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APPENDIX L: THROUGH-THE-WALL PRODUCTS

L.1 INTRODUCTION

Some residential unitary products are designed primarily as replacement products to fit within

an existing building space with fixed dimensions. The fixed space, which might be either an interior

enclosure, a part of the building’s envelope, or both, can constrain the product’s ability to improve

efficiency using the same options available to products that do not face the same constraints,

particularly increasing heat exchanger surface. Section 4.6 of the Engineering Analysis chapter of

this TSD provides additional information on these space-constrained products which are also known

as niche-products.

Products that install through an exterior wall are particularly susceptible to those constraints

since they must exchange outdoor air through a single surface and fit within an existing wall opening

with fixed dimensions that can be costly to modify. These products are termed Through-the-Wall

(TTW) equipment. Two distinct versions of TTW products are identified: the condensing unit of

a split-system air conditioner or heat pump; and a single-package air conditioner or heat pump. The

purpose of this appendix is to provide a detailed description of the engineering methodology and

results used to estimate the cost of achieving efficiency improvements in TTW products and the

consumer economic analyses resulting from those improvements. The engineering analysis is

presented in Section L.2 and the consumer economic analysis is presented in Section L.3.

L.2 ENGINEERING ANALYSIS

The engineering analysis for TTW products consisted of the purchase and evaluation of three

common TTW units to identify efficiency improvement opportunities and estimate the

manufacturing cost and retail price impacts of implementing those efficiency improvements. We

evaluated three through-the-wall (TTW) products from two manufacturers as shown in Table L.2.1.

The products include samples that the manufacturers identified as being the most constrained (2.5

tons cooling) as well as one sample that is a prevalent model but is less constrained (1.5 tons

cooling). We evaluated two split systems (SAC 1.5 Ton and SAC 2.5 Ton) and one packaged system

(PAC). Along with the split TTW condensers, we obtained the matching split fancoil. However,

since producers of split TTW condensers do not typically design or specify their own fancoils, we

did not consider possible improvements to the fancoil as part of our analysis.

The purpose of our evaluations was to estimate the manufacturing cost impacts of achieving

performance improvements (as measured by SEER) in the range of 10 to 30 percent. This range of

performance improvement corresponds to increasing SEER from 10 to between 11 and 13. Our

evaluations included both laboratory tests and spreadsheet analyses. We did not evaluate any heat

pumps, so we did not attempt to evaluate possible improvements in Heating Seasonal Performance

Factor (HSPF) ratings. However, we believe that the HSPF-SEER relationship expressed in Section

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4.8.1 of this TSD based on examination of all available residential unitary heat pumps also applies

to TTW products.

Table L.2.1 TTW Products Evaluated

Manufacturer Description Published

SEER

Short-Hand

Designation

A 1.5 ton air-conditioning

condensing unit

10.0 SAC 1.5 Ton

A 2.5 ton air-conditioning

condensing unit

10.0 SAC 2.5 Ton

B 2.5 ton packaged air

conditioner with gas-fired

heater1

9.7 PAC

1) We did not include the gas-fired heater in our manufacturer-cost analysis.

L.2.1 Physical Characteristics of Baseline Products

Baseline products are those unmodified products listed in Table L.2.1 as we received them

from the distributors. Table L.2.2 describes the key components we observed in the baseline

products.

Table L.2.2 Key Components of TTW Products

Component SAC 1.5 Ton SAC 2.5 Ton PAC

Compressor Reciprocating (10.7

EER)

Reciprocating (10.9

EER)

Scroll (10.9 EER)

Condenser Air Mover Forward-Inclined Blower Forward-Inclined Blower Propeller Fan 

Condenser Motor 1⁄4 Hp, 1140 RPM, PSC,

67.1% Efficiency

1⁄4 Hp, 1140 RPM, PSC,

67.1% Efficiency

1/4 Hp, 1075 RPM, 60%

Efficiency

Condenser Coil 3/8” rifled-tube, 3 rows

deep by 17 tubes high,

lanced fin, 16 fpi, 26.5”

by 16.5” face

3/8” rifled-tube, 4 rows

deep by 17 tubes high,

lanced fin, 16 fpi, 26.5”

by 16.6” face

3/8” rifled tube, 4 rows

deep by 20 tubes high,

single-sine-wave fin, 18

fpi, 24.0” by 20.0” face

Expansion Device -- -- Capillary Tubes (4 in

parallel)

Evaporator Air Mover -- -- Confidential

Evaporator Fan Motor -- -- 1/3 Hp, 1120 RPM, 3

speed, 63% Efficiency

Evaporator Coil -- -- 3/8” rifled-tube, 4 rows

deep by 16 tubes high,

single-sine-wave fin, 14

fpi, 24.0” by 16.0” face

L.2.2 Modeling TTW Efficiency

To serve as a basis for our analysis of possible efficiency improvements, we developed

spreadsheet models for each TTW product based on the compressor manufacturers’ performance

maps, generalized fan performance curves, and available test data (including detailed data from

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a

 See Code of Federal Regulations – Energy; Office of the Federal Register, National Archives and Records

Administration; January 1, 1999 revision; Subpart B; Appendix M.

b Super Radiator Coil Selection Programs, Version 1.71G; Super Radiator Coil; April 17, 1998.

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performance certification tests). The compressor manufacturer’s performance maps were curve fit

using polynomial equations for cooling capacity, compressor power, and refrigerant mass-flow rate

for each compressor. We estimated SEER using the compressor performance map and condenser

performance characteristics inferred from results of Test B of the SEER test procedure.a Based on

the condenser blower power draw (from the equipment manufacturer) and total power draw (from

Test B), we determined compressor power draw. Using the compressor performance map at a 45°F

evaporating temperature, we determined the condensing temperature that best matched the

compressor power draw and the Test B cooling capacity.

Condenser heat rejection is equivalent to the sum of evaporator capacity and compressor

power draw, less heat loss from the compressor shell and the discharge line. Using the evaporator

capacity (from Test B), the compressor power draw, and the assumed compressor shell and discharge

line heat loss, we calculated condenser heat rejection.

We characterized the performance of outdoor blowers and fans using three parameters:

pressure coefficient, flow coefficient, and specific speed. We modeled the SAC blowers using

published impeller data for wheel sizes ranging from 4 in. to 8 in. in diameter. We modeled the PAC

condenser fan using published propeller fan data for diameters from 16 in. to 20 in. We calculated

the three parameters for each blower/fan size and type. We then correlated pressure and flow

coefficients as a function of specific speed. These correlations allowed us to evaluate the

performance of any size blower or fan at any flow rate and static pressure.

Using a commercially available heat exchanger sizing programb

, we estimated the pressure

drop through the condenser. We approximated the balance of condenser-air static pressure loss

based on each unit’s specific blower/fan power draw (supplied by the equipment manufacturer) and

performance curve. The pressure loss associated with the velocity pressure is twice the velocity

head.

Based on condenser heat rejection, condenser airflow (either from the equipment

manufacturer or a different airflow selected for analysis), and the air temperature entering the

condenser (82°F for Test B), we calculated the air temperature leaving the condenser. Based on the

condensing temperature and the entering and leaving air temperatures, we calculated the condenser

log mean temperature difference (LMTD).

