# Energy Conservation Program: Energy Conservation Standards for Dehumidifying Direct-Expansion Dedicated Outdoor Air Systems

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URL: https://www.frixlaw.com/law-library/documents/fr%3A2022-01375

## Record

- **Collection:** Federal Register
- **Document type:** Proposed Rule
- **Published:** February 1, 2022
- **Citation:** 87 FR 5560

## Text

DEPARTMENT OF ENERGY
10 CFR Parts 429 and 431
[EERE-2017-BT-STD-0017]
RIN 1904-AD92
Energy Conservation Program: Energy Conservation Standards for Dehumidifying Direct-Expansion Dedicated Outdoor Air Systems

AGENCY:

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

ACTION:

Notice of proposed rulemaking and request for comment.

SUMMARY:

In this notice of proposed rulemaking (NOPR), DOE proposes to establish new energy conservation standards for dehumidifying direct-expansion dedicated outdoor air systems (DX-DOASes) that are of equivalent stringency as the minimum levels specified in the amended American Society of Heating, Refrigerating and Air-Conditioning Engineers (“ASHRAE”) Standard 90.1 “Energy Standard for Buildings Except Low-Rise Residential Buildings” (“ASHRAE Standard 90.1”) when tested pursuant to the most recent applicable industry standard for this equipment. DOE has preliminarily determined that it lacks clear and convincing evidence to adopt standards more stringent than the levels specified in ASHRAE Standard 90.1. DOE also announces a public meeting via webinar to receive comment on these proposed standards and associated analyses and results.

DATES:

DOE will hold a public meeting via webinar on Monday, February 28, 2022, from 1:00 p.m. to 4:00 p.m. See section VIII, “Public Participation,” for webinar registration information, participant instructions and information about the capabilities available to webinar participants.

Comments:
DOE will accept comments, data, and information regarding this NOPR no later than April 4, 2022.

Comments regarding the likely competitive impact of the proposed standard should be sent to the Department of Justice contact listed in the
ADDRESSES
section on or before March 3, 2022.

ADDRESSES:

Interested persons are encouraged to submit comments using the Federal eRulemaking Portal at
www.regulations.gov.
Follow the instructions for submitting comments. Alternatively, interested persons may submit comments, identified by docket number EERE-2017-BT-STD-0017, by any of the following methods:

1.
Federal eRulemaking Portal: www.regulations.gov.
Follow the instructions for submitting comments.

2.
Email:
to
CommACHeatingEquipCat2017STD0017@ee.doe.gov.
Include docket number EERE-2017-BT-STD-0017 in the subject line of the message.

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

Although DOE has routinely accepted public comment submissions through a variety of mechanisms, including postal mail and hand delivery/courier, the Department has found it necessary to make temporary modifications to the comment submission process in light of the ongoing corona virus 2019 (COVID-19) pandemic. DOE is currently suspending receipt of public comments via postal mail and hand delivery/courier. If a commenter finds that this change poses an undue hardship, please contact Appliance Standards Program staff at (202) 586-1445 to discuss the need for alternative arrangements. Once the COVID-19 pandemic health emergency is resolved, DOE anticipates resuming all of its regular options for public comment submission, including postal mail and hand delivery/courier.

Docket:
The docket for this activity, which includes
Federal Register
notices, comments, and other supporting documents/materials, is available for review at
www.regulations.gov.
All documents in the docket are listed in the
www.regulations.gov
index. However, not all documents listed in the index may be publicly available, such as information that is exempt from public disclosure.

The docket web page can be found at
www.regulations.gov/docket/EERE-2017-BT-STD-0017.
The docket web page contains instructions on how to access all documents, including public comments, in the docket. See section VIII for information on how to submit comments through
www.regulations.gov.

Written comments regarding the burden-hour estimates or other aspects of the collection-of-information requirements contained in this proposed rule may be submitted to Office of Energy Efficiency and Renewable Energy following the instructions at
www.reginfo.gov.

EPCA requires the Attorney General to provide DOE a written determination of whether the proposed standard is likely to lessen competition. The U.S. Department of Justice Antitrust Division invites input from market participants and other interested persons with views on the likely competitive impact of the proposed standard. Interested persons may contact the Division at
energy.standards@usdoj.gov
on or before the date specified in the
DATES
section. Please indicate in the “Subject” line of your email the title and Docket Number of this proposed rulemaking.

FOR FURTHER INFORMATION CONTACT:

Ms. Catherine Rivest, U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Building Technologies Office, EE-5B, 1000 Independence Avenue SW, Washington, DC 20585-0121. Email:
ApplianceStandardsQuestions@ee.doe.gov.

Mr. Matthew Ring, U.S. Department of Energy, Office of the General Counsel, GC-33, 1000 Independence Avenue SW, Washington, DC 20585-0121. Telephone: (202) 586-2555. Email:
Matthew.Ring@hq.doe.gov.

For further information on how to submit a comment, review other public comments and the docket, or participate in the public 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 part 429:

Air-Conditioning, Heating, and Refrigeration Institute (AHRI) Standard 920-2020 (I-P), “2020 Standard for Performance Rating of Direct Expansion-Dedicated Outdoor Air System Units,” approved February 4, 2020.

American National Standards Institute (ANSI)/AHRI Standard 1060-2018, “2018 Standard for Performance Rating of Air-to-Air Exchangers for Energy Recovery Ventilation Equipment,” approved 2018.

Copies of AHRI Standard 920-2020 (I-P), and ANSI/AHRI Standard 1060-2018 can be obtained from the Air-conditioning, Heating, and Refrigeration Institute, 2311 Wilson Blvd., Suite 400, Arlington, VA 22201, (703) 524-8800, or online at:
www.ahrinet.org.

For a further discussion of these standards, see section VII.L of this document.

Table of Contents

I. Synopsis of the Proposed Rule

II. Introduction

A. Authority

B. Background

1. ASHRAE Standard 90.1 Efficiency Levels for DX-DOASes

2. Update to the Industry Metric

3. History of Standards Rulemaking for DX-DOASes

C. Deviation From Appendix A

III. General Discussion

A. Scope of Coverage

B. Equipment Classes

C. Test Procedure

D. Considerations for Energy Conservation Standards

1. Technological Feasibility

a. General

b. Maximum Technologically Feasible Levels

2. Significant Additional Conservation of Energy

3. Economic Justification

a. Economic Impact on Manufacturers and Consumers

b. Savings in Operating Costs Compared to Increase in Price (LCC and PBP)

c. Energy Savings

d. Lessening of Utility or Performance of Products

e. Impact of Any Lessening of Competition

f. Need for National Energy Conservation

g. Other Factors

IV. Crosswalk Analysis

A. Overview

B. ISMRE-to-ISMRE2 Crosswalk

1. Dehumidification Efficiency Test Procedure Changes

2. Technical Analysis

C. ISCOP-to-ISCOP2 Crosswalk

1. Heating Efficiency Test Procedure Changes

2. Technical Analysis

D. Crosswalked Standard Levels

V. Conclusions

A. Proposed Energy Conservation Standards

B. Consideration of More Stringent Efficiency Levels

VI. Representations, Certification and Compliance Requirements

A. Representations

B. Certification and Enforcement Provisions

1. Scope

2. Equipment Selection and Sampling Plan

3. Certification Requirements

4. Enforcement Provisions

C. Compliance Dates

VII. Procedural Issues and Regulatory Review

A. Review Under Executive Orders 12866 and 13563

B. Review Under the Regulatory Flexibility Act

1. Description of Reasons Why Action Is Being Considered

2. Objectives of, and Legal Basis for, Rule

3. Description on Estimated Number of Small Entities Regulated

4. Description and Estimate of Compliance Requirements Including Differences in Cost, if Any, for Different Groups of Small Entities

5. Duplication, Overlap, and Conflict With Other Rules and Regulations

6. Significant Alternatives to the Rule

C. Review Under the Paperwork Reduction Act

D. Review Under the National Environmental Policy Act of 1969

E. Review Under Executive Order 13132

F. Review Under Executive Order 12988

G. Review Under the Unfunded Mandates Reform Act of 1995

H. Review Under Executive Order 12630

I. Review Under Executive Order 13211

J. Information Quality

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

L. Description of Materials Incorporated by Reference

VIII. Public Participation

A. Participation in the Webinar

B. Procedure for Submitting Prepared General Statements for Distribution

C. Conduct of the Webinar

D. Submission of Comments

E. Review Under the Treasury and General Government Appropriations Act, 2001

F. Issues on Which DOE Seeks Comment

IX. Approval of the Office of the Secretary

I. Synopsis of the Proposed Rule

Title III, Part C
1

of the Energy Policy and Conservation Act, as amended (EPCA),
2

established the Energy Conservation Program for Certain Industrial Equipment. (42 U.S.C. 6311-6317) Such equipment includes dehumidifying direct-expansion dedicated outdoor air systems (DX-DOASes), the subject of this proposed rulemaking.

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

2
All references to EPCA in this document refer to the statute as amended through the Energy Act of 2020, Public Law 116-260 (Dec. 27, 2020).

EPCA requires DOE to amend the existing Federal energy conservation standard for certain types of listed commercial and industrial equipment (generally, commercial water heaters, commercial packaged boilers, commercial air-conditioning and heating equipment, and packaged terminal air conditioners and heat pumps) each time ASHRAE Standard 90.1 is amended with respect to such equipment. (42 U.S.C. 6313(a)(6)(A)) For each type of equipment, EPCA directs that if ASHRAE Standard 90.1 is amended, DOE must adopt amended energy conservation standards at the updated efficiency level in ASHRAE Standard 90.1, unless clear and convincing evidence supports a determination that adoption of a more stringent efficiency level as a national standard would produce significant additional energy savings and be technologically feasible and economically justified. (42 U.S.C. 6313(a)(6)(A)(ii))

If DOE adopts as a uniform national standard the efficiency levels specified in the amended ASHRAE Standard 90.1, DOE must establish such standard not later than 18 months after publication of the amended industry standard. (42 U.S.C. 6313(a)(6)(A)(ii)(I)) If DOE determines that a more-stringent standard is appropriate under the statutory criteria, DOE must establish such more-stringent standard not later than 30 months after publication of the revised ASHRAE Standard 90.1. (42 U.S.C. 6313(a)(6)(B))

ASHRAE officially released the 2016 edition of ASHRAE Standard 90.1 (ASHRAE Standard 90.1-2016) on October 26, 2016, which for the first time created separate equipment classes for DX-DOASes with corresponding standards, thereby triggering DOE's above referenced obligations pursuant to EPCA to either: (1) Establish uniform national standards for DX-DOASes at the minimum levels specified in the amended ASHRAE Standard 90.1; or (2) adopt more stringent standards based on clear and convincing evidence that adoption of such standards would produce significant additional energy savings and be technologically feasible and economically justified. ASHRAE Standard 90.1-2016 set minimum efficiency levels using the integrated seasonal moisture removal efficiency (ISMRE) metric for all DOAS classes and the integrated seasonal coefficient of performance (ISCOP) metric for air-source heat pump and water-source heat pump DOAS classes. ASHRAE Standard 90.1-2016 specifies that both metrics are measured in accordance with Air-conditioning, Heating, and Refrigeration Institute (AHRI) Standard 920-2015, “Performance Rating of DX-Dedicated Outdoor Air System Units” (AHRI 920-2015).
3

Subsequently, AHRI took to revise AHRI 920.

3
AHRI 920-2015 additionally references ASHRAE Standard 198-2013, “Method of Test for Rating DX-Dedicated Outdoor Air Systems for Moisture Removal Capacity and Moisture Removal Efficiency” (ASHRAE Standard 198-2013), as the method of test for DX-DOAS units.

In October 2019, ASHRAE officially released the 2019 edition of ASHRAE Standard 90.1 (ASHRAE Standard 90.1-2019). ASHRAE Standard 90.1 did not update the energy efficiency levels for DX-DOASes established in ASHRAE Standard 90.1-2016. On February 4, 2020 AHRI officially released the 2020 edition of AHRI 920 (AHRI 920-2020), which addresses a number of issues with the prior test procedure and provides an updated ISMRE metric (
i.e.,
ISMRE2) and an updated ISCOP metric (
i.e.,
ISCOP2).

In accordance with the EPCA provisions discussed, DOE proposes new energy conservation standards for DX-DOASes. The proposed standards, which are expressed in terms of ISMRE2 for all DX-DOAS classes in dehumidification mode, and ISCOP2 for heat pump DX-DOAS classes in heating mode, are shown in Table I.1. DOE has tentatively determined that the proposed standards, which are expressed in terms of ISMRE2 and

ISCOP2, are of equivalent stringency as the standards in ASHRAE Standard 90.1-2016 (and ASHRAE Standard 90.1-2019), which are expressed in terms of ISMRE and ISCOP. DOE proposes that the standards, if adopted, would apply to all DX-DOASes listed in Table I.1 manufactured in, or imported into, the United States starting on the date 18 months following the effective date of a final rule adopting such standards.

Table I.1—Proposed Energy Conservation Standards for DX-DOASes

Equipment type
Subcategory
Efficiency level

Dehumidifying direct-expansion dedicated outdoor air systems
(AC)—Air-cooled without ventilation energy recovery systems
ISMRE2 = 3.8.

