the room is circulated without bringing air from the outside into the room; and air cleaning, where electrostatic filtration, ultraviolet radiation, or ozone generators clean the air as it circulates through the unit. 80 FR 34843, 34845 (June 18, 2015). DOE received no comments related to the inclusion of other functions in the room AC definition in response to the June 2015 RFI. DOE understands that these functions do not represent the key functionality of a room AC, and therefore is not proposing that these functions be addressed in the room AC definition at this time.

DOE proposes to add the term “cooled” to the room AC definition, so that it refers to a system that “. . . delivers

cooled,

conditioned air to an enclosed space . . .” (emphasis added). DOE believes that this revised wording would better represent the key function of a room AC, and would avoid any potential for the room AC definition to cover other indoor air quality systems that could be described as “conditioning” the air, but that would not be appropriately included within the scope of coverage of a room AC.

Additionally, as described previously, the current definition of room AC specifies that it includes a prime source of refrigeration. DOE contends that using the word “prime” to describe the source of refrigeration in the current definition is extraneous and could be construed as referring to a “primary” refrigeration system, a distinction that could inadvertently exclude future products that implement a different technology as the primary source of air conditioning, while implementing a refrigeration loop as the “secondary” means of cooling or heating. Primary and secondary means of conditioning air are not uncommon in certain refrigeration products and chiller systems; in fact, some room ACs with heating functionality implement a resistance heater as a supplemental form of heating to the primary heat pump, for use under extreme temperature conditions. DOE also notes that the recently codified portable AC definition was not limited to products with a prime source of refrigeration. For these reasons, DOE proposes to remove the word “prime” from the room AC definition.

DOE proposes to incorporate by reference ASHRAE Standard 16 and ANSI/AHAM RAC-1. In particular, Section 3 of ASHRAE Standard 16-2016 contains several definitions for terms defined in EPCA and DOE regulations: Room air conditioner, packaged terminal air conditioner, and packaged terminal heat pump. Where there is a conflict with the EPCA definition, the EPCA definition controls. DOE elsewhere proposes general language to make clear that regulatory text drafted by DOE takes precedence over conflicting language in a document incorporated by reference. Therefore, DOE proposes to include a statement in new Section 0 “Incorporation by Reference,” in appendix F as follows: “If there is any conflict between any industry standard(s) and this appendix, follow the language of the test procedure in this appendix, disregarding the conflicting industry standard language.”

DOE also proposes to reorganize the room AC definition to improve its readability. As noted above, the minor editorial revisions and specifications discussed in this section are not intended to modify the scope of the room AC definition.

In summary, DOE proposes to modify the room AC definition in 10 CFR 430.2 to read as follows:

“

Room air conditioner

means a window-mounted or through-the-wall-mounted encased assembly, other than a `packaged terminal air conditioner,' that delivers cooled, conditioned air to an enclosed space, and is powered by single-phase electric current. It includes a source of refrigeration and may include additional means for ventilating and heating.

DOE requests comment on the proposed amendments to the room AC definition in 10 CFR 430.2.

DOE also proposes to further specify the scope of coverage of appendix F by adding a new beginning section stating that appendix F covers the test requirements used to measure the energy performance of room ACs. In doing so, DOE would clearly limit the scope of products tested in accordance with appendix F, and would harmonize appendix F with test procedures for other similar covered products, which also include similar introductory statements of scope.

DOE requests comment on the proposed new beginning section to appendix F that would explicitly state the scope of coverage.

B. Industry Test Standards

The DOE room AC test procedure in appendix F references the following two industry standards as the basis of the cooling mode test: ANSI/AHAM RAC-

1-2008 and ANSI/ASHRAE Standard 16-2009. ANSI/AHAM RAC-1-2008 provides the specific test conditions and associated tolerances, while ANSI/ASHRAE Standard 16-2009 describes the test setup, instrumentation and procedures used in the DOE test procedure. The cooling capacity, efficiency metric, and other indicators are then calculated based on the results obtained through the application of these test methods, described in appendix F and 10 CFR 430.23(f).

New versions of ANSI/AHAM RAC-1 and ANSI/ASHRAE Standard 16 have been released since the publication of the current DOE test procedure. DOE assessed the updated versions of these standards to determine if any updates to the DOE test procedure were warranted.

1. ANSI/AHAM RAC-1

The cooling mode test in appendix F is conducted in accordance with the testing conditions, methods, and calculations in Sections 4, 5, 6.1, and 6.5 of ANSI/AHAM RAC-1-2008, as summarized in Table III-1.

Table III-1—Summary of ANSI/AHAM RAC-1-2008 Sections Referenced in Appendix F

ANSI/AHAM RAC-1-2008 Section

Description

General test requirements, including power supply and test tolerances

Test conditions and requirements for a standard measurement test

6.1

Determination of cooling capacity in British thermal units per hour (Btu/h)

6.5

Determination of electrical input in watts (W)

Since DOE last revised its room AC test procedure in 2011, ANSI/AHAM RAC-1 has been updated and the current standard was released in 2015 as ANSI/AHAM RAC-1-2015, “Room Air Conditioners” (ANSI/AHAM RAC-1-2015).

In the August 2017 RFI, DOE asserted that the updates to ANSI/AHAM RAC-1 appear to provide added specificity but would not substantively impact the results of DOE's cooling mode test. Specifically, ANSI/AHAM RAC-1-2015 introduced new provisions for the measurement of standby and off mode power in Section 6.3, as well as the calculations for annual energy consumption and CEER in Sections 6.4−6.8. Because those updates do not impact the sections relevant to appendix F, DOE noted that it expects that updating the references to ANSI/AHAM RAC-1-2015 in appendix F would not substantively affect test results or test burden. 82 FR 36349, 36353 (Aug. 4, 2017).

Friedrich Air Conditioning (Friedrich) and AHAM supported updating the reference to ANSI/AHAM RAC-1-2015. (Friedrich, No. 2 at p. 6; AHAM, No. 3 at p. 6) AHAM encouraged DOE to limit any revisions to the room AC test procedure to updating the referenced industry test methods to the most recent versions. (AHAM, No. 3 at p. 2)

Although ANSI/AHAM RAC-1-2015 maintains the same general organization as ANSI/AHAM RAC-1-2008, ANSI/AHAM RAC-1-2015 adds test requirements and conditions for standby and off mode, and heating mode in sections 4 and 5, respectively. Because the DOE test procedure already addressed standby and off mode testing prior to their inclusion in the latest version of the ANSI/AHAM RAC standard and the DOE test procedure does not address heating mode, which is now included in ANSI/AHAM RAC-1-2015, and to avoid confusion regarding the appropriate applicability of ANSI/AHAM RAC, DOE proposes to update the existing references to Sections 4 and 5 of ANSI/AHAM RAC-1-2008 with references to only to the cooling mode-specific subsections of ANSI/AHAM RAC-1-2015: Sections 4.1, 4.2, 5.2.1.1, and 5.2.4.

DOE also notes that the provisions in ANSI/AHAM RAC-1-2015 for measuring electrical power input appear in Section 6.2, rather than Section 6.5 of ANSI/AHAM RAC-1-2008. To reflect this change in section numbers, DOE proposes to update appendix F to reference Section 6.2 of ANSI/AHAM RAC-1-2015 to determine the electrical power input in cooling mode. Because there is no change in substance, simply adjusting the section number cannot affect the test conduct, burden, or results.

DOE requests comment on the proposal to incorporate by reference ANSI/AHAM RAC-1-2015 to adjust the section references in appendix F to limit references to cooling mode-specific sections (by excluding standby, off mode, and heat mode sections), and to update the section reference for measuring electrical power input.

2. ANSI/ASHRAE Standard 16

Appendix F currently references the 1983 version of ANSI/ASHRAE Standard 16, which was reaffirmed in 2009, for cooling mode temperature conditions, methods, and calculations. ANSI/AHAM RAC-1-2015 also references the 1983 version of ANSI/ASHRAE Standard 16 reaffirmed in 2009.

In the August 2017 RFI, DOE noted that a new version of ANSI/ASHRAE Standard 16, published in 2016 (ANSI/ASHRAE Standard 16-2016). ANSI/ASHRAE Standard 16-2016 made a number of updates to the industry standard, including an air-enthalpy test approach as an alternative to the calorimeter approach, heating mode testing, additional clarification on placement of air samplers and thermocouples, stability requirement definitions, and new figures for additional tests and to also improve previous figures. The general cooling mode methodology, however, remains unchanged. 82 FR 36349, 36353 (Aug. 4, 2017). The addition of the air-enthalpy approach provides more flexibility in conducting the tests, and the heating mode test is based on the tests previously included in ANSI/ASHRAE Standard 58-1986 “Method of Testing for Rating Room Air Conditioner and Packaged Terminal Air Conditioner Heating Capacity.”

AHAM supported updating appendix F to reference ANSI/ASHRAE Standard 16-2016, excluding the adoption of Sections 7.1(b)−(d), which contain the air-enthalpy method and Section 7.1.2, which contains the heating mode test). (AHAM, No. 3 at pp. 6−7) AHAM suggested that ANSI/ASHRAE Standard 16-2016 provides additional clarification on placement of air samplers and thermocouples, adds stability requirement definitions, adds new figures for additional tests, and fixes old figures. (

Id.

) DOE recognizes that the general calorimeter test methodology is unchanged in ANSI/ASHRAE Standard 16-2016 and has tentatively determined that the additional detail and clarifying updates would improve the repeatability and reproducibility of test results. First, ANSI/ASHRAE Standard 16-2016 provides best practices for thermocouple and air sampler placement, recognizing that the unique characteristics of each test chamber will result in particular air flow and temperature gradients in the chamber, influenced by the interaction of the reconditioning equipment and the test unit. These practices address the distances for placing the air sampler from the unit discharge points and thermocouple spacing on the air sampling device. Second, Figure 1 and Figure 2 of ANSI/ASHRAE Standard 16 are also updated with additional details and references. Third, Section 5 of ANSI/ASHRAE Standard 16-2016 includes additional provisions regarding instrument calibration and accuracy.

Fourth, ANSI/ASHRARE Standard 16-2016 requires measuring data at more frequent intervals to minimize the sensitivity of the final average value to variations in individual data points, resulting in a more repeatable and reproducible test procedure. DOE expects that requiring more frequent data measurements will have minimal impact on testing burden because most testing laboratories are already using a data acquisition system that has the capability to take more frequent measurements. For these reasons, DOE contends that the improvements in ANSI/ASHRAE Standard 16-2016 warrant inclusion in the updates to appendix F.

DOE requests comment on the proposal to incorporate relevant sections of ANSI/ASHRAE Standard 16-2016 into appendix F.

ANSI/ASHRAE Standard 16-2016 also updates requirements for the accuracy of instruments. The 2009 reaffirmation of ANSI/ASHRAE Standard 16 requires, in section 5.4.2, accuracy to ±0.5 percent of the quantity measured for instruments used for measuring all electrical inputs to the calorimeter compartments. ANSI/ASHRAE Standard 16-2016, in section 5.6.2, includes more specific language (

e.g.,

explicitly mentioning the power input to the test unit, heaters, and other cooling load contributors). To ensure that the electrical input for all key equipment is properly measured, DOE proposes to incorporate these requirements and maintain the requirement of accuracy to ±0.5 percent of the quantity measured for instruments used for measuring all electrical inputs, to the test unit, all reconditioning equipment, and any other equipment that operates within the calorimeter walls.

DOE requests comment on the proposal to incorporate the requirements of ANSI/ASHRAE Standard 16-2016 while maintaining that an accuracy of ±0.5 percent of the quantity measured is applicable to all devices measuring electrical input for the room AC test procedure.