We assumed that the condenser LMTD remains roughly constant as condenser airflow rate

changes. We used the compressor performance map iteratively to find a condensing temperature that

resulted in roughly matching the target LMTD. We then calculated SEER using:

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c

 A Degradation Coefficient of 0.25 corresponds to a Part-Load Performance Factor (PLF(0.5)) of 0.875.

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• 365 W evaporator power draw per 1000 cfm through the evaporator and 400 cfm/ton cooling

capacity (from the SEER test procedure);

• Condenser blower/fan power draw from a) the manufacturer, if condenser airflow rate is not

varied, or b) the blower/fan correlations described above, if condenser airflow rate is varied;

and

• A Degradation Coefficient (CD) of 0.25 (from the SEER test procedure).c

Using this analytical approach, we predicted the performance of the equipment we evaluated

and compared it to the published performance for each unit (see Table L.2.3). Predicted performance

fell within 11 percent of actual performance, which is acceptable given the degree of simplification

inherent in our approach. To reduce the effects of the disparities in baseline performance predictions,

we express any predicted efficiency improvements as percentages relative to the manufacturers’

published baseline SEER ratings rather than as absolute SEER adders.

Table L.2.3 Comparison of Published and Calculated Performance for Baseline Units

SAC 1.5 Ton SAC 2.5 Ton PAC

Calculated SEER 9.79 9.21 10.76

Published SEER 10.0 10.0 9.7

Percent Difference - 2.1% - 7.9% + 10.9%

L.2.3 Design Options

To analyze the cost and efficiency impacts of modifications to the design or components of

the baseline equipment, we utilized the “design option” approach. In this approach, we analyze

individual options and assess their impacts on system efficiency, rather than analyzing system

efficiency and drawing conclusions regarding the design options utilized to attain an efficiency level.

L.2.3.1 General Approach to Evaluating Design Options

We focused our evaluation on component changes and other performance improvement

options that are:

• Apparent to a typical experienced design engineer and manufacturer;

• Compatible with current manufacturing processes;

• Readily available from suppliers;

• Moderate in manufactured cost impact; and

• Consistent with the physical size constraints for these products (i.e., do not increase overall

package dimensions).

Table L.2.4 lists the performance improvement options considered. Each option is discussed

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further in Section L.2.3.2.

Table L.2.4 Performance Improvement Options Evaluated/Recommended

Option SAC 1.5 Ton SAC 2.5 Ton PAC

Eval. Rec. Eval. Rec. Eval. Rec.

Reduce Cabinet/Panel Air Leakage X X X X X

Dual Condenser Blowers1 XXXX

Increase Condenser Blower Outlet Area1 X X

Increase Condenser Airflow Rate X X X X X X

Improve Condenser Airflow Distribution X X X

Reduce Condenser Air Recirculation X X X

Higher-Efficiency Compressor X X X X X X

Mount Condenser Fan Above Condenser2, 3 X X

Mount Dual Fans Above Condenser2,4 X

Taller Condenser5 X

Higher-Efficiency Condenser Fan Motor X X

Improve Evaporator Airflow Distribution6 X X

Improve Evaporator Refrigerant Distribution X

1) Mutually exclusive options.

2) Mutually exclusive options.

3) Mounting the fan above the condenser should improve condenser airflow in the PAC unit, but we did not attempt

to quantify the benefit or take credit for it in our analysis.

4) The only benefit of dual condenser fans is to allow more space for a taller condenser.

5) Taller condensers were not evaluated for the SAC units due to space constraints.

6) Modifying the design of the air-filter-mounting bracket may improve evaporator airflow distribution in the PAC unit,

but we did not attempt to quantify the benefit or take credit for it in our analysis.

Emerging technologies were not considered because they do not meet the criteria listed above

for ease of implementation and moderate cost impact. Manufacturers of mainstream residential airconditioning products can achieve performance levels at or above those attainable by TTW

equipment without employing these options. Therefore, we did not consider it appropriate to

consider performance levels that would require use of emerging technologies for TTW products.

Some performance-improvement options were ruled out based on simple inspection or

physical size constraints. Others required a combination of laboratory testing and analysis to

evaluate. We did not attempt to demonstrate experimentally that the recommended design changes

would result in the estimated performance improvements.

In the discussions below, we provide only brief discussions of the options not recommended,

but provide a more thorough discussion of options that we recommend (i.e., that meet the criteria

of being relatively easy to implement and of moderate cost impact.)

L.2.3.2 Discussion of Individual Design Options

L.2.3.2.1 Reduce Cabinet/Panel Air Leakage

Residential air-conditioning products generally incorporate sheet metal parts for cabinets,

access panels, dividers (for example, between the hot and cold sides of a packaged unit), fan shrouds,

blower housings, ducts, etc. Product design, dimensional tolerances on sheet metal parts, sealing

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techniques, and assembly techniques, and other factors determine the extent to which air can bypass

heat exchangers, leak into or out of ducts, and/or recirculate around air movers. All of these

potential air-leakage paths can reduce performance, and eliminating significant air-leakage paths can

be a very cost-effective way to improve performance.

The air-leakage tests performed on each unit are discussed in Sections L.2.3.2.1.1 through

L.2.3.2.1.3 below, and results are presented in Section L.2.3.2.1.4.

L.2.3.2.1.1 Air Leakage in SAC 1.5 Ton Unit

Upon inspection of the SAC 1.5 Ton unit, we found some obvious airflow leakage paths,

including:

• Back access panel seal with cabinet; 

• Knockouts for refrigeration piping and electrical wiring;

• Blower housing mount; and

• Excessive gap between blower wheel and blower housing.

To assess the performance penalty associated with eliminating most of the major leakage

paths, we measured the total airflow through the unit as received, and again after sealing leakage

paths with silicone rubber caulk and duct tape. We then estimated the impact on system performance

associated with the increase in condenser airflow. We did not attempt to reduce the gap between the

blower housing and blower wheel, so any improvement associated with this would be in addition to

our estimate.

We conducted the total airflow tests with no load on the condenser. We used a 12” x 12”

vortex-shedding flow meter, connected to the unit’s condenser air inlet with transition ductwork.

We used sections of straight duct both upstream and downstream of the flow meter as recommended

by the flow-meter manufacturer. We recorded airflow measurements for 3 to 5 minutes and averaged

the results. We repeated each test three times, then averaged the three results for a final average flow

rate.

Since we suspected that the back panel and the piping/wiring cutouts were responsible for

most of the leakage, we repeated the tests with no sealing in these areas (referred to as the partially

sealed test).

The results of these tests are shown in Section L.2.3.2.1.4 below.

L.2.3.2.1.2 Air Leakage in SAC 2.5 Ton Unit

The SAC 2.5 Ton unit exhibited similar leakage paths, except that the unit we received had

been factory sealed (using a silicone rubber caulk) around the blower housing mount. We performed

total air-flow tests as outlined above for the SAC 1.5 Ton unit, except that we didn’t perform the

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partially sealed test as it would have been no different than testing the unit as received.

