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CHAPTER 3. ENGINEERING ANALYSIS

TABLE OF CONTENTS

3.1 INTRODUCTION ........................................................................................................... 3-1

3.2 EQUIPMENT CLASSES ANALYZED.......................................................................... 3-1

3.3 METHODOLOGY OVERVIEW.................................................................................... 3-3

3.3.1 Approach.............................................................................................................. 3-3

3.3.2 Selection of Representative Sensible Cooling Capacities ................................... 3-4

3.3.3 Selection of Baseline Efficiency Levels.............................................................. 3-5

3.3.4 Identification of Efficiency Levels for Analysis.................................................. 3-6

3.3.5 Pricing Data ......................................................................................................... 3-7

3.3.6 Construction of Price-Efficiency Curves............................................................. 3-8

3.4 ENGINEERING ANALYSIS SUMMARY OF RESULTS.......................................... 3-12

LIST OF TABLES

Table 3.3.1 Equipment Classes for Computer Room Air Conditioners and Their ASHRAE 

Standard 90.1-2010 Efficiency Level .............................................................................. 3-2

Table 3.3.2 Equipment Classes Analyzed in the Engineering Analysis and Their Representative 

Capacities......................................................................................................................... 3-5

Table 3.3.3 Baseline SCOP Efficiency Levels for Computer Room Air Conditioners............... 3-6

Table 3.3.4 Efficiency Levels for Analysis of Computer Room Air Conditioners ..................... 3-7

Table 3.4.1 Price-Efficiency Points for Air-Cooled Computer Room Air Conditioners .......... 3-12

Table 3.4.2 Price-Efficiency Points for Water-Cooled Computer Room Air Conditioners...... 3-12

Table 3.4.3 Price-Efficiency Points for Water-Cooled Computer Room Air Conditioners with a 

Fluid Economizer........................................................................................................... 3-13

Table 3.4.4 Price-Efficiency Points for Glycol-Cooled Computer Room Air Conditioners..... 3-13

Table 3.4.5 Price-Efficiency Points for Glycol-Cooled Computer Room Air Conditioners with a 

Fluid Economizer........................................................................................................... 3-13

LIST OF FIGURES

Figure 3.3.1 Extrapolation Flow Chart of the Price-Efficiency Curves for Computer Room Air 

Conditioner Classes ....................................................................................................... 3-11
3-1

CHAPTER 3. ENGINEERING ANALYSIS

3.1 INTRODUCTION

This engineering analysis establishes the relationship between the cost and the energy 

efficiency. This relationship serves as the basis for cost-benefit calculations for individual 

consumers, manufacturers, and the Nation. The engineering analysis identifies the representative 

baseline equipment, which is the starting point for analyzing possible energy efficiency 

improvements. The engineering analysis also identifies higher efficiency levels and the 

corresponding increase in price associated with achieving those higher efficiency levels. Using 

this cost-efficiency relationship and the results of the downstream analysis (mark-up analysis, 

life-cycle costs, payback period analysis), DOE can estimate customer prices resulting from 

amended energy conservation standards. DOE then examines the costs and benefits associated

with each increased efficiency level.

For this rulemaking, DOE only performed an engineering analysis on computer room air 

conditioners because the other equipment classes either had no models on the market or a very 

low potential energy savings at higher efficiency levels than those in ASHRAE Standard 90.1-

2010. For equipment classes for which DOE performed a potential energy savings analysis and 

the energy savings results, please see chapter 4. This chapter will only focus on computer room 

air conditioners.

To develop the engineering analysis for computer room air conditioners (the only 

ASHRAE equipment class DOE analyzed in the engineering analysis), DOE used an efficiencylevel approach in conjunction with a pricing survey to develop the price-efficiency relationships. 

DOE discusses the equipment classes it analyzed; the identification of representative capacities 

for analysis, baseline efficiency levels, and the efficiency levels above the baseline; the process 

for collecting pricing data; and the methodology for developing the price-efficiency results. The 

engineering analysis produces a set of price-efficiency results that represents the average 

incremental contractor cost of increasing energy efficiency levels above the baseline for 

computer room air conditioners.