3. ANSI/ASHRAE Standards 41.1, 41.2, 41.3, 41.6, and 41.11

ANSI/ASHRAE Standard 16-2016 references certain industry standards in specifying certain test conditions and measurement procedures. DOE is also proposing to incorporate those industry standards specified in the relevant sections of ANSI/ASHRAE Standard 16-2016. Specifically, DOE is proposing to incorporate by reference: ANSI/ASHRAE Standard 41.1-2013, “Standard Method for Temperature Measurement, as referenced in ANSI/ASHRAE Standard 16-2016 section 5.1.1 for all temperature measurements except for dew-point temperature; ANSI/ASHRAE Standard 41.2-1987 (RA 1992), “Standard Methods for Laboratory Airflow Measurement,” as referenced in Section 5.5.1 of ANSI/ASHRAE Standard 16-2016 for airflow measurements; ANSI/ASHRAE Standard 41.3-2014, “Standard Methods for Pressure Measurement,” as referenced in section 5.2.5 of ANSI/ASHRAE Standard 16-2016 for the prescribed use of pressure measurement instruments; ANSI/ASHRAE Standard 41.6-2014, “Standard Method for Humidity Measurement,” as referenced in section 5.1.2 of ANSI/ASHRAE Standard 16-2016 for measuring dew-point temperatures using hygrometers; and ANSI/ASHRAE Standard 41.11-2014, “Standard Methods for Power Measurement,” as referenced in section 5.6.4 of ANSI/ASHRAE Standard 16-2016 regarding the use and application of electrical instruments during tests. Incorporating these standards will clarify which versions of the standards are required to conduct tests according to the procedure in appendix F.

DOE requests comment on the proposal to incorporate ANSI/ASHRAE Standard 41.1-2013, ANSI/ASHRAE Standard 41.2-1987 (RA 1992), ANSI/ASHRAE Standard 41.3-2014, ANSI/ASHRAE Standard 41.6-2014, and ANSI/ASHRAE Standard 41.11-2014 in appendix F.

C. Variable-Speed Room Air Conditioner Test Procedure

Historically, room ACs have been designed using a single-speed compressor, which operates at full cooling capacity while the compressor is on. To match the cooling load of the space, which in most cases is less than the full cooling power of the compressor, a single-speed compressor cycles on and off. This cycling behavior introduces inefficiencies due to the surge in power draw at the beginning of each “on” cycle, before the compressor reaches steady-state performance. Variable-speed room ACs became available on the U.S. market in 2018. These units employ an inverter compressor that can reduce its speed to match the observed cooling load. Accordingly, a variable-speed compressor runs continuously, adjusting its speed up or down as required, thereby avoiding compressor cycling.

The current DOE test procedure measures the performance of a room AC while operating under a full cooling load;

i.e.,

the compressor is operated continuously in its “on” state. As a result, the DOE test does not capture any inefficiencies due to compressor cycling. Consequently, the efficiency gains that can be achieved by variable-speed room ACs due to the avoidance of cycling losses are not measured by the current test procedure. DOE proposes to amend its room AC test procedure to include a methodology for determining and applying a “performance adjustment factor” for variable-speed room ACs to reflect the avoidance of cycling losses that would be experienced in a representative consumer installation.

DOE conducted investigative testing comparing the performance of a variable-speed room AC with a single-speed room AC under reduced cooling load conditions. DOE installed each room AC in a calorimeter test chamber, set the unit thermostat to 80 degrees Fahrenheit (°F), and applied a range of fixed cooling loads to the indoor chamber.

16 17

The calorimeter chamber was configured so that the indoor chamber temperature could vary, thereby allowing the test unit to maintain the target indoor chamber temperature by adjusting its cooling operation in response to the changing temperature of the indoor chamber.

Figure III-1 shows the efficiency gains and losses for the range of reduced cooling loads tested for each unit, relative to the performance of each unit as tested using appendix F under a full cooling load.

A cooling load is “applied” by adjusting and fixing the rate of heat added to the indoor test chamber to a level at or below that of the nominal cooling capacity of the test unit.

This approach aims to represent a consumer installation in which the amount of heat added to a room may be less than the rated cooling capacity of the room AC (

e.g.,

electronics or lighting turned off, people or pets leaving the room, and external factors such as heat transfer through walls and windows reducing with outdoor temperature).

DOE notes that this test chamber configuration differs from the configuration used in appendix F. Appendix F uses a constant-temperature configuration, in which the indoor chamber temperature is held fixed (

i.e.,

the indoor temperature does not drop while the room AC is operational).

For single-speed room ACs under appendix F, the thermostat is typically set as low as possible to ensure that the unit does not cycle on and off during the cooling mode test period.

EP11JN20.000

In Figure III-1, the distance of each data point from the x-axis represents the change in efficiency relative to the full-load efficiency for each unit. (The data points at 100-percent cooling load correspond to the appendix F test conditions.) The single-speed room AC efficiency decreases in correlation with a reduction in cooling load, reflecting cycling losses that become relatively larger as the cooling load decreases. In contrast, the efficiency of the variable-speed room AC increases as the cooling load decreases, reflecting the lack of cycling losses and inherent improvements in compressor efficiency associated with lower compressor speeds. These results demonstrate that the current test procedure does not account for significant efficiency gains that variable-speed room ACs can achieve under reduced temperature conditions.

1. Methodology

To measure the efficiency gains for variable-speed room ACs that are not captured by the current DOE test procedure, DOE considered the alternate test procedure provided in the LG Waiver and the Grant of Midea Interim Waiver (collectively, “the waivers”) for specified basic models of variable-speed room ACs. 84 FR 20111 (May 8, 2019) and 84 FR 68159 (December 13, 2019). The alternate test procedure provides a methodology for obtaining a CEER value by adjusting the CEER value as tested at the 95 °F test condition according to appendix F using a “performance adjustment factor” (PAF).

Conceptually, the approach for variable-speed room ACs involves measuring performance over a range of four test conditions with fixed compressor speeds, which collectively comprise representative use. These temperature conditions were derived from the DOE test procedure for central ACs with variable-speed compressors and include three reduced-temperature test conditions—under which variable speed room ACs perform more efficiently than single-speed room ACs—and the test condition specified in the current test procedure. The single-speed room AC test procedure, however, does not factor in the reduced-temperature test conditions under which single-speed units also will perform more efficiently (although not as well as variable-speed room ACs). As a result, comparing variable-speed performance at all test conditions against a single-speed unit at the highest-temperature test condition would not yield a fair comparison. The PAF represents the average relative benefit of variable-speed over single-speed across the whole range of test conditions. It is applied to the measured variable-speed room AC performance only at the high-temperature test condition to provide a comparison to the single-speed existing CEER metric based on representative use.

The steps for determining a variable-speed room AC's PAF are summarized as follows:

• Measure the capacity and energy consumption of the sample unit at the single test condition used for single-speed room ACs (95 °F dry-bulb outdoor temperature), with the compressor speed fixed at the maximum (full) speed.

• Measure the capacity and energy consumption of the sample unit at three additional test conditions (92 °F, 87 °F, and 82 °F dry-bulb outdoor temperature),

with compressor speed fixed at full, intermediate, and minimum (low) speed, respectively.

Using theoretically determined adjustment factors,

calculate the equivalent performance of a single-speed room AC with the same cooling capacity and electrical power input at the 95 °F dry-bulb outdoor temperature, with no cycling losses (

i.e.,

a “theoretical comparable single-speed” room AC) for each of the three test conditions.

The additional reduced-temperature conditions are described further in section III.C.2 of this document.

The compressor speeds are described further in section III.C.3 of this document.

These adjustment factors are described further in section III.C.4 of this document.

• Calculate the annual energy consumption in cooling mode at each of the four cooling mode test conditions for a variable-speed room AC, as well as for a theoretical comparable single-speed room AC with no cycling losses. This theoretical single-speed room AC would perform the same as the variable-speed test unit at the 95 °F test

condition, but perform differently at the other test conditions.

• Calculate an individual CEER value at each of the four cooling mode test conditions for the variable-speed room AC, as well as for a theoretical comparable single-speed room AC with no cycling losses.

• Using cycling loss factors derived from an industry test procedure,

calculate an adjusted CEER value at each of the four cooling mode test conditions for a theoretical comparable single-speed room AC, which includes cycling losses.

The derivation of these cycling loss factors is described in more detail in section III.C.5 of this document.

• Using weighting factors

representing the fraction of time experienced at each test condition in representative real-world operation, calculate a weighted-average CEER value (reflecting the weighted-average performance across the four test conditions) for the variable-speed room AC, as well as for a theoretical comparable single-speed room AC.

These “fractional temperature bin” weighting factors are described in more detail in section III.C.6 of this document.

• Using these weighted-average CEER values for the variable-speed room AC and a theoretical comparable single-speed room AC, calculate the PAF as the percent improvement of the weighted-average CEER value of the variable-speed room AC compared to a theoretical comparable single-speed room AC.

This PAF represents the improvement resulting from the implementation of a variable-speed compressor.

The performance adjustment factor is described in more detail in section III.C.7 of this document.

DOE's proposed approach to addressing the performance improvements associated with variable-speed room ACs is consistent with the test procedures required in the waivers. The following sections of this document describe each aspect of the proposal in greater detail.

2. Test Conditions

As discussed previously, variable-speed room ACs provide improved performance at reduced cooling loads by reducing the compressor speed to match the load, thereby avoiding compressor cycling and associated cycling inefficiencies. DOE recognizes that throughout the cooling season, room ACs operate under various outdoor temperature conditions. DOE also asserts that these varying outdoor conditions present a range of reduced cooling loads in the conditioned space, under which a variable-speed room AC would perform more efficiently than a theoretical comparable single-speed room AC.

To measure this improved performance, DOE proposes a test procedure for variable-speed room ACs that adds three test conditions (92 °F, 87 °F, and 82 °F dry-bulb outdoor temperature) to the current 95 °F, consistent with the test conditions in the waivers. DOE notes that these temperatures represent potential outdoor temperature conditions between the current 95 °F test condition and the indoor setpoint of 80 °F (below which no active cooling would be necessary). These additional test conditions are also consistent with the representative temperatures for bin numbers 6, 5, and 4 in Table 19 of DOE's test procedure for central ACs at appendix M.

DOE requests comment on the proposal to adopt for all variable-speed room ACs these additional test conditions from test procedures required in the waivers for variable-speed room ACs.

3. Variable-Speed Compressor Operation

The DOE test procedure maintains fixed test conditions in the indoor chamber and requires configuring the test unit settings to achieve maximum cooling capacity. As a result, units under test constantly operate at their full cooling capacity, even at the reduced outdoor temperature test conditions described in section III.C.2 of this document, without the compressor cycling (for single-speed units) or compressor speed reduction (for variable-speed units) that would be expected under real-world operation. Therefore, DOE proposes additional test procedure adjustments, beyond reduced outdoor temperature test conditions, to fully represent the potential efficiency gains associated with variable-speed room ACs at reduced cooling loads.

As described previously, in a typical consumer installation, reduced outdoor temperatures would result in reduced indoor cooling loads. A test that would provide constant reduced cooling loads could be considered, but as discussed below in section III.E.1.e of this document, DOE concludes such a test would not be feasible at this time. Therefore, to better represent what would occur in typical consumer usage at reduced outdoor temperatures, DOE proposes to test variable-speed room ACs by fixing a particular compressor speed at each of the outdoor test conditions, as described further in the following sections.

a. Compressor Speeds

To ensure the compressor speeds are representative of actual speeds at the expected cooling loads at each of the outdoor test conditions, DOE proposes to require that the compressor speed be set to full speed at the two highest outdoor temperature test conditions (based on test A

Full

at 95 °F and test B

Full

at 92 °F), at intermediate compressor speed at the 87 °F test condition (based on test E

Int

), and at low compressor speed at the 82 °F test condition (based on test D

Low

), consistent with the tests and requirements in Table 8 of the 2017 version of Air-Conditioning, Heating, and Refrigeration Institute (AHRI) Standard 210/240, (AHRI Standard 210/240), “Performance Rating of Unitary Air-conditioning & Air-source Heat Pump Equipment,” which specifies representative test conditions and the associated compressor speeds for variable-speed unitary air conditioners. DOE also proposes to add definitions for “full compressor speed”, “intermediate compressor speed”, and “low compressor speed”, which specify how each speed would be determined, as described further in section III.D of this document.

DOE requests comment on the proposal to require fixing the compressor speed settings for variable-speed room ACs to full speed at the 95 °F and 92 °F test conditions, intermediate speed at the 87 °F test condition, and low speed at the 82 °F test condition, in accordance with the requirements in Table 8 of AHRI Standard 210/240.

b. Instructions for Fixing Compressor Speeds

DOE understands that setting and maintaining a specific room AC compressor speed is not typically possible without special control instructions from manufacturers. Therefore, because maintaining fixed compressor speeds is critical to the repeatability of the variable-speed room AC test procedure, DOE proposes that manufacturers provide in each certification report for a variable-speed room AC basic model all necessary instructions to maintain the compressor speeds required for each test condition when testing that basic model. These include the compressor frequency set points at each test condition, instructions necessary to maintain the compressor speeds required for each test condition, and the control settings used for the variable components.

