CHAPTER 4. SCREENING ANALYSIS 

TABLE OF CONTENTS 

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

4.2 TECHNOLOGIES THAT DO NOT AFFECT DAILY ENERGY CONSUMPTION ... 4-2 

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

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

4.2.3 Variable Speed Compressors ............................................................................... 4-2 

4.2.4 Liquid-Suction Heat Exchangers ......................................................................... 4-3 

4.3 SCREENED-OUT TECHNOLOGIES ............................................................................ 4-3 

4.3.1 Thermoacoustic Refrigeration ............................................................................. 4-3 

4.3.2 Magnetic Refrigeration ........................................................................................ 4-3 

4.3.3 Electro-Hydrodynamic Enhanced Heat Transfer ................................................. 4-4 

4.3.4 Copper Rotor Motors ........................................................................................... 4-4 

4.4 REMAINING TECHNOLOGIES ................................................................................... 4-4 

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CHAPTER 4. SCREENING ANALYSIS
 

4.1 INTRODUCTION 

This chapter addresses the screening analysis that the U.S. Department of Energy (DOE) 

conducted in support of the ongoing energy conservation standards rulemakings for refrigerated 

bottled or canned beverage vending machines. These rulemakings are mandated by the Energy 

Policy Act of 2005 and are effective for equipment manufactured 3 years after the date of 

publication of this final rule establishing energy conservation standards. 

In the market and technology assessment (chapter 3), DOE presented an initial list of 

technologies that can reduce the energy consumption of refrigerated beverage vending machines. 

The goal of the screening analysis is to screen out technologies that will not be considered 

further in the rulemaking analyses. Some of the technologies considered in chapter 3 can reduce 

annual energy consumption under real-world conditions, but may not reduce daily energy 

consumption (DEC), as measured by the American National Standards Institute/American 

Society of Heating, Refrigerating and Air-Conditioning Engineers (ANSI/ASHRAE) Standard 

32.1–2004, Methods of Testing for Rating Vending Machines for Bottled, Canned, and Other 

Sealed Beverages. DOE removed from consideration those technologies that do not reduce DEC. 

DOE evaluated the remaining technologies using the screening criteria set forth in the Energy 

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

Section 325(o) 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)). 

EPCA also 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 for making a determination whether to eliminate from 

consideration any technology that presents unacceptable problems with respect to the following 

criteria: 

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 

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the standard, then that technology will be considered practicable to manufacture, install, and 

service. 

Adverse impacts on equipment utility or equipment availability. If DOE determines 

that a technology has 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, it 

will not be considered further. 

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

significant adverse impacts on health or safety, it will not be considered further. 

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

unacceptable effects on the policies stated in section 5(b) of the Process Rule, those technologies 

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

four criteria, it will be screened out. Section 4.3 below documents the reasons for eliminating any 

technology. 

4.2 TECHNOLOGIES THAT DO NOT AFFECT DAILY ENERGY CONSUMPTION 

As stated above, technologies that do not reduce DEC are not considered beneficial in the 

context of this rulemaking. Therefore, DOE removed the following technologies from 

consideration: higher efficiency expansion valves, condenser fan motor controllers, variable 

speed compressors, and liquid-suction heat exchangers (LSHXs). 

4.2.1 Higher Efficiency Expansion Valves 

Higher efficiency expansion valves can reduce the annual energy consumption of 

refrigerated beverage vending machines by adapting to varying loads and ambient conditions. 

Because ANSI/ASHRAE Standard 32.1–2004 is a steady-state test (i.e., there are no changes in 

refrigerated-product loading or ambient conditions), there is no opportunity for higher efficiency 

expansion valves to reduce DEC. 

4.2.2 Condenser Fan Motor Controllers 

Condenser fan motor controllers can adapt condenser operation to changing ambient 

temperatures, and thereby reduce annual energy consumption of beverage vending machines. 

However, because testing under the ANSI/ASHRAE Standard 32.1–2004 test procedure is 

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

condenser fan motor controller on DEC. 

4.2.3 Variable Speed Compressors 

Variable speed compressors reduce energy consumption under real-world conditions by 

matching their capacity to the refrigeration load, which can change due to variations in ambient 

conditions and product loading. This technology therefore eliminates the inefficiencies that occur 

due to mismatched capacity and load in a single-speed compressor during part-load operation. 