We do not know whether the manufacturer uses silicone rubber caulking on all 2.5 ton units

and none of the 1.5 ton units, whether they caulk any unit when in their judgement its warranted, or

whether they have some other basis for use of caulk.

L.2.3.2.1.3 Air Leakage in PAC Unit

In our judgement, the PAC unit is designed and manufactured with good attention to airflow

leakage, consistent with normal practice for residential air-conditioning products. While there may

be room for minor improvements (such as a small leak path around the evaporator blower), we doubt

significant performance improvement would result. We tested the PAC unit as received, consistent

with the procedure outlined above for the SAC units. We did not, however, attempt to seal leakage

paths and retest.

L.2.3.2.1.4 Results of Air-Leakage Evaluation

Table L.2.5 lists the results of the total airflow tests. Obviously, the approach we used to

measure airflow introduces significant pressure losses that will not be present in installed units.

However, we used the test results to calculate a percentage change in airflow only, and we did not

use the absolute results in evaluating impact on performance.

Table L.2.5 Total Airflow Test Results

Unit Flow Rate as

Received1

Flow Rate when

Partially Sealed2

Flow Rate when

Fully Sealed

Average Increase

in Flow Rate

SAC 1.5 Ton 690 cfm

700 cfm

690 cfm

710 cfm

715 cfm

705 cfm

730 cfm

725 cfm

730 cfm

5%

SAC 2.5 Ton 695 cfm

700 cfm

700 cfm

--

755 cfm

750 cfm

750 cfm

8%

PAC 1140 cfm

1160 cfm

1160 cfm

-- -- --

1) The experimental apparatus used to measure airflow places additional resistance in the airflow path. Therefore,

these measurements do not correspond to normal condenser airflow as installed.

2) The back panel (including cutouts for piping and wiring) was left unsealed for this test.

We then estimated the system performance impact associated with increased condenser

airflow using the analytical approach described in Section L.2.2 (but assuming constant blower

power draw). We conducted this analysis for the SAC 2.5 Ton unit only, and assumed the

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performance improvement estimates (as percentages) would apply to the SAC 1.5 Ton unit as well.

We investigated condenser airflow-rate increases ranging from 0 to 20 percent (see Table L.2.6).

Table L.2.6 Estimated Performance Improvement Associated with Increased Condenser

Airflow (at no Increase in Power Draw)

Percent Increase in Airflow 0% 5% 10% 20%

Evaporating Temperature 45°F 45°F 45°F 45°F

Condensing Temperature 116.4°F 114.8°F 113.6°F 111.3°F

 System Performance Multiplier1 -- 1.02 1.04 1.07

1)Performance relative to normal airflow (0 percent increase). Assumes no increase in condenser air-mover power draw.

Table L.2.7 summarizes the estimated system performance improvements associated with

reducing air-leakage paths. Again, these estimates do not include improvements associated with

reducing clearances between the blower wheel and blower housing. Although it does not impact

SEER, the air leakage through the back panel and cutouts may impact installed performance by a

greater margin than reflected in Table L.2.6. For units installed in a conditioned space, conditioned

air will leak through the back panel and be discharged outdoors, resulting in increased infiltration

losses in the building. These losses would not impact the SEER rating, but certainly could impact

actual energy consumption in the field. 

Table L.2.7 Estimated System Performance Improvements Associated with Reduced Air

Leakage

SAC 1.5 Ton SAC 2.5 Ton

Increase in Airflow Rate1 5% 8%

System Performance Multiplier2 1.02 1.03

1) From Table L.2.5

2) From Table L.2.6, interpolating for the SAC 2.5 Ton unit.

L.2.3.2.2 Dual Condenser Blowers

The SAC 1.5 Ton and SAC 2.5 Ton units discharge air through a 4.5” by 28.5” rectangular

opening above the condenser. Both units have a blower housing discharge opening (4.5” by 9”) that

is much smaller than the available space. A larger blower housing discharge area would lower the

discharge velocity (keeping total airflow constant), thereby lowering pressure losses associated with

the abrupt expansion at the blower exit. One way to achieve a larger blower discharge area is to use

two blowers. A common motor having two shafts can drive the two blowers.

We used the general analytical approach described in Section L.2.2 to evaluate dual blowers.

Table L.2.8 lists the estimated system performance impact of using dual blowers in the SAC units.

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Table L.2.8 Estimated System Performance Improvements Associated with Dual Blowers

SAC 1.5 Ton SAC 2.5 Ton

Baseline1

 Airflow 900 cfm 1000 cfm

Baseline1

 Motor 1/2 hp 3/4 hp

Dual Blower Airflow 1000 cfm 1100 cfm

Dual Blower Motor 1/2 hp 3/4 hp

System Performance 1.04 1.04

1) “Baseline” refers to the current design employing a single blower.

L.2.3.2.3 Increase Condenser Blower Outlet Area

Another way to effect lower expansion losses at the blower exit for the SAC units is to

simply select a blower having a larger discharge area, but that is otherwise suitable for the

application. The blowers we found that had larger discharge areas exceeded the height available (4.5

inches). Suitable blowers may be available, or they certainly could be developed, but it is likely that

the associated performance improvements would be similar to those estimated for dual blowers in

Section L.2.3.2.2. Therefore, we did not consider this option further.

L.2.3.2.4 Increase Condenser Airflow Rate

Using the analytical approach described in Section L.2.2, we evaluated the system

performance impacts of changing condenser airflow rate. The results of our analytical modeling

suggest that, while the performance benefits may be modest, the condenser airflow may not be

optimized in any of the three units. We did not consider noise levels, however, and increasing

condenser airflow will, in general, increase noise. Table L.2.9 lists the estimated performance

multipliers associated with optimizing condenser airflow. 

Table L.2.9 Estimated System Performance Improvements Associated with Optimized

Condenser Airflow

SAC 1.5 Ton SAC 2.5 Ton PAC

Baseline Condenser Airflow Rate 700 cfm 900 cfm 1200 cfm

Baseline Motor 1/3 hp 1/2 hp 1/2 hp

Optimized Condenser Airflow Rate 900 cfm 1000 cfm 1400 cfm

Required Motor 1/2 hp 3/4 hp 3/4 hp

System Performance Multiplier 1.03 1.02 1.01

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L.2.3.2.5 Improve Condenser Airflow Distribution

We measured the condenser airflow distribution (at the condenser inlet) in each unit using

a digital anemometer (“hot-wire” probe). We rotated the probe to obtain the maximum reading at

each measurement point. We divided the face of each condenser into a grid, and measured air

velocity at the center of each grid section, reading a three-to-five second average. We repeated each

test three times and averaged the results. We normalized the results to the average velocity reading

over the face of the condenser. There was no load on the condensers during the tests. Tables L.2.10

to L.2.12 show the test results.