DOE requests comment on the proposal to require that manufacturers provide in their certification reports the

control settings for each variable-speed room AC basic model required to achieve the fixed compressor speed for each test condition.

c. Boost Compressor Speed

DOE is aware that a variable-speed room AC's full compressor speed may not be its fastest speed. In particular, the fastest compressor speed may be one that is automatically initiated and used for a brief period of time to rapidly reduce the indoor temperature to within typical range of the set point. This compressor speed is referred to as “Boost Compressor Speed” in AHRI Standard 210/240 and is defined as a speed faster than full compressor speed, at which the unit will operate to achieve increased capacity. DOE understands that boost compressor speed operation is typically limited in duration and would not significantly contribute to annual energy consumption, as manufacturers have described it as used for limited periods of time on occasions where the indoor room temperature is far out of normal operating range of the set point. Once the indoor room temperature is within the typical operating range of the setpoint, the room AC returns to the “Full Compressor Speed,” as defined in AHRI Standard 210/240. AHRI Standard 210/240 does not measure boost compressor speed energy use, and in a final rule published on June 8, 2016, DOE declined to include provisions for measuring boost compressor speed energy use in the central AC test procedure. 81 FR 36992, 37029. Accordingly, DOE does not propose to measure boost compressor speed performance and energy consumption in appendix F at this time because of the expected insignificant impact on annual energy consumption and performance, to harmonize with the industry approach for variable-speed compressor testing, and because DOE has previously opted to forgo including it for other air conditioning products.

Id.

DOE requests comment on the proposal not to address boost compressor speed performance and energy consumption in appendix F at this time.

4. Capacity and Electrical Power Adjustment Factors

In the proposed approach, a capacity adjustment factor is used to estimate the increased cooling capacity of a room AC at lower outdoor temperature conditions, using a linear extrapolation based on the measured capacity at the 95 °F test condition. Similarly, an electrical power adjustment factor is used to estimate the reduced electrical power draw of a room AC at lower outdoor temperature conditions, using a linear extrapolation based on the measured electrical power draw at the 95 °F test condition. To determine these two adjustment factors, DOE used the MarkN model to model room AC performance at reduced outdoor temperature conditions. These modeling results suggested linear capacity and electrical power adjustment factors of 0.0099 per °F and 0.0076 per °F, respectively.

To confirm the validity of these modeled adjustment factors, DOE tested a sample of 14 single-speed room ACs at a range of reduced outdoor temperature test conditions (92 °F, 87 °F, and 82 °F) and compared the predicted values of cooling capacity and electrical power with the measured values at each test condition. Table III-2 and Table III-3 summarize the results for cooling capacity and electrical power, respectively.

Table III-2—Comparison Between Modeled and Tested Cooling Capacity

Unit

92 °F

Model

(Btu/h)

Tested

(Btu/h)

Diff.

(%)

87 °F

Model

(Btu/h)

Tested

(Btu/h)

Diff.

(%)

82 °F

Model

(Btu/h)

Tested

(Btu/h)

Diff.

(%)

5,890

5,850

−0.6

6,170

6,070

−1.8

6,460

6,300

−2.5

10,920

10,810

−0.9

11,440

11,060

−3.4

11,970

11,330

−5.4

12,160

12,340

+1.5

12,740

12,880

+1.1

13,330

13,320

−0.1

12,430

12,320

−0.9

13,030

12,640

−3.0

13,620

12,890

−5.7

8,660

8,490

−2.0

9,070

8,570

−5.9

9,490

8,680

−9.3

12,400

12,180

−1.8

13,000

12,310

−5.6

13,590

12,360

−10.0

5,360

5,410

+0.8

5,620

5,590

−0.6

5,880

5,770

−1.9

5,760

5,640

−2.0

6,030

5,850

−3.2

6,310

6,000

−5.3

5,440

5,530

+1.6

5,700

5,730

+0.6

5,960

5,790

−3.0

6,520

6,410

−1.7

6,830

6,490

−5.2

7,140

6,520

−9.6

6,350

6,320

−0.5

6,650

6,500

−2.4

6,960

6,820

−2.0

8,150

8,180

+0.4

8,540

8,530

−0.1

8,930

9,080

+1.6

8,830

8,630

−2.3

9,260

8,960

−3.2

9,680

9,090

−6.5

21,860

22,440

+2.6

22,920

23,270

+1.5

23,970

24,260

+1.2

Average

−0.4

−2.2

−4.2

Note:

Unit 4 was not included because it is a variable-speed unit and the modeling factors are only applicable to single-speed units that do not adjust performance at reduced outdoor temperature conditions.

Table III-3—Comparison Between Modeled and Tested Electrical Power Draw

Unit

92 °F

Model

(W)

Tested

(W)

Diff.

(%)

87 °F

Model

(W)

Tested

(W)

Diff.

(%)

82 °F

Model

(W)

Tested

(W)

Diff.

(%)

414

412

+0.6

398

393

+1.3

382

375

+1.9

894

887

+0.8

859

846

+1.6

825

807

+2.2

989

984

+0.5

950

938

+1.3

912

895

+2.0

1,080

1,073

+0.7

1,038

1,024

+1.4

996

978

+1.8

705

701

+0.6

677

668

+1.4

650

636

+2.2

1,116

1,106

+0.9

1,073

1,046

+2.6

1,030

993

+3.7

433

430

+0.7

416

412

+1.0

399

394

+1.3

435

430

+1.1

418

413

+1.2

401

392

+2.3

435

+0.2

418

417

+0.2

401

403

-0.4

537

535

+0.5

517

510

+1.3

496

483

+2.6

514

0.0

494

492

+0.4

474

470

+0.9

643

638

+0.8

618

610

+1.3

593

584

+1.5

647

646

+0.2

622

615

+1.1

597

585

+1.9

2,074

2,068

+0.3

1,993

2,006

−0.6

1,912

1,935

−1.2

Average

+0.6

+1.1

+1.6

Note:

The results in Table III-2 generally indicate close agreement (

i.e.,

less than 5 percent difference on average) between the modeled cooling capacity (based on an adjustment factor of 0.0099 per °F) and the measured capacity at each test condition. On average, the tested cooling capacity was within 0.4 percent of the modeled value at the 92 °F test condition, 2.2 percent at the 87 °F test condition, and 4.2 percent at the 82 °F test condition.

Similarly, the results in Table III-3 generally indicate close agreement between the modeled electrical power draw (based on an adjustment factor of 0.0076 per °F) and the measured electrical power draw at each test condition. On average, the tested electrical power draw was within 0.6 percent of the modeled value at the 92 °F test condition, 1.1 percent at the 87 °F test condition, and 1.6 percent at the 82 °F test condition.

DOE has tentatively determined that the average difference of less than 5 percent between the modeled values and the experimental values confirms the validity of these modeled adjustment factors. Therefore, DOE proposes using the modeled adjustment factors of 0.0099 per °F and 0.0076 per °F for capacity and electrical power, respectively, to calculate the theoretical comparable single-speed room AC performance at reduced outdoor temperature test conditions.

DOE requests comment on the proposal to use the capacity and electrical power adjustment factors of 0.0099 per °F and 0.0076 per °F, respectively.

5. Cycling Loss Factors

To represent the cycling losses of a theoretical comparable single-speed room AC at reduced outdoor temperature test conditions and expected reduced cooling loads, DOE identified cycling loss factors to apply to the interim CEER values at each of the four cooling mode test conditions for a theoretical comparable single-speed room AC. Table III-4 shows the proposed cycling loss factors for each of the four proposed test conditions.

Table III-4—Proposed Cycling Loss Factors

Test condition

Evaporator inlet air, °F

Dry bulb

Wet bulb

Condenser inlet air, °F

Dry bulb

Wet bulb

Cycling loss factor

Test Condition 1

1.0

Test Condition 2

72.5

0.971

Test Condition 3

0.923

Test Condition 4

0.875

These cycling loss factors are based on the default cycling loss factors in Section 11.2 of AHRI Standards 210/240. The cycling loss factor at the 82 °F test condition for a theoretical comparable single-speed room AC is consistent with the default cooling degradation coefficient of 0.25, which corresponds to a part-load (cycling loss) factor of 0.875, as determined in Section 11.2 of AHRI Standard 210/240. The remaining cycling loss factors for the other test conditions are consistent with linear interpolation between the cycling loss factor of 0.875 at the 82 °F test condition and the cycling loss factor of 1.0 at the 95 °F test condition, at which no cycling is expected.

DOE requests comment on the proposal to implement cycling loss factors consistent with AHRI Standard 210/240 to represent the expected performance of a theoretical comparable single-speed room AC at reduced outdoor temperature test conditions.

6. Test Condition Weighting Factors

In the proposed approach, the four interim CEER values representing each of the four cooling mode test conditions are combined, using four weighting factors, into a single weighted-average CEER value. The resulting weighted-average CEER value represents the weighted-average performance across the range of outdoor test conditions. DOE calculated weighting factors based on the fractional temperature bin hours in Table 19 of DOE's test procedure for central ACs at appendix M. DOE identified the fractional temperature bin hours representing the four test conditions in the proposed approach, and normalized these four values from appendix M so that they sum to 1.00.

Table III-5 shows the proposed weighting factors for each of the four proposed test conditions.

Table III-5—Proposed Temperature Condition Weighting Factors

Test condition

Evaporator inlet air, °F

Dry bulb

Wet bulb

Condenser inlet air, °F

Dry bulb

Wet bulb

CEER weighting

factor

Test Condition 1

0.05

Test Condition 2

72.5

0.16

Test Condition 3

0.31

Test Condition 4

0.48

DOE requests comment on the proposed weighting factors associated with each of the outdoor test conditions.

7. Performance Adjustment Factor

The final step in the proposed approach is to calculate the PAF, representing the improvement over a theoretical comparable single-speed room AC resulting from the implementation of a variable-speed compressor. The PAF would be calculated as the percent improvement of the weighted-average CEER value of the variable-speed room AC compared to the weighted-average CEER value of a theoretical comparable single-speed room AC under the four defined test conditions.

After calculating the PAF, it would be multiplied by the CEER value of the variable-speed unit when tested at the 95 °F test condition according to appendix F, resulting in the final CEER metric for the variable-speed room AC.

DOE expects that the variable-speed room AC CEER values would be comparable to single-speed room AC CEER values as a result of applying the adjustment factor to the variable-speed room AC CEER value determined in accordance with the current single-speed test method in appendix F. By adjusting the variable-speed room AC CEER values to be comparable to single-speed room AC CEER values, consumers will have the information they need to understand the relative efficiency of both types of room AC.

DOE requests comment on the proposed calculations to determine a PAF, which would adjust the CEER of a variable-speed room AC to appropriately account for its efficiency improvements relative to a theoretical comparable single-speed room AC under varying operating conditions.

8. Air-Enthalpy Test Alternative

DOE recognizes the additional test burden associated with testing variable-speed room ACs at multiple test conditions as proposed. In an effort to minimize that additional test burden, the Grant of LG Interim Waiver test procedure provided that LG could optionally test its variable-speed room ACs using the air-enthalpy method. Following the publication of the Grant of LG Interim Waiver, DOE conducted investigative testing to further analyze the air-enthalpy method and its suitability for testing room ACs. As described below, this testing demonstrated that this method was unrepresentative and inconsistent, and remedying these deficiencies would be unduly burdensome.

DOE tested nine room ACs according to the air-enthalpy procedure prescribed by ANSI/ASHRAE Standard 37-2009, “Methods of Testing for Rating Electrically Driven Unitary Air-Conditioning and Heat Pump Equipment.” DOE constructed plenums to match the cross sectional area of each room AC evaporator and condenser exhaust, with instrumented ducts connected to each. A variable-speed fan at the end of each duct was used to maintain a zero static pressure at the test unit exhaust. Tests were conducted in accordance with the indoor and outdoor test conditions specified in appendix F, and the instrumentation in the duct measured the psychrometric characteristic of the air in addition to the air flow rate to obtain the cooling capacity. To determine whether there was reasonable correlation between the two sets of results and, thus, whether the air-enthalpy procedure would be a viable alternative approach, DOE compared the cooling capacities measured according to this air-enthalpy method to the capacities obtained via the calorimeter method currently specified in appendix F. Table III-6 shows the measured cooling capacity and efficiency obtained for each of these eight test units using the air-enthalpy and calorimeter methods, and highlights the differences in results between the two approaches.