(AC w/VERS)—Air-cooled with ventilation energy recovery systems
ISMRE2 = 5.0.

(ASHP)—Air-source heat pumps without ventilation energy recovery systems
ISMRE2 = 3.8, ISCOP2 = 2.05.

(ASHP w/VERS)—Air-source heat pumps with ventilation energy recovery systems
ISMRE2 = 5.0, ISCOP2 = 3.20.

(WC)—Water-cooled without ventilation energy recovery systems
ISMRE2 = 4.7.

(WC w/VERS)—Water-cooled with ventilation energy recovery systems
ISMRE2 = 5.1.

(WSHP)—Water-source heat pumps without ventilation energy recovery systems
ISMRE2 = 3.8, ISCOP2 = 2.13.

(WSHP w/VERS)—Water-source heat pumps with ventilation energy recovery systems
ISMRE2 = 4.6, ISCOP2 = 4.04.

DOE has tentatively determined that, based on the information presented and its analyses, there is not clear and convincing evidence that more stringent efficiency levels for this equipment would result in a significant additional amount of energy savings, is technologically feasible and economically justified. Clear and convincing evidence would exist only where the specific facts and data made available to DOE regarding a particular ASHRAE amendment demonstrates that there is no substantial doubt that a standard more stringent than that contained in the ASHRAE Standard 90.1 amendment is permitted because it would result in a significant additional amount of energy savings, is technologically feasible and economically justified. DOE normally performs multiple in-depth analyses to determine whether there is clear and convincing evidence to support more stringent energy conservation standards (
i.e.,
whether more stringent standards would produce significant additional conservation of energy and be technologically feasible and economically justified). However, as discussed in the sections, III.D.1.a., III.D.1.b., III.D.3.a., and III.D.3.b of this NOPR, due to the lack of available market and performance data, DOE is unable to conduct the analysis necessary to evaluate the potential energy savings or evaluate whether more stringent standards would be technologically feasible or economically justifiable, with sufficient certainty. As such, DOE is not proposing standards at levels more stringent than those specified in ASHRAE Standard 90.1-2016 (and ASHRAE Standard 90.1-2019).

II. Introduction

The following section briefly discusses the statutory authority underlying this proposed rule, as well as some of the relevant historical background related to the establishment of standards for DX-DOASes.

A. Authority

EPCA authorizes DOE to regulate the energy efficiency of a number of consumer products and certain industrial equipment. Title III, Part C of EPCA, added by Public Law 95-619, Title IV, section 441(a) (42 U.S.C. 6311-6317, as codified), established the Energy Conservation Program for Certain Industrial Equipment, which sets forth a variety of provisions designed to improve energy efficiency. Small, large, and very large commercial package air conditioning and heating equipment are included in the list of “covered equipment” for which DOE is authorized to establish and amend energy conservation standards and test procedures. As discussed in the following section, this includes Unitary DOASes and, more specifically, dehumidifying Unitary DOASes, which are the subject of this notice. (42 U.S.C. 6311(1)(B)-(D))

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

Additionally, DOE is to consider amending the energy efficiency standards for certain types of commercial and industrial equipment, including the equipment at issue in this document, whenever ASHRAE amends the standard levels or design requirements prescribed in ASHRAE/IES Standard 90.1, and at a minimum, every six 6 years. (42 U.S.C. 6313(a)(6)(A)-(C))

Subject to certain criteria and conditions, DOE is required to develop test procedures to measure the energy efficiency, energy use, or estimated annual operating cost of each covered product. (42 U.S.C. 6314) Manufacturers of covered equipment must use the Federal test procedures as the basis for: (1) Certifying to DOE that their equipment complies with the applicable energy conservation standards adopted pursuant to EPCA (42 U.S.C. 6316(b); 42 U.S.C. 6296), and (2) making representations about the efficiency of that equipment (42 U.S.C. 6314(d)). Similarly, DOE uses these test procedures to determine whether the equipment complies with relevant standards promulgated under EPCA.

Federal energy efficiency requirements for covered equipment established under EPCA generally supersede State laws and regulations concerning energy conservation testing, labeling, and standards. (42 U.S.C.

6316(a) and (b); 42 U.S.C. 6297) DOE may, however, grant waivers of Federal preemption for particular State laws or regulations, in accordance with the procedures and other provisions set forth under EPCA. (
See
42 U.S.C. 6316(b)(2)(D))

ASHRAE Standard 90.1 sets industry energy efficiency levels for small, large, and very large commercial package air-conditioning and heating equipment, packaged terminal air conditioners, packaged terminal heat pumps, warm air furnaces, packaged boilers, storage water heaters, instantaneous water heaters, and unfired hot water storage tanks (collectively “ASHRAE equipment”). For each type of listed equipment, EPCA directs that if ASHRAE amends Standard 90.1, DOE must adopt amended standards at the new ASHRAE efficiency level, unless DOE determines, supported by clear and convincing evidence, that adoption of a more stringent level would produce significant additional conservation of energy and would be technologically feasible and economically justified. (42 U.S.C. 6313(a)(6)(A)(ii))

In deciding whether a more-stringent standard is economically justified, under either the provisions of 42 U.S.C. 6313(a)(6)(A) or 42 U.S.C. 6313(a)(6)(C), DOE must determine whether the benefits of the standard exceed its burdens. DOE must make this determination after receiving comments on the proposed standard, and by considering, to the maximum extent practicable, the following seven factors:

(1) The economic impact of the standard on manufacturers and consumers of the products subject to the standard;

(2) The savings in operating costs throughout the estimated average life of the covered products in the type (or class) compared to any increase in the price, initial charges, or maintenance expenses for the covered products that are likely to result from the standard;

(3) The total projected amount of energy (or as applicable, water) savings likely to result directly from the standard;

(4) Any lessening of the utility or the performance of the covered products likely to result from the standard;

(5) The impact of any lessening of competition, as determined in writing by the Attorney General, that is likely to result from the standard;

(6) The need for national energy and water conservation; and

(7) Other factors the Secretary of Energy (“Secretary”) considers relevant.

(42 U.S.C. 6313(a)(6)(B)(ii)(I)-(VII))

In relevant part, subparagraph (B) specifies that: (1) In making a determination of economic justification, DOE must consider, to the maximum extent practicable, the benefits and burdens of an amended standard based on the seven criteria described in EPCA; (2) DOE may not prescribe any standard that increases the energy use or decreases the energy efficiency of a covered product; and (3) DOE may not prescribe any standard that interested persons have established by a preponderance of evidence is likely to result in the unavailability in the United States of any product type (or class) of performance characteristics (including reliability, features, sizes, capacities, and volumes) that are substantially the same as those generally available in the United States. (42 U.S.C. 6313(a)(6)(B)(ii)-(iii))

EPCA also contains what is known as an “anti-backsliding” provision, which prevents the Secretary from prescribing any amended standard that either increases the maximum allowable energy use or decreases the minimum required energy efficiency of a covered product. (42 U.S.C. 6313(a)(6)(B)(iii)(I)))

Unitary DOASes (and DX-DOASes) had not previously been addressed in DOE rulemakings and are not currently subject to Federal test procedures or energy conservation standards.

B. Background

EPCA defines “commercial package air conditioning and heating equipment” as air-cooled, water-cooled, evaporatively-cooled, or water source (not including ground water source) electrically operated, unitary central air conditioners and central air conditioning heat pumps for commercial application.
4

(42 U.S.C. 6311(8)(A); 10 CFR 431.92) Industry standards generally describe unitary central air conditioning equipment as one or more factory-made assemblies that normally include an evaporator or cooling coil and a compressor and condenser combination. Units equipped to also perform a heating function are included as well.
5

Unitary DOASes provide conditioning of outdoor ventilation air using a refrigeration cycle (which normally consists of a compressor, condenser, expansion valve, and evaporator),
6

and therefore, DOE has initially concluded that Unitary DOASes are a category of commercial package air conditioning and heating equipment subject to EPCA.

4
EPCA further classifies “commercial package air conditioning and heating equipment” into categories based on cooling capacity (
i.e.,
small, large, and very large categories). (42 U.S.C. 6311(8)(B)-(D); 10 CFR 431.92) “Small commercial package air conditioning and heating equipment” means equipment rated below 135,000 Btu per hour (cooling capacity). (42 U.S.C. 6311(8)(B); 10 CFR 431.92) “Large commercial package air conditioning and heating equipment” means equipment rated: (i) At or above 135,000 Btu per hour; and (ii) below 240,000 Btu per hour (cooling capacity). (42 U.S.C. 6311(8)(C); 10 CFR 431.92) “Very large commercial package air conditioning and heating equipment” means equipment rated: (i) At or above 240,000 Btu per hour; and (ii) below 760,000 Btu per hour (cooling capacity). (42 U.S.C. 6311(8)(D); 10 CFR 431.92) DOE generally refers to these broad classifications as “equipment types.”

5

See
American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) Standard 90.1, “Energy Standard for Buildings Except Low-Rise Residential Buildings.”

6
Other types of dedicated outdoor air systems are available that do not utilize direct expansion (
e.g.,
units that use chilled water, rather than refrigerant, as the heat transfer medium).

From a functional perspective, Unitary DOASes operate similarly to other categories of commercial package air conditioning and heat pump equipment, in that they provide conditioning using a refrigeration cycle. Unitary DOASes provide ventilation and conditioning of 100-percent outdoor air to the conditioned space, whereas for typical commercial package air conditioners that are central air conditioners, outdoor air makes up only a small portion of the total airflow (usually less than 50 percent). Unitary DOASes are typically installed in addition to a local, primary cooling or heating system (
e.g.,
commercial unitary air conditioner, variable refrigerant flow system, chilled water system, water-source heat pumps)—the Unitary DOAS conditions the outdoor ventilation air, while the primary system provides cooling or heating to balance building shell and interior loads and solar heat gain.

An industry consensus test standard has been established for a subset of Unitary DOASes, dehumidifying Unitary DOASes (DX-DOASes). On July 7, 2021, DOE published a NOPR proposing definitions, a new Federal test procedure, energy efficiency metrics, and representation requirements for DX-DOASes
7

(the “July 2021 Test Procedure NOPR”). 86 FR 36018.

7
In the July 2021 Test Procedure NOPR, DOE refers to Unitary DOASes and DX-DOASes as DX-DOASes and DDX-DOASes, respectively. DOE has recently published a supplemental test procedure NOPR, in which DOE proposes to use the Unitary DOAS and DX-DOAS terminology. This NOPR uses the Unitary DOAS and DX-DOAS terminology, which is consistent with the supplemental test procedure NOPR.

1. ASHRAE Standard 90.1 Efficiency Levels for DX-DOASes

As first established in ASHRAE Standard 90.1-2016, ASHRAE Standard 90.1-2019 specifies 14 separate equipment classes for DX-DOASes and sets minimum efficiency levels using

the integrated seasonal moisture removal efficiency (ISMRE) metric for all DX-DOAS classes and also the integrated seasonal coefficient of performance (ISCOP) metric for air-source heat pump and water-source heat pump DX-DOAS classes. ASHRAE Standard 90.1-2019 specifies that both metrics are to be measured in accordance with ANSI/AHRI Standard 920-2015, “Performance Rating of DX-Dedicated Outdoor Air System Units” (ANSI/AHRI 920-2015). ANSI/AHRI 920-2015 specifies the method for testing DX-DOASes, in part, through a reference to ANSI/ASHRAE Standard 198-2013, “Method of Test for Rating DX-Dedicated Outdoor Air Systems for Moisture Removal Capacity and Moisture Removal Efficiency” (ANSI/ASHRAE 198-2013). The energy efficiency standards specified in ASHRAE Standard 90.1 are based on ANSI/AHRI 920-2015 and ANSI/ASHRAE 198-2013, and these standards are shown in Table II.1.

Table II.1—ASHRAE Standard 90.1 Efficiency Levels for DX-DOASes

Equipment class
Energy efficiency levels

Air-cooled: Without energy recovery
4.0 ISMRE.

Air-cooled: With energy recovery
5.2 ISMRE.

Air-source heat pumps: Without energy recovery
4.0 ISMRE, 2.7 ISCOP.

Air-source heat pumps: With energy recovery
5.2 ISMRE, 3.3 ISCOP.

Water-cooled: Cooling tower condenser water, without energy recovery
4.9 ISMRE.

Water-cooled: Cooling tower condenser water, with energy recovery
5.3 ISMRE.

Water-cooled: Chilled water, without energy recovery
6.0 ISMRE.

Water-cooled: Chilled water, with energy recovery
6.6 ISMRE.

Water-source heat pumps: Ground-source, closed loop, without energy recovery
4.8 ISMRE, 2.0 ISCOP.

Water-source heat pumps: Ground-source, closed loop, with energy recovery
5.2 ISMRE, 3.8 ISCOP.

Water-source heat pumps: Ground-water source, without energy recovery
5.0 ISMRE, 3.2 ISCOP.

Water-source heat pumps: Ground-water source, with energy recovery
5.8 ISMRE, 4.0 ISCOP.

Water-source heat pumps: Water-source, without energy recovery
4.0 ISMRE, 3.5 ISCOP.

Water-source heat pumps: Water-source, with energy recovery
4.8 ISMRE, 4.8 ISCOP.