Table L.2.10 SAC 1.5 Ton – Condenser Airflow Distribution1

1.61 0.66 0.64 0.42 1.43

1.46 0.53 0.57 0.34 0.81

1.91 0.82 0.94 0.64 1.16

1.68 1.01 1.20 0.56 1.63

1) Measurements are normalized to the average velocity. The table is

oriented as if facing the upstream face of the condenser. Each grid

section is 5.33” by 4.125”. The condenser face is 26.5” long by 16.5”

high.

Table L.2.11 SAC 2.5 Ton – Condenser Airflow Distribution1

1.15 0.19 0.38 0.36 0.93

1.66 0.60 0.49 0.37 0.71

1.65 1.12 1.18 1.13 1.27

1.48 1.56 1.48 0.48 0.80

1) Measurements are normalized to the average velocity. The table is

oriented as if facing the upstream face of the condenser. Each grid

section is 5.33” by 4.125”. The condenser face is 26.5” long by 16.5”

high.

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Table L.2.12 PAC – Condenser Airflow Distribution1

0.95 1.04 1.09 1.13 0.96 0.87

1.08 1.10 1.12 1.10 1.03 0.94

1.06 1.08 1.05 1.15 1.03 0.95

0.98 1.00 1.01 1.10 0.96 0.92

0.97 0.90 0.93 1.02 0.81 0.68

1) Measurements are normalized to the average velocity. The

table is oriented as if facing the upstream face of the

condenser. Each grid section is 4” by 4”. The condenser face

is 24” long by 20” high.

While there is some airflow maldistribution in the SAC units (probably due to the blower

housing blocking part of the condenser and the orientation of the blower inlets), improving airflow

distribution can be difficult, especially given the tight packaging constraints. We did not include

improved condenser airflow distribution as a performance-improvement option.

L.2.3.2.6 Reduce Condenser Air Recirculation

Each of the TTW products evaluated exhausts condenser air directly above the inlet to the

condenser – which is probably the only practical way to package a TTW product. In the case of the

PAC unit, louvers covering the exhaust air plenum actually serve to direct air downward, in the path

of the air entering the condenser. (Presumably, the louvers are angled this way to divert rain.) Given

this configuration, some of the discharge air could become be drawn into the condenser inlet,

increasing the average inlet air temperature above ambient temperature.

We tested each unit using simple flow-visualization techniques to see if there was evidence

of condenser-air recirculation. While our test method was not quantitative, we judged the

recirculation effects to be minor for all three units. Therefore, we did not include reduced condenserair recirculation as a performance-improvement option.

L.2.3.2.7 Higher-Efficiency Compressor

We used the analytical approach described in Section L.2.2 to evaluate the performance

impacts of using higher-efficiency compressors. First, we identified a compressor having physical

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dimensions and a nominal cooling capacity similar to the baseline (current) compressor, but having

a higher rating-point efficiency. We approximated the performance of each higher-efficiency

compressor by simply multiplying the performance predicted for the baseline compressor by the ratio

of the rating-point efficiencies (EERs) for the baseline and higher-efficiency compressors. Table

L.2.13 lists the results. 

Table L.2.13 Estimated System Performance Improvements Associated with HigherEfficiency Compressors

SAC 1.5 Ton SAC 2.5 Ton PAC

Baseline Compressor Manufacturer AAB

Baseline Compressor EER1 10.7 10.9 10.9

Higher-Efficiency Compressor AAA

Higher-Efficiency Compressor EER1 11.1 11.5 11.5

System Performance Multiplier2 1.02 1.05 1.04

1) Compressor EER at ARI rating point.

2) System performance multiplier is not the ratio of compressor EERs, but rather the ratio of system SEERs.

L.2.3.2.8 Mount Condenser Fan above Condenser

We observed in the PAC unit that the condenser fan (mounted immediately downstream of

the condenser) discharges against the wall separating the indoor and outdoor portions of the unit.

This probably results in pressure losses that may be avoided by mounting the condenser fan above

the condenser, at the point the condenser air is discharged from the unit. While we recommend

consideration of this design change, we did not attempt to quantify its benefit, nor did we take credit

for it in our performance improvement estimates.

L.2.3.2.9 Mount Dual Fans Above Condenser

This is a variation on mounting a single condenser fan above the condenser in the PAC unit.

The only reason for considering dual fans (mounted side by side) is to allow additional room for a

taller condenser (see discussion in Section L.2.3.2.10). However, we judged that sufficient space

already exists above the condenser to mount a single fan and still increase condenser height by a

significant amount (up to 20 percent). While we didn’t perform an analysis, we judged that any

additional increase in condenser height permitted by dual fans is unlikely to improve performance

commensurate with the cost premium (for dual fans and taller condenser) and, therefore, did not

include it as a performance-improvement option.

L.2.3.2.10 Taller Condenser

The tight packaging of the SAC units precludes use of a condenser having increased face area

without increasing overall unit dimensions. The SAC condensers are already three and four rows

deep (for the SAC 1.5 Ton and SAC 2.5 Ton units, respectively) with significant airside pressure

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drop. Increasing condenser depth further will likely provide diminishing returns. However, the PAC

unit, which is much taller than the SAC units, provides ample space to increase condenser height

without impacting overall unit dimensions.

We used the approach outlined in Section L.2.2 to analyze a 20 percent increase in condenser

height in the PAC unit. This increase is consistent with the maximum height increase we judged to

be feasible while still permitting mounting of the condenser fan above the condenser (as discussed

in Section L.2.3.2.8). We maintained a constant condenser face velocity, resulting in a 20 percent

increase in condenser airflow (and an associated increase in condenser fan power draw). Our

analysis resulted in a system performance multiplier of 1.02 associated with a 20 percent taller

condenser. 

L.2.3.2.11 Higher-Efficiency Condenser Fan Motor

Each SAC unit uses a 67.1 percent (nominal) efficient, 1⁄4 Hp, Permanent Split Capacitor

(PSC) motor. This is a reasonably high efficiency for fractional horsepower motors without resorting

to expensive electronically commutated DC motors. The PAC unit, however, uses a 60 percent

(nominal) efficient, 1⁄4 Hp motor. We evaluated substituting a 67 percent efficient fan motor for the

60 percent efficient motor in the PAC unit, using the analytical approach outlined in Section L.2.2.

The resulting system performance multiplier is 1.01.

L.2.3.2.12 Improve Evaporator Airflow Distribution

We measured the evaporator airflow distribution (at the evaporator inlet) in the PAC unit,

using a test procedure similar to that described in Section L.2.3.2.5 for condenser airflow

distribution. Table L.2.14 shows the test results.

Table L.2.14 PAC – Evaporator Airflow Distribution1

1.13 0.70 0.82 0.84 0.83 0.87

1.42 1.21 1.14 1.03 1.04 0.96

1.24 1.27 1.21 1.17 1.26 1.01

0.82 0.50 0.39 1.37 1.10 0.75

1) Measurements are normalized to the average velocity. The

table is oriented as if facing the upstream face of the

evaporator. Each grid section is 4” by 4”. The evaporator face

is 24” long by 16” high. The air filter was removed during the

tests.

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d Technical Support Document for the Notice of Proposed Rulemaking for Central Air Conditioners and Heat Pumps;

65 FR 59950; October 5, 2000

L-14

The results show some maldistribution of airflow, especially in the lower left section. A

bracket used to support the air filter is a likely contributor to low airflow in the lower left section.

