CHAPTER 4. SCREENING ANALYSIS

TABLE OF CONTENTS

4.1	 INTRODUCTION ........................................................................................................... 4­1
 

4.2	 TECHNOLOGIES THAT DO NOT AFFECT CALCULATED DAILY
 

ENERGY CONSUMPTION ........................................................................................... 4­2
 

4.2.1	 Higher Efficiency Expansion Valves................................................................... 4­2
 

4.2.2	 Condenser Fan Motor Controllers ....................................................................... 4­2
 

4.2.3	 Anti­Sweat Heater Controllers............................................................................. 4­3
 

4.2.4	 Liquid­Suction Heat Exchangers......................................................................... 4­3
 

4.3	 SCREENED­OUT TECHNOLOGIES............................................................................ 4­3
 

4.3.1	 Improved Air Curtains......................................................................................... 4­3
 

4.3.2	 Thermoacoustic Refrigeration ............................................................................. 4­4
 

4.3.3	 Magnetic Refrigeration ........................................................................................ 4­4
 

4.3.4	 Electro­Hydrodynamic Enhanced Heat Transfer................................................. 4­4
 

4.3.5	 Copper Rotor Motors........................................................................................... 4­5
 

4.4	 REMAINING TECHNOLOGIES ................................................................................... 4­5
 

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CHAPTER 4. SCREENING ANALYSIS
 

4.1 INTRODUCTION
 

This document addresses the screening analysis that the U.S. Department of

Energy (DOE) conducted in support of the ongoing energy conservation standards

rulemakings for commercial refrigeration equipment (CRE), including commercial icecream freezers; self­contained commercial refrigerators, commercial freezers, and

commercial refrigerator­freezers without doors; and remote condensing commercial

refrigerators, commercial freezers, and commercial refrigerator­freezers. These

rulemakings are mandated by the Energy Policy Act of 2005 (EPACT 2005), and are

effective for equipment manufactured on or after January 1, 2012.

In the market and technology assessment (Chapter 3), DOE presented an initial

list of technologies that can reduce the energy consumption of commercial refrigeration

equipment. The goal of the screening analysis is to screen out technologies that will not

be considered further in the rulemaking analyses. DOE understands that some of the

technologies considered in Chapter 3 can reduce annual energy consumption under realworld conditions, but may not reduce calculated daily energy consumption (CDEC), as

measured by the American National Standards Institute/American Society of Heating,

Refrigerating and Air­Conditioning Engineers (ANSI/ASHRAE) Standard 72­2005,

Method of Testing Commercial Refrigerators and Freezers. Therefore, DOE removed

from consideration those technologies that have no effect or do not reduce CDEC. DOE

evaluated the list of remaining technologies using the screening criteria set forth in the

Energy Policy and Conservation Act (EPCA). (42 U.S.C. 6311­6317)

Section 325(o) of EPCA establishes criteria for prescribing new or amended

standards that are designed to achieve the maximum improvement in energy efficiency.

Further, EPCA directs the Secretary of Energy to determine whether a standard is

technologically feasible and economically justified. (42 U.S.C. 6295(o)(2)(A), as

directed by 42 U.S.C. 6316(a)(1)­(3). In addition, EPCA establishes guidelines for

determining whether a standard is economically justified. (42 U.S.C. 6295(o)(2)(B)) In

view of the EPCA requirements for determining whether a standard is technologically

feasible and economically justified, Appendix A to subpart C of Title 10, Code of Federal

Regulations, Part 430 (10 CFR Part 430), “Procedures, Interpretations, and Policies for

Consideration of New or Revised Energy Conservation Standards for Consumer

Products” (the Process Rule), sets forth procedures to guide DOE in its consideration and

promulgation of new or revised efficiency standards. These procedures elaborate on the

statutory criteria provided in 42 U.S.C. 6295(o) and, in part, eliminate problematic

technologies early in the process of prescribing or amending an energy efficiency

standard. In particular, sections 4(b)(4) and 5(b) of the Process Rule provide guidance to

DOE in determining whether to eliminate from consideration any technology that

presents unacceptable problems with respect to the following criteria:

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Technological feasibility. Technologies incorporated in commercial equipment

or in working prototypes will be considered technologically feasible.

Practicability to manufacture, install, and service. If mass production of a

technology in commercial equipment and reliable installation and servicing of the

technology could be achieved on the scale necessary to serve the relevant market at the

time of the effective date of the standard, then that technology will be considered

practicable to manufacture, install, and service.

Impacts on equipment utility or equipment availability. If DOE determines

that a technology will have significant adverse impact on the utility of the equipment to

significant sub­groups of consumers, or result in the unavailability of any covered

equipment type with performance characteristics (including reliability), features, sizes,

capacities, and volumes that are substantially the same as equipment generally available

in the United States at the time, DOE will not consider it further.