Table III-6—Cooling Capacity and Efficiency Using the Air-Enthalpy Method and the Calorimeter Method

Unit #

Indoor

air flow

(CFM)

Calorimeter

capacity

(Btu/h)

Air-enthalpy

capacity

(Btu/h)

Capacity

difference

(%)

Calorimeter

EER

(Btu/Wh)

Air-enthalpy

EER

(Btu/Wh)

EER

difference

(%)

131

5,210

4,803

−7.8

11.8

10.6

−9.7

161

5,591

5,059

−9.5

12.6

11.3

−10.1

126

5,284

4,908

−7.1

11.9

10.9

−8.0

147

5,228

4,715

−9.8

10.8

9.7

−10.7

152

6,164

5,650

−8.3

11.7

10.6

−9.4

197

7,914

7,814

−1.3

12.0

11.8

−1.8

227

8,576

8,165

−4.8

13.0

12.4

−4.1

459

2,1233

2,1626

+1.8

10.0

10.1

+0.7

The results in Table III-6 indicate a range of differences between the air-enthalpy method and the calorimeter methods, for both cooling capacity and efficiency, which appears to correlate with the evaporator exhaust, or indoor, air flow rate from each unit. Five of the eight units (Units 8 through 12) demonstrated relatively poor agreement between the two methods, with an average decrease in cooling capacity of 8.5 percent and an average decrease in efficiency of 9.4 percent when using the air-enthalpy method. These units all had indoor air flow rates at or below 161 cubic feet per minute (CFM). Conversely, the unit with the largest air flow rate of 459 CFM (Unit 15) showed a small increase in capacity and efficiency when tested using the air-enthalpy method. The remaining two units (Units 13 and 14) had air flow rates between 161 CFM and 459 CFM, and showed only a modest decrease of

less than 5 percent in both capacity and efficiency.

DOE asserts that these results depend on the measurement apparatus available to the testing laboratory for the air-enthalpy method. DOE understands that air-enthalpy test equipment currently used by testing laboratories is not typically designed to accurately measure air conditioning products with airflow rates lower than approximately 200 CFM because typical test equipment is optimized for larger air conditioners with significantly higher airflow rates. The results for Units 8 through 12 support this assertion: All of these had evaporator airflows substantively below 200 CFM, and the performance for each unit measured using the air-enthalpy and calorimeter approaches differed by more than five percent on average. DOE is aware that air-enthalpy equipment that is optimized to measure units with airflow between 50 and 500 CFM exists. However, such equipment may be costly to design, develop, and produce, because it is not readily available and may require custom manufacturing. In addition, the air-enthalpy method does not measure any heat transfer within and through the unit chassis, while the calorimeter test does. Because of the unrepresentative and inconsistent results obtained with the air-enthalpy test equipment that testing laboratories are likely to already own, as well as the higher cost and limited availability of equipment that would be necessary to obtain consistent results for all room ACs of differing airflow rates, DOE contends that the air-enthalpy test method would be unduly burdensome for testing laboratories to implement for room ACs at this time. DOE further notes that, in the waivers, DOE did not allow the air-enthalpy test method as an alternative to the calorimeter test method due to the concerns outlined above. 84 FR 20111 (May 8, 2019), 84 FR 68159 (Dec. 13, 2019). Therefore, DOE is not proposing in this NOPR to allow testing of variable-speed room ACs using the air-enthalpy test method.

DOE seeks comment on the proposal to not include an optional alternative air-enthalpy test method for variable-speed room ACs in appendix F.

9. Product Specific Reporting Provisions

As described, the proposed amendment to Appendix F to test variable-speed room ACs at multiple cooling mode test conditions would require testing each unit with a fixed compressor speed at each test condition. To ensure test reproducibility, DOE is proposing to require, in 10 CFR 429.15, manufacturers to provide DOE all necessary instructions to maintain the compressor speeds required for each test condition for a variable-speed basic model, as additional product-specific information pursuant to 10 CFR 429.12 (b)(13). DOE expects that this requirement would add a

de minimis

incremental burden to the existing reporting requirements.

DOE requests comment on the proposal to include in 10 CFR 429.15 compressor frequencies and control settings as additional product-specific information for certification of each variable-speed room AC basic model.

10. Estimated Annual Operating Cost Calculation

In conjunction with the proposed amendments for testing variable-speed room ACs, DOE is proposing corresponding amendments to the calculation that provides the basis of the annual energy consumption and operating cost information presented to consumers on the EnergyGuide Label. These changes would allow for an appropriate comparison of the annual energy consumption and operating costs between single-speed room ACs and variable-speed room ACs. As such, DOE proposes that for variable-speed room ACs, the average annual energy consumption used in calculating the estimated annual operating cost in 10 CFR 430.23(f) would be a weighted average of the annual energy consumption at each of the four test conditions in newly added Table 1 of appendix F and the annual energy consumption in inactive mode or off mode. DOE proposes, however, that the electrical power input reported for variable-speed room ACs for purposes of certification in 10 CFR 429.15(b)(2) would be the value measured at the 95 °F rating condition, to maintain consistency with the cooling capacity measured at the same condition.

DOE requests comment on the proposal to calculate estimated annual operating cost for variable-speed room ACs using a weighted-average annual energy consumption based on the four cooling mode test conditions in the proposed, new Table 1 of appendix F. DOE also requests comment on the proposal to report variable-speed room AC input power for certification purposes using the value measured at the 95 °F rating condition.

11. Potential Cost Impacts

The test procedure amendments proposed above would result in additional test burden and cost for testing variable-speed room ACs, mainly due to the additional time associated with testing cooling mode performance of variable-speed room ACs under four total test conditions, compared to the single cooling mode test currently required in appendix F. Under the LG Waiver, LG is already testing its variable-speed room ACs using the proposed approach and accordingly would incur no additional cost due to the proposed test procedure amendments. Likewise, under the Grant of Midea Interim Waiver, Midea is also already testing its variable-speed room ACs using the proposed approach and so would not incur any additional cost either due to the proposed test procedure amendments. DOE is not aware of other manufacturers of variable-speed room ACs, although the additional burden described above would be applicable to any entities that begin manufacturing a variable-speed room AC and introduce it to the U.S. market. Given that variable-speed room ACs are not available in the U.S. market from any other manufacturers besides LG and Midea, the proposed test procedure amendments in this NOPR regarding variable-speed room ACs would not result in any additional cost to manufacturers.

D. Definitions

DOE proposes to add a number of definitions to appendix F to accompany the proposed amendments described in this document. None of these proposed definitions would modify the current scope of covered products. The following sections describe each proposed definition in detail.

DOE proposes to define three key terms that currently appear in Appendix F but have no definitions: cooling mode, cooling capacity, and combined energy efficiency ratio. Although room ACs may sometimes operate in other modes as discussed further in section III.E of this proposed rule, the room AC CEER metric determined in appendix F is based primarily on performance in cooling mode, and several of the proposed amendments also reference “cooling mode.” DOE proposes to establish the following definitions for cooling mode, cooling capacity, and combined energy efficiency ratio in appendix F:

“Cooling mode” means an active mode in which a room air conditioner has activated the main cooling function according to the thermostat or temperature sensor signal or switch (including remote control).

“Cooling capacity” means the amount of cooling, in Btu/h, provided to an indoor conditioned space, determined in Section 4.1 of appendix F.

“Combined energy efficiency ratio” is the energy efficiency of a room air conditioner as measured in Btu/Wh and

determined in Section 5.2.2 of appendix F for single-speed room air conditioners and Section 5.3.12 of appendix F for variable-speed room air conditioners.

To accompany the proposed amendments affecting variable-speed basic models, DOE proposes to define single-speed and variable-speed room ACs as follows:

“Single-speed room air conditioner” means a type of room AC that cannot automatically adjust the compressor speed based on detected conditions.

“Variable-speed room air conditioner” means a type of room AC that can automatically adjust compressor speed based on detected conditions.

In addition, DOE proposes to establish definitions for the three compressor speeds required for variable-speed testing. DOE proposes to refer to these compressor speeds as “full,” “intermediate,” and “low” based on the test procedure terminology of AHRI Standard 210/240. The proposed definitions are as follows:

“Full compressor speed (full)” means the compressor speed at which the unit operates at full load test conditions, achieved by following the instructions certified by the manufacturer.

“Intermediate compressor speed (intermediate)” means a compressor speed higher than the low compressor speed by one third of the difference between low compressor speed and full compressor speed with a tolerance of plus 5 percent (designs with non-discrete speed stages) or the next highest inverter frequency step (designs with discrete speed steps), achieved by following the instructions certified by the manufacturer.

“Low compressor speed (low)” means the compressor speed at which the unit operates at low load test conditions, achieved by following the instructions certified by the manufacturer, such that Capacity

, the measured cooling capacity at test condition 4 in Table 1 of appendix F, is not less than 47 percent and not greater than 57 percent of Capacity

, the measured cooling capacity with the full compressor speed at test condition 1 in Table 1 of appendix F.

DOE is proposing a definition for low compressor speed based on the definition in AHRI Standard 210/240. To ensure that the low and intermediate compressor speeds result in representative cooling capacity under reduced loads, as explained in the following paragraphs, DOE is additionally proposing that the low compressor speed definition require that the test unit's measured cooling capacity at Test Condition 4, specified in Table III-5 of this document, be not less than 47 percent and not greater than 57 percent, of the measured cooling capacity when operating at the full compressor speed at Test Condition 1, also specified in Table III-5 of this document.

DOE developed this range based on the Building Load Calculation, Equation 11.60, in AHRI Standard 210/240, which relates the building load to an AC's full-load cooling capacity and outdoor temperature. DOE adapted this calculation for the room AC test procedure by normalizing Equation 11.60 so that full-load operation is assumed to occur at a 95 °F outdoor temperature, consistent with the outdoor test condition defined in the current room AC test procedure, rather than 98 °F as assumed by Equation 11.60. DOE used the normalized equation to determine the representative cooling load at an outdoor temperature of 82 °F as a percentage of the full-load cooling capacity at an outdoor temperature of 95 °F. Based on this analysis, an outdoor temperature of 82 °F would result in a cooling load of 57 percent of full-load cooling capacity. Therefore, DOE proposes that the representative cooling load at the low compressor speed and outdoor temperature of 82 °F (

i.e.

the temperature represented by Test Condition 4 in Table III-5), is 57 percent of the unit's cooling capacity when operating at 95 °F (

i.e.,

Test Condition 1 in Table III-5).

DOE recognizes that variable-speed room ACs may use compressors that vary their speed in discrete steps and may not be able to directly operate at a speed that provides 57 percent cooling capacity precisely; therefore, the defined cooling capacity associated with the low compressor speed is best presented as a range rather than a single value. DOE proposes that a 10-percent range would accommodate compressors that vary their speed in discrete steps.

DOE further proposes using 57 percent cooling load as the upper bound of the 10-percent range to define the cooling capacity associated with the lower compressor speed (

i.e.,

the range would be defined as 47 to 57 percent). The justification for using 57 percent as an upper bound, rather than as a midpoint in the 10-percent range, is as follows. Defining the upper bound of the 10-percent cooling load range as 57 percent would ensure that a variable-speed room AC is capable of matching the representative cooling load (57 percent of the maximum) at the 82 °F outdoor test condition, while providing the performance benefits associated with variable-speed operation. In contrast, if the 10-percent range were to be defined as, for example, 52 to 62 percent (with 57 percent as the midpoint), a variable-speed room AC could be tested at 60 percent, for example, without demonstrating the capability to maintain variable-speed performance down to 57 percent.

In summary, DOE proposes in newly added section 2.16 of appendix F to define “low compressor speed (low)” as the compressor speed specified by the manufacturer at which the unit operates at low load test conditions, such that the measured cooling capacity at the 82 °F outdoor test condition shall be no less than 47 percent and no greater than 57 percent of the unit's cooling capacity when operating at the 95 °F test condition.