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Because the ANSI/ASHRAE Standard 32.1–2004 test procedure prescribes steady-state 

conditions, a variable speed compressor undergoing this test would be limited to single-speed 

operation. The resulting energy efficiency ratio would be no better than a properly sized singlespeed compressor, so there would be no appreciable energy savings. Similarly, under 

ANSI/ASHRAE Standard 32.1–2004, the performance of a high-efficiency variable-speed 

compressor would be comparable to a high-efficiency single-speed compressor. 

4.2.4 Liquid-Suction Heat Exchangers 

An LSHX is an indirect liquid-to-vapor heat transfer device that evaporates any residual 

liquid refrigerant remaining in an evaporator discharge line, and thereby minimizes the risk of 

liquid refrigerant carrying over to the compressor suction. In general, LSHXs are installed in 

refrigeration systems to ensure proper system operation and increasing system performance. Due 

to the combination of refrigerant type, operating temperature, ambient conditions, and other 

factors, an LSHX does not consistently reduce DEC, as measured by the ANSI/ASHRAE 

Standard 32.1–2004 test procedure. 

4.3 SCREENED-OUT 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. Four technologies were screened out: thermoacoustic refrigeration, magnetic 

refrigeration, electro-hydrodynamic (EHD) heat exchangers, and copper rotor motors. 

4.3.1 Thermoacoustic Refrigeration 

Thermoacoustic refrigeration uses high-amplitude sound waves in a pressurized gas to 

pump heat from one place to another. Because this technology is in the research stage, DOE 

believes that 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. 

Because this technology is in the research stage, DOE also cannot assess whether thermoacoustic 

refrigeration will have any adverse impacts on utility to significant subgroups of customers, 

result in the unavailability of any type of refrigerated beverage vending machines, or present any 

significant adverse impacts on health or safety. 

4.3.2 Magnetic Refrigeration 

Magnetic refrigeration is a cooling technology that is 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 refrigerated 

beverage vending machines. However, DOE understands that magnetic refrigeration is in the 

research stage and, therefore, believes that 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. Because this technology is in the research 

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stage, DOE also cannot assess whether it will have any adverse impacts on utility to significant 

subgroups of customers, result in the unavailability of any type of refrigerated beverage vending 

machines, or present any significant adverse impacts on health or safety. 

4.3.3 Electro-Hydrodynamic Enhanced Heat Transfer 

EHD enhancement of heat transfer is the result of applying a high-voltage 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 phase-change processes (e.g., boiling and condensation). Because 

EHD-enhanced heat transfer is in the research stage and is not being used in commercially 

produced or sold refrigerated beverage vending machines, DOE believes that 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. Because this technology is in the 

research stage, DOE also cannot assess whether it will have any adverse impacts on utility to 

significant subgroups of customers, result in the unavailability of any type of beverage vending 

machines, or present any adverse impacts on health or safety. 

4.3.4 Copper Rotor Motors 

Motor manufacturers have long known that substituting copper for die-cast aluminum in 

rotors would significantly reduce motor losses and improve electrical energy efficiency. 

However, manufacturing die-cast copper rotors requires specialized equipment, significant 

investment, and proprietary know-how 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 believes that 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 of the standard. Further, DOE cannot assess whether the manufacture and use of 

copper rotor motors would have any adverse impacts on the utility of refrigerated beverage 

vending machines to significant subgroups of customers, result in the unavailability of any type 

of refrigerated beverage vending machines, or present any significant adverse impacts on health 

or safety. 

4.4 REMAINING TECHNOLOGIES 

After eliminating those technologies that do not reduce DEC and do not meet the 

requirements of sections 4(a) and 5(b) of the Process Rule, DOE is considering the following 

technologies: 

 higher efficiency lighting 

 higher efficiency lighting ballasts 

 higher efficiency evaporator fan motors 

 evaporator fan motor controllers 

 higher efficiency evaporator fan blades 

 improved evaporator design 

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 low-pressure differential evaporators 

 improved or thicker insulation 

 defrost mechanism 

 higher efficiency compressors 

 improved condenser design 

 higher efficiency condenser fan motors 

 higher efficiency condenser fan blades 

 improved glass pack design (for Class A machines) 

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