Adverse impacts on health or safety. If DOE determines that a technology will

have significant adverse impacts on health or safety, DOE will not consider it further.

In sum, if DOE determines that a technology, or a combination of technologies,

has unacceptable effects on the policies stated in section 5(b) of the Process Rule, it will

be eliminated from consideration. If a particular technology fails to meet one or more of

the four criteria, it will be screened out. The reasons for eliminating any technology are

documented in section 4.3.

4.2 TECHNOLOGIES THAT DO NOT AFFECT CALCULATED DAILY

ENERGY CONSUMPTION

The ANSI/ASHRAE Standard 72­2005 test procedure calls for a steady­state test.

So, technologies that only reduce energy use under transient conditions will not affect the

measured CDEC. Therefore, DOE removed the following technologies from

consideration: higher efficiency expansion valves, condenser fan motor controllers, antisweat heater controllers, and liquid­suction heat exchangers (LSHXs).

4.2.1 Higher Efficiency Expansion Valves

Higher efficiency expansion valves can reduce the annual energy consumption of

commercial refrigeration equipment by adapting to varying loads and ambient conditions.

Because ANSI/ASHRAE Standard 72­2005 is a steady­state test (i.e., there are no

changes in refrigerated­product loading or ambient conditions), there is no opportunity

for higher efficiency expansion valves to reduce CDEC. Consequently, DOE did not

consider higher efficiency expansion valves in the engineering analysis.

4.2.2 Condenser Fan Motor Controllers

Condenser fan motor controllers can adapt condenser operation to changing

ambient temperatures (effectively by creating floating head pressure), and thereby reduce

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annual energy consumption of self­contained commercial refrigeration equipment.

However, because testing under the ANSI/ASHRAE Standard 72­2005 test procedure is

conducted at a constant temperature, there is no opportunity to account for the adaptive

technology of a condenser fan motor controller to reduce CDEC. Therefore, DOE did not

consider condenser fan motor controllers in the engineering analysis.

4.2.3 Anti­Sweat Heater Controllers

A CRE manufacturer typically sizes anti­sweat heaters according to the maximum

ambient temperature and humidity of a particular operating environment. The end­user

must maintain that environment to prevent condensation (i.e., fog) from forming on

surfaces such as display case glass. Anti­sweat heater controllers modulate the operation

of anti­sweat heaters by reducing anti­sweat heater power when humidity is low. Antisweat heater controllers operate most effectively when the dew point cannot be constantly

maintained. Because the ANSI/ASHRAE Standard 72­2005 test procedure is conducted

at a constant temperature and humidity, there is no opportunity to account for the

adaptive technology of an anti­sweat heater controller to reduce CDEC. Therefore, DOE

did not consider anti­sweat heater controllers in the engineering analysis.

4.2.4 Liquid­Suction Heat Exchangers

An LSHX is an indirect liquid­to­vapor heat transfer device that evaporates any

residual liquid refrigerant that remains in the evaporator discharge line, and thereby

minimizes the risk of liquid refrigerant carrying over to the compressor suction.

Generally, LSHXs are installed in refrigeration systems to ensure proper system

operation and increase system performance. However, the combination of refrigerant

type, operating temperature, ambient conditions, and other factors determines whether an

LSHX will increase or decrease the CDEC as measured by the ANSI/ASHRAE Standard

72­2005 test procedure. Because an LSHX does not consistently reduce CDEC, DOE did

not consider this technology in the engineering analysis.

4.3 SCREENED­OUT TECHNOLOGIES

This section addresses the technologies that DOE screened out because they did

not meet the requirements of sections 4(a) and 5(b) of the Process Rule. DOE considered

the following four factors: (1) technological feasibility; (2) practicability to manufacture,

install, and service; (3) adverse impacts on equipment utility to consumers; and (4)

adverse impacts on health or safety. The technologies that were screened out are air

curtain design, thermoacoustic refrigeration, magnetic refrigeration, electrohydrodynamic (EHD) heat exchangers, and copper rotor motors.

4.3.1 Improved Air Curtains

An air curtain is a fan­powered device that creates a moving wall (curtain) of air,

which separates two spaces of different temperatures. The curtain prevents the loss of

refrigerated air from the display area of semivertical commercial refrigerators, for

example, and prevents the entry of warm ambient air. Since improved air curtains are in

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the research stage, it would not be practicable to manufacture, install, and service this

technology on the scale necessary to serve the relevant market at the time of the effective

date of the standard. Also, because this technology is in the research stage, DOE cannot

assess whether improved air curtains will have any adverse impacts on utility to

significant sub­groups of consumers, result in the unavailability of any type of

commercial refrigeration equipment, or present any significant adverse impacts on health

or safety. Therefore, DOE screened out improved air curtains as a design option for

improving the energy efficiency of commercial refrigeration equipment.