3.2 EQUIPMENT CLASSES ANALYZED

As mentioned in chapter 2 of this TSD (Market Assessment), computer room air 

conditioners were previously an uncovered product by DOE, but newly covered under ASHRAE 

Standard 90.1-2010; therefore, DOE undertook this analysis to determine whether to adopt the 

ASHRAE standards or more stringent standards as DOE standards. ASHRAE Standard 90.1-

2010 separates computer room air conditioners into 30 equipment classes based upon its heat 
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rejection method (air-cooled, water-cooled, or glycol-cooled), sensible cooling capacity (<65,000 

Btu/h, ≥65,000 Btu/h and <240,000 Btu/h, or ≥240,000 Btu/h and <760,000 Btu/h), orientation 

(upflow or downflow), and whether or not a fluid economizer is used. However, due to a lack of 

data for certain equipment classes, DOE could not analyze each of the 30 equipment classes. 

DOE instead focused its efforts on the equipment classes with the most efficiency data available

and extrapolated that analysis to the other equipment classes. Table 3.3.1 of the 30 equipment 

classes for computer room air conditioners is generated below. The following paragraphs 

discuss how DOE selected equipment classes for its analysis.

Table 3.3.1 Equipment Classes for Computer Room Air Conditioners and Their ASHRAE 

Standard 90.1-2010 Efficiency Level

Equipment Class Size Category (Sensible Capacity1) Upflow

SCOP

Downflow

SCOP

Air-Cooled

<65,000 Btu/h 2.20 2.09

≥65,000 Btu/h and <240,000 Btu/h 2.10 1.99

≥240,000 Btu/h and <760,000 Btu/h 1.90 1.79

Water-Cooled

<65,000 Btu/h 2.60 2.49

≥65,000 Btu/h and <240,000 Btu/h 2.50 2.39

≥240,000 Btu/h and <760,000 Btu/h 2.40 2.29

Water-Cooled with a 

Fluid Economizer

<65,000 Btu/h 2.55 2.44

≥65,000 Btu/h and <240,000 Btu/h 2.45 2.34

≥240,000 Btu/h and <760,000 Btu/h 2.35 2.24

Glycol Cooled

<65,000 Btu/h 2.50 2.39

≥65,000 Btu/h and <240,000 Btu/h 2.15 2.04

≥240,000 Btu/h and <760,000 Btu/h 2.10 1.99

Glycol Cooled with a 

Fluid Economizer

<65,000 Btu/h 2.45 2.34

≥65,000 Btu/h and <240,000 Btu/h 2.10 1.99

≥240,000 Btu/h and <760,000 Btu/h 2.05 1.94

In the market assessment, DOE noted that upflow and downflow units were treated as the 

same in the California Energy Commission’s (CEC) database and in most manufacturers’ 

product literatures. DOE found that all upflow models in its database also had a corresponding 

downflow model in which the interior components were arranged in a different manner within 

the same exterior shell. DOE assumed that because both orientations have the same major 

components, the prices and incremental costs for increasing efficiency for both orientations 

would be the same. Therefore, to lower the number of equipment classes analyzed, DOE only 

analyzed downflow units in this engineering analysis because more data were available for these 

equipment classes. Since DOE assumed that the prices and incremental costs for increasing 

 

1 Note that ASHRAE Standard 90.1-2010 uses sensible cooling capacity rather than total cooling capacity for their 

size categories.
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efficiency for the upflow models would be the same as for the downflow models, DOE did not 

extrapolate the downflow results to the upflow equipment class in the engineering analysis.

For the 15 downflow equipment classes analyzed in the engineering analysis, DOE 

focused the analysis on the four equipment classes where the largest number of models was 

available on the market and where DOE received enough pricing information to generate a trend: 

1) small (i.e., sensible capacity <65,000 Btu/h) air-cooled computer room air conditioners

2) large (i.e., sensible capacity ≥65,000 Btu/h and <240,000 Btu/h) air-cooled computer 

room air conditioners

3) small water-cooled computer room air conditioners

4) large water-cooled computer room air conditioners

For the other 11 downflow equipment classes, DOE extrapolated the results from these 

four primary equipment classes. An explanation of how the results were extrapolated to the 

equipment classes that were not directly analyzed is in section 3.3.4 below.