DOE requests comment on the proposal to add new definitions for cooling mode, cooling capacity, combined energy efficiency ratio, single-speed room air conditioner, variable-speed room air conditioner, variable-speed compressor, full compressor speed (full), intermediate compressor speed (intermediate), and low compressor speed (low) in appendix F.

E. Active Mode Testing

The following sections describe proposed amendments and other considerations regarding the active mode testing provisions of appendix F.

1. Cooling Mode

a. General Test Approach

The current DOE room AC test procedure uses a calorimeter test method to determine the cooling capacity and associated electrical power input of a room AC. Under this approach, the test unit is installed between two chambers, one representing the indoor side and the other representing the outdoor side, which are both maintained at constant conditions by reconditioning equipment. The room AC operates in cooling mode, transferring heat from the indoor side to the outdoor side, while the reconditioning equipment counteracts the effects of the room AC to maintain constant test chamber conditions. The room AC cooling capacity is determined by measuring the required energy inputs to the reconditioning equipment.

In response to the June 2015 RFI, AHAM noted that it planned to conduct a round-robin test to identify sources of potential variation in the room AC test procedure. AHAM stated that because it believes that the current room AC standards are stringent, and that slight variation in the test procedure would

have a significant impact in meeting standards, any DOE test procedure amendments should address potential sources of variation. (AHAM, June 2015 RFI, No. 5 at p. 5) In this NOPR, DOE is proposing various test procedure modifications intended to improve repeatability and reproducibility and mitigate potential areas of variation. While DOE has not quantified the cost impacts of these proposed changes, based on its analysis described in section III.L.1 of this document, DOE believes that they would serve to reduce test burden by reducing the potential need for tests to be re-run due to variation. DOE welcomes AHAM's round-robin test data to identify areas of variation in the room AC test procedure and encourages other interested parties to provide comment and feedback on this issue.

b. Test Setup and Air Sampling

In the August 2017 RFI, DOE noted that Section 4.2.7 of ANSI/ASHRAE 16-2009, which is incorporated by reference in the DOE test procedure, requires the calorimeter chamber conditions to be verified by air sampled from a location that is representative of the temperatures surrounding the unit and that simulate the conditions in which the unit operates in the field. As DOE stated, there is no procedure to verify whether the measured chamber temperature reading is representative of conditions at the test unit condenser and evaporator inlet, which may be affected by recirculation from the condenser and evaporator exhaust, respectively, thereby potentially reducing test repeatability and reproducibility. 82 FR 36349, 36353. In the August 2017 RFI, DOE requested data on more specific requirements for air sampling devices within the calorimeter test chambers to improve test repeatability.

Id.

Friedrich asserted that the positioning of the air samplers impacts test repeatability, especially for through-the-wall units which intake and exhaust condenser air on the same plane. Friedrich recommended that the air sampler measurements be verified using a thermocouple grid at the evaporator and condenser air inlets. (Friedrich, No. 2 at p. 5)

AHAM stated that it does not currently have information that the thermocouple placement as prescribed in ANSI/ASHRAE Standard 16-2009 affects test repeatability and suggested that a balanced temperature is achieved throughout the calorimeter chamber. AHAM further noted that, unlike in a psychrometric test approach, the current calorimeter test approach takes into account any recirculation that would occur in the field. (AHAM, No. 3 at p. 6)

DOE is aware that the size, capability, and orientation of components within calorimeter test chambers may vary significantly, and that third-party laboratories extensively analyze their chambers and testing apparatus to maintain consistent and accurate air sampling measurements. DOE also understands that temperature gradients and unique airflow patterns can result from the interaction of a chamber reconditioning apparatus and the room AC under test, and that these interactions are particular to and dependent upon factors such as chamber size and shape, chamber equipment arrangement, size of reconditioning apparatus, and others, as noted in ANSI/ASHRAE Standard 16-2016 Section 8.2.7. Therefore, DOE contends that universal requirements for air sampling instrumentation and thermocouple placement could potentially reduce test accuracy and reproducibility. As discussed in section III.B.2 of this document, DOE is proposing to update the reference to ANSI/ASHRAE Standard 16 to the most current 2016 version, which includes additional clarification on best practices for air sampler and thermocouple placement.

c. Air-Enthalpy Test

As discussed in section III.B.2 of this document, DOE is proposing to use the calorimeter test method specified in ANSI/ASHRAE Standard 16-2016 for determining the cooling mode performance in appendix F. ANSI/ASHRAE Standard 16-2016 additionally contains an air-enthalpy test method (also referred to as a psychrometric test method), in which a technician places instruments in or near the evaporator air stream to measure the rate of cooled air added to the conditioned space. In the June 2015 RFI and the August 2017 RFI, DOE discussed the potential differences in accuracy and test burden associated with the two test methods and requested comment on the air-enthalpy method, specifically its applicability, accuracy, and associated test burden. 80 FR 34843, 34847 (July 18, 2015) and 82 FR 36349, 36353 (Aug. 4, 2017).

AHAM opposed the use of the air-enthalpy method as an alternative to the calorimeter method, stating that the calorimeter method is supported by historical data and is repeatable, while the repeatability of the air-enthalpy method for room ACs had not yet been assessed. According to AHAM, implementing this alternative test method would likely increase variation in testing and cause challenges for third-party verification and enforcement testing. (AHAM, June 2015 RFI, No. 5 at p. 3; AHAM, No. 3 at p. 7)

Friedrich also opposed the use of the air-enthalpy method for room ACs, based on internal testing that it stated showed a 2 to 3-percent variation in test results for the calorimeter method. Friedrich suggested that the variability of a psychrometric method for room ACs would be greater than the current variability associated with the calorimeter method. Friedrich added that psychrometric testing: (1) would not represent actual installation conditions, (2) would add uncertainty to the exhaust air wet-bulb temperature measurements, and (3) would fail to capture cooling from the portion of the room AC chassis installed in the room. Friedrich supported not updating the reference of ANSI/ASHRAE Standard 16-2009 in the DOE test procedure until further round-robin investigation is completed. (Friedrich, No. 2 at pp. 6-7)

DOE recognizes that installing test ducts on the evaporator and condenser exhausts to measure the air-enthalpy and calculate cooling capacity may impact the air flow, particularly on the evaporator side where room ACs typically locate the inlet and outlet in close proximity, and thus produce results that may not be representative of typical installations. The calorimeter method requires no test ducts or instrumentation that might impede or redirect airflow. DOE also agrees with Friedrich that, unlike the calorimeter method, the air-enthalpy method does not capture heat loss through the chassis to the room and further notes that the air-enthalpy method also may not capture possible heat transfer due to internal air leakage through the chassis between the indoor and outdoor test chambers.

As discussed in section III.C.8 of this document, DOE conducted testing to investigate any differences in test results between the air-enthalpy and calorimeter approaches. That testing showed a wide range of discrepancies between the air-enthalpy method and the calorimeter method, for both cooling capacity and efficiency. The largest differences were observed for units with evaporator airflows below 200 CFM, suggesting that the air-enthalpy test method as typically conducted with existing instrumentation does not produce results representative of actual room AC performance or comparable to measured performance in a calorimeter chamber. DOE expects that obtaining more accurate results would require specialized test equipment that is

limited in availability and costly to design, develop, and produce.

Finally, DOE notes that the results of AHAM's round-robin testing results are not yet available to further evaluate the repeatability and reproducibility of the air-enthalpy method.

For these reasons, DOE is not proposing to allow the use of the air-enthalpy method for determining room AC cooling mode performance at this time.

Although DOE is proposing to reference ANSI/ASHRAE Standard 16-2016, which includes an optional air-enthalpy method, DOE proposes to only reference those sections in ANSI/ASHRAE Standard 16-2016 that apply to the calorimeter method.

DOE seeks comment on the proposal not to include an air-enthalpy test approach for determine cooling mode performance of room ACs.

d. Side Curtain Heat Leakage and Infiltration Air

DOE considered the installation requirements for room ACs during testing and the impact of installation on efficiency performance, as described in the following sections.

Room ACs are designed to be installed in a window opening or through a wall, with the compressor and condenser outside the conditioned space and the evaporator inside the conditioned space, as shown in Figure III-2.

EP11JN20.001

The unit's outer case (

i.e.,

“chassis”) provides a boundary between the outdoor and indoor sides, leading to potential air leakage (and therefore, heat leakage) into or out of the conditioned space. This leakage can occur within the room AC chassis (

i.e.,

internal heat leakage) or around the chassis (

i.e.,

external heat leakage), and may negatively impact the performance of the room AC. External heat leakage consists of two main forms: (1) Infiltration of outdoor air into the conditioned space; and (2) heat leakage through and around non-chassis installation components, designed to secure the room AC and prevent air leakage.

Section 4.2.2 of ANSI/ASHRAE Standard 16-2009, referenced by the current DOE room AC test procedure, directs that the test unit be installed with no efforts made to seal the internal construction of the unit.

Consequently, any internal heat leakage through the room AC that would occur in a typical consumer installation is accounted for in the current room AC test procedure.

Note that the same requirements are retained in Section 6.1.1.4 of ANSI/ASHRAE Standard 16-2016.

Regarding the external sealing to avoid heat leakage, section 4.2.2 of ANSI/ASHRAE Standard 16-2009 requires that the test unit be installed in a way that is similar to its normal installation. DOE is aware that common industry practice for testing louvered room ACs is to install the room AC using a sealed setup,

i.e.,

the area around the test unit is sealed. This sealing prevents any inclusion of air leakage around the unit chassis. Any remaining gaps are typically insulated with tape to ensure a complete seal around the test unit. Consequently, any external heat leakage around the unit that may occur in a typical consumer installation is not typically accounted for by laboratories when conducting the room AC test procedure. DOE considered whether to clarify the installation instructions for room ACs to account for external heat leakage. In the following subsections, DOE describes the proposed additional direction intended to further account for the external heat leakage in a typical consumer installation.

Non-Louvered (Through-The-Wall) Room ACs

Non-louvered room ACs, (

i.e.,

those intended for through-the-wall installations) are installed inside a wall sleeve. Although the wall sleeve is designed to fit snugly within the wall, there is usually a small gap between the wall sleeve and the room AC, leading to potential air leakage into the conditioned space. Also, the room AC and wall sleeve represent a break in the building envelope through which thermal bridging

may occur, thereby transferring unwanted heat into the conditioned space. The air and heat leakage mechanisms for through-the-wall installations are shown in Figure III-3.

Thermal bridging refers to the conductive heat transfer that can occur through the room AC chassis and wall sleeve, which are usually made of metal. The metal acts as an “easy” path for heat transfer between the indoor side and the outdoor side of the building, reducing the effective insulation of the building and leading to heat gain, which is undesirable when a consumer seeks to cool an indoor space.

EP11JN20.002

DOE is aware that many manufacturers currently test non-louvered room ACs with compatible wall sleeves, in accordance with the existing requirement in the DOE test procedure that no effort be made to seal the unit internally before cooling mode testing. Regarding external sealing to avoid heat leakage, DOE is also aware that manufacturers typically test non-louvered room ACs with the included trim frame and other manufacturer-provided installation materials. As the non-louvered room ACs are installed in accordance with the manufacturer instructions provided to consumers, this setup would be similar to its normal installation.

Note that Section 6.1.1.4 of ANSI/ASHRAE Standard 16-2016 requires the air conditioner be installed per the manufacturer instructions, which DOE contends is consistent with the normal installation requirements in ANSI/ASHRAE Standard 16-2009.

Some test laboratories have requested additional direction regarding the general setup—specifically, whether a wall sleeve is required when testing non-louvered room ACs, and if so, which wall sleeve must be used. Therefore, DOE proposes to specify in a new section 3.1.1 of appendix F that room ACs designed for through-the-wall installation (

i.e.,

non-louvered room ACs) must be installed inside a compatible wall sleeve (in accordance with the installation instructions provided to consumers), with the trim frame and other manufacturer-provided installation materials that are included in the retail package when purchasing the unit, where applicable. DOE believes that this proposed instruction would improve the representativeness and the reproducibility of test results. Because these supplemental instructions are consistent with the current requirement to install the test unit in a way that is similar to its normal installation and with DOE's understanding of current testing practice, these proposed amendments are not expected to increase test burden or change the test conduct from appendix F.