2. Update to the Industry Metric

As discussed in the July 2021 Test Procedure NOPR, AHRI revised AHRI 920 and published an updated version on February 4, 2020, AHRI Standard 920-2020 (I-P), “Performance Rating of Direct Expansion Dedicated Outdoor Air System Units” (AHRI 920-2020). 86 FR 36018, 36026. The updates to AHRI 920 include certain revised test conditions and weighting factors for ISMRE and ISCOP, which were redesignated as ISMRE2 and ISCOP2, respectively. These revisions result in the ISMRE2 and ISCOP2 metrics that more accurately reflect the actual energy use for DX-DOASes, improve the repeatability and reproducibility of the test methods, and also reduce testing burden compared to ISMRE and ISCOP. For example, the revised weighting factors reflect the number of hours per year for each test condition, and the revised test conditions are based on weather data from Typical Meteorological Year 2 (TMY2)
8

provided by the National Renewable Energy Laboratory. 86 FR 36018, 36029. A detailed discussion of the summary of the AHRI 920 updates is provide in the July 2021 Test Procedure NOPR. 86 FR 36018, 36026-36027.

8
TMY stands for “typical meteorological year” and is a widely used type of data available through the National Solar Radiation Database. TMYs contain one year of hourly data that best represents median weather conditions over a multiyear period. The datasets have been updated occasionally, thus TMY, TMY2, and TMY3 data are available.
See nsrdb.nrel.gov/about/tmy.html
(last accessed April 28, 2021).

The July 2021 Test Procedure NOPR proposes to add a new appendix B to subpart F of part 431, titled “Uniform test method for measuring the energy consumption of dehumidifying direct expansion-dedicated outdoor air systems,” that would include the new test procedure requirements for DX-DOASes. 86 FR 36018, 36022. The proposed appendix B test procedure for DX-DOASes incorporates by reference AHRI Standard 920-2020, the most recent version of the test procedure recognized by ASHRAE Standard 90.1 for DX-DOASes, and the relevant industry standards referenced therein.
Id.

The amendments adopted in AHRI 920-2020 result in changes to the measured efficiency metrics as compared to the results under ANSI/AHRI 920-2015, which as noted above, is the test procedure used to measure DX-DOAS efficiency levels in Standard 90.1-2016 and 90.1-2019. In the July 2021 Test Procedure NOPR DOE noted that it will address any potential differences in the measured energy efficiency under the most recent industry test procedure as compared to the industry test procedure on which the ASHRAE Standard 90.1 levels are based at such time as DOE evaluates the ASHRAE Standard 90.1 levels for DX-DOASes (
i.e.,
by developing an appropriate “crosswalk”, as necessary). 86 FR 36018, 36027.

Accordingly, because the measured energy efficiency metrics in the July 2021 Test Procedure NOPR are different from those used by the ASHRAE 90.1-2019, DOE has developed a crosswalk analysis for these proposed standards, which translates the existing ASHRAE Standard 90.1-2019 ISMRE and ISCOP standards to the new metrics proposed in the July 2021 Test Procedure NOPR. The crosswalk analysis is discussed in detail in section IV of this document.

3. History of Standards Rulemaking for DX-DOASes

On September 11, 2019—prior to the publication of AHRI 920-2020 and the July 2021 Test Procedure NOPR proposing to incorporate by reference the updated AHRI 920-2020—DOE published an analysis of new industry standards for DX-DOASes in a notice of data availability and request for information (the September 2019 NODA/RFI).
9

84 FR 48006. The September 2019 NODA/RFI solicited information from the public to help DOE determine whether new standards for DX-DOASes at levels more stringent than specified in ASHRAE Standards 90.1 would result in significant energy savings and whether such standards would be technologically feasible and economically justified. The September 2019 NODA/RFI also presented incremental efficiency levels for air-

cooled DX-DOASes (based on the ANSI/AHRI 920-2015 metrics, ISMRE and ISCOP) and annual unit energy consumption estimates for these levels.

9
The September 2019 NODA/RFI also requested comment and data regarding standards for computer room air conditioners, which are being addressed in a separate rulemaking.

DOE received five comments relevant to DX-DOASes in response to the September 2019 NODA/RFI from the interested parties listed in Table II.2.

Table II.2—September 2019 NODA/RFI Written Comments

Commenter(s)
Reference in this NOPR
Commenter type

7 AC Technologies
7AC
Manufacturer.

Air-conditioning, Heating, & Refrigeration Institute
AHRI
Trade Association.

Ingersoll Rand Trane
Trane
Manufacturer.

Pacific Gas and Electric Co., San Diego Gas and Electric Co., Southern California Edison
CA IOUs
Utilities.

Pano Koutrouvelis
DU
Individual.

A parenthetical reference at the end of a comment quotation or paraphrase provides the location of the item in the public record.
10

10
The parenthetical reference provides a reference for information located in the docket of DOE's rulemaking to develop energy conservation standards for DX-DOASes. (Docket No. EERE-2017-BT-STD-0017, which is maintained at
www.regulations.gov
). The references are arranged as follows: (Commenter name, comment docket ID number, page of that document).

C. Timing of ASHRAE Test Procedures and Appendix A

Section 8(d) of 10 CFR part 430, subpart C, appendix A (“appendix A”) establishes a general principal that new test procedures and amended test procedures that impact measured energy use or efficiency should be finalized prior to the close of the comment period for a NOPR proposing new or amended energy conservation standards. DOE also noted, however, that a one-size-fits-all requirement to finalize new or amended test procedures a set number of days before issuing a proposed standard does not allow DOE to account for the particular circumstances of a rulemaking and may result in unnecessary delays. 86 FR 70920. In this instance, ASHRAE 90.1-2016 (
i.e.,
the standard which triggered DOE to establish uniform national standards for DX-DOASes) was published over six years ago, however EPCA requires DOE to establish such standards no later than 18 months following the publication of ASHRAE 90.1-2016. (42 U.S.C. 6313(a)(6)(A)(ii)(I)) DOE is proposing energy conservation standards for DX-DOASes before the current test procedure rule is finalized to accelerate DOE's efforts to meet its EPCA obligation to establish energy conservation standards. In addition, DOE notes that DOE has proposed in the July 2021 Test Procedure NOPR to incorporate by reference AHRI 920-2020, which was published roughly two years ago. Given DOE's obligation to adopt the relevant industry test procedure unless DOE determines, supported by clear and convincing evidence, that it does not produce results which reflect energy use during a representative average use cycle or is unduly burdensome to conduct (42 U.S.C. 6314(a)(2-4)), stakeholders would have had a reasonable level of confidence of the test procedure DOE would use as the basis of the proposed efficiency levels, and finalization of the test procedure rulemaking is unlikely to affect that understanding.

III. General Discussion

DOE developed this proposal after considering oral and written comments, data, and information from interested parties that represent a variety of interests. The following discussion addresses issues raised by these commenters.

A. Scope of Coverage

As discussed in the September 2019 NODA/RFI, the inclusion of energy efficiency levels in ASHRAE Standard 90.1-2016 for DX-DOASes
11

triggered DOE to consider energy conservation standards for this type of equipment. 84 FR 48006, 48010.

11
The September 2019 NODA/RFI used the term “DOAS”.
See generally
84 FR 48006.

As discussed in the July 2021 Test Procedure NOPR, Unitary DOASes meet the EPCA definition for “commercial package air conditioning and heating equipment,” and, thus, are to be considered as a category of that covered equipment (42 U.S.C. 6311(8)(A)), and the upper capacity limit of commercial package air conditioning subject to the DOE test procedures is 760,000 Btu per hour, based on the definition of “very large commercial package air conditioning and heating equipment.” (42 U.S.C. 6311(8)(D)) 86 FR 36018, 36023-36024. In response to the September 2019 NODA/RFI, AHRI commented that it supported a maximum capacity for regulated products that is equivalent to 760,000 Btu per hour at Standard Rating Condition A in AHRI 920. (AHRI, No. 7, p. 9) In the July 2021 Test Procedure NOPR DOE noted that for DX-DOASes, AHRI 920-2020 does not provide a method for determining capacity in terms of Btu per hour, but instead, it specifies a determination of capacity in terms of moisture removal capacity (MRC). 86 FR 36018, 36024. DOE is proposing to translate the upper capacity for coverage of commercial package air conditioning and heating units established in EPCA (
i.e.,
760,000 Btu per hour) from Btu per hour to MRC for DX-DOASes.
Id.
The equivalent upper capacity limit proposed for DX-DOASes is 324 lbs moisture/hr at Standard Rating Condition A in AHRI 920.
Id.

In this NOPR DOE proposes that the proposed energy conservation standards would apply to DX-DOASes with an MRC less than or equal to 324 lbs moisture/hr. This scope of coverage would be consistent with the definitions of “Unitary DOAS” and “DX-DOAS” proposed in the July 2021 Test Procedure NOPR:

(1) “Direct expansion-dedicated outdoor air system, or Unitary DOAS, means a category of small, large, or very large commercial package air-conditioning and heating equipment which is capable of providing ventilation and conditioning of 100-percent outdoor air or marketed in materials (including but not limited to, specification sheets, insert sheets, and online materials) as having such capability” and

(2) “Dehumidifying direct expansion-dedicated outdoor air system, or DX-DOAS, means a direct expansion-dedicated outdoor air system that is capable of dehumidifying air to a 55 °F dew point—when operating under Standard Rating Condition A as specified in Table 4 or Table 5 of AHRI 920-2020 (incorporated by reference, see § 431.95) with a barometric pressure of 29.92 in Hg—for any part of the range of airflow rates advertised in manufacturer materials, and has a moisture removal capacity of less than 324 lb/h.”

86 FR 36018, 36057.

The CA IOUs requested that DOE clarify whether split-system DX-DOASes (with remote condenser units) are included within the scope of coverage, stating that AHRI 920 applies to both “single package” and “remote condenser” DX-DOASes. (CA IOUs, No. 6, p. 4) DOE is proposing to include split-system DX-DOASes within the scope of coverage, consistent with the scope of the ASHRAE Standard 90.1 minimum efficiency levels
12

for DX-DOASes and AHRI 920-2020. Just as split systems are included in the scope of other categories of commercial package air-conditioning and heating equipment (
e.g.,
computer room air conditioners, variable-refrigerant flow multi-split systems) DOE is proposing to include them in the scope for DX-DOASes. (
See,
for example, the definitions of “Computer Room Air Conditioner” and “Variable Refrigerant Flow Multi-Split Air Conditioner” at 10 CFR 431.92.)

12
Tables 6.8.1-13 and 6.8.1-14 of ASHRAE Standard 90.1-2019 indicates that it provides minimum efficiency levels for “Electrically Operated DX-DOAS Units, Single-Package and Remote Condenser.”

B. Equipment Classes

When evaluating and establishing energy conservation standards, DOE divides covered products into product classes by the type of energy used or by capacity or other performance-related features that justify differing standards.

ASHRAE Standard 90.1-2016 created 14 separate equipment classes for DX-DOASes. EPCA generally requires DOE to establish energy conservation standards for commercial package air-conditioning and heating equipment at the minimum efficiencies set forth in ASHRAE Standard 90.1. (
See
42 U.S.C. 6313(a)(6)(A)) DOE is proposing to establish eight DX-DOAS equipment classes that correspond to eight of the 14 classes in ASHRAE Standard 90.1—this proposal, including the omission of the remaining six classes, is discussed in the following paragraphs.

14 separate equipment classes (indicated as “equipment types” and “subcategories”) were created by ASHRAE Standard 90.1-2016 and maintained in ASHRAE Standard 90.1-2019 (see Table II.1). These are differentiated by condensing type (air-cooled, air-source heat pump, water-cooled, and water-source heat pump). ASHRAE Standard 90.1 does not delineate classes for DX-DOASes based on capacity. AHSRAE Standard 90.1 does separate classes into those with ventilation energy recovery systems (VERS)—often referred to as simply “energy recovery”—and those without VERS. The July 2021 Test Procedure NOPR proposed to include a definition for VERS at 10 CFR 431.92 that reads, “Ventilation energy recovery system, or VERS, means a system that pre-conditions outdoor ventilation air entering the equipment through direct or indirect thermal and/or moisture exchange with the exhaust air, which is defined as the building air being exhausted to the outside from the equipment.” 86 FR 36018, 36057.

The ASHRAE Standard 90.1 requirements for water-cooled condensing units are divided into two application conditions: Cooling tower condenser water and chilled water. The requirements for water-source heat pump units are divided into three application conditions: Ground-source closed loop, ground-water-source, and water-source. However, these application rating conditions are labeled as “subcategories” in ASHRAE Standard 90.1-2019. Moreover, as discussed more below, AHRI 920-2020, the update to the industry test procedure upon which the DX-DOAS efficiency ratings in Standard 90.1 are based, but which has not yet been incorporated into Standard 90.1, identifies some of these application rating conditions as optional for purposes of the test procedure.