Redesign of this bracket is suggested. The evaporator is also mounted at an angle relative to the

airflow path, and the airflow path takes right-angle bends just upstream and just downstream of the

evaporator. With the physical constraints of the package, it may be difficult to improve airflow

distribution significantly. We, therefore, did not include it as a performance-improvement option.

L.2.3.2.13 Improve Evaporator Refrigerant Distribution

The PAC evaporator has eight parallel refrigerant circuits. Poor refrigerant distribution

among the circuits (caused, for example, by evaporator airflow maldistribution or uneven refrigerant

distribution to the circuits by the expansion device) could pose a significant system performance

penalty. We attempted to infer the nature of refrigerant distribution by measuring the superheat at

the exit of each refrigerant circuit. Unfortunately, the header design prevented making accurate

temperature measurements on individual circuits at their exits. We, therefore, settled for measuring

temperatures at exit of the seventh pass (of eight passes) on each circuit. We also measured

refrigerant temperature entering the fourth pass of each circuit (to provide refrigerant saturation

temperature), and the exiting refrigerant temperature downstream of the header (to determine overall

superheat) . We used wall-mounted, Type T thermocouples for all temperature measurements.

Given the limitations of our test procedure, we cannot conclude that no refrigerant

maldistribution was present. However, the test results did not show evidence of gross

maldistribution. Also, the evaporator and expansion device design suggest that reasonable measures

were taken to prevent maldistribution of refrigerant. We did not include improved evaporator

refrigerant distribution as a performance-improvement option.

L.2.4 Estimated Manufactured-Cost Impacts

As part of our previous work in support of the Notice of Proposed Rulemaking for central

air conditioners and heat pumps,d

 we developed a manufactured-cost model for a 3-ton air

conditioner based on reverse engineering. We expanded this model to include the three TTW

products. The key assumptions employed include:

• Annual production volumes of 10,000 units (down from 100,000 in the original model);

• TTW manufacturers out-source condenser and evaporator fabrication (consistent with current

practice for SAC and PAC);

• SAC out-sources all sheet-metal fabrication, paying a 50 percent vendor markup;

• PAC fabricates sheet-metal parts in house;

• Labor, packaging, and enclosure-material costs can be scaled, based on nominal cooling

capacity, from costs for 3-ton central air conditioners; and

 EE-RM-STD-98-440 COMMENT 312
L-15

• TTW manufacturing is seasonal. We assumed that plant capacity is double the average

production volume to allow for fluctuations in demand. (This plant capacity assumption has

little impact on manufactured costs due to the relatively low equipment utilization rates

associated with the production volumes.)

We updated cost estimates for all components costing more than $3, including compressors,

condensers, evaporators, motors, fans/blowers, and controls. The TTW model accounted for about

90 percent of the total unit cost. We based cost estimates for major components on actual vendor

quotations and estimated other component costs.

Table L.2.15 compares the baseline manufactured-cost estimates to those approximated by

backing out distribution-chain markups from wholesale equipment prices. The agreement is

generally very good – well within the estimated accuracy of the TTW cost model (+/- 15 percent).

Table L.2.15 Comparison of Baseline Estimated Manufactured Cost and Derivation of

Retail Price Estimate

SAC 1.5 Ton SAC 2.5 Ton PAC

Wholesale Price Paid $697.50 $892.50 $1495.00

Manufacturer Markup (Multiplier)1 1.23

Distributor Markup (Multiplier)1 1.37

Wholesale Price Less Markups $414 $530 $887

Estimated Cost Credit for Heating Package2 -- -- $50

Adjusted Wholesale Price Less Markups $414 $530 $837

ADL Reverse Engineering Model Prediction $443 $513 $887

Difference 6.6% -3.2% 5.6%

Estimated Adder for Indoor Unit3 $60 $73 --

Markup (Mfr cost to Retail)4 2.42

Estimated Retail Price $1221 $1422 $2153

1) Source: Technical Support Document for the Notice of Proposed Rulemaking for Central Air Conditioners and Heat

Pumps; 65 FR 59950; October 5, 2000; Pp. 4-19 and 4-20.

2) The PAC wholesale price includes a gas-heating package. We deducted the estimated manufactured cost of the

heating package to estimate the cost without a heating package.

3) Based on matched fancoil cost estimates derived from the reverse engineering analysis performed on mainstream

products as detailed in Appendix B and Appendix C.

4) See Appendix D.

Table L.2.16 lists estimated manufactured-cost adders (increases in the baseline cost

estimates listed in Table L.2.15) for the performance-improvement options judged to have the most

promise.

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L-16

Table L.2.16 Estimated Manufactured-Cost Adders

Option SAC 1.5 Ton SAC 2.5 Ton PAC

Reduce Cabinet/Panel

Air Leakage

Materials & Labor 

+$3

Materials & Labor 

+$3

--

Dual Condenser Blowers Difference between

Motor A (1/4hp) and

Blower A vs. Motor B

(1/3 hp) and dual Blower

B

+$33

Difference between

Motor A (1/4 hp) and

single Blower D vs.

Motor C (1/2 hp) and

dual Blower C

+$21

--

Increase Condenser

Airflow Rate

Difference between

Motor A (1/4 hp) and

Blower A vs. Motor B

(1/3 hp) and Blower C

+$5

Difference between

Motor A (1/4 hp) and

Blower D vs. Motor B

(1/3 hp) and Blower D

+$7

Difference between

Motor D (1/4 hp) and

Motor C (1/2 hp)

-$12

Higher-Efficiency

Compressor

Difference between

Compressor A and

Compressor B

(11.1 EER)

+$273

Difference between

Compressor C and

Compressor D

(11.5 EER)

+$244

Difference between

Compressor E and

Compressor F

+$245

Mount Condenser Fan

Above Condenser

-- -- Assume no change in

fan and no difference in

mounting cost

+$0

Higher-Efficiency

Condenser Fan Motor

-- -- Difference between

Motor E and Motor A

+$14

20% Taller Condenser -- -- Replace Heat Exchanger

A(24” x 20”) with one

20% taller

+$30

1) Cost estimates are derived from list retail prices, and hence included larger markups than an OEM would

normally pay. We cut the advertised prices by 40-60 percent as our estimate of the price the OEM would pay,

depending on market volume of the exact component.

2) For this motor type, the larger 1⁄2 hp motors are made at higher production volumes than equivalent 1⁄4 hp

motors, and are thus slightly less expensive. This effect will fluctuate with market conditions.

3) Assumes cost of the 11.1 EER compressor is the same as for a comparable 11.0 EER model.

4) Assumes cost of the 11.5 EER compressor is the same as for a comparable 11.4 EER model.

5) Assumes cost of the 10.9 EER compressor is the same as for a comparable 10.9 EER model from a different

manufacturer.