DOE requests comment on the proposal to specify in appendix F that non-louvered room ACs, which are designed for through-the-wall installation, must be installed using a compatible wall sleeve (per manufacturer instructions), with the provided or manufacturer-required rear grille, and with the included trim frame and other manufacturer-provided installation materials.

Louvered (Window) Room ACs

Louvered room ACs, designed for window installation, are typically installed using manufacturer-provided side curtains to cover the area of the window opening that is not covered by the unit itself. Side curtains reduce, but generally do not eliminate, air leakage between the conditioned and unconditioned space. Some heat leakage is also possible through the side curtains themselves and surrounding installation materials.

For hung-sash windows,

the top sash can be positioned in direct contact with the top side of the chassis. Two side curtains extend horizontally from the sides of the chassis. For this type of installation, the air leakage pathways are: (1) Through the gap between the surface of the chassis and the edges of the window opening, which are usually covered with side curtains (described below); and (2) through the gap between the two sashes. Manufacturers typically provide weather stripping to reduce air leakage between the window sashes.

A sash is a window panel that usually holds one or more panes of glass. In hung-sash windows, the sashes can be moved vertically along a rail in order to open or close the window.

For sliding windows,

the sash can be positioned in direct contact with the left or right side of the chassis. One curtain is typically provided that extends upward from the chassis to the top edge of the window opening. With this type of installation, the air leakage pathways are: (1) Through the gap between the surface of the chassis and top edge of the window opening, which is usually covered with a curtain; and (2) through the gap between the two sashes.

In sliding windows, the sashes can be moved horizontally along a rail.

For casement windows, which have no sliding sashes, the window panels are attached to hinges and rotate to open or close the window. Consequently, the width and height of the window opening cannot be adjusted to match the size of the room AC chassis. Because of this, casement-type room ACs are usually designed for a narrow range of window widths. With this type of installation, the gaps between the surface of the chassis and the edges of the window opening represent significant leakage pathways.

Figure III-4 and Figure III-5 show the various air infiltration and heat leakage pathways for louvered room ACs.

EP11JN20.003

EP11JN20.004

As described previously, Section 4.2.2 of ANSI/ASHRAE Standard 16-2009 requires that the test unit be installed in a way that is similar to its normal installation. No further direction is provided as to what constitutes normal installation. DOE is aware that common industry practice is to set up a louvered room AC for testing so that all air leakage around the unit chassis is precluded. DOE understands that current industry practice is to snugly install the room AC in the test chamber partition wall using insulating material to approximate the insulating properties of the fixed part of the separating partition, as shown in Figure III-6. Any remaining gaps are typically insulated with tape to ensure a complete seal around the test unit. Under those conditions, the test measures energy needed to compensate for internal heat leakage through the unit and the thermal bridging, but any external leakage (

i.e.,

infiltration air leakage around the unit chassis or heat leakage through the manufacturer-provided installation materials) is eliminated, neglecting any effect external air leakage may have on energy efficiency.

EP11JN20.005

The current U.S. Environmental Protection Agency (EPA) ENERGY STAR Product Specification for Room Air Conditioners Version 4.1 (ENERGY STAR V4.1),

requires that window units be provided with weather stripping and/or gasket materials appropriate for all window size(s) for which the unit is designed. Furthermore, the criteria require that the side curtains be tight fitting to minimize air leaks and contain insulation in the panel with a minimum insulation value of R1.

ENERGY STAR-qualified room ACs, with R1 side curtains, comprised 26 percent of basic models on the market as of September 2018.

The ENERGY STAR Certification Criteria V4.1 is available at

https://www.energystar.gov/sites/default/files/ENERGY%20STAR%20Version%204.0%20Room%20Air%20Conditioners%20Program%20Requirements.pdf

The insulation value is determined by the Federal Trade Commission's (FTC) Labeling and Advertising of Home Insulation regulations, 16 CFR part 460.

Discussion of Comments

In the August 2017 RFI, DOE noted that, when conducting the calorimeter test prescribed in ANSI/ASHRAE Standard 16-2009 and referenced by appendix F, the test unit is installed so that all air and heat leakage around the unit that would normally be present in a typical installation is precluded by means of sealing. DOE requested comment on testing room ACs in accordance with the manufacturer-provided installation materials. 82 FR 36349, 36352 (Aug. 4, 2017).

Friedrich opposed the use of manufacturer-provided installation materials that are included in the retail package when purchasing the unit for room AC testing. Friedrich noted that DOE has not specified a required side curtain surface area for testing, which Friedrich stated could result in laboratories using varying side curtain surface areas, leading to significant test result variability and potential consumer confusion. Friedrich also suggested that laboratories may not be capable of testing with side curtains in place without significant test apparatus modifications. Friedrich further noted that, if the psychrometric method specified in ANSI/ASHRAE Standard 16-2016 were adopted, the heat loss between rooms would not be captured even when using manufacturer-provided side curtains. Friedrich also suggested that manufacturer-provided installation materials are not necessary because the existing test requirement of no more than 0.005 inches of water column pressure difference between the indoor and outdoor test chambers limits the effects of heat and air loss between the test chambers. (Friedrich, No. 2 at pp. 3-4) DOE agrees that requiring the use of side curtains may introduce additional variability in the test procedure, specifically regarding the size of the test chamber partition wall openings used by labs, leading to differing side curtain extensions and thus different air and heat leakage impacts. DOE further recognizes the additional test burden associated with modifying the partition wall and installing side curtains and believes that this burden outweighs the benefit of measuring the potentially minimal air and heat leakage due to the small pressure differential limit between the two test chambers.

AHAM noted that heat loss through the installation materials is already accounted for in Section 4.2.2 of ANSI/ASHRAE Standard 16-2009, referenced in appendix F, which requires that the room AC be installed in a manner similar to its normal installation with no effort to seal the internal construction of the unit to prevent air leakage, other than specifically provided by the manufacturer's consumer installation instructions. AHAM asserted that any modification to the instructions in ANSI/ASHRAE Standard 16-2009 would provide little additional value and is not necessary to ensure the test procedure is representative of an average use cycle. According to AHAM, doing so would increase test variation due to varying test lab window sizes and would require laboratories to stock different sizes of insulated partitions.

AHAM noted that window kits are not used in the portable AC test procedure, and that the portable AC test procedure only measures duct heat loss and infiltration air heat transfer because portable ACs draw condenser air from the conditioned space, which AHAM believes is not applicable to room ACs. AHAM claimed that the test burden increase from requiring the use of installation materials would not be justified by the minimal benefit to consumers. (AHAM, No. 3 at p. 5) As discussed above, DOE is aware that common laboratory practice is to forgo the use of manufacturer-provided installation materials included in the retail package and instead to seal to prevent air and heat leakage around the unit. DOE is also aware that laboratories typically modify the chamber partition wall to fit each test unit by adding or removing partition wall insulating materials. DOE also notes that, as discussed later in this section, Sections 6.1.1.4 and Section 8.4.2 of ANSI/ASHRAE Standard 16-2016 require that the perimeter of the AC under test must be sealed to the separating partition, which is consistent with common practice when testing room ACs and ensures repeatability and reproducibility. Therefore, DOE recognizes that an alteration to the common practice by requiring the use of all manufacturer-provided installation materials, including side curtains, may present additional test burden.

The California IOUs and Joint Advocates commented that room ACs should be installed with manufacturer-provided installation materials. (California IOUs, No. 4 at p. 4; Joint Advocates, No. 6 at p. 3) The California IOUs believe that the current test setup does not reflect real-world room AC operation and thus is contrary to EPCA's representative use requirements. According to the California IOUs, room ACs are typically installed in windows and secured with side curtains, wall sleeves, and other manufacturer-provided materials that are included in the retail package when purchasing the unit and are usually poorly insulated and allow for air infiltration, unlike the insulated wall in a calorimeter chamber. The California IOUs, therefore, encouraged DOE to capture the efficiency impacts of air infiltration, heat leakage, and pressure differentials in the room AC test procedure by requiring the use of all manufacturer-provided installation materials. (California IOUs, No. 4 at p. 4) The Joint Advocates asserted that the current DOE test procedure for room ACs does not represent actual unit efficiency for consumers, and therefore the Joint Advocates believe that testing room ACs with manufacturer-provided installation materials would incentivize improvements for installation materials to reduce infiltration air leakage. The Joint Advocates stated that reducing infiltration air would save energy and improve consumer comfort by reducing hot air entering from outdoors. (Joint Advocates, No. 6 at p. 3)

As discussed previously, DOE recognizes that the common practice for installing room ACs for testing does not necessarily utilize all manufacturer-provided installation materials. However, DOE recognizes the potentially significant variability and additional test burden associated with the use of side curtains and other manufacturer-provided installation materials that are not currently used. Further, DOE notes that Sections 6.1.1.4 and Section 8.4.2 of ANSI/ASHRAE Standard 16-2016 require that the perimeter of the AC under test must be sealed to the separating partition, which is consistent with common practice when testing room ACs. This requirement represents a change from the instructions in ANSI/ASHRAE Standard 16-2009, which in Section 4.2.2, as discussed, requires that the room AC be installed in a manner similar to its normal installation.

DOE conducted testing to investigate the inherent air infiltration and conductive heat transfer effects associated with manufacturer-provided installation materials included in the retail package when purchasing the unit. DOE tested 13 room ACs both with and without manufacturer-provided installation materials, otherwise following the appendix F test procedure and conditions. DOE installed each room AC in accordance with both ANSI/ASHRAE Standard 16-2009 and manufacturer instructions in a 34-inch wide window opening of the calorimeter test chamber partition wall. Because room AC chassis vary in width and height, the area filled by side curtains varied from unit to unit in the 34-inch wide window opening, and the height of the window opening was adjusted to match the height of each unit. Table III-7 displays the results of testing with and without manufacturer-provided installation materials under appendix F conditions.

Table III-7—Impact of Manufacturer-Provided Installation Materials on Room Air Conditioner Cooling Capacity

Unit No.

Energy star rated

Measured cooling capacity

Without

installation

materials

(

Btu/h

)

With

installation

materials

(

Btu/h

)

Measured cooling capacity

change with installation

materials

(

Btu/h

)

(

)

Yes

5720

5450

−270

−4.7

10600

10530

−70

−0.7

Yes

11750

11950

+210

+1.8

Yes

20630

20470

−150

−0.7

5210

5260

+50

+1.0

Yes

5590

5580

−10

−0.2

5280

5420

+130

+2.5

Yes

5240

5270

+30

+0.6

6160

6050

−110

−1.8

Yes

7910

7940

+30

+0.4

Yes

8580

8340

−230

−2.7

Yes

21230

21200

−40

−0.2

DOE expected that the measured cooling capacity with installation materials would be consistently lower (worse) than the measured cooling capacity without installation materials (for which the unit is tightly sealed during testing to prevent air and heat leakage). However, as shown in Table III-7, DOE observed no consistent change in cooling capacity when using manufacturer-provided installation materials included in the retail package when purchasing the unit, with capacity impacts ranging from a reduction of 4.7 percent to an increase of 2.5 percent relative to the measured capacity without installation materials. Additionally, DOE found that the magnitude and direction (positive or negative) of the measured capacity impacts did not correlate with the presence of insulated side-curtains (

i.e.,

units that ship with minimum R1 side curtains were measured as having both higher and lower cooling capacity when tested with the side curtains installed). Nor did the magnitude and direction of the measured cooling capacity change correlate with the rated cooling capacity. Instead, the unexpected presence of positive cooling capacity changes suggests that the observed variations are driven more by measurement uncertainty than heat transfer losses.

Regardless of the source of the variation, however, all capacities measured while using manufacturer-provided installation materials were within 5 percent of those measured without installation materials. Because the variation in test results was minimal, DOE expects that any potential

benefits of more representative cooling capacity measurements by testing with manufacturer-provided installation materials included in the retail package when purchasing the unit would be small and would be outweighed by the burden associated with such a testing configuration. Therefore, DOE is not proposing to require the use of manufacturer-provided installation materials in appendix F for louvered room ACs at this time.

