CHAPTER 4. SCREENING ANALYSIS

TABLE OF CONTENTS

4.1 INTRODUCTION

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4.2 SCREENED

- OUT TECHNOLOGIES

................................ ................................ ............ 4

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4.3 TECHNOLOGIES THAT DO NOT IMPACT EER AS MEASURED

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4.3.1 Thermostatic Expansion Valves And Electronic Expansion Valves

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4.3.2 Thermostatic Cyclic Controls

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4.3.3 Multi

- speed Compressors

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4.4 TECHNOLOGY OPTIONS FOUND IN BASELINE UNITS

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4.5 TECHNOLOGY OPTIONS WITH INSUFFICIENT INFORMATION REGARDING

ENERGY EFFICIENCY BENEFITS

................................ ................................ .............. 4

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4.6 REMAINING TECHNOLOGY OPTIONS

................................ ................................ .... 4

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LIST OF TABLES

Table 4.4.1 Technologies Found in Common Baseline SPVU Designs

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Table 4.6.1 Retained Design Opti ons for SPVUs

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- i4.1 INTRODUCTION

This chapter discusses the screening analysis conducted by the U.S. Department of Energy (DOE) of the technology options identified in the market and technology assessment for

s ingle p ackage v ertical u nits (SPVUs) . In Chapter 3, the market and technology assessment, DOE presented an initial list of technology options that can be used to reduce energy consumption of SPVUs . The goal of the screening analysis is to identify any technology o ptions

that will be eliminat ed from further consideration in the rulemaking analyses.

The candidate technology options are assessed based on DOE analysis as well as inputs from stakeholders including manufacturers, trade organizations, and energy efficiency advocates. Technology op tions which are judged to be viable approaches for improving energy efficiency are retained as inputs to the subsequent engineering analysis. Technology options that are not incorpor ated in commercial products or in working prototypes or fail to meet certa in criteria as to practicability to manufacture, install and service, as to impacts on product utility or availability,

or as to health or safety will be eliminated from consideration in accordance with 10 CFR 430, subpart C, appendix A, section 4(a)(4)(i

- iv ). Some of these technologies can reduce the annual energy consumption of SPVUs in actual applications but may not improve the energy efficiency ratio (EER) or the coefficient of performance (COP) of SPVUs as measured by the DOE test procedure. Such tec hnologies also are not passed on to the engineering analysis for consideration because they would not be implemented as a result of more stringent energy conservation

standards.

Section 325(o) of the Energy Policy and Conservation Act ( EPCA ) establishes criteria for prescribing new or amended standards 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 jus tified. (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)) 10 CFR 430, “Procedures, Interpretations and

Policies fo r Consideration of New or Revised Energy Conservation Standards for Consumer Products” sets forth procedures to guide DOE in its consideration and promulgation of new or revised equipment energy conservation standards. These procedures elaborate on the st atutory 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 conservation standard. In particular, 10 CFR 430, subpart C, appendix A, section 4(a)(4)(i

- iv) guide DOE in determining whether to eliminate from consideration any technologies that present unacceptable problems with respect to the following criteria:

1. Technological feasibility

. DOE will consider technologies incorporated in commercial products or in working prototypes to be technologically feasible.

2. Practicability to manufacture, install, and service

. If mass production and reliable installation and servicing of a technology in commercial products could be achieved on the scale

necessary to serve the relevant market at the time the standard comes into effect, then DOE will consider that technology practicable to manufacture, install, and service.

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- 13. Adverse impacts on product utility or equipment availability

. If DOE determines a technology would have a significant adverse impact on the utility of the equipment to significant subgroups of customers, or would result in the unavailability of any covered equipment type with performance characteristics (including reliability), features, sizes, capacit ies, and volumes that are substantially the same as equipment generally available in the United States at the time, it will not consider this technology further.

4. Adverse impacts on health or safety

. If DOE determines that a technology will have significant adverse impacts on health or safety, it will not consider this technology further.

In sum, if DOE determines that a technology, or a combination of technologies, has unacceptable impacts based on the factors identified in 10 CFR 430, subpart C , appendix A, section 4(a)(4)(i

- iv) , 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. Further, certain technology options may be removed from consideration if it is determined that (1) they do not impact the efficiency metric as measured by the current test procedure; (2) they are already found in baseline units; or (3) there is little information documenting the efficiency benefits of the technology in SPVUs.

Se ctions 4.3, 4.4, and 4.5 list the technologies that were removed from consideration for each respective reason.

4.2 SCREENED

- OUT TECHNOLOGIES

This section describes the technologies that DOE eliminated for failure to meet one of the following four factors: ( 1) technological feasibility; (2) practicability to manufacture, install, and service; (3) impacts on equipment utility or equipment availability; and (4) adverse impacts on health or safety. DOE did not screen out any technologies based on these criteria

.

