CHAPTER 4.SCREENING ANALYSIS

TABLE OF CONTENTS

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

4.2 SCREENED-OUT TECHNOLOGIES............................................................................ 4-2

4.3 TECHNOLOGIES THAT DO NOT IMPACT EER AS MEASURED.......................... 4-2

4.3.1 Thermostatic Expansion Valves And Electronic Expansion Valves................... 4-2

4.3.2 Thermostatic Cyclic Controls.............................................................................. 4-3

4.3.3 Multi-speed Compressors.................................................................................... 4-3

4.4 TECHNOLOGY OPTIONS FOUND IN BASELINE UNITS ....................................... 4-3

4.5 TECHNOLOGY OPTIONS WITH INSUFFICIENT INFORMATION REGARDING 

ENERGY EFFICIENCY BENEFITS.............................................................................. 4-3

4.6 REMAINING TECHNOLOGY OPTIONS .................................................................... 4-4

LIST OF TABLES

Table 4.4.1 Technologies Found in Common Baseline SPVU Designs...................................... 4-3

Table 4.6.1 Retained Design Options for SPVUs........................................................................ 4-4

4-i
4.1 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 

single package vertical units (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 options 

that will be eliminated 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 options 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 

incorporated in commercial products or in working prototypes or fail to meet certain 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 technologies 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 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)) 10 CFR 430, “Procedures, Interpretations and 

Policies for 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 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 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.

4-1
3. 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, capacities, 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. 

Sections 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 three technologies because they have no effect on or do not increase 

EER or COP as measured by the DOE test procedure. The test procedure measures efficiency at

full-load steady-state conditions, 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 

engineering analysis, 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/or COP.

4.3.1 Thermostatic Expansion Valves and Electronic Expansion Valves

DOE did not consider expansion valve technologies for SPVACs or SPVHPs. 

Thermostatic expansion valves (TXV) and electronic expansion valves (EEV) are both flowcontrol 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 

4-2
outdoor temperatures. 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 would remain constant during 

testing. As a result, DOE did 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 technology 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 

points. Because the DOE energy test 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 opportunity 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 EER 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

Increased 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

4-3
Finally, DOE also could not analyze technology options that have little or no 

documentation regarding 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 effect that microchannel 

heat exchangers have 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 methods described above, DOE 

considered the technologies listed 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 

4-4