DOE requests comment on the proposal, consistent with ANSI/ASHRAE Standard 16-2016, Sections 6.1.1.4 and Section 8.4.2, not to require installing louvered room ACs with the manufacturer-provided installation materials, including side curtains, and instead to require testing with the partition wall sealed to the unit.

e. Test Conditions

In the June 2015 RFI, DOE noted that the current room AC test procedure measures performance only under full-cooling-load outdoor test conditions of 95 °F dry-bulb and 75 °F wet-bulb, and therefore, technologies that improve performance under less extreme part-load conditions, such as variable-speed compressors and variable-opening expansion devices, would not improve rated performance under the current test procedure. DOE noted that for central ACs and heat pumps, the seasonal energy efficiency ratio (SEER) accounts for various annual conditions by testing at multiple rating conditions. DOE therefore requested comment on the merits of revising the current room AC test procedure to account for the benefit of technologies that improve performance under multiple cooling mode temperature conditions. 80 FR 34843, 34848 (June 18, 2015).

The Natural Resources Defense Council, Appliance Standards Awareness Project, Alliance to Save Energy, National Consumer Law Center, and Northwest Energy Efficiency Alliance (hereafter the “Joint Commenters”) stated that measuring part-load performance in the DOE room AC test procedure would encourage manufacturers to develop products with variable-speed capabilities and other part-load technologies not available as of 2015 in room ACs available on the market. The Joint Commenters suggested that a metric that captures part-load performance could result in additional energy savings because room ACs are often used as the primary air conditioning source, either for a single room or an entire house, and thus are used more frequently than just for supplemental air conditioning on the hottest days and would likely benefit from part-load efficiency improvements. (Joint Commenters, June 2015 RFI, No. 7 at pp. 1-2)

The California IOUs commented that the effective and efficient use of part-load operation can be useful in maintaining a more constant room temperature while reducing overall energy consumption. However, they noted that the impact of part-load efficiency would depend on the number of operating hours associated with part-load operation in the overall performance metric. Therefore, the California IOUs suggested that DOE assess the potential efficiency benefits of part-load technologies and the number of operating hours under part-load conditions per year, claiming that including part-load efficiency in the regulated metric would only be effective if part-load operation represents a significant part of the annual operating hours. The California IOUs suggested that the part-load operating hours should not include hours during the summer, when room ACs typically operate at full-load conditions, nor should the inclusion of part-load operation result in a reduction of overall room AC operating efficiencies or an increase in peak demand. If DOE finds that part-load efficiency has a minimal impact on overall performance, the California IOUs expressed continued support for the current test condition. (California IOUs, June 2015 RFI, No. 8 at p. 3)

AHAM opposed part-load performance measurements, based on DOE's conclusion in the January 2011 Final Rule that such measurements would result in significant effort and additional test burden with minimal energy savings. (AHAM, June 2015 RFI, No. 5 at p. 4) In the January 2011 Final Rule, DOE stated that sufficient information was not available at the time to assess whether technologies that improve part-load efficiency would be cost effective, and that many of the technology options that could improve full-load efficiency would also improve part-load efficiency, so the current test conditions were indicative of the efficiency at a range of conditions. Thus, DOE decided to not amend the test procedure to measure part-load performance at that time. Nevertheless, DOE noted in the January 2011 Final Rule that it could consider amendments if additional information on this subject were to become available for future rulemakings. 76 FR 971, 1016 (Jan. 6, 2011). DOE notes that the market has developed since the January 2011 Final Rule, and that at least three variable-speed room ACs are now on the market. DOE expects that manufacturers will continue to introduce variable-speed room ACs to the market in the near term, because, on December 28, 2017, EPA released its ENERGY STAR 2018 Emerging Technology Award Criteria for Room ACs with Efficient Variable Output, which recognizes room ACs with variable-speed compressors that are more than 25 percent more efficient than a similar room AC with a single-speed compressor.

DOE expects that the introduction of these ENERGY STAR award criteria will incentivize manufacturers to further adopt variable-speed compressors in room ACs.

Additional information on the ENERGY STAR Emerging Award for Industry Stakeholders is available at

https://www.energystar.gov/about/awards/energy-star-emerging-technology-award/energy-star-emerging-technology-award-industry

Multiple Test Conditions

On June 1, 2016, DOE established a test procedure for portable ACs that assesses cooling performance under two cooling mode test conditions, representative of typical conditions and extreme conditions (hereafter the “June 2016 Portable AC Final Rule”). 81 FR 35241, 35249-35250. As discussed, room ACs are currently tested at a single outdoor test condition, 95 °F dry-bulb and 75 °F wet-bulb temperature, which aligns with only one of the two cooling mode test conditions for portable ACs. Considering the many similarities between the two products (

i.e.,

consumer utility, usage patterns, internal components), DOE requested comment in the August 2017 RFI on whether it would be appropriate to harmonize the two test procedures by including an additional test condition for room AC cooling mode testing (specifically, 83 °F dry-bulb and 67.5 °F wet-bulb outdoor temperature). 82 FR 36349, 36351-36352 (Aug. 4, 2017).

Friedrich opposed an additional cooling mode test condition for room ACs, stating that room ACs are optimized for the current 95 °F test condition and any changes to the test procedure would require system and component design changes. For example, Friedrich asserted that less expensive and more reliable capillary tube expansion devices would likely need to be replaced with more expensive and complex thermostatic expansion valves or variable orifice metering devices. Friedrich stated that just one component change could increase manufacturing cost by more than 15 percent as well as increase repair and installation complexity, and that the current room AC chassis may not have sufficient space to accommodate such devices. (Friedrich, No. 2 at pp. 1-2) DOE recognizes that

optimizing performance at any test condition likely would require design and component modifications, which may include adjusting the expansion device, blower motor, compressor, and other performance-related modification. DOE understands that any time a design change is initiated, significant engineering and manufacturing costs are incurred, for example, to fit larger and more complex components into size-restricted chassis. However, although an amended test procedure requiring testing room ACs at additional cooling mode test conditions would necessitate a corresponding amendment to the energy conservation standards for room ACs, the design and manufacturing costs incurred to redesign units to perform optimally at these conditions are outside of the scope of a test procedure rulemaking analysis. DOE notes that it would analyze in an energy conservation standards rulemaking any design and manufacturing costs potentially incurred to improve the efficiency of products.

AHAM and Friedrich opposed the proposed additional cooling mode test condition, saying that it would add significant test burden by effectively doubling the number of tests needed to certify a room AC, lengthening test time, and resulting in less laboratory availability, which could significantly slow time to market and disrupt production schedule. (AHAM, No. 3 at p. 4; Friedrich, No. 2 at p. 2) DOE agrees that an additional cooling mode test condition would increase test burden, though it would not require an adjustment in test unit installation and would instead necessitate adjusting only the outdoor test chamber conditions, since the indoor conditions remain the same for both cooling mode test conditions. DOE expects the total additional burden associated with testing a reduced operating test would be 4 to 5 hours. This reflects the time required to adjust the outdoor test chamber test conditions (about 2 hours for the chamber to reach a lower outdoor temperature test condition), and the additional test time, which is estimated to be 2 to 3 hours (approximately 1 to 2 hours for chamber and unit stabilization and 1 hour for the rating test period, as specified by ANSI/ASHRAE Standard 16-2009).

AHAM further stated that if DOE did consider an additional cooling mode test condition it would be inappropriate to consider an additional cooling mode test condition comparable to that which is established for dual-duct portable ACs (

i.e.,

the most similar portable AC configuration to room ACs). AHAM cited a September 2016 AHAM Home Comfort Survey that indicated the vast majority of portable ACs on the market are a single-duct configuration. As a result, most portable ACs would be tested with a single outdoor cooling mode test condition. AHAM therefore suggested it would be inappropriate to select test conditions for room ACs that align with the type of portable AC that a minority of consumers own and would not result in a comparable rating between all portable ACs and room ACs. (AHAM, No. 3 at p. 4) DOE notes that the additional cooling mode test condition that was adopted for dual-duct portable ACs was developed using room AC ownership data and a climate analysis; and, because the supporting data were derived from room ACs, DOE asserts that the previous analysis conducted in support of the portable AC test procedure applies to room ACs.

AHAM and Friedrich also contended that including a second test condition could confuse consumers, suggesting that adding a cooler test condition would result in a larger Seasonally Adjusted Cooling Capacity (SACC) compared to the cooling capacity as measured under the current conditions, which could result in consumers purchasing units that have too little capacity and are unable to meet cooling needs during peak periods. Friedrich further commented that if DOE were to proceed with these changes to the test procedure, it should coordinate with EPA and the Federal Trade Commission (FTC) to harmonize metrics across efficiency programs. (AHAM, No. 3 at p. 4; Friedrich, No. 2 at p. 2) DOE agrees that introducing a second cooling mode test condition for all room ACs would result in a general increase in the reported cooling capacities for all units, which may cause confusion for consumers who have become familiar with the typical capacity values in this well-established market.

Under the Memorandum of Understanding that EPA and DOE signed on September 30, 2009, DOE is responsible for the test methods and metrics to be used in the ENERGY STAR program when qualifying products. Therefore, if DOE were to modify the energy efficiency metric for room ACs in appendix F, EPA would accordingly consider revised ENERGY STAR qualification criteria based upon the amended DOE test procedure. Additionally, EPCA requires that any revisions to the labels for room ACs, for which the FTC is responsible, include disclosure of the estimated annual operating cost (determined in accordance with DOE's test procedures prescribed under section 6293 of EPCA), unless the Secretary determines that disclosure of estimated annual operating cost is not technologically feasible, or the FTC determines that such disclosure is not likely to assist consumers in making purchasing decisions or is not economically feasible. (42 U.S.C. 6294(c)(1)) Were DOE to amend the room AC test procedure to include an additional test condition, DOE understands that the FTC would develop any revised labeling requirements to disclose a revised annual energy cost calculation based on any modified energy efficiency metric.

DOE notes that consumer confusion about the number of temperature conditions was not a concern for portable ACs because DOE only recently established a test procedure for portable ACs that requires multiple cooling mode test conditions. Before that there was no DOE test procedure; the DOE test procedure for portable ACs has always required multiple cooling mode temperature conditions.

The California IOUs opposed an additional cooling mode test condition, suggesting it would not be representative of actual usage conditions in California, where room ACs operate at peak capacity or close to it (

i.e.,

at conditions represented by the 95 °F dry-bulb test condition) for longer than 750 hours per year and are typically purchased in reaction to heatwaves, when peak cooling is required. The California IOUs cautioned that allocating less weight to the 95 °F dry-bulb cooling mode test condition may devalue the cooling mode operating performance that is most valued by consumers and is the basis for their purchase decisions. (California IOUs, No. 5 at p. 2) AHAM added that the current room AC test procedure tests the “worst case” energy use scenario and there is no reason to test room ACs under new test conditions that would result in less energy use. (AHAM, No. 3 at p. 4) Friedrich stated that room ACs optimized for a new reduced-temperature test condition would not have enough capacity to meet the cooling load at the existing higher-temperature condition. (Friedrich, No. 2 at p. 2) The California IOUs also claimed that an additional cooling mode test condition would interfere with calculating a room AC's peak demand power draw, which can have a large impact on peak load operation and is often the basis for future program development, rate structure, and overall power needs. (California IOUs, No. 5 at pp. 2-3)

The California IOUs and Joint Advocates commented that if DOE were to include an additional part-load cooling mode test condition, the test procedure would likely capture the benefits of technologies, such as variable-speed compressors, that enable

improved part-load performance. These commenters further stated that, in addition to improving part-load performance and efficiency by reducing compressor cycling and improving heat exchanger effectiveness, variable-speed compressors would provide more consistent room temperature and humidity control, improved dehumidification, and reduced noise levels. They suggested that adding variable-speed compressors would enable utilities to create incentives for consumers to use more intelligently controlled and connected room ACs with little impact on consumer comfort and would enable more flexible demand side resources to integrate increasing amounts of intermittent renewable energy sources into the grid. (California IOUs, No. 5 at p. 3; Joint Advocates, No. 6 at p. 2) However, the California IOUs suggested that further data are necessary prior to modifying the room AC test procedure to measure room AC performance and efficiency at part-load test conditions and to identify an appropriate alternative test condition and operating hours that would effectively capture part-load operation. (California IOUs, No. 5 at p. 4) Friedrich suggested that variable-speed compressors would not be feasible for room ACs due to increased installation and controls costs, as well as chassis space constraints. (Friedrich, No. 2 at p. 2) AHAM urged DOE to wait until variable-speed compressors are available in a number of products that would be sufficient to evaluate the impacts of a test procedure change before considering a test procedure change to account for them. (AHAM, No. 3 at p. 5)

DOE agrees with some, but not all, of these comments. The inclusion of additional cooling mode test conditions would better reflect operation under multiple temperature conditions, and product information based on testing using such conditions may create an incentive to increase the proportion of variable-speed room ACs on the market. Use of variable-speed compressors, in turn, may be beneficial to both consumers and utilities, because room ACs would operate more effectively and efficiently under multiple indoor and outdoor temperature conditions. However, DOE also recognizes that a test procedure that measures performance at both peak temperature conditions and a less extreme temperature condition would require a new overall weighted metric that would combine the performance under both temperature conditions because it would change measured energy consumption. DOE further recognizes that room AC performance has historically been based on peak performance under elevated outdoor temperature test conditions, which is the condition under which consumers most expect their room ACs to perform, and that peak performance would no longer be clearly portrayed by a weighted metric.