L.2.5 Summary of Performance-Improvement Options and Manufactured-Cost Impacts

Tables L.2.17 through L.2.19 summarize the recommended performance-improvement

options and their respective manufactured-cost impacts for the SAC 1.5 Ton, SAC 2.5 Ton, and PAC

units, respectively. For the range of performance-improvement options investigated, the system

performance improvement is roughly proportional to the manufactured-cost impact. (This

observation cannot, however, be extrapolated to further increases in system performance.) The

tables provide strong evidence that TTW products can readily achieve 11 SEER, with the possible

exception of the PAC unit. The PAC unit can readily achieve about a ten- percent improvement,

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L-17

consistent with the performance improvement associated with raising the requirement for nonheating TTW products from 10 SEER to 11 SEER.

Table L.2.17 SAC 1.5 Ton – Estimated Performance Improvement and Associated

Manufactured-Cost Adder

Option1 Cumulative Performance

Improvement

Cumulative Cost/Price Impact

Multiplier SEER Mfr Cost/

Percent

Retail

Price3

Baseline Unit 1.00 10.0 $0 0.0% $0

Reduce Cabinet/Panel Air Leakage2 1.02 10.2 $3 0.7% $6

Increase Condenser Airflow Rate 1.05 10.5 $8 1.8% $15

Dual Condenser Blowers 1.09 10.9 $41 9.3% $79

Higher-Efficiency Compressor 1.12 11.2 $68 15.3% $131

1) Options listed in the logical order of implementation.

2) Improvement in actual field performance may be greater due to reduced infiltration.

3) Based on a total markup 1.92 on incremental changes in cost. See Appendix D.

Table L.2.18 SAC 2.5 Ton – Estimated Performance Improvement and Associated

Manufactured-Cost Adder

Option1 Cumulative Performance

Improvement

Cumulative Cost/Price Impact

Multiplier SEER Mfr Cost/

Percent

Retail

Price3

Baseline Unit 1.00 10.0 $0 0.0% $0

Reduce Cabinet/Panel Air Leakage2 1.03 10.3 $3 0.6% $6

Increase Condenser Airflow Rate 1.05 10.5 $10 1.9% $19

Higher-Efficiency Compressor 1.09 10.9 $34 6.6% $66

Dual Condenser Blowers 1.14 11.4 $55 10.7% $106

1) Options listed in the logical order of implementation.

2) Improvement in actual field performance may be greater due to reduced infiltration.

3) Based on a total markup 1.92 on incremental changes in cost. See Appendix D.

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L-18

Table L.2.19 PAC – Estimated Performance Improvement and Associated ManufacturedCost Adder

Option1 Cumulative Performance

Improvement

Cumulative Cost/Price Impact

Multiplier SEER Mfr Cost/

Percent

Retail

Price6

Baseline Unit2 1.00 9.7 $0 0.0% $0

Mount Condenser Fan Above

Condenser3

1.00 9.7 $0 0.0% $0

Improve Evaporator Airflow

Distribution4

1.00 9.7 $0 0.0% $0

Increase Condenser Airflow Rate5 1.01 9.8 ($1) -0.0% ($2)

Higher-Efficiency Compressor 1.05 10.2 $23 2.6% $44

Higher-Efficiency Condenser Fan

Motor

1.07 10.4 $37 4.2% $71

Taller Condenser 1.09 10.6 $67 7.6% $129

1) Options listed in the logical order of implementation.

2) This is the baseline SEER with the gas-heating package. Without the gas-heating package, the baseline SEER

could be slightly higher.

3) Mounting the condenser fan above the condenser should reduce system pressure losses, but we did not

attempt to quantify this benefit.

4) Modifying the design of the air-filter-mounting bracket may improve evaporator airflow distribution, but we did not

attempt to quantify this benefit or take credit for it in our analysis.

5) The manufactured-cost impact is slightly negative due to differences in motor supplier sales volume.

6) Based on a total markup 1.92 on incremental changes in cost. See Appendix D.

L.3 LIFE-CYCLE COST ANALYSIS

The life-cycle cost (LCC) analysis for TTW products was accomplished by using the same

spreadsheet models that were used for the general LCC analysis (refer to Chapter 5). But since TTW

products are almost entirely used in multi-family residences, the LCC analysis for TTW products is

conducted only on those central air-conditioned households in multi-family buildings. As defined

by the 1997 Residential Energy Consumption Survey (RECS), multi-family households are those

households that reside in apartments buildings with two or more units. 

L.3.1 Inputs to the LCC Analysis

The LCC analysis for TTW products utilizes the same inputs as those used in the general

LCC analysis (as described in Chapter 5) but with the following exceptions: 1) manufacturing cost

estimates for baseline and standard-level TTW products are based on data presented earlier in this

Appendix (Sections L.2.5 and L.2.6), 2) compressor replacement costs are based on costs specific

to TTW products, and 3) annual energy consumption, equipment efficiency, and electricity price data

are based only those central air conditioned households residing in multi-family residences.

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L-19

L.3.1.1 Baseline and Standard-Level Manufacturing Costs

Tables L.3.1 through L.3.3 present the baseline and standard-level manufacturing costs for

the three TTW units analyzed: SAC 1.5 Ton, SAC 2.5 Ton, and PAC. In addition to the

manufacturing cost estimates, the consumer equipment price (i.e., retail price) and the total installed

cost to the consumer are also are presented in each of the following tables. Manufacturing cost

estimates are summarized from information presented earlier in tables L.2.15 through L.2.19.

Consumer equipment prices and total installed costs are generated with the same markups, sales tax,

and installation prices as used in the general LCC analysis (refer to Chapter 5 and Appendix D).

Since the markups, sales tax, and installation prices are represented with probability distributions

rather than single-point values, the consumer equipment prices shown in Tables L.3.1 through L.3.3

are weighted-average values.

Table L.3.1 SAC 1.5 Ton TTW Unit: Baseline and Standard-Level Weighted-Average

Manufacturing Costs, Consumer Equipment Prices, and Total Installed Costs

Manufacturing Cost Consumer Equipment Price Total Installed Cost

SEER 1998$ 1998$ 1998$

10 $503 $1,221 $2,500

10.2 $506 $1,227 $2,506

10.5 $511 $1,236 $2,515

10.9 $544 $1,300 $2,579

11.2 $571 $1,352 $2,631

Table L.3.2 SAC 2.5 Ton TTW Unit: Baseline and Standard-Level Weighted-Average

Manufacturing Costs, Consumer Equipment Prices, and Total Installed Costs

Manufacturing Cost Consumer Equipment Price Total Installed Cost

SEER 1998$ 1998$ 1998$

10 $586 $1,422 $2,701

10.3 $589 $1,428 $2,707

10.5 $596 $1,441 $2,720

10.9 $620 $1,488 $2,767

11.4 $641 $1,528 $2,807

Table L.3.3 PAC TTW Unit: Baseline and Standard-Level Weighted-Average

Manufacturing Costs, Consumer Equipment Prices, and Total Installed Costs

Manufacturing Cost Consumer Equipment Price Total Installed Cost

SEER 1998$ 1998$ 1998$

9.7 $887 $2,153 $3,520

9.8 $886 $2,151 $3,518

10.2 $910 $2,197 $3,564

10.4 $924 $2,224 $3,591

10.6 $954 $2,282 $3,649

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L-20

L.3.1.2 Compressor Replacement Costs

As described in Chapter 5, Section 5.2.3.10, Lifetime and Compressor Replacement Cost,

the LCC analysis assumes that a compressor needs to be replaced in the 14th year of the system’s life.