The EPCA definition for “commercial package air conditioning and heating equipment” does not include ground-water-source equipment (
see
42 U.S.C. 6311(8)(A)), therefore DOE is not considering the ground-water-source application condition for its regulated equipment classes. In response to the September 2019 NODA/RFI, the CA IOUs commented in support of the exclusion of ground-water-source equipment from the regulated equipment classes. (CA IOUs, No. 6, p. 4)

In the September 2019 NODA/RFI, DOE requested comment on the approach of evaluating water-cooled DX-DOASes as a single category (with classes still disaggregated by those models with and without VERS) using the specified cooling tower condenser water entering temperature conditions, and evaluating water-source heat pump DX-DOASes as a single category (with classes still disaggregated by those models with and without VERS) using only the specified water-source inlet fluid temperature conditions. 84 FR 48006, 48021-48022. As part of its analysis for the September 2019 NODA/RFI, DOE considered whether to evaluate separately the two water-cooled DOAS classes or whether the water-cooled cooling tower condenser water classes and the water-cooled chilled water classes should be grouped together and represented as water-cooled DOASes (with classes still disaggregated by those models with energy recovery and those models without energy recovery). DOE also considered whether to evaluate separately the two remaining water-source heat pump classes or whether the water-source heat pump ground-source closed loop classes and the water-source heat pump water-source classes should be grouped together and represented as water-source heat pump DOASes (with classes still disaggregated by those models with energy recovery and those models without energy recovery). 84 FR 48021.

Based on DOE's review of equipment specifications of water-cooled and water-source heat pump DOASes and comments on the concurrent test procedure evaluation, DOE determined that most water-cooled DOASes use the same equipment for different applications and that water-source heat pump DOASes use the same equipment design for different applications. DOE stated that it is not aware of water-cooled DOAS units that are exclusively designed for use with cooling tower or chilled water. Likewise, DOE stated that it is not aware of water-source heat pump DOAS units that are exclusively designed for use with water-source or ground-source closed-loop applications. It is also DOE's understanding that ASHRAE Standard 90.1 efficiency levels are different across comparable classes within the water-cooled condensing type (
e.g.,
comparing energy recovery classes to energy recovery classes) and across comparable classes within the water-source condensing type because of the different test/application conditions, as opposed to equipment design differences. For example, when testing a DOAS to obtain a water-cooled chilled water DOAS rating, a colder condenser water entering temperature is used than when testing it to obtain a water-cooled cooling tower DOAS rating, reflecting the typically cooler temperature of chilled water loops in commercial buildings, as compared with cooling tower water loops.
Id.

As a result, in the September 2019 NODA/RFI, DOE combined the water-cooled cooling tower condenser water classes and the water-cooled chilled water classes and evaluated water-cooled DOASes as a single set of classes (with classes disaggregated by those models with energy recovery and those models without energy recovery) that is subject to a single set of operating conditions. DOE also combined the water-source heat pump ground-source closed loop classes and the water-source heat pump water-source classes and

evaluated the water-source heat pump DOASes as a single set of classes (with classes still disaggregated by those models with energy recovery and those models without energy recovery) that is subject to a single set of operating conditions. AHRI, the CA IOUs, and Trane commented in support of this proposed approach. (AHRI, No. 7, p. 9; CA IOUs, No. 6, p. 4; Trane, No. 5, p. 3)

In the July 2021 Test Procedure NOPR, DOE noted that AHRI 920-2020 still provides separate inlet fluid rating conditions for the different water-cooled and water-source heat pump DX-DOAS applications but identifies the chilled water conditions and ground-source closed loop conditions as optional application rating conditions. 86 FR 36018, 36033. On this topic, AHRI commented that in almost all cases, a single design is used for water-cooled equipment used with cooling tower water and chilled water, and, similarly, a single design is used for all of the water-source applications, adding that for each of these cases, a single set of water conditions can be used for testing.
Id.
Section 2.2.1(c)(i) of the proposed appendix B test procedure specifies the use of the “Condenser Water Entering Temperature, Cooling Tower Water” conditions for rating water-cooled DX-DOASes and the “Water-Source Heat Pumps” conditions for rating water-source heat pump DX-DOASes. 86 FR 36018, 36060. DOE stated in the July 2021 Test Procedure NOPR that it would consider establishing standards and the corresponding certification requirements in the context of these inlet fluid temperature conditions. 86 FR 36018, 36033.

Based on its review and feedback from stakeholders, DOE has determined that separate equipment classes for each one of these subcategories in the proposed standards is not necessary, and that the 8 proposed equipment classes are most representative of DX-DOAS equipment and rating applications in the field. DOE understands that the water-cooled equipment “subcategories” in ASHRAE Standard 90.1-2019 are meant to represent different application requirements for the same equipment, and thus DOE's proposed equipment class structure does not split water-cooled equipment into cooling tower water and chilled water subcategories. As proposed, all water-cooled equipment would be rated to the cooling tower water conditions, and standards would be established for water-cooled DX-DOASes with and without VERS. Similarly, the equipment class structure DOE is proposing does not split water-source heat pump equipment into the three subcategories in ASHRAE Standard 90.1-2019. Because of the statutory exclusion of ground-water-source equipment and because ground-source closed loop conditions are optional to test to in AHRI 920-2020, all water-source heat pump equipment would be rated to the water-source heat pump water conditions, and standards would be established for water-source heat pump DX-DOASes with and without VERS. This approach is consistent with other commercial package air conditioning and heating equipment. For example, water-source heat pumps include application test conditions for water-loop, ground-water, and ground-loop heat pumps, but DOE only requires that equipment be rated using the water-loop conditions (see Table 3 to 10 CFR 431.97). This approach avoids testing under multiple application conditions for a single equipment design. In addition, even if tested at different application conditions because the DOAS equipment uses a single design, it is expected that the relative ranking of equipment efficiency would be the same.

7AC commented that DX-DOASes with liquid desiccant heat exchangers (LDHXs) and variable-speed compressors may achieve high ISMRE efficiencies and recommended the addition of a new category with a minimum ISMRE of 7 that covers packaged units with and without exhaust air. (7AC, No. 4, p. 1) DOE understands that liquid-to-air transfer membranes can improve dehumidification efficiency when coupled with standard air conditioners. This technology uses porous membranes with liquid desiccants to absorb water vapor from the supply air stream. In its review of LDHX DX-DOASes, DOE has initially determined that this equipment would be covered under the definition of “relief-air-cooled DX-DOAS” in Section 3.6.2 of AHRI 920-2020 (which is incorporated into section 2.2.1(a) of the proposed appendix B test procedure) due to the way in which building return air is typically used to regenerate the liquid desiccant and cool the condenser in the refrigeration cycle. This definition specifically classifies relief-air-cooled units under the air-cooled equipment category. Furthermore, DX-DOASes with exhaust air streams are generally also included within the air-cooled equipment category demarcated in AHRI 920-2020, thus DOE is not proposing to create a separate equipment class for LDHX DX-DOASes or DX-DOASes with exhaust air.

DOE is proposing energy conservation standards for eight DX-DOASes equipment classes, consistent with the classes provided in ASHRAE Standard 90.1 as discussed above and shown in Table III.1.

Table III.1—Proposed Equipment Classes for DX-DOASes

Equipment class in ASHRAE Standard 90.1
Proposed equipment class in Federal Energy Conservation Standards

Air-cooled: Without energy recovery
(AC)—Air-cooled without ventilation energy recovery systems.

Air-cooled: With energy recovery
(AC w/VERS)—Air-cooled with ventilation energy recovery systems.

Air-source heat pumps: Without energy recovery
(ASHP)—Air-source heat pumps without ventilation energy recovery systems.

Air-source heat pumps: With energy recovery
(ASHP w/VERS)—Air-source heat pumps with ventilation energy recovery systems.

Water-cooled: Cooling tower condenser water, without energy recovery
(WC)—Water-cooled without ventilation energy recovery systems.

Water-cooled: Cooling tower condenser water, with energy recovery
(WC w/VERS)—Water-cooled with ventilation energy recovery systems.

Water-source heat pumps: Water-source, without energy recovery
(WSHP)—Water-source heat pumps without ventilation energy recovery systems.

Water-source heat pumps: Water-source, with energy recovery
(WSHP w/VERS)—Water-source heat pumps with ventilation energy recovery systems.

Issue-1: DOE requests comment on the proposed eight equipment classes for energy conservation standards of DX-DOASes.

C. Test Procedure

EPCA sets forth generally applicable criteria and procedures for DOE's adoption and amendment of test procedures. (42 U.S.C. 6314(a)) Manufacturers of covered products must use these test procedures to certify to DOE that their product complies with energy conservation standards and to quantify the efficiency of their product.

DOE does not currently have test procedures or energy conservation standards established for DX-DOASes. In response to the September 2019 NODA/RFI, AHRI indicated that it strongly agreed with DOE's tentative conclusion that DOE's existing test procedures are not appropriate for DX-DOAS units. (AHRI, No. 7, p. 7)

ASHRAE Standard 90.1-2019 references ANSI/AHRI 920-2015, which relies on the metrics of ISMRE and ISCOP, and the standards for DX-DOASes in ASHRAE Standard 90.1-2019 are in terms of ISMRE and ISCOP. ANSI/AHRI 920-2015 was superseded with the publication of AHRI 920-2020, which relies on the updated metric ISMRE2 and ISCOP2.

The July 2021 Test Procedure NOPR proposes a new Federal test procedure for DX-DOASes that would incorporate AHRI 920-2020, which is the most recent version of the test procedure recognized by ASHRAE Standard 90.1 for DX-DOASes. 86 FR 36018, 36022. The proposed test procedure incorporates AHRI 920-2020 in its entirety, with certain minor clarifications DOE has preliminarily determined would be consistent with the industry test procedure. 86 FR 36018, 36047. AHRI 920-2020 specifies Standard Rating Conditions (
i.e.,
controlled operating conditions) with instructions for instrumentation, test set-up, tolerances, method of test, and calculations of capacity and efficiency. The proposed DOE test procedure would establish ISMRE2 as the dehumidification efficiency metric for all DX-DOASes and ISCOP2 as the heating efficiency metric for heat pump DX-DOASes. 86 FR 36018, 36027-36029. DOE is proposing to define ISMRE2 and ISCOP2 consistent with AHRI 920-2020.
Id.

AHRI commented that, among other things, the current version of AHRI 920 transitions the efficiency metrics for DX-DOASes from ISMRE and ISCOP to ISMRE2 and ISCOP2. AHRI stated that two major differences between ISMRE and ISMRE2 are: With the new metric, DX-DOASes will no longer be required to reheat conditioned air to space-neutral conditions (70-75 °F supply air), and excess dehumidification beyond the design supply air dew point is no longer credited at part-load conditions. AHRI commented that the heating metric changes are similar: The heating coefficient of performance is now determined at the staging that most closely provides a supply air temperature within the allowable range. AHRI also noted that two new application rating metrics were added in AHRI 920-2020: ISMRE2
70
and COP
DOAS,x
. Additionally, AHRI commented that new provisions have been included in AHRI 920-2020 for the testing and performance calculations of DX-DOASes with VERS. (AHRI, No. 7, p. 8-9)

The CA IOUs raised the concern that a dehumidification efficiency metric may not be appropriate for DX-DOASes based on an analysis showing that, on a national shipment-weighted basis, the outdoor air dew point is above 55 °F
13

only 36.7 percent of the time; therefore, the CA IOUs suggested that DOE consider adjustments to the DX-DOAS test procedure that contribute to a standard that reflects sensible cooling and/or fan-only ventilation conditions. The CA IOUs did not dispute that the primary use-case of a DX-DOAS system is to cool and dehumidify outdoor air, however they claim not all installation locations will have dehumidification requirements as aggressive as the tested conditions required for an ISMRE rating. (CA IOUs, No. 6, p. 6)

13
AHRI 920-2020 requires that DX-DOASes dehumidify outdoor ventilation air to a maximum dew point of 55 °F as a representative set point for dehumidified building supply air. Therefore, if the outdoor air dew point temperature is below 55 °F, there would typically not be any dehumidification load on the DX-DOAS, and the remaining cooling load would be for sensible cooling only.

DOE addressed this subject in the July 2021 Test Procedure NOPR (
see
86 FR 36027). In particular, DOE received comments from AHRI stating that DX-DOASes are installed with separate complementary sensible-cooling-only systems that provide cooling to address the interior loads, and that adding sensible cooling to the metric for DX-DOAS would skew efficiency values toward the non-primary function of the DX-DOAS. This focus of DX-DOAS performance on dehumidification loads supports DOE's proposal to adopt the ISMRE2 dehumidification efficiency metric in AHRI 920-2020. 86 FR 36018, 36027. Nevertheless, the sensible cooling provided by a DX-DOAS unit may be valuable in many applications because it reduces the cooling that must be provided by interior cooling systems, especially at high outdoor temperatures. DOE may consider in a future rulemaking whether the efficiency metric should be revised to include sensible cooling; however, EPCA prescribes that the test procedures for commercial package air conditioning and heating equipment must be those generally accepted industry testing procedures or rating procedures developed or recognized by industry as referenced in ASHRAE Standard 90.1 (
i.e.,
AHRI 920 for DX-DOASes). (42 U.S.C. 6314(a)(4)(A))

The July 2021 Test Procedure NOPR discusses major updates to the AHRI 920 test procedure, as well as the efficiency metrics, in depth. 86 FR 36018, 36025-36045. DOE is addressing comments regarding specific aspects of the proposed test procedure in the concurrent test procedure rulemaking.

In this NOPR, DOE is proposing to establish energy conservation standards for DX-DOASes in terms of ISMRE2 and ISCOP2.