3.3 METHODOLOGY OVERVIEW

This section describes the analytical methodology DOE used in the engineering analysis.

The results of the engineering analysis are a set of price-efficiency relationships, which are used 

as the basis for the cost-benefit analyses.

3.3.1 Approach

DOE typically structures its engineering analysis around one of three methodologies. 

These are: (1) the design-option approach, which calculates the incremental costs of adding 

specific design options to a baseline model; (2) the efficiency-level approach, which calculates 

the relative costs of achieving increases in energy efficiency levels, without regard to the specific

design options used to achieve such increases; and/or (3) the reverse engineering or costassessment approach, which involves a “bottom-up” manufacturing cost assessment based on a 

detailed bill of materials derived from teardowns of the product being analyzed. Deciding which 

methodology to use for the engineering analysis depends on the product, the design options 

under study, and any historical data that DOE can draw on.

For analyzing computer room air conditioners, DOE used an efficiency-level approach 

with a pricing survey in order to estimate the cost of achieving different sensible coefficient of 

performance (SCOP) levels. With the efficiency level approach, DOE could focus on the relative 

price difference of the units at different SCOP ratings but still capture a variety of design options 

available on the market. The efficiency levels used in the engineering analysis were 

representative of computer room air conditioners available on the market at the time of this 
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analysis. DOE obtained pricing data from equipment distributors of three2 major computer room 

air conditioner manufacturers, which was used to develop the price-efficiency relationship for 

computer room air conditioners.

3.3.2 Selection of Representative Sensible Cooling Capacities

Equipment prices can vary significantly depending upon differences in sensible cooling 

capacity. To help limit the variation in equipment prices from cooling capacity, DOE analyzed a 

range of sensible cooling capacities for each equipment class that was representative of that 

class. Using a representative sensible cooling capacity allows DOE to analyze specific 

equipment in detail that can provide information representative of the entire equipment class and 

also allows DOE to perform analysis at the baseline efficiency level as well as higher efficiency 

levels. The baseline units are discussed further in section 3.3.5 of this analysis.

DOE chose a representative capacity for analysis within each of the three size categories

of computer room air conditioners in ASHRAE Standard 90.1-2010 (i.e., <65,000 Btu/h, 

≥65,000 Btu/h and <240,000 Btu/h, and ≥240,000 Btu/h and <760,000 Btu/h). DOE selected the 

representative capacity in each equipment class using the average sensible capacity of all the 

models DOE found on the market in a given equipment size class, rounded to the nearest ton of 

cooling. This representative capacity also generally corresponded to the mode of sensible cooling 

capacities (the highest number of models) with efficiency information for that equipment class. 

Table 3.3.2 shows the computer room equipment classes and the representative sensible cooling 

capacities at which DOE collected information for the engineering analysis.

 

2 Of the five major manufacturers of computer room air conditioners, DOE found that efficiency information needed 

to estimate the SCOP rating was only available from three of the manufacturers. Thus, DOE obtained pricing 

information for all manufacturers where efficiency information was available.
3-5

Table 3.3.2 Equipment Classes Analyzed in the Engineering Analysis and Their 

Representative Capacities

Equipment Class Size Category

(Btu/h)

Representative 

Sensible Cooling 

Capacity

(Btu/h)

Air-Cooled

Small (<65,000) 36,000 

Large (≥65,000 and <240,000) 132,000 

Very Large (≥240,000 and <760,000) 288,000 

Water-Cooled

Small 36,000 

Large 132,000 

Very Large 288,000 

Water-Cooled with a 

Fluid Economizer

Small 36,000 

Large 132,000 

Very Large 288,000 

Glycol Cooled

Small 36,000 

Large 132,000 

Very Large 288,000 

Glycol Cooled with a 

Fluid Economizer

Small 36,000 

Large 132,000 

Very Large 288,000 

For the small and large product classes, DOE focused its data collection efforts on units 

near the representative capacity. For the very large product class, there were only five units in the 

database that had efficiency information at this size so DOE collected data for all five of these 

units. Due to the limited amount of data available for the very large equipment DOE did not 

analyze them explicitly but rather extrapolated the analysis from the large equipment classes to 

apply it to the very large classes, as explained in section 3.3.4. 