Tables L.3.4 through L.3.6 show the manufacturer cost, average consumer price, and the present

value of the consumer price (discounted based on an average rate of 5.6%) for each of the three TTW

units analyzed. It is important to note that the compressor replacement price is the price for the

compressor only. The labor cost associated with the compressor’s installation is assumed to remain

constant as system efficiency increases.

Table L.3.4 SAC 1.5 Ton TTW Unit: Compressor Replacement Costs

Efficiency

Manufacturer Cost

Consumer Price

SEER In year replaced Present Value

10 $102 $232 $108

10.2 $102 $232 $108

10.5 $102 $232 $108

10.9 $102 $232 $108

11.2 $170 $356 $166

Table L.3.5 SAC 2.5 Ton TTW Unit: Compressor Replacement Costs

Efficiency

Manufacturer Cost

Consumer Price

SEER In year replaced Present Value

10 $128 $292 $136

10.3 $128 $292 $136

10.5 $128 $292 $136

10.9 $162 $353 $165

11.4 $162 $353 $165

Table L.3.6 PAC TTW Unit: Compressor Replacement Costs

Efficiency

Manufacturer Cost

Consumer Price

SEER In year replaced Present Value

9.7 $179 $408 $190

9.8 $179 $408 $190

10.2 $202 $450 $210

10.4 $202 $450 $210

10.6 $202 $450 $210

L.3.1.3 Multi-Familiy Households: Annual Energy Use, Equipment Efficiency, and

Electricity Prices

As noted earlier, because TTW products are almost entirely used in multi-family residences,

the LCC analysis for TTW products is conducted only on those central air-conditioned households

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L-21

in multi-family buildings. Table L.3.7 summarizes the weighted-average input values for multifamily households and compares them to the weighted-average input values for all households in

the 1997 RECS utilizing central air conditioners and heat pumps. Other than the sample size, multifamily households differ significantly from the overall sample in that the annual space-cooling

energy use is significantly lower. Also, multi-family average and marginal electricity prices are both

higher than those for the overall sample. 

Table L.3.7 Comparison of Input Values for All Households and Multi-Family Households

Category All Households Multi-Family

Household Population Data

Number of Households 1218 176

Sum of Weights 23,420,428 3,361,055

Percent of AC or HP Household Population - 14.4%

Weighted-Average Annual Energy Use and Efficiency Data

Stock Space-Cooling Energy Use (kWh/yr) 2132 1361

Stock Space-Cooling Efficiency (SEER) 9.13 8.84

Baseline Space-Cooling Energy Use (kWh/yr) 1947 1203 1

Weighted-Average Electricity Prices

Average Electricity Price (¢/kWh) 8.90 9.49

Marginal Electricity Price (¢/kWh) 8.62 9.01

1

 Baseline energy use pertains to 10 SEER equipment. For 9.7 SEER baseline equipment the use is 1241 kWh/yr.

L.3.2 LCC Results

LCC results are presented for the three TTW units analyzed. Since the value of most LCC

inputs are uncertain and are represented by a distribution of values rather than a single point-value,

the LCC results will also be a distribution of values. 

L.7.2.1 Baseline LCC

The first step in developing LCC results is to develop the baseline LCC. The baseline

efficiency level is assumed to equal 10 SEER for SAC TTW units and 9.7 SEER for PAC TTW

units. The baseline LCC for each TTW unit are represented by a distribution of values. The actual

distributions are not shown here. But Table L.3.8 presents the mean, median, minimum, and

maximum LCCs for the baseline efficiency level for each of the three TTW units analyzed.

 EE-RM-STD-98-440 COMMENT 312
L-22

Table L.3.8 Baseline LCC for TTW Units: Mean, Median, Min, and Max Values

Unit Type Minimum Median Mean Maximum

SAC 1.5 Ton $2,330 $4,271 $4,576 $14,673

SAC 2.5 Ton $2,387 $4,564 $4,867 $16,828

PAC $3,227 $5,799 $6,001 $16,980

L.3.2.2 Change in LCC

The change in LCC results are presented as differences in the LCC relative to the baseline

design. Similar to the baseline LCC, the LCC differences are depicted as a distribution of values.

The primary results are presented as either a frequency chart showing the distribution of LCC

differences with its corresponding probability of occurrence or a cumulative chart showing the

cumulative distribution of LCC differences along with the corresponding probability of occurrence.

These charts are not presented here. Rather, Tables L.3.9 through L.3.11 are provided summarizing

the change in LCC from the baseline by percentile groupings (i.e., of the distribution of results) for

each of the three TTW units analyzed. The mean and the percent of LCCs that are reduced for each

standard-level are also shown. 

As an example of how to interpret the information in Tables L.3.9 through L.3.11, the 10.2

SEER efficiency level for SAC 1.5 Ton is reviewed. The 10.2 SEER efficiency level in Table L.7.9

(row 1) shows that the maximum (zero percentile column) change in LCC is savings of $169.

(Negative values are net savings.) For 90% of the cases studied (90th percentile), the change in LCC

is a cost of $1 or less. The largest increase in LCC is $7 (100th percentile). The mean change in LCC

is a net savings of $17. The last column shows that 87% of the sample have reduced LCC (i.e.,

change in LCC less than or equal to zero). 

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L-23

Table L.3.9 Summary of LCC Results for SAC 1.5 Ton

Efficiency Level

(SEER)

Change in LCC from Baseline

Shown by Percentiles of the Distribution of Results (values in 1998$)

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 

10.2 $-169 $-44 $-29 $-21 $-15 $-11 $-7 $-4 $-2 $1 $7 10.5 $-503 $-109 $-71 $-50 $-36 $-26 $-17 $-9 $-3 $4 $16 10.9 $-658 $-128 $-64 $-29 $-6 $11 $26 $39 $50 $62 $112 11.2 $-803 $-73 $5 $43 $69 $87 $103 $121 $142 $171 $312 

Table L.3.10 Summary of LCC Results for SAC 2.5 Ton

Efficiency Level

(SEER)

Change in LCC from Baseline

Shown by Percentiles of the Distribution of Results (values in 1998$)

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 

10.3 $-296 $-68 $-45 $-34 $-25 $-19 $-14 $-9 $-6 $-2 $8 10.5 $-450 $-103 $-66 $-45 $-33 $-22 $-13 $-6 $1 $7 $21 10.9 $-745 $-107 $-45 $-14 $7 $23 $36 $47 $59 $75 $140 11.4 $-939 $-171 $-78 $-30 $3 $27 $48 $67 $84 $103 $181 

Table L.3.11 Summary of LCC Results for PAC

Efficiency Level

(SEER)

Change in LCC from Baseline

Shown by Percentiles of the Distribution of Results (values in 1998$)