Furthermore, DOE notes information about variable-speed room ACs is limited: There are few variable-speed products on the market, and data about them is limited. DOE does not believe that the benefits of measuring performance at reduced outdoor temperature test conditions for all room ACs would outweigh the expected substantial increase in test burden, utility impacts, and consumer confusion that would result. Therefore, DOE is proposing to continue using a single test condition for testing single-speed room ACs, with no changes to the current CEER metric. However, as discussed in section III.C.2 of this document, DOE is proposing to require testing multiple test conditions for variable-speed room ACs, in order to capture the relative efficiency improvements associated with variable-speed operation. The test procedure would represent the performance of variable-speed room ACs using adjustments to the CEER calculations to obtain the same metric, which is based on performance at the maximum 95 °F outdoor rating condition.

This understanding is based on discussion in the June 2010 Room AC Test Procedure Supplemental Notice of Proposed Rulemaking and comments from the California IOUs discussed above. 75 FR 37633-37634 (June 29, 2010). (California IOUs, No. 5 at p. 2)

DOE requests comment on the proposal not to include additional cooling mode test conditions for single-speed room ACs.

Cooling Test Alternatives

The current DOE test procedures for room ACs and packaged terminal air conditioners (PTACs) involve fixed temperature and humidity tests in a calorimeter at full-load or part-load conditions, during which specific dry-bulb and wet-bulb temperatures are maintained throughout the cooling mode test period. The DOE test procedure for central ACs requires testing at multiple cooling mode test conditions, with fixed temperature and humidity at each condition, similar to the current room AC test procedure, which has one test condition with a fixed temperature and humidity.

The Joint Advocates stated that the lower-temperature test condition discussed in the August 2017 RFI is a fixed temperature and humidity test and would not capture single-speed compressor cycling losses that would occur in typical temperature conditions. By comparison, a dynamic-cooling-load test, such as that being developed by the Canadian Standards Association, during which the compressor would cycle off when the setpoint is reached, may capture such cycling losses. The Joint Advocates suggested that the most representative room AC test procedure (

i.e.,

a dynamic-cooling-load test that measures part-load performance) would spur adoption of variable-speed compressors and adjustable fan speeds because it would capture cycling losses in single-speed units and increased efficiency from these technologies. (Joint Advocates, No. 6 at pp. 2-3)

DOE is aware of two approaches to measure part-load performance of a room AC, constant-cooling-load testing and dynamic-cooling-load testing. In a constant-cooling load test, a cooling load is applied to the indoor room using reconditioning equipment, and this cooling load does not change throughout the test. In a dynamic-cooling-load test, the cooling load applied to the indoor room follows a load profile which approximates how the cooling load on a typical unit would change throughout the day. In both the dynamic-cooling-load test suggested by the Joint Advocates and a constant-cooling-load test explored in DOE investigative testing, the chamber indoor cooling load is provided at a specified rate or value throughout testing instead of maintaining specific temperature conditions within the test chamber. In theory, this approach would be most representative of actual usage, where cooling loads are constant or variable due to external factors (

e.g.,

weather, door/window openings) and internal factors (

e.g.,

room occupants, appliance operation). Under a constant-cooling-load or dynamic-cooling-load test, a room AC with a single-speed compressor would cycle the compressor as the setpoint is reached, thereby introducing efficiency losses, whereas a variable-speed compressor could maintain constant operation at reduced speeds to match the cooling load with no cycling losses. As explained below, DOE explored this approach but is not proposing it because an increased test burden and reduced repeatability and reproducibility outweigh potential benefits.

DOE investigated the status of test data and uniform procedures to test with a specified constant or dynamic cooling load but found no widely adopted and industry-accepted test procedure for room ACs or other AC

products that uses a constant-cooling-load or dynamic-cooling-load test. DOE is aware of investigative efforts to test central ACs under varying cooling load conditions, but those have yielded only preliminary results which did not involve room ACs and did not provide sufficient evidence to show that a constant or dynamic load test would be repeatable and reproducible and not overly burdensome to conduct.

37 38

The Canadian Standards Association has conducted dynamic-load testing for heat pumps. A summary is available at

http://neep.org/sites/default/files/NEEPCSAHarley2017-06-28.pdf.

Researchers at the University of Tokyo investigated the operation of split-type ACs under constant-load conditions in 2012.

https://docs.lib.purdue.edu/cgi/viewcontent.cgi?referer=&httpsredir=1article=2335context=iracc

Due to the limited data available regarding constant-cooling-load testing, DOE conducted investigative testing to better understand the benefits and potential challenges associated with a constant-cooling-load test for room ACs. These tests were conducted using a variable-speed room AC rated at 18,000 Btu/h and a conventional single-speed room AC rated at 12,100 Btu/h. The single-speed room AC was selected because it was the louvered unit in the test sample closest in capacity to the variable-speed unit. DOE installed each room AC in a calorimeter test chamber, set the unit thermostat to 80 °F to match the indoor temperature specified in the appendix F test procedures, and then applied a fixed cooling load to the indoor room that was below the nominal rated cooling capacity of the test unit. The calorimeter chamber was configured to permit the indoor chamber temperature to vary, thereby allowing the test unit to eventually reach its thermostat set point and to adjust its cooling in response to the cooling load demands on the indoor room, as opposed to the constant-temperature test, which results in unvarying cooling operation. Table III-8 shows the results of these tests. All percentages are displayed are relative to full-cooling-load values measured during constant-temperature tests.

Table III-8—Fixed Cooling-Load-Based Test Single-Speed Room Air Conditioner

Outdoor test condition (°F dry-bulb)

Chamber-

imposed

cooling load

(%)

Compressor on time

(%)

Percent of

full-load power

(%)

EER

(Btu/Wh)

Percent of

full-load EER

(%)

9.2

10.6

10.7

10.6

11.8

12.0

13.1

13.3

As discussed previously in section III.C of this document, and shown in Figure III-1, when tested under these same test conditions, the variable-speed room AC adjusted its compressor speed to match the applied cooling load, resulting in increased efficiency of between 9 percent and 25 percent at decreased cooling loads of 85 percent and 45 percent of the full-load cooling capacity, respectively, compared to the tested cooling capacity of the variable-speed room AC under the appendix F test procedure.

When tested according to the same constant-cooling-load test, the single-speed unit operated continuously until the unit thermostat setpoint was satisfied, at which time the unit cycled off the compressor. When the chamber temperature rose above the thermostat setpoint, the single-speed room AC activated the compressor. This off-and-on compressor cycling process continued throughout the rating test period. As shown in Table III-8, the fractional time the compressor was on (“compressor on time”) for a single compressor cycle during the test ranged from 84 percent to 48 percent as the cooling load decreased from 80 percent to 46 percent, respectively, of the tested cooling capacity. DOE also observed during testing that the total compressor cycle time (

i.e.,

the sum of a single period of compressor on time and compressor off time) decreased as cooling loads reduced, resulting in more frequent cycling and subsequent increased cycling losses.

As shown in Table III-8, DOE observed that the single-speed room AC was able to provide cooling that closely matched the chamber-imposed cooling load by cycling the compressor (

i.e.,

the percentage of compressor on time approximated the cooling load percentage). However, the single-speed room AC average input power during those same tests did not decrease at the same rate as the cooling capacity, which was indicative of the fan or blower remaining on when the compressor cycled off, as well as the significant additional power necessary to start up the compressor at the beginning of each compressor on cycle (

i.e.,

the percent of full-load power consumption during the same test was consistently higher than the cooling load percentage, as shown in Table III-8). As a result of the disproportionate cooling capacity and power decreases at reduced cooling loads, the overall efficiency of a single-speed room AC in terms of EER at reduced cooling loads decreased by up to 20 percent at a reduced load of about 50 percent of the full-load cooling capacity, as shown in Table III-8.

The overall efficiency of the variable-speed room AC in terms of EER increased by about 24 percent under similar reduced load conditions, as shown in Figure III-1.

EER, is defined as the ratio of cooling capacity to unit power, in contrast to CEER, which additionally includes inactive mode or off mode power. Because the investigative testing did not include inactive mode or off mode testing, the investigative testing results are reported in EER.

Constant-cooling load tests have initially confirmed behavior that would be expected of room ACs in the field under conditions associated with partial loads (

i.e.,

lower outdoor temperatures at which the cooling load is typically smaller). During the constant-cooling-load test, single-speed room ACs cycle in proportion to the cooling load, and variable-speed room ACs adjust the compressor speed to match the measured cooling load in the room. Therefore, DOE would expect that

cycling losses decrease the efficiency of single-speed room ACs at lower outdoor temperature conditions, an effect which variable-speed room ACs avoid. However, DOE contends that load-based tests, for reasons presented below, are currently not feasible for room ACs.

DOE is concerned that the constant-cooling-load test would reduce repeatability and reproducibility. Based on investigative testing, DOE found that conducting a constant-cooling-load test in an ANSI/ASHRAE Standard 16-2009-compliant calorimeter test chamber would impact repeatability and reproducibility. Table III-9 shows the results of indoor wet-bulb temperatures for the cooling-load-based tests conducted by DOE.

Table III-9—Indoor Wet-Bulb Temperatures for Cooling-Load-Based Tests

Tested unit

Outdoor test

condition

(°F dry-bulb)

Cooling load

(%)

Average

indoor

temperature

(°F wet-bulb)

Difference from rating

condition

(°F wet-bulb)

Single-Speed

67.6

0.6

67.2

0.2

67.0

0.0

67.1

0.1

67.1

−0.1

67.5

0.1

66.5

0.5

66.8

−0.5

67.1

−0.2

Average

67.1

0.1

Variable-Speed

67.9

0.9

68.0

1.0

67.0

0.0

67.0

0.0

67.0

0.0

67.0

0.0

67.0

0.0

67.0

0.0

67.0

0.0

67.0

0.0

Average

67.2

0.2

As shown in Table III-9, at cooling loads less than 75 percent of the tested unit cooling capacity, the indoor wet-bulb temperature variation sometimes exceeded the 0.3 °F arithmetic average tolerance required by ANSI/ASHRAE Standard 16-2009. DOE believes this is because the test chamber lacks a dehumidifier and instead relies on the test unit to remove moisture from the indoor chamber and assist in maintaining the wet-bulb temperature. The single-speed and variable-speed room ACs were unable to remove sufficient water vapor from the indoor-side chamber while cycling on and off or while operating at reduced compressor speed, respectively, causing the indoor chamber wet-bulb temperature to vary from 67 °F up to 0.6 °F for the single-speed unit, and up to 1.0 °F for the variable-speed unit.

Also, because the chamber used for testing was not designed to accommodate constant-cooling-load testing, the chamber controls were not capable of automatically achieving a specific cooling load condition. Instead, an iterative process was necessary to manually program and adjust the heating, cooling, and humidification inputs to the room to achieve the desired cooling load. This difficulty in automatically achieving specific loading conditions contributed significant increased testing time and test burden arising from the need to ensure uniform test chamber dimensions. In addition, the chamber size and particular conditioning equipment may affect the rate at which the indoor chamber temperature and relative humidity decrease in response to the room AC operation, or increase after a single-speed unit cycles off, thus affecting cycle time and frequency, which in turn impact cycling losses and measured

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