3.3.3 Selection of Baseline Efficiency Levels

In the next step of the engineering analysis, DOE selected baseline efficiency levels as 

reference points for each equipment class, against which it measured changes resulting from 

potential amended energy conservation standards. DOE defined the baseline efficiency levels for 

computer room air conditioners in the engineering analysis as reference points to compare the 

energy savings and cost of equipment with higher energy efficiency levels. Typically, units at the 

baseline efficiency level just meet Federal energy conservation standards and provide basic 

consumer utility. However, computer room air conditioners are newly covered equipment by 

DOE and, therefore, have no Federal energy conservation standards. But, since EPCA directs 

that DOE must adopt amended energy conservation standards at the new efficiency levels in 

ASHRAE Standard 90.1, unless clear and convincing evidence supports a determination that the 

adoption of a more stringent level would produce significant additional energy savings and be 

technologically feasible and economically justified (42 U.S.C. 6313(a)(6)(A)(ii)), DOE cannot 
3-6

consider any energy conservation standards below the efficiency levels specified in ASHRAE 

Standard 90.1-2010. Therefore, for the engineering analysis DOE set the baseline efficiency 

level for each equipment class of computer room air conditioners equal to the efficiency level in 

ASHRAE. Table 3.3.3 shows the baseline efficiency level for each equipment class of computer 

room air conditioners.

Table 3.3.3 Baseline SCOP Efficiency Levels for Computer Room Air Conditioners

Equipment Class1 Size Category

(Btu/h)

ASHRAE Standard 90.1-2010 

Efficiency Level

(SCOP)

Air-Cooled

<65,000 2.2

≥65,000 and <240,000 2.1

≥240,000 and <760,000 1.9

Water-Cooled

<65,000 2.6

≥65,000 and <240,000 2.5

≥240,000 and <760,000 2.4

Water-Cooled with a 

Fluid Economizer

<65,000 2.55

≥65,000 and <240,000 2.45

≥240,000 and <760,000 2.35

Glycol Cooled

<65,000 2.5

≥65,000 and <240,000 2.15

≥240,000 and <760,000 2.1

Glycol Cooled with a 

Fluid Economizer

<65,000 2.45

≥65,000 and <240,000 2.1

≥240,000 and <760,000 2.05 1 As noted in Section 3.2, DOE focused its analysis on downflow only models.

3.3.4 Identification of Efficiency Levels for Analysis

After selecting the baseline efficiency levels, DOE identified higher efficiency levels for

each equipment class based on an extensive review of the data DOE compiled from the CEC 

database and manufacturers’ product literature. DOE converted the EER information provided in 

these sources (which was determined using the ASHRAE 127-2001 test procedure) into the new 

SCOP metric used in the updated ASHRAE 127-2007 test procedure. DOE used the “rule of 

thumb” formula described in ASHRAE 127-2007 to convert from the ASHRAE 127-2001 EER 

rating to the ASHRAE 127-2007 SCOP rating, as described in chapter 2 of this TSD. As 

previously noted in section 3.2, DOE only had enough data to directly analyze four equipment 

classes, small air-cooled, large air-cooled, small water-cooled, and large water-cooled. For each 

of these four equipment classes, DOE identified the baseline efficiency level (see section 3.3.3)

and the market max tech efficiency level on the market and chose three additional evenly spaced 

efficiency levels in between the baseline and the market max-tech levels for a total of five 

efficiency levels. For the other eleven equipment classes where DOE did not have enough 

market efficiency data, DOE selected efficiency levels based on the efficiency differences 
3-7

between the SCOP of the different equipment classes as specified by ASHRAE Standard 90.1-

2010 in the same manner which DOE extrapolated price-efficiency curves (see section 3.3.6 and

Figure 3.3.1). DOE analyzed the efficiency levels in Table 3.3.3, which span the entire efficiency 

range of computer room air conditioner efficiency levels found in DOE’s database. Table 3.3.4

below shows the SCOP efficiency levels for each of the 15 equipment classes DOE analyzed in 

the engineering analysis.