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 

9.8 $-114 $-30 $-21 $-17 $-14 $-11 $-9 $-7 $-6 $-5 $-2 

10.2 $-398 $-62 $-25 $-6 $7 $17 $25 $32 $39 $49 $89 10.4 $-535 $-85 $-32 $-5 $12 $27 $38 $48 $59 $71 $118 10.6 $-683 $-61 $4 $36 $59 $76 $90 $104 $116 $133 $209 

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L-24

L.3.2.3 LCC Results based on ±2% Threshold

The results in Tables L.3.9 through L.3.11 show the percent of households with reduced

LCC. But considering that the baseline LCC for each product class is significantly greater than the

LCC differences shown in Tables L.3.9 through L.3.11, it is more useful to demonstrate which

consumers experience net LCC savings or costs within a particular threshold due to a higher

standard-level. As described in Chapter 5 (Section 5.2.4.4, LCC Results based on ±2% Threshold),

only those consumers with net LCC savings or costs beyond 2% of the baseline LCC are considered

to incur substantial impacts due to an increase in the standard. Table L.3.12 summarizes the baseline

LCCs for the three TTW units analyzed and also provides the 2% threshold at which consumers are

considered to be impacted by a standard-level.

Table L.3.12 TTW Unit Baseline Life-Cycle Costs and Threshold for Significant Impacts

Unit Baseline Life-Cycle Cost

Threshold for Adverse Impacts:

2% of Baseline LCC

SAC 1.5 Ton $4,576 $92

SAC 2.5 Ton $4,867 $97

PAC $6,001 $120

Tables L.3.13 through L.3.15 and Figures L.3.1 through L.3.6 depict the LCC results for the

three TTW units analyzed based on the above defined 2% threshold. The tables show the average

LCC values for the baseline level (10 SEER) and the various standard-levels analyzed. As presented

earlier in Tables L.3.9 through L.3.11, Tables L.3.13 through L.3.15 also provide for each TTW unit

the difference in LCC at each standard-level relative to the baseline. The differences represent either

an LCC savings or an LCC cost increase. In addition, each table shows the subset of consumers at

each standard-level who are impacted in one of three ways: 1) consumers who achieve net LCC

savings greater than 2% of the baseline LCC, 2) consumers who fall within ±2% of the baseline

LCC, or 3) consumers who achieve a net LCC increase exceeding 2% of the baseline LCC.

Accompanying each percentage value is the average LCC savings or increase that corresponds to

each subset of consumers. For example, in the case of the 10.2 SEER standard-level for SAC 1.5

Ton (Table L.3.13), the percentage of consumers with net savings beyond the 2% threshold is 1%

and the corresponding average LCC savings for those consumers is $112. 

For each product class, two figures are presented; one showing the mean LCC by standardlevel and the other showing the percentage of consumers for each standard-level that fall within the

three consumer subsets. For the figure presenting the percentage of consumers within each of the

three consumer subsets, the corresponding average LCC savings or increase is also presented.

 EE-RM-STD-98-440 COMMENT 312
L-25

Average Percent of consumers with

SEER

Average 

LCC

LCC (Savings) 

Costs

Net Savings 

(>2%) 

Avg LCC 

(Save) Cost

Impacts within

±2% Threshold

Avg LCC 

(Save) Cost

Net Costs 

(>2%)

10 $4,576 - - - - - - 

10.2 $4,559 ($17) 1% ($112) 99% ($16) 0% 

10.5 $4,534 ($42) 14% ($150) 86% ($25) 0% 

10.9 $4,561 ($15) 15% ($188) 85% $14 0% 

11.2 $4,638 $62 9% ($217) 44% $33 47% 

Table L.3.13 LCC Results for SAC 1.5 Ton TTW Units

$4,576 $4,559 $4,534 $4,561 $4,638

$0

$1,000$2,000$3,000$4,000$5,000

10 10.2 10.5 10.9 11.2

Efficiency (SEER)

Average Life-Cycle Cost

Figure L.3.1 Average LCCs for SAC 1.5 Ton TTW Units

1% ($112)

14%

($150)

15%

($188) 

(

99%

($16)

86%

($25)

85%

$14

0%

10%20%30%40%50%60%70%80%90%

100%

10.2 10.5 10.9 

Efficiency (SEER)

Percent of consumers 

Figure L.3.2 Percent of SAC 1.5 Ton TTW 

Costs, Impacts within ±2% Th

 EE-RM-STD-98-440 COMMENT 312
L-26

Average Percent of consumers with

SEER

Average 

LCC

LCC (Savings) 

Costs

Net Savings 

(>2%) 

Avg LCC 

(Save) Cost

Impacts within

±2% Threshold

Avg LCC 

(Save) Cost

Net Costs 

(>2%)

10 $4,867 - - - - - - 

10.3 $4,838 ($29) 4% ($135) 96% ($24) 0% 

10.5 $4,830 ($37) 11% ($153) 89% ($23) 0% 

10.9 $4,866 ($1) 11% ($192) 87% $21 2% 

11.4 $4,858 ($9) 17% ($236) 70% $23 13% 

Table L.3.14 LCC Results for SAC 2.5 Ton TTW Units

$4,867 $4,838 $4,830 $4,866 $4,858

$0

$1,000$2,000$3,000$4,000$5,000

10 10.2 10.5 10.9 11.2

Efficiency (SEER)

Average Life-Cycle Cost

Figure L.3.3 Average LCCs for SAC 2.5 Ton TTW Units

4% ($135)

11%

($153)

11%

($192)

(

96%

($24)

89%

($23)

87%

$21

2% $106 

0%

10%20%30%40%50%60%70%80%90%

100%

10.2 10.5 10.9 

Efficiency (SEER)

Percent of consumers 

Figure L.3.4 Percent of SAC 2.5 Ton TTW 

Costs, Impacts within ±2% Th

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L-27

Average Percent of consumers with

SEER

Average 

LCC

LCC (Savings) 

Costs

Net Savings 

(>2%) 

Avg LCC 

(Save) Cost

Impacts within

±2% Threshold

Avg LCC 

(Save) Cost

Net Costs 

(>2%)

9.7 $6,001 - - - - - - 9.8 $5,986 ($15) 0% $0 100% ($15) 0% 

10.2 $6,004 $3 4% ($177) 96% $10 0% 

10.4 $6,007 $6 6% ($204) 94% $20 0% 

10.6 $6,053 $52 5% ($228) 78% $51 17% 

Table L.3.15 LCC Results for PAC TTW Units

$6,001 $5,986 $6,004 $6,007 $6,053

$0

$1,000$2,000$3,000$4,000$5,000$6,000

9.7 9.8 10.2 10.4 10.6

Efficiency (SEER)

Average Life-Cycle Cost

Figure L.3.5 Average LCCs for PAC TTW Units

4% ($177) 6% ($204) 5% 

94%

$20

96%

$10

100%

($15)

0%

10%20%30%40%50%60%70%80%90%

100%

9.8 10.2 10.4 

Efficiency (SEER)

Percent of consumers

Figure L.3.6 Percent of PAC TTW Unit Co

Impacts within ±2% Threshol

 EE-RM-STD-98-440 COMMENT 312