4.3 TECHNOLOGIES THAT DO NOT IMPACT EER AS MEASURED

DOE eliminated t hree technologies because they have no effect on or do not increase EER or COP as measured by the DOE test procedure

. T he test procedure measures efficiency at

full

- load steady

- state cond itions, and these technologies exhibit benefits at partial

- loads

. However, these technologies can reduce the energy consumption of SPVUs in actual applications since they affect cyclic operation. Although these technologies were not considered in the

eng ineering analysi s, DOE does not discourage their use by manufacturers

, because of their potential to reduce annual energy consumption. For each technology removed for this reason, DOE provided an explanation of why the technology does not affect EER and/o r COP

.

4.3.1 T h ermostatic Expansion Valves a nd Electronic Expansion V alves

DOE did not consider expansion valve technolog ies for SPVACs or SPVHPs. Thermostatic expansion valves (TXV) and electronic expansion valves (EEV) are both flow

control alternatives to the capillary tube . They meter the flow of refrigerant from the condenser

to the evaporator and adapt better to changes in operating conditions, such as those due to variations in ambient temperature, which affect the condensing temperature. SPVACs and SPVHPs are measured using the EER metric, with testing occurring at constant indoor and

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- 2outdoor temperature s . Therefore, the benefits of a TXV or EEV will not affect the EER rating of a SPVU because the orifice of the valve and the flow of refrigerant woul d remain constant during testing. As a result , DOE d id not consider TXVs or EEVs to be technologies for improving the

EER of SPVACs and SPVHP.

4.3.2 Thermostatic Cyclic Controls

Remote thermostatic cyclic controls offer seasonal energy savings by more accurately monitoring room temperature and allowing for modulation of performance to match room

conditions . However, this technology does not improve upon the steady state operation as measured with EER and COP. Thus, DOE is not considering this technolo gy option.

4.3.3 Multi

- speed Compressors

Two

- speed, variable

- speed, or modulating

- capacity compressors can increase efficiency over a broad operating range, but they do not inherently increase the efficiency at the SPVU rating point s . Because the DOE energy te st procedure specifies steady

- state maximum

- capacity conditions for evaluation of active mode efficiency, the speed of a variable

- speed compressor would remain at a constant maximum capacity (e.g. highest speed) during the test. As a result, there is no op portunity to measure the energy savings that such compressors can provide during

part

- load conditions, when, instead of cycling at high speed, they operate a reduced capacity to satisfy the load. In fact, the losses associated with the inverter board of a variable

- speed compressor would decrease the maximum

- capacity EER. Therefore, DOE did not further analyze this technology in the engineering analysis.

4.4 TECHNOLOGY OPTIONS FOUND IN BASELINE UNITS

After eliminating those technologies that do not increase EE R and screening out those technologies that do not meet the requirements of 10 CFR 430, subpart C, appendix A, section 4(a)(4)(i

- iv) , DOE identified the technologies commonly found in all SPVU baseline and more efficient equipment as listed in Table 4.4

. 1

. Although DOE did not consider these technologies as options for improving the efficiency in comparison to the baseline, the costs of these components was captured in the engineering analysis at the baseline efficiency level.

Table 4.4

. 1 Technologies Found in Common Baseline SPVU Designs

Increased Heat Transfer Surface Area Increased fin density

Incr eased Heat Transfer Coefficient Improved fin design (wavy

- fin) Improved tube design (rifled tubing) Hydrophilic film coating on fins

4.5 TECHNOLOGY OPTIONS WITH INSUFFICIENT INFORMATION

REGARDING ENERGY EFFICIENCY BENEFITS

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- 3Finally, DOE also could not analyze technology options that have little or no documentation regardin g improvements to the overall system’s energy efficiency. As noted in Chapter 3, SPVU manufacturers have been experimenting with microchannel heat exchangers

. However, DOE is not aware of any research or data that documents the effec t that microchannel heat exchangers ha ve on the energy efficiency of SPVUs. Therefore, DOE is not considering microchannel heat exchangers in its engineering analysis.

4.6 REMAINING TECHNOLOGY OPTIONS

After eliminating all the technologies options by the me thods described above , DOE

consider ed the technologies list ed in Table 4.6

. 1

. Each of these technologies was evaluated further in the subsequent engineering analysis.

Table 4.6

. 1 Retained Design Options for SPVUs

Increased Heat Transfer Surface Area

Increased frontal coil area Increased depth of coil Dual condensing heat exchangers Component Improvements Improved fan motor efficiency Improved compressor efficiency Improved fan blade efficiency

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