4.3.2 Thermoacoustic Refrigeration

Thermoacoustic refrigeration uses high­amplitude sound waves in a pressurized

gas to pump heat from one place to another. This technology is in the research stage.

Consequently, it would not be practicable to manufacture, install, and service on the scale

necessary to serve the relevant market at the time of the effective date of the standard.

DOE also cannot assess whether thermoacoustic refrigeration will have any adverse

impacts on utility to significant sub­groups of consumers, result in the unavailability of

any type of commercial refrigeration equipment, or present any significant adverse

impacts on health or safety. Therefore, DOE screened out thermoacoustic refrigeration as

a design option for improving the energy efficiency of commercial refrigeration

equipment.

4.3.3 Magnetic Refrigeration

Magnetic refrigeration is a cooling technology based on the magnetocaloric effect

in which a reversible change in temperature of a suitable material is caused by exposing

the material to a changing magnetic field. Magnetic refrigeration can be used to attain

extremely low temperatures and can be adapted to the cooling temperatures used in

common commercial refrigeration equipment. However, magnetic refrigeration is in the

research stage and, therefore, it would not be practicable to manufacture, install, and

service this technology on the scale and in the timeframe necessary to serve the relevant

market at the time of the effective date of the standard. DOE also cannot assess whether

it will have any adverse impacts on utility to significant sub­groups of consumers, result

in the unavailability of any type of commercial refrigeration equipment, or present any

significant adverse impacts on health or safety. Therefore, DOE screened out magnetic

refrigeration as a design option for improving the energy efficiency of commercial

refrigeration equipment.

4.3.4 Electro­Hydrodynamic Enhanced Heat Transfer

EHD enhancement of heat transfer is the result of applying a high­voltage

electrostatic potential field across a heat transfer fluid, such as a refrigerant or refrigerant

mixture. The applied field destabilizes the thermal boundary layer, thereby producing

better mixing of the bulk fluid flow and increasing the net heat transfer coefficient. This

procedure appears to be more effective when applied to phase­change processes (e.g.,

boiling and condensation). Because EHD enhanced heat transfer is in the research stage

and is not used in commercially produced or sold commercial refrigeration equipment, it

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would not be practicable to manufacture, install, and service this technology on the scale

necessary to serve the relevant market at the time of the effective date of the standard.

Also, because this technology is in the research stage, DOE cannot assess whether it will

have any adverse impacts on utility to significant sub­groups of consumers, result in the

unavailability of any type of commercial refrigeration equipment, or present any adverse

impacts on health or safety. Therefore, DOE screened out EHD enhanced heat transfer as

a design option for improving the energy efficiency of commercial refrigeration

equipment.

4.3.5 Copper Rotor Motors

Motor manufacturers have long known that substituting copper for die­cast

aluminum in rotors would significantly reduce motor losses and improve electrical

energy efficiency. However, manufacturing die­cast copper rotors requires specialized

equipment, significant investment, and proprietary know­how that are not yet suitable for

production of the millions of motors produced annually. DOE recognizes the advantages

of this significant advance in motor technology, but it would not be practicable to

manufacture, install, and service copper rotor motors on the scale necessary to serve the

relevant market at the time of the effective date the standard. Further, DOE cannot assess

whether the manufacture and use of copper rotor motors would have any adverse impacts

on the utility of commercial refrigeration equipment to significant sub­groups of

consumers, result in the unavailability of any type of commercial refrigeration

equipment, or present any significant adverse impacts on health or safety. Therefore,

DOE screened out copper rotor motors as a design option for improving the energy

efficiency of commercial refrigeration equipment.

4.4 REMAINING TECHNOLOGIES

After eliminating those technologies that do not reduce CDEC and screening out

technologies that do not meet the requirements of sections 4(a)(4) and 5(b) of the Process

Rule, DOE is considering the following technologies:

• higher efficiency lighting

• higher efficiency lighting ballasts

• remote lighting ballast location

• higher efficiency evaporator fan motors

• evaporator fan motor controllers

• higher efficiency evaporator fan blades

• increased evaporator surface area

• low­pressure differential evaporators

• improved or thicker insulation

• defrost mechanisms

• defrost cycle controls

• higher efficiency compressors (self­contained equipment only)

• increased condenser surface area (self­contained equipment only)

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• higher efficiency condenser fan motors (self­contained equipment only)

• higher efficiency condenser fan blades (self­contained equipment only)

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