Table 3.3.4 Efficiency Levels for Analysis of Computer Room Air Conditioners

Equipment Class

Efficiency Levels (SCOP)

Baseline 

Level

Level 

1

Level 

2

Level 

3

Level 

4

Air-Cooled

<65,000 Btu/h 2.20 2.40 2.60 2.80 3.00

≥65,000 Btu/h and 

<240,000 Btu/h

2.10 2.35 2.60 2.85 3.10

≥240,000 Btu/h and 

<760,000 Btu/h

1.90 2.15 2.40 2.65 2.90

Water-Cooled

<65,000 Btu/h 2.60 2.80 3.00 3.20 3.40

≥65,000 Btu/h and 

<240,000 Btu/h

2.50 2.70 2.90 3.10 3.30

≥240,000 Btu/h and 

<760,000 Btu/h

2.40 2.60 2.80 3.00 3.20

Water-Cooled with a Fluid 

Economizer

<65,000 Btu/h 2.55 2.75 2.95 3.15 3.35

≥65,000 Btu/h and 

<240,000 Btu/h

2.45 2.65 2.85 3.05 3.25

≥240,000 Btu/h and 

<760,000 Btu/h

2.35 2.55 2.75 2.95 3.15

Glycol-Cooled

<65,000 Btu/h 2.50 2.70 2.90 3.10 3.30

≥65,000 Btu/h and 

<240,000 Btu/h

2.15 2.35 2.55 2.75 2.95

≥240,000 Btu/h and 

<760,000 Btu/h

2.10 2.30 2.50 2.70 2.90

Glycol-Cooled with a 

Fluid Economizer

<65,000 Btu/h 2.45 2.65 2.85 3.05 3.25

≥65,000 Btu/h and 

<240,000 Btu/h

2.10 2.30 2.50 2.70 2.90

≥240,000 Btu/h and 

<760,000 Btu/h

2.05 2.25 2.45 2.65 2.85

3.3.5 Pricing Data

Next, DOE selected units for which it would obtain pricing information. The units 

selected represent a variety of technologies and SCOP ratings but were limited to models for 

which DOE could estimate the SCOP rating. DOE collected pricing data for all units near the 

representative capacity. To simulate a typical request from a contractor that would install 

computer room air conditioners, DOE requested the pricing information for individual models in 

quantities of 10 to be shipped to Oakland, California. DOE chose Oakland as the shipping 
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destination for a central location. Although the shipping cost was not broken out as a separate 

aspect of the purchase price (i.e., all price quotes were total price that included shipping) and

since all three manufactures are based in California, DOE assumed that shipping prices would be 

similar between the manufacturers. DOE received pricing information for 32 models: 6 small aircooled units, 6 large air-cooled units, 2 very large air-cooled units, 5 small water-cooled units, 7

large water-cooled units, 1 very large water-cooled unit, 2 small glycol-cooled units, 1 large 

glycol-cooled unit, and 2 very large glycol-cooled units (one with a fluid economizer and one 

without one). DOE only received pricing information for one unit with a fluid economizer 

because that was the only unit with efficiency information that was near the representative 

capacity. DOE then used this pricing information along with the estimated SCOP information 

(derived from EER as described in chapter 2) to build price-efficiency curves. 

3.3.6 Construction of Price-Efficiency Curves

Once DOE aggregated all the pricing information with their corresponding efficiency 

information, DOE normalized the prices to the representative capacity for each equipment class 

by calculating the price per Btu/h of sensible cooling capacity and adjusting it to the 

representative capacity. Then, DOE did an initial assessment of the normalized pricing 

information for the equipment classes where it was able to collect data.