D. Considerations for Energy Conservation Standards

In this proposed rulemaking to establish energy conservation standards for DX-DOASes, DOE is proposing to adopt ISMRE2 and ISCOP2 minimum efficiency levels of equivalent stringency to the ISMRE and ISCOP minimum efficiency levels currently published in ASHRAE Standard 90.1.

As discussed in section II.A of this document, EPCA requires DOE to amend the existing Federal energy conservation standard for covered equipment each time ASHRAE amends
14

Standard 90.1 with respect to such equipment. (42 U.S.C. 6313(a)(6)(A)) When triggered in this manner, DOE must adopt the minimum level specified in the amended ASHRAE Standard 90.1, unless DOE determines that there is clear and convincing evidence to support a determination that a more stringent standard level would produce significant additional conservation of energy and be technologically feasible and economically justified. (42 U.S.C. 6313(a)(6)(A)(ii)) If DOE makes such a determination, it must publish a final rule to establish the more stringent standards. (42 U.S.C. 6313(a)(6)(B)) DOE

states in Section 9(b) of Appendix A to subpart C of part 430 that clear and convincing evidence would exist only where the specific facts and data made available to DOE regarding a particular ASHRAE amendment demonstrate that there is no substantial doubt that a standard more stringent than that contained in the ASHRAE Standard 90.1 amendment is permitted because it would result in a significant additional amount of energy savings, is technologically feasible and economically justified.

14
Although EPCA does not explicitly define the term “amended” in the context of what type of revision to ASHRAE Standard 90.1 would trigger DOE's obligation, DOE's longstanding interpretation has been that the statutory trigger is an amendment to the standard applicable to that equipment under ASHRAE Standard 90.1 that increases the energy efficiency level for that equipment.
See
72 FR 10038, 10042 (March 7, 2007).

DOE normally performs multiple in-depth analyses to determine whether there is clear and convincing evidence to support more stringent energy conservation standards (
i.e.,
whether more stringent standards would produce significant additional conservation of energy and be technologically feasible and economically justified). Table III.2 shows the statutory requirements and DOE's corresponding analytical approach, including DOE's approach to the seven-factor analysis for determining whether a standard is economically justified.

Table III.2—EPCA Requirements and Corresponding DOE Analysis

EPCA requirement
Corresponding DOE analysis

Significant Energy Savings
• Shipments Analysis.

• National Impact Analysis.

• Energy Use Determination.

Technological Feasibility
• Market and Technology Assessment.

• Screening Analysis.

• Engineering Analysis.

Economic Justification:

1. Economic Impact on Manufacturers and Consumers
• Manufacturer Impact Analysis.

• Life-Cycle Cost and Payback Period Analysis.

• Life-Cycle Cost Subgroup Analysis.

• Shipments Analysis.

2. Lifetime Operating Cost Savings Compared to Increased Cost for the Product
• Markups for Product Price Determination.

• Energy and Water Use Determination.

• Life-Cycle Cost and Payback Period Analysis.

3. Total Projected Energy Savings
• Shipments Analysis.

• National Impact Analysis.

4. Impact on Utility or Performance
• Screening Analysis.

• Engineering Analysis.

5. Impact of Any Lessening of Competition
• Manufacturer Impact Analysis.

6. Need for National Energy and Water Conservation
• Shipments Analysis.

• National Impact Analysis.

7. Other Factors the Secretary Considers Relevant
• Employment Impact Analysis.

• Utility Impact Analysis.

• Emissions Analysis.

• Monetization of Emission Reductions Benefits.

• Regulatory Impact Analysis.

DOE received comments from DU regarding the EPCA seven-factor test and the analytical framework for establishing energy conservation standards. DU commented that the sixth factor for economic justification, “need for national energy and water conservation,” is too broad and should specify a goal for savings by the year the amended standards go into effect. DU also requested clarification on whether the analytical methods used to determine national energy savings are limited to a cross-sectional analysis and if so, the rationale behind eliminating the time series. (DU, No. 3, p. 1) DOE notes that the seven factors in EPCA were specified by Congress. Regarding the national energy savings (NES), DOE notes that it is not a cross-sectional analysis. In the September 2019 NODA/RFI, a 30-year time series of shipments was used to calculate the NES for DX-DOASes.

As previously described, DOE normally conducts the analysis depicted in Table III.2 to determine whether clear and convincing evidence supports more stringent energy conservation standards. In this instance, however, DOE has tentatively determined that a lack of data precludes such an analysis and therefore precludes a finding of clear and convincing evidence. DOE provided a technical support document (TSD)
15

with the September 2019 NODA/RFI to present initial findings for certain of these analyses for DX-DOASes. Chapter 4 of the September 2019 NODA/RFI TSD discusses DOE's detailed methodology for estimating national energy savings. When DOE conducts a national energy savings analysis, it calculates the cumulative energy savings over the analysis period by summing the annual energy savings for each year in the analysis period, thereby considering the long-term impacts—as opposed to a limited cross-section of time. However, as described in the following subsections, DOE does not have sufficient data to revise and expand upon these analyses presented in the TSD at this time.

15
The September 2019 NODA/RFI TSD is available as Document No. 2 at
www.regulations.gov/docket/EERE-2017-BT-STD-0017.

1. Technological Feasibility

a. General

To evaluate whether more stringent standards than those in the updated ASHRAE Standard 90.1 would be technologically feasible, DOE generally first conducts a market and technology assessment to survey all current technology options in products on the market and prototype designs that could improve the efficiency of the subject equipment. DOE then conducts a screening analysis based on information gathered on all current technology options and prototype designs that could improve the efficiency of the products or equipment that are the subject of the rulemaking. As the first step in such an analysis, DOE develops a list of technology options for consideration in consultation with manufacturers, design engineers, and other interested parties. DOE then determines which of those means for improving efficiency are technologically

feasible. DOE considers technologies incorporated in commercially-available products or in working prototypes to be technologically feasible.
See generally
10 CFR 431.4; 10 CFR part 430, subpart C, appendix A, sections 6(c)(3)(i) and 7(b)(1).

After DOE has determined that particular technology options are technologically feasible, it further evaluates each technology option in light of the following additional screening criteria: (1) Practicability to manufacture, install, and service; (2) adverse impacts on product utility or availability; (3) adverse impacts on health or safety, and (4) unique-pathway proprietary technologies.
See generally
10 CFR 431.4; 10 CFR part 430, subpart C, appendix A, sections 6(c)(3)(ii)-(v) and 7(b)(2)-(5).

DOE is not aware of an existing database or compilation containing a comprehensive list of DX-DOAS models and performance metrics. As noted, DX-DOASes are not currently subject to Federal energy conservation standards, and so manufacturers of DOASes are not required to certify or report to DOE the energy efficiency of such equipment. The AHRI Directory does not currently list DX-DOAS equipment performance ratings. Similarly, DOE was not able to find ISMRE or ISCOP ratings in much of the manufacturer equipment specifications. It is unclear to what extent the market has responded to the industry standards initially specified in ASHRAE Standard 90.1-2016.

Also as discussed, in the edition of AHRI 920 immediately following the edition in which an industry testing standard was established for DOAS, AHRI adopted updated metrics for DX-DOASes (
i.e.,
ISMRE2 and ISCOP2). Similarly, DOE was not able to find ISMRE2 or ISCOP2 ratings in much of the manufacturer equipment specifications. Because this test procedure was fairly recently published, it is not clear to what extent the test data has been developed based on the updated industry testing standard (
i.e.,
AHRI 920-2020), although DOE expects that this test procedure represents the industry consensus for testing DX-DOASes.

In the September 2019 NODA/RFI, DOE analyzed two incremental efficiency levels (ELs) above the ASHRAE Standard 90.1 minimum ISMRE efficiency levels for air-cooled DX-DOASes (with and without VERS) based on technology options that are expected to be available for DX-DOASes. 84 FR 48006, 48026. The ELs were also based, in part, on an initial assessment of EER data for commercial unitary air conditioners due to the lack of market data using the AHRI 920 performance metrics. 84 FR 48006, 48026. DOE tentatively determined based on manufacturer feedback that the baseline design would likely include staged compressors, and that the design change from the baseline efficiency level (the ASHRAE Standard 90.1 minimum) to EL 1 would involve changing from staged compressor operation to variable-capacity digital scroll compressors. The design changes from EL 1 to EL 2 include increasing the condenser heat exchanger size and fin density, increasing the total condenser fans horsepower, and reducing the capacity of the compressors needed. Due to the similarity in designs, DOE considered that the same technology options and resulting increase in efficiency from the analysis for DX-DOASes without VERS would be applied for DX-DOASes with VERS.
Id.

The CA IOUs commented that the analysis should take into account all equipment classes of DX-DOAS because, while air-cooled DX-DOASes may comprise the vast majority of DX-DOAS shipments, there are other equipment classes with the potential for energy savings. (CA IOUs, No. 6, p. 6) The CA IOUs also disagreed with the efficiency level distribution and asked DOE to develop a more sophisticated efficiency analysis. (CA IOUs, No. 6, p. 7) AHRI also disagreed with DOE's incremental efficiency levels because they were derived from a single manufacturer's equipment at a single capacity size. (AHRI, No. 7, p. 8) The CA IOUs urged DOE to conduct a cost-effectiveness analysis for new DX-DOAS standards and apply the experience curve methodology DOE recommended in 2011
16

, including both price decline to-date and a forecast of continued price decline, in order to avoid overestimating the true costs of efficiency improvements. (CA IOUs, No. 6, pp. 7-8) AHRI provided confidential business data containing limited estimations of the ISMRE ranges for DX-DOASes by cooling capacity (in Btu/hr) and disaggregated by VERS (without distinguishing between the 8 DX-DOAS equipment classes), as noted in AHRI's public comment. (AHRI, No. 7, p. 10)

16
In 2011, DOE published a notice of data availability discussing the experience curve methodology. 76 FR 9696 (Feb. 22, 2011).

DOE acknowledges that the efficiency levels for air-cooled DX-DOASes presented in the September 2019 NODA/RFI may not be representative of the DX-DOAS market because they were derived from a very limited amount of publicly available data, and additionally, these efficiency levels are no longer in terms of the metrics DOE is proposing to regulate. In this NOPR, DOE has tentatively determined that this type of engineering analysis cannot be completed due to the lack of available market and performance data. A lack of performance data using the ISMRE2 and ISCOP2 metrics impedes DOE's ability to correlate efficiency levels to DX-DOAS design options, and AHRI's data did not provide further details for this aspect of the analysis. As a result, the development of cost-efficiency curves is not possible at this time.

AHRI commented that the efficiency benefits of employing variable-capacity digital scroll compressors were overestimated in the September 2019 NODA/RFI analysis, and that this technology option is implemented primarily for control purposes. AHRI stated that while a digital scroll compressor provides capacity control, it does not provide an efficiency increase over three- or four-step compressor control, and, furthermore, a digital scroll compressor would provide a modest improvement over a single- or two-step DX-DOASes based on the equipment cycling. AHRI also asserted that DX-DOASes with single- or two-step staging do not provide the necessary control consumers require, and so they are rarely purchased. (AHRI, No. 7, p. 10) Trane also commented that the benefits of digital scroll compressors are more closely correlated to staging control than efficiency. (Trane, No. 5, p. 3)

Both AHRI and Trane commented that there is considerable variation in the technology options that may be utilized at the baseline efficiency level. (AHRI, No. 7, p. 10; Trane, No. 5, p. 3) However, AHRI generalized that small equipment (below 10 tons) utilize two-stage or digital compressors, without inverter control, with small heat exchangers; and above 10 tons, equipment typically utilizes four-stage or digital compressors, without inverter control, with larger heat exchangers. (AHRI, No. 7, p. 10) AHRI stated that for the purposes of the technology analysis, industry would support the first step to improving energy efficiency being the addition of inverter control, and the second step being including a larger condenser with more surface area. (
Id
). Additionally, the CA IOUs provided that DX-DOAS heat exchangers tend to be larger than those in typical commercial unitary air conditioners. (CA IOUs, No. 6, p. 7)

DOE appreciates these comments on technology options and has incorporated this feedback into aspects of the crosswalk analysis. DOE included

DX-DOASes with two stages of capacity and digital scroll compressors in its ISMRE-to-ISMRE2 crosswalk analysis. Additionally, the technology options referenced by AHRI were used in DOE's analytical modeling of baseline heat pump DX-DOASes to evaluate the impact of the test procedure changes for the heating efficiency metric. DOE has initially determined that the proposed ISCOP2 standards for heat pump DX-DOASes are technologically feasible because DOE performed the ISCOP-to-ISCOP2 crosswalk based on the baseline technology options recommended by stakeholders—
i.e.,
staged scroll compressors, no inverter control, and representative baseline heat exchangers for DX-DOASes. This is discussed in section IV.C.2 of this NOPR.

As discussed in section III.B of this NOPR, 7AC indicated that combining a variable-speed compressor with an economically-sized LDHX can result in an ISMRE of 7.5 without VERS and an ISMRE of 8.5 with VERS. (7AC, No. 4, p. 1) Because DOE could not identify any other manufacturers of DX-DOASes which employ LDHXs in commercially-distributed equipment, and DOE expects that this technology option utilizes proprietary technology that represents a unique pathway to achieving a particular efficiency level. For this reason, DOE did not consider LDHX technology in its analysis of whether more stringent standards would be technologically feasible or as part of the crosswalk analysis.