From the initial assessment, DOE noticed that the prices for ceiling mount units were 

usually lower than floor mount units with a similar sensible cooling capacity; so in order for the 

analysis to compare as similar units as possible, DOE omitted the pricing data for the 5 ceiling 

mount units it had gathered (1 small air-cooled unit, 2 small water-cooled units, and 2 large 

water-cooled units). Then, DOE took the remaining 27 data points for floor mount units and 

plotted them on graphs of their corresponding equipment class and used an exponential 

regression analysis to fit a curve that best defined the data trend. DOE used an exponential 

regression curves because typically the price-efficiency relationship for appliances follows an 

exponential fit; and in this case, DOE found that an exponential-curve fit best represented the 

data that was collected. DOE only had enough data points to adequately form exponential 

regression curve for four equipment classes: small air-cooled, large air-cooled, small-water 

cooled, and large-water cooled. For the remaining 11 equipment classes, DOE extrapolated the 

analysis based on results, SCOP differences in ASHRAE Standard 90.1-2010, and price 

differences from the four primary equipment classes. DOE used the SCOP differences in 

ASHRAE because there was not enough SCOP data in DOE’s database to determine the changes 

in SCOP between equipment classes. DOE assumed that the differences in the SCOP levels in 

ASHRAE Standard 90.1-2010 approximated the industry-average SCOP differences between 

equipment classes.
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For the very large air-cooled and water-cooled equipment classes, DOE did not have 

enough data to develop the price-efficiency relationship and extrapolated the results from the 

price-efficiency curves for the large air-cooled and large water-cooled equipment classes. For 

very large air-cooled equipment, DOE shifted the large air-cooled price-efficiency curve down 

by 0.20 SCOP (the difference in SCOP levels between large and very large air-cooled equipment

in ASHRAE Standard 90.1-2010). Then, DOE calculated the average percent increase in price 

between large air-cooled and very large air-cooled units in the same model line. DOE found that 

the average price difference of models for which data was collected was a 44 percent increase in 

price for the very large air-cooled equipment class from the large air-cooled equipment class. 

Thus, DOE multiplied the prices in the price-efficiency curve by 1.44 to approximate the average 

increase in price between the large and very large air-cooled equipment class. For the very large 

water-cooled equipment class, DOE used the same methodology as for air-cooled units. DOE

shifted the large price-efficiency curve down by 0.10 SCOP (the difference in SCOP as noted by 

ASHRAE Standard 90.1-2010) and multiplied the prices in the large water-cooled equipment 

class price-efficiency curve by 1.90 to estimate the average price-efficiency relationship for the 

very large water-cooled equipment class.

For the small, large, and very large glycol-cooled equipment classes, DOE was unable to 

obtain enough price and efficiency data to generate a price-efficiency relationship; as a result, 

DOE extrapolated the price-efficiency relationship for these equipment classes based on the 

results from the water-cooled equipment class. From the pricing survey, DOE found that in both 

of the instances where DOE had pricing information for a model that was optionally watercooled or glycol-cooled (large and very large sizes), the glycol-cooled unit was the same exact 

price as its corresponding water-cooled unit. (For the remaining three glycol-cooled models for 

which DOE had obtained pricing information, DOE did not have pricing information for a 

similar model water-cooled unit for comparison and could not draw any conclusions) Based on 

this information, DOE assumed that the price for glycol units would be the same as the price for 

water-cooled units at the same representative capacity. Next, DOE shifted the SCOP rating of 

glycol-cooled units down by 0.1 for the small class, 0.35 for the large class, and 0.3 for the very 

large class (which were the SCOP differences according to ASHRAE Standard 90.1-2010).

For the six equipment classes with a fluid economizer (i.e., small, large, and very large 

water-cooled and small, large, and very large glycol-cooled), DOE translated the price-efficiency 

curves from the corresponding water-cooled and glycol-cooled equipment classes without a fluid 

economizer. Because a fluid economizer adds additional static pressure for the blower to 

overcome, DOE believes that these units require more fan energy and thus have a lower SCOP 

rating then those models without a fluid economizer. Thus, DOE shifted the price-efficiency 

curves down by 0.05 SCOP, which was the difference as specified in ASHRAE Standard 90.1-

2010 between units with and without a fluid economizer. As noted in section 3.3.5, DOE was 
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only able to collect pricing data for one unit with a fluid economizer (a very large glycol-cooled 

unit). DOE compared the price of this unit with the fluid economizer to the price of the same unit 

without the fluid economizer to determine the price increase associated with the addition of a 

fluid economizer. DOE found that the percentage difference in the price of a model with a fluid 

economizer versus the price of a model without a fluid economizer was 5.82 percent. DOE 

assumed that this percentage difference of adding a fluid economizer would hold true for the 

small and large equipment classes, so DOE multiplied the prices in the price-efficiency curves 

for those classes without a fluid economizer by 1.0582 to generate the corresponding priceefficiency curves for the equipment classes with a fluid economizer.