Issue-2: DOE continues to seek information that may inform a market and technology assessment for the DX-DOAS industry, including data on technology options which may increase the ISMRE2 and/or ISCOP2 efficiencies of DX-DOASes.

b. Maximum Technologically Feasible Levels

When evaluating more stringent standards, DOE typically must determine the maximum improvement in energy efficiency or maximum reduction in energy use that is technologically feasible for such product. (
See
42 U.S.C. 6313(a)(6)(A)(ii)(II)) Accordingly, in the engineering analysis, DOE typically determines the maximum technologically feasible (“max-tech”) improvements in energy efficiency using the design parameters for the most efficient equipment available on the market or in working prototypes.

Prior to the publication of AHRI 920-2020, the September 2019 NODA/RFI DOE estimated that the max-tech efficiency for air-cooled DX-DOASes without VERS was an ISMRE of 6.0, whereas for air-cooled DX-DOASes with VERS the max-tech efficiency was an ISMRE of 7.2. 84 FR 48006, 48026. In response, the CA IOUs provided data that showed the range of manufacturer-published ISMRE ratings reached a maximum of 8.9 ISMRE for air-cooled DX-DOASes without VERS and 10.8 ISMRE for air-cooled DX-DOASes with VERS. (CA IOUs, No. 6, p. 7)

As discussed, DOE has proposed to incorporate by reference AHRI 920-2020 in its test procedure, which relies on different metrics than what were presented in the September 2019 NODA/RFI and what were provided by commenters. As discussed further in section IV.B.1 of this NOPR, the DX-DOAS designs that are likely to yield the highest ISMRE and ISCOP efficiencies under the ANSI/AHRI 920-2015 test procedure are not likely to yield the highest ISMRE2 and ISCOP2 efficiencies under AHRI 920-2020 (and the proposed DOE test procedure) due to significant differences in the test procedures, and therefore DOE cannot rely on ISMRE/ISCOP efficiency ratings alone (
i.e.,
without knowledge of the specific design options utilized) to identify max-tech efficiencies using the proposed test procedure.

Due to the lack of data in terms of AHRI 920-2020 efficiency metrics, DOE is currently unable to identify the most efficient equipment available on the market in terms of the proposed metrics. As such, DOE is unable to estimate the field-installed energy use and cost of the most efficient equipment (in terms of the proposed metrics) available on the market (factoring in parameters such as price markups, installation application, life-cycle cost and payback period, and overall shipments). Hence, DOE was unable to evaluate the technological feasibility of standards more stringent than the levels in the updated ASHRAE Standard 90.1.

2. Significant Additional Conservation of Energy

The “significant additional conservation of energy” language in 42 U.S.C. 6313(a)(6)(A) indicates that Congress intended for DOE to ensure that, in addition to the savings from the ASHRAE standards, DOE's standards would yield additional energy savings that are significant. In DOE's view, this statutory provision shares the requirement with the statutory provision applicable to covered products and non-ASHRAE equipment that “significant conservation of energy” must be present (42 U.S.C. 6295(o)(3)(B))—and supported with “clear and convincing evidence”—to permit DOE to set a more stringent requirement than ASHRAE.
See
85 FR 8626, 8666-8667.

In determining whether energy savings are significant, DOE considers the specific circumstances surrounding a given rulemaking.
17

In making this determination, DOE looks at, among other things, the FFC effects of the proposed standards. These effects include the energy consumed in electricity production (depending on load shape), in distribution and transmission, and in extracting, processing, and transporting primary fuels (
i.e.,
coal, natural gas, petroleum fuels), and thus present a more complete picture of the impacts of energy conservation standards, including greenhouse gas emissions.

17
Procedures, Interpretations, and Policies for Consideration in New or Revised Energy Conservation Standards and Test Procedures for Consumer Products and Commercial/Industrial Equipment, 86 FR 70892, 70901 (Dec. 13, 2021).

DOE has initially determined that there is insufficient data on the developing DX-DOAS market to conduct an analysis of potential energy savings resulting from more stringent standards. AHRI 920-2020 is a relatively recent industry test standard, published in February 2020, and thus AHRI has not yet established a certification database listing DX-DOAS ISMRE2 and ISCOP2 ratings. In the September 2019 NODA/RFI DOE also noted that the AHRI Directory does not list DX-DOAS equipment performance ratings, and that DOE was not able to find ISMRE or ISCOP ratings in much of the manufacturer equipment specifications. 84 FR 48006, 48026. DOE requested data on the market efficiency distribution, field installation applications and performance, the determination of unit energy consumption (UEC), equipment lifetimes, and shipments (
see
84 FR 48006, 48036); however, DOE did not receive sufficient information with regards to these aspects of its analysis in order to determine the energy savings of more stringent efficiency levels for each of the 8 proposed DX-DOAS equipment classes.

3. Economic Justification

As noted previously, EPCA provides seven factors to be considered in determining whether standard levels more stringent than the levels specified in the updated ASHRAE Standard 90.1 are economically justified. (42 U.S.C. 6313(a)(6)(B)(ii)(I)-(VII)) The following sections provide an overview of each of those seven factors and consideration of the factors in this NOPR.

a. Economic Impact on Manufacturers and Consumers

In determining the impacts of a potential standard on manufacturers, DOE typically conducts a manufacturer impact analysis (MIA). DOE first uses an annual cash-flow approach to determine the quantitative impacts. This step includes both a short-term assessment—based on the cost and capital requirements during the period between when a regulation is issued and when entities must comply with the regulation—and a long-term assessment over a 30-year period. The industry-wide impacts analyzed include (1) INPV, which values the industry on the basis of expected future cash flows, (2) cash flows by year, (3) changes in revenue and income, and (4) other measures of impact, as appropriate. Second, DOE analyzes and reports the impacts on different types of manufacturers, including impacts on small manufacturers. Third, DOE considers the impact of standards on domestic manufacturer employment and manufacturing capacity, as well as the potential for standards to result in plant closures and loss of capital investment. Finally, DOE takes into account cumulative impacts of various DOE regulations and other regulatory requirements on manufacturers.

For individual consumers, measures of economic impact include the changes in life-cycle costs (LCC) and the payback period (PBP) associated with new or amended standards. For consumers in the aggregate, DOE also calculates the national net present value of the consumer costs and benefits expected to result from particular standards. DOE also evaluates the impacts of potential standards on identifiable subgroups of consumers that may be affected disproportionately by a standard.

As noted, DOE is unaware of any database or compilation containing a comprehensive list of DX-DOAS models and performance metrics. This presents significant challenges to performing an accurate assessment of the DX-DOAS industry structure.

DOE normally uses projections of annual equipment shipments to calculate the national impacts of potential amended or new energy conservation standards on energy use, industry net present value (NPV), and future manufacturer cash flows. The shipments model typically takes an accounting approach, tracking market shares of each product class and the vintage of units in the stock. Stock accounting uses product shipments as inputs to estimate the age distribution of in-service product stocks for all years. The age distribution of in-service product stocks is a key input to calculations of both the national energy savings and NPV because operating costs for any year depend on the age distribution of the stock.

For the September 2019 NODA/RFI, DOE developed DX-DOAS shipments estimates based on manufacturer feedback that shipments in 2016 were around 36,000 units and that DX-DOAS growth is expected to be similar to that of variable refrigerant flow multi-split system equipment. 84 FR 48006, 48030. A report by the Cadeo Group estimated variable refrigerant flow multi-split system equipment shipments to have double-digit growth through 2022. Therefore, to project shipments past 2016, DOE used a 10-percent growth rate through 2022 and then followed the same growth rate as other commercial unitary air-conditioning equipment, basing that growth rate on the reference case shipment projections in the National Impact Analysis spreadsheet from the January 15, 2016 direct final rule for commercial unitary air conditioners and heat pumps and commercial warm air furnaces (81 FR 2420).
Id.

Manufacturers estimated that air-cooled DX-DOASes represent 95 percent of all DX-DOAS shipments, and DOE assumed that this percentage would remain constant for the duration of the 30-year shipments analysis.
Id.
For the September 2019 NODA/RFI, DOE only analyzed the two air-cooled DX-DOAS equipment classes, and so reduced the annual shipments projections developed above by 5 percent to capture only the air-cooled product classes.
Id.
DOE allocated 59-percent of shipments to air-cooled DOAS without energy recovery and 41-percent of shipments to air-cooled DOAS with energy recovery, based on manufacturer estimates of the breakdown by equipment class.
Id.

In response, the CA IOUs provided an analysis of an online database of construction projects called ConstructConnect Insight, which suggests that DX-DOAS shipments have been increasing at an 18% annual rate since 2012. (CA IOUs, No. 6, p. 5) Additionally, the CA IOUs agreed that variable refrigerant flow and water-source heat pump systems are a good starting point for estimating DX-DOAS shipments but encouraged DOE to take into account radiant cooling, PTAC, and fan-coil installation projects as well. (
Id.
) AHRI suggested that DX-DOASes can also be paired with chilled beams and room fan coils. (AHRI, No. 7, p. 11) Trane suggested that DOE may have significantly overstated the DX-DOAS market in the September 2019 NODA/RFI. (Trane, No. 5, p. 3) AHRI provided a similar statement, specifically indicating that the 2016 shipments value for DX-DOAS was overestimated. (AHRI, No. 7, pp. 10-11) AHRI also noted that significant DX-DOAS shipment volume is relatively new to the market. (
Id.
) AHRI submitted confidential business data containing shipments estimates for DX-DOASes.

DOE acknowledges that DX-DOASes are paired with many types of space conditioning systems and that while most DX-DOASes are installed with variable refrigerant flow and water source heat pumps, other systems such as chilled beams, package terminal systems, and fan coils are paired with DX-DOASes. The confidential data submission from AHRI provided a time series of DX-DOAS shipments from 2010 to 2018. The time series provides the total number of DX-DOAS shipments along with estimates of the market share by equipment capacity and the availability of units with VERS, and this would allow DOE to improve its shipments projections. However, the shipments data does not break the shipments down by equipment class. DOE received no comments regarding the estimate that air-cooled DX-DOASes represent 95 percent of shipments or on the breakdown of DX-DOAS with and without VERS. However, DOE still lacks the breakdown of shipments for the other equipment classes. As stated earlier in this section, the shipments model is used to measure the national impacts of potential amended or new energy conservation standards. Without an engineering analysis (
see
section III.D.2.c of this document) and an energy use analysis (
see
section III.D.2.d of this document), DOE is unable to produce the other inputs necessary to project the national impact of standards more stringent than those in ASHRAE Standard 90.1-2019. Therefore DOE did not update the shipments model for this NOPR.

Were DOE to establish standards as proposed, as well as accompanying certification requirements, this information would become more readily available should DOE consider amending standards for DX-DOASes in any future rulemaking.
18

Chapter 2 of

the September 2019 NODA/RFI TSD presents DOE's market assessment to the extent that DOE was able to retrieve publicly accessible information for DX-DOASes. Since the September 2019 NODA/RFI, DOE has, identified additional manufacturers of DX-DOASes, and these manufacturers are listed in Table III.3 (which supersedes Table 2.3 in the September 2019 NODA/RFI TSD).

18
In situations where ASHRAE has not acted to amend the levels in Standard 90.1 for the equipment types enumerated in the statute, EPCA provides for a 6-year-lookback to consider the potential for amending the uniform national standards. (42 U.S.C. 6313(a)(6)(C)) Specifically, pursuant to the amendments to EPCA under the American Energy Manufacturing Technical Corrections Act (Pub. L. 112-210 (Dec. 18, 2012)), DOE is required to conduct an evaluation of each class of covered equipment in ASHRAE Standard

90.1 “every 6 years” to determine whether the applicable energy conservation standards need to be amended. (42 U.S.C. 6313(a)(6)(C)(i)) DOE must publish either a NOPR to propose amended standards or a notice of determination that existing standards do not need to be amended. (42 U.S.C. 6313(a)(6)(C)) In proposing new standards under the 6-year review, DOE must undertake the same considerations as if it were adopting a standard that is more stringent than an amendment to ASHRAE Standard 90.1. (42 U.S.C. 6313(a)(6)(C)(i)(II))

Table III.3—Manufacturers of DX-DOASes

Manufacturers
AHRI member

AAON
Yes.

AnnexAir
No.

Daikin
Yes.

Greenheck
Yes.

Ingersoll Rand
Yes.

Johnson Controls
Yes.

Madison Industries
Yes.

Modine Manufacturing Company
Yes.

Multistack
Yes.

Munters Group AB
No.

Nortek Global HVAC
Yes.

Soler and Palau Industries
Yes.

DOE did not perform an MIA for this rulemaking because there is not enough information available on the DX-DOAS market to determine which entities are already compliant with the proposed energy conservation standards (
i.e.,
producing DX-DOASes which currently meet or exceed the proposed ISMRE2 and ISCOP2 minimum efficiency levels) and what portion of annual cash flow these DX-DOASes comprise. However, DOE did examine potential impacts on small manufacturers in its regulatory flexibility analysis, which is presented in section VII.B of this NOPR.

For individual consumers, DOE measures the economic impact by calculating the changes in LCC and PBP associated with new or amended standards. These measures are discussed further in the following section. For consumers in the aggregate, DOE would also calculate the national net present value of the consumer costs and benefits expected to result from particular standards, while taking into account the impacts of potential standards on identifiable subgroups of consumers that may be affected disproportionately by a standard.

DOE continues to seek information that may inform a market and technology assessment for the DX-DOAS industry, including data on ISMRE2 and ISCOP2 market efficiency distributions, and shipments.

DOE did not perform an LCC or an assessment of NPV for this rulemaking because there was not enough information available to develop the inputs required to measure the individual or aggregate consumer savings from higher standards. The LCC would require an engineering analysis, an energy use analysis, operating cost inputs, and a distribution of efficiencies that are available on the market. These inputs allow DOE to develop equipment prices, representative efficiency levels, annual operating costs, and a no-standards case distribution of equipment efficiencies to determine which consumers will be impacted by a higher standard. The NIA takes the weighted average national results from the LCC and combines them with shipments forecasts by equipment class and efficiency level in order to measure the national impact, in terms of consumer NPV and full-fuel-cycle energy savings. As stated previously, DOE was unable to develop cost-efficiency curves for DX-DOASes or to conduct an energy use analysis with enough degree of certainty that would allow it to propose a standard level more stringent than ASHRAE Standard 90.1 (
see
section III.D.2 of this document). Without these inputs, DOE is unable to produce the LCC and NIA for this NOPR.

b. Savings in Operating Costs Compared to Increase in Price (LCC and PBP)

EPCA requires DOE to consider the savings in operating costs throughout the estimated average life of the covered product in the type (or class) compared to any increase in the price of, or in the initial charges for, or maintenance expenses of, the covered product that are likely to result from a standard. (42 U.S.C. 6313(a)(6)(B)(ii)(II)) DOE conducts this comparison in its LCC and PBP analysis.

The LCC is the sum of the purchase price of a product (including its installation) and the operating expense (including energy, maintenance, and repair expenditures) discounted over the lifetime of the product. The LCC analysis requires a variety of inputs, such as product prices, product energy consumption, energy prices, maintenance and repair costs, product lifetime, and discount rates appropriate for consumers. To account for uncertainty and variability in specific inputs, such as product lifetime and discount rate, DOE uses a distribution of values, with probabilities attached to each value.

The PBP is the estimated amount of time (in years) it takes consumers to recover the increased purchase cost (including installation) of a more-efficient product through lower operating costs. DOE calculates the PBP by dividing the change in purchase cost due to a more-stringent standard by the change in annual operating cost for the year that standards are assumed to take effect.

For its LCC and PBP analysis, DOE assumes that consumers will purchase the covered products in the first year of compliance with new or amended standards. The LCC savings for the considered efficiency levels are calculated relative to the case that reflects projected market trends in the absence of new or amended standards.

In the September 2019 NODA/RFI DOE developed an efficiency distribution that assumed that one-third of the products were at each of the three efficiency levels. 84 FR 48006, 48030. DOE requested comment on this approach and input on how to determine the no-standards case efficiency distribution given the lack of publicly available data on equipment efficiency. DOE also sought historical shipment weighted efficiency data by equipment class.

In response, AHRI and Trane both generally supported the approach DOE took which assumed that one-third of the units were at each of the proposed efficiency levels. (AHRI, No. 7, p. 11; Trane, No. 5, p. 3). AHRI and Trane both commented that they do not collect shipments data by efficiency level. (AHRI, No. 7, p. 11; Trane, No. 5, p. 3)

DOE also lacked data on the equipment lifetime for DX-DOASes in the September 2019 NODA/RFI. However, DOE had developed lifetimes for other commercial package air conditioning equipment in previous rulemakings,
19

therefore the DX-DOAS lifetime was set to be the same as that of a 15-ton commercial package air conditioner. 84 FR 48006, 48031. DOE also requested comment on DX-DOAS lifetimes.

19
Direct Final Rule Life-Cycle-Cost Analysis Spreadsheet is available at:
www.regulations.gov/document?D=EERE-2013-BT-STD-0007-0106.
(Last accessed on August 9, 2021)

In response, AHRI, the CA IOUs, and Trane all agreed with the approach that a DX-DOAS lifetime would be similar to that of a 15-ton commercial package air conditioner. (AHRI, No. 7, p. 11,

Trane, No. 5, p. 3, CA IOUs, No. 6, p. 7)

A preliminary energy use analysis was presented in the September 2019 NODA/RFI, and DOE requested feedback on its calculation approach as well as data from field studies and laboratory testing to further inform the estimation of real-world energy usage from performance ratings. 84 FR 48006, 48026-48027.

7AC commented that the actual energy consumption in buildings can be significantly higher than the tested ISMRE suggests, primarily at lower loads where the regular on/off cycling reduces actual energy load. (7AC, No. 4, p. 1) DOE understands that 7AC is referring to cycling start-up losses which occur when staged compressor systems turn on and off to meet a reduced cooling (or heating) demand. The impact of cycling losses is now captured in AHRI 920-2020, which DOE has proposed to incorporate into a new DOE test procedure for DX-DOASes. Specifically, the updated test procedure includes provisions for weighted averaging when the target conditions can be bracketed by two stages, as well as cyclic degradation calculations and a supplementary cooling penalty when the lowest stage provides excess conditioning capacity (which is when cycling losses would occur). 86 FR 36018, 36032-36033.

7AC also agreed that field data should be sought to complement the lab data and correlate ISMRE in the lab with performance in the field. (7AC, No. 4, p. 1) Additionally, 7AC indicated that LDHX-based units are being installed with remote monitoring equipment that will enable the measurement of total cooling and total power use, the cost of which has come down dramatically and that DOE should seek similar arrangements with other equipment providers. (
Id.
) 7AC did not provide data correlating tested performance ratings to performance in field-installed conditions. AHRI stated that it was unable to provide data in response to DOE's request. (AHRI, No. 7, p. 10) AHRI suggested that DOE consider addendum “bi” of ASHRAE Standard 90.1-2013, which limits heating supply air to a maximum of 60 °F when the majority of a building is expected to require cooling, in any energy use estimates. (AHRI, No. 7, p. 11)

The elimination of the supplemental heat penalty in the ISMRE2 metric (
see
section IV.B.1 of this document) makes it so that DX-DOASes are no longer required to deliver supply air of at least 70 °F in the test procedure. In the July 2021 Test Procedure NOPR, DOE discussed that DX-DOASes typically cool air to, at most, a few degrees above the 55 °F dew point temperature that is specified in AHRI 920. 86 FR 36018, 36031. Therefore, DOE expects that the establishment of ISMRE2 as a regulated metric for DX-DOASes would not preclude manufacturers from producing DX-DOASes which are compliant with the aforementioned provision in ASHRAE Standard 90.1-2013.

The energy use analysis presented in the September 2019 NODA/RFI relied on the energy use for ventilation and space cooling from the 2012 Commercial Building Energy Consumption Survey
20

(CBECS 2012) to develop the ASHRAE level unit energy consumption (UEC) estimates. The UECs for higher ELs were scaled based on the ISMRE levels presented in the September 2019 NODA/RFI. 84 FR 48006, 48026-48027. With an integrated metric, the power consumption at part loads is critical to understanding the energy consumption at various efficiency levels; however, no part-load data was available to DOE at the time of publication in September 2019. DOE included 30 percent of the space cooling energy use from CBECS 2012 along with the ventilation energy use to derive the UEC. 84 FR 48006, 48027.

20

See www.eia.gov/consumption/commercial/data/2012/index.php?view=microdata
(Last accessed on August 9, 2021).

Trane agreed with associating building ventilation cooling with the DX-DOAS unit but disagreed with adding 30 percent of the building annual cooling load to this value because it may overstate the typical cooling duty cycle. (Trane, No. 5, p. 3) Trane stated that many DX-DOAS systems are designed to provide no cooling for the building and requested that published case studies be cited to determine the estimated cooling load percentage handled by the DX-DOAS. (
Id.
)

DOE would consider such data in its energy use analysis should it become available. However, DOE is not presenting an energy use analysis in this NOPR due to insufficient market data, performance data, and field use data. In response to Trane, while DX-DOASes may not be designed to provide space cooling, there is no variable in CBECS 2012 for dehumidification. DX-DOASes provide dehumidification by cooling the ventilation air, therefore DOE included 30 percent of the space cooling energy use from CBECS 2012 along with the ventilation energy use to derive the UEC.

DOE requested field data or performance data of DX-DOASes in the September 2019 NODA/RFI and received no data. In order to develop UECs that are representative of DX-DOAS installations across the U.S., DOE would require data on the equipment performance at different load conditions. This data could consist of manufacturer performance data or field data for equipment rated using ISMRE2 and ISCOP2, if applicable. As DX-DOASes would be newly regulated equipment and ISMRE2 and ISCOP2 are new metrics even within the DX-DOAS market, there is no energy consumption data available. In addition, DOE was unable to develop appropriate efficiency levels to analyze (
see
section III.D.2.c of this document). Given the lack of available data regarding the performance of DX-DOASes, DOE is unable to estimate the UECs.

DOE did not perform an LCC and PBP analysis for this NOPR. As discussed in the preceding paragraphs there is not enough information available to develop the inputs to the LCC and PBP models.

c. Energy Savings

Although significant conservation of energy is a separate statutory requirement for adopting an energy conservation standard, EPCA requires DOE, in determining the economic justification of a standard, to consider the total projected energy savings that are expected to result directly from the standard. (42 U.S.C. 6313(a)(6)(B)(ii)(III))

In the September 2019 NODA/RFI, DOE presented its initial national energy savings methodology and estimates for air-cooled DX-DOASes with and without VERS. 84 FR 48006, 48030-48033. The NES requires inputs from the energy use analysis. As stated in section III.D.2.d, DOE was unable to conduct an energy use analysis. Therefore, DOE has not conducted or updated an NES analysis for this NOPR.

d. Lessening of Utility or Performance of Products

In establishing product classes and in evaluating design options and the impact of potential standard levels, DOE evaluates potential standards that would not lessen the utility or performance of the considered products. (42 U.S.C. 6313(a)(6)(B)(ii)(IV)) DOE has tentatively determined that the standards proposed in this document would not reduce the utility or performance of the equipment under consideration in this rulemaking because DOE is proposing to adopt standards of equivalent stringency to those already found in ASHRAE Standard 90.1.

e. Impact of Any Lessening of Competition

EPCA directs DOE to consider the impact of any lessening of competition, as determined in writing by the Attorney General, that is likely to result from a proposed standard. (42 U.S.C. 6313(a)(6)(B)(ii)(V)) DOE invites comment from the public regarding the competitive impacts that are likely to result from this proposed rule.

f. Need for National Energy Conservation

DOE also considers the need for national energy and water conservation in determining whether a new or amended standard is economically justified. (42 U.S.C. 6313(a)(6)(B)(ii)(VI)) The energy savings from the proposed standards are likely to provide improvements to the security and reliability of the Nation's energy system. Reductions in the demand for electricity also may result in reduced costs for maintaining the reliability of the Nation's electricity system.

DOE maintains that environmental and public health benefits associated with the more efficient use of energy are important to take into account when considering the need for national energy conservation. The proposed standards are likely to result in environmental benefits in the form of reduced emissions of air pollutants and greenhouse gases (“GHGs”) associated with energy production and use.

The utility impact analysis, emissions analysis, and emissions monetization all rely on the national energy savings estimates from the NIA. As discussed previously, DOE did not conduct an NIA and as a result could not conduct these downstream analyses.

g. Other Factors

In determining whether an energy conservation standard is economically justified, DOE may consider any other factors that the Secretary deems to be relevant. (42 U.S.C. 6313(a)(6)(B)(ii)(VII)) To the extent DOE identifies any relevant information regarding economic justification that does not fit into the other categories described previously, DOE could consider such information under “other factors.”

IV. Crosswalk Analysis

A. Overview

As discussed in section III.D of this NOPR, DOE is proposing to adopt ISMRE2 and ISCOP2 minimum efficiency levels of equivalent stringency to the ISMRE and ISCOP minimum efficiency levels currently published in ASHRAE Standard 90.1. The determination of these equivalent ISMRE2 and ISCOP2 efficiency levels is referred to as a “crosswalk analysis.”

AHRI commented that the current ASHRAE Standard 90.1 levels reflect the current DX-DOAS market, however, that use of ANSI/AHRI 920-2015 is not ideal and this test procedure was undergoing revisions at the time. AHRI stated that harmonizing the Federal energy conservation standards with ASHRAE Standard 90.1 energy efficiency levels would help reduce compliance and test burdens on manufacturers; however, the metrics would change with the revision to AHRI 920. AHRI commented that the changes may seem drastic between the first and second edition of a standard, but they were agreed to by relevant stakeholders. (AHRI, No. 7, pp. 7-9) Trane commented that the conditions and rating calculations were changed in the update to AHRI 920 so that independent test labs could easily generate reliable results for these products, and Trane prefers that AHRI 920-2020 be the basis for any new standard levels adopted by DOE for DX-DOASes. (Trane, No. 5 at p. 3)

As discussed in section II.B of this NOPR, in the July 2021 Test Procedure NOPR, DOE proposed a new Federal test procedure for DX-DOASes that would incorporate AHRI 920-2020, which is the most recent version of the test procedure (AHRI 920) recognized by ASHRAE Standard 90.1 for DX-DOASes. 86 FR 36018, 36022. The proposed test procedure incorporates AHRI 920-2020 in its entirety, with certain minor clarifications DOE has preliminarily determined would be consistent with the industry test procedure. 86 FR 36018, 36047. The updates to AHRI 920 include certain revised test conditions and weighting factors for ISMRE and ISCOP, which were redesignated as ISMRE2 and ISCOP2, respectively. These revisions result in the ISMRE2 and ISCOP2 metrics that more accurately reflect the actual energy use for DX-DOASes, improve the repeatability and reproducibility of the test methods, and also reduce testing burden compared to ISMRE and ISCOP.

The minimum energy efficiency levels specified for DX-DOASes in ASHRAE Standard 90.1-2019 are not based on equipment efficiency as measured pursuant to AHRI 920-2020 (
i.e.,
ISMRE2 and ISCOP2). As a result, should DOE adopt the test procedure as proposed in the July 2021 TP NOPR, the efficiency measurements from the version of the industry test procedure recognized in ASHRAE Standard 90.1-2019 for DX-DOASes (
i.e.,
ISMRE and ISCOP), would not be comparable to efficiency measurements under the DOE test procedure. DOE would generally be required to adopt the ISMRE and ISCOP levels in ASHRAE Standard 90.1-2019 as the basis for energy conservation standards; however, in the case of an amended test procedure that would alter the measured energy efficiency or measured energy use of a covered ASHRAE equipment, EPCA prescribes requirements to amend the applicable energy conservation standard so that products or equipment that complied under the prior test procedure remain compliant under the amended test procedure. (
See generally
42 U.S.C. 6293(e); 42 U.S.C. 6314(a)(4)(C)) While these provisions are not explicitly applicable to DX-DOASes in the present case because DOE currently has no test procedure or energy conservation standards for this equipment, DOE considers them as generally instructive for conducting the crosswalk analysis.

EPCA provides that in the case of any amended test procedure, DOE must determine, in the rulemaking carried out with respect to prescribing such procedure, to what extent, if any, the proposed test procedure would alter the measured energy efficiency, measured energy use, or measured water use of the subject ASHRAE equipment as determined under the existing test procedure. (
See
42 U.S.C 6293(e); 42 U.S.C. 6314(a)(4)(C)) If the Secretary determines that the amended test procedure will alter the measured efficiency or measured use, the Secretary shall amend the applicable energy conservation standard during the rulemaking carried out with respect to such test procedure. In such case, under the process prescribed in EPCA DOE is directed to measure, pursuant to the amended test procedure, the energy efficiency or energy use of a representative sample of covered products that minimally comply with the existing standard. (
See
42 U.S.C. 6293(e)(2); 42 U.S.C. 6314(a)(4)(C)) The average of such energy efficiency or energy use determined under the amended test procedure constitutes the amended energy conservation standard for the applicable covered products. (
Id.
)

As stated, EPCA requires DOE to adopt uniform national standards for DX-DOASes at the minimum level specified in the amended ASHRAE Standard 90.1, unless the Secretary determines, by rule published in the
Federal Register
, and supported by clear and convincing evidence, that adoption of a uniform national standard more stringent than the amended

ASHRAE Standard 90.1 would result in significant additional conservation of energy and is technologically feasible and economically justified. (42 U.S.C. 6313(a)(6)(A)(ii)) DOE has preliminarily determined that, in the present case given the limited data available, conducting a crosswalk analysis generally consistent with the process prescribed in 42 U.S.C. 6293(e)(2) would result in efficiency levels that are of the same stringency as those in ASHRAE Standard 90.1-2019.

A crosswalk analysis requires data on the performance of a representative sample of DX-DOASes under both test procedures. In response to the September 2019 NODA/RFI, 7AC offered to provide DOE with a full performance map of a 10-ton LDHX DX-DOAS. (7AC, No. 4, p. 1) However, as noted in section III.D.1.a of this NOPR, DOE understands LDHX technology to be a proprietary technology and thus could not consider it as representative for the crosswalk analysis. Trane suggested that it could provide information as confidential business information. (Trane, No. 5, p. 3) AHRI committed to working with DOE to develop an acceptable crosswalk based on calculations and test data, if available. (AHRI, No. 7, p. 9) DOE did not receive any submissions from stakeholders containing data that would help DOE conduct the crosswalk analysis. DOE determined the ISMRE-to-ISMRE2 crosswalk based on testing conducted by DOE and Pacific Gas and Electric. DOE determined the ISCOP-to-ISCOP2 crosswalk based on a technical analysis of heat pump performance. The methodology and results of the crosswalk analysis are presented in detail in the Crosswalk Analysis Support Document (CASD)
21

and are summarized in the following sections of this document.

21
The CASD is available at
www.regulations.gov/docket/EERE-2017-BT-STD-0017.

B. ISMRE-to-ISMRE2 Crosswalk

1. Dehumidification Efficiency Test Procedure Changes

In the September 2019 NODA/RFI, DOE requested comment and data on developing a potential crosswalk from the efficiency levels in ASHRAE 90.1-2016 based on ANSI/AHRI 920-2015 to efficiency levels based on the revisions to AHRI 920 (
i.e.,
AHRI 920-2020). 84 FR 48006, 48022. While DOE is proposing to adopt the test procedure in AHRI 920-2020 with minor revisions, these revisions are not expected to have an impact on DX-DOAS ratings. 86 FR 36018, 36046. As such, the minor revisions to the procedure in AHRI 920-2020 proposed by DOE would not impact the crosswalk or the following discussion.

DOE received comments from two stakeholders regarding the test procedure updates in AHRI 920-2020 which affect the dehumidification efficiency rating. (AHRI, No. 7, pp. 8-9; CA IOUs, No. 6, pp. 6-7) The comments from stakeholders regarding the potential impacts of the update from ANSI/AHRI 920-2015 to AHRI 920-2020 on the ISMRE-to-ISMRE2 crosswalk are presented in Table IV.1. Although the comments do not provide quantitative indication of the expected change in the measurement, they suggest the direction and general magnitude of the change in the ISMRE-to-ISMRE2 crosswalk.

Table IV.1—Test Procedure Updates Impacting ISMRE-to-ISMRE2 Crosswalk

ANSI/AHRI 920-2015
AHRI 920-2020

Expected impact on dehumidification
efficiency rating

Specifies inlet (outdoor ventilation air and return air) dry bulb and wet bulb conditions for four Standard Rating Conditions (SRCs) A, B, C, and D

Revises inlet conditions at SRCs C & D
a

Decrease in MRE at SRC D for units with VERS due to less favorable conditions.
a

Specifies minimum required external static pressures (ESPs) for supply air streams as a function of supply airflow rate

Increases minimum required ESPs for supply air streams;
a
establishes minimum required ESPs for return air streams (for units with VERS)
a

b

Decrease in ISMRE2 due to increased fan power at higher static pressures.
b

Specifies weighting coefficients to calculate ISMRE from the moisture removal efficiencies (MREs) at the four SRCs

Revises weighting coefficients;
a

b
re-labels efficiency metric as ISMRE2
a

b

Increase in ISMRE2 due to greater weight on SRCs A and B.
b

Does not include instructions for achieving the target supply air conditions for units with staged capacity control

Provides an interpolation method and a degradation coefficient calculation to determine efficiency for units with staged capacity control
a

Decrease in ISMRE2 for units with staged capacity because excess dehumidification is not credited.
a

Penalizes delivery of supply air below 70 °F (the “supplementary heat penalty”)

Eliminates the supplementary heat penalty for ISMRE2
a

b

Increase in ISMRE2 due to removal of penalty;
b
increase in ISMRE2 due to decrease in discharge head pressure (higher head pressures are required to increase reheat capacity, but also increase compressor power draw).
b

Does not require a consistent supply air dew point temperature across all SRCs

Requires that SRCs B-D target the supply air dew point temperature achieved at SRC A within a 0.3 °F condition tolerance
a

Decrease in ISMRE2 for units with staged capacity because excess dehumidification is not credited.
a

Does not specify how to calculate MRE for units with VERS

Includes instructions for calculating the total moisture removal capacity for units with VERS;
a
provides specific equations to apply the interpolation method and degradation coefficient method to units with VERS
a

Decrease in ISMRE2 for units with staged capacity because excess dehumidification is not credited.
a

a
(AHRI, No. 7, pp. 8-9).

b
(CA IOUs, No. 6, pp. 6-7).

Comments from AHRI and the CA IOUs indicated that the various test procedure updates may generally lend to decreases in the dehumidification efficiency rating. (AHRI, No. 7, pp. 8-9; CA IOUs, No. 6, pp. 6-7)

2. Technical Analysis

DOE conducted investigative testing on four DX-DOASes and collaborated with Pacific Gas and Electric on testing of a fifth DX-DOAS to measure the average impact of the test procedure updates on the dehumidification efficiency metric.
22

A crosswalk consistent with the process prescribed at 42 U.S.C. 6293(e) would typically involve testing minimally compliant units, or in this case, testing units that had efficiencies at the minimum level specified in ASHRAE Standard 90.1-2019. As noted previously, ISMRE ratings for DX-DOASes are generally not available to determine which models may perform at the minimum ISMRE levels in ASHRAE Standard 90.1-2019. In its testing DOE determined that these DX-DOAS units had efficiencies above the ISMRE minima specified in ASHRAE Standard 90.1-2019. In order to account for this, DOE assessed the ISMRE-to-ISMRE2 crosswalk on the basis of an overall percent-change in the dehumidification efficiency metric, which can then be used to estimate the net impact of the updates to AHRI 920. The test results are summarized in Table IV.2.

22
Data from Sample No. 3 was collected as part of a collaboration between Pacific Gas & Electric and DOE. Sample point no. 3 is the result of testing one DX-DOAS with multiple control configurations, as discussed in section 2.2 of the CASD. These configurations investigated a range of staging, reheat, and airflow control options available to manufacturers for testing DX-DOASes within the allowances of ANSI/AHRI 920-2015 and AHRI 920-2020. The data shown in Table IV.4 for Sample point no. 3 are the average results of the control configurations tested. Data for each individual configuration is provided in the CASD.

Table IV.2—Investigative Testing Results

Sample No.
Equipment class
MRC at SRC A

ASHRAE
Standard 90.1
minimum
ISMRE

Tested
ISMRE

Tested
ISMRE2

Percent
change

1
AC w/o VERS
111 lb/h
4.0
5.1
5.7
+12%

2
AC w/o VERS
94 lb/h
4.0
7.6
6.4
−16%

3
AC w/o VERS
72 lb/h
4.0
4.6
5.2
+14%

4
AC w/ VERS
256 lb/h
5.2
6.9
6.0
−13%

5
WSHP w/ VERS
136 lb/h
4.8
8.6
6.8
−21%

Average

−5%

On average, the updates to AHRI 920 have a net impact of reducing the dehumidification efficiency ratings of DX-DOASes by five percent. These results are consistent with the comments provided by stakeholders indicating a general decrease in ratings. The tested units ranged from a reduction of 21% to an increase of 14%. The units which were negatively impacted by the test procedure changes were those which had the highest ISMRE ratings compared to the ASHRAE Standard 90.1-2019 minima (samples no. 2, 4, and 5). The units which had ISMRE ratings closer to the ASHRAE Standard 90.1-2019 minima (samples no. 1 and 3), by contrast, increased in rating; therefore, DOE tentatively does not expect DX-DOASes which are only minimally compliant with the ASHRAE Standard 90.1-2019 ISMRE levels to reduce in rating by more than five percent based on the limited test data available indicating that an increase in rating is possible for these designs. DOE would consider additional crosswalk data from DX-DOAS models which are minimally compliant with the ASHRAE Standard 90.1-2019 ISMRE levels should such data become publicly available.

Based on the available data, DOE is proposing ISMRE2 standards that are five percent lower than the ASHRAE Standard 90.1-2019 ISMRE levels. DOE's methodology is described in further detail in sections 2.2-2.3 of the CASD, and the resulting ISMRE2 levels are proposed in Table IV.4 of this NOPR.

C. ISCOP-to-ISCOP2 Crosswalk

1. Heating Efficiency Test Procedure Changes

DOE received comments from AHRI regarding the test procedure updates in AHRI 920-2020 which affect the heating efficiency rating. (AHRI, No. 7, pp. 8-9) These comments are presented in Table IV.3. DOE did not receive comments indicating the actual impacts of each test procedure update on the heating efficiency metric.

Table IV.3—Test Procedure Updates Impacting ISCOP-to-ISCOP2 Crosswalk

ANSI/AHRI 920-2015
AHRI 920-2020 & July 2021 test procedure NOPR

Specifies inlet (outdoor ventilation air and return air) dry bulb and wet bulb conditions for two SRCs E and F
Revises inlet conditions at SRCs E & F.

Specifies minimum required external static pressures (ESPs) for supply air streams as a function of supply airflow rate

Increases minimum required ESPs for supply air streams;
a
establishes minimum required ESPs for return air streams (for units with VERS).
a

Specifies weighting coefficients to calculate ISCOP from the coefficients of performance (COPs) at the two SRCs

Revises weighting coefficients;
a
re-labels efficiency metric as ISMRE2.
a

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2022-01375. Public record. Not legal advice.