Figure 3.3.1 shows a visual summary of how DOE extrapolated the data. The boxes in 

green are the four primary equipment classes which DOE had enough data to analyze directly, 

and the boxes in blue are the equipment classes to which DOE extrapolated the data. The arrows 

connecting the boxes show how the price-efficiency data was extrapolated to the equipment 

classes in the blue boxes. The arrows have equations next to them to show how the SCOP and 

the price were adjusted for each extrapolation. 
3-11

Figure 3.3.1 Extrapolation Flow Chart of the Price-Efficiency Curves for Computer Room 

Air Conditioner Classes

Small Air-Cooled Large Air-Cooled Very Large AirCooled

Very Larger WaterCooled

Large WaterCooled

Small WaterCooled

Small WaterCooled with a Fluid 

Economizer

Large WaterCooled with a Fluid 

Economizer

Very Large WaterCooled with a Fluid 

Economizer

Very Large GlycolCooled

Large GlycolCooled

Small GlycolCooled

Small GlycolCooled with a Fluid 

Economizer

Large GlycolCooled with a Fluid 

Economizer

Very Large GlycolCooled with a Fluid 

Economizer

SCOP– 0.05

Price x 1.0582

SCOP – 0.10

Price x 1.90

SCOP – 0.20

 Price x 1.44

SCOP– 0.05

Price x 1.0582

SCOP– 0.05

Price x 1.0582

SCOP– 0.05

Price x 1.0582

SCOP– 0.05

Price x 1.0582

SCOP– 0.05

Price x 1.0582

SCOP 

– 0.1; Price is equal

SCOP 

– 0.35; Price is equal

SCOP 

– 0.30; Price is equal
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3.4 ENGINEERING ANALYSIS SUMMARY OF RESULTS

The result of the engineering analysis is a set of price-efficiency relationships. Creating 

the price-efficiency relationship involved four steps: (1) plotting the distributor prices versus 

SCOP for the four equipment classes that were directly analyzed, (2) using a regression analysis 

to fit a curve that best defines the aggregated data, (3) extrapolating the results to the other 

eleven equipment classes, and (4) calculating the price at each efficiency level for analysis. Table 

3.4.1 through Table 3.4.5 show the price-efficiency results in the form of total price of the unit

versus SCOP efficiency. Note that the only equipment classes in which DOE had enough 

information to run a regression analysis were the small air-cooled class, the large air-cooled 

class, the small water-cooled class, and the large water-cooled class. In the rulemaking process, 

the results from the engineering analysis are used in the life-cycle cost (LCC) analysis to 

determine customer prices for computer room air conditioners.

Table 3.4.1 Price-Efficiency Points for Air-Cooled Computer Room Air Conditioners

Small (<65,000 Btu/h) Large (≥65,000 Btu/h and 

<240,000 Btu/h)

Very Large (≥240,000 Btu/h 

and <760,000 Btu/h

Efficiency 

Level (SCOP)

Price Efficiency 

Level (SCOP)

Price Efficiency 

Level (SCOP)

Price

2.20 $6,681 2.10 $22,621 1.90 $32,575

2.40 $7,854 2.35 $24,383 2.15 $35,112

2.60 $9,232 2.60 $26,282 2.40 $37,847

2.80 $10,852 2.85 $28,329 2.65 $40,794

3.00 $12,756 3.10 $30,536 2.90 $43,972

Table 3.4.2 Price-Efficiency Points for Water-Cooled Computer Room Air Conditioners

Small (<65,000 Btu/h) Large (≥65,000 Btu/h and 

<240,000 Btu/h)

Very Large (≥240,000 Btu/h 

and <760,000 Btu/h

Efficiency 

Level (SCOP)

Price Efficiency 

Level (SCOP)

Price Efficiency 

Level (SCOP)

Price

2.60 $14,233 2.50 $12,883 2.40 $24,453

2.80 $11,528 2.70 $17,315 2.60 $32,864

3.00 $9,337 2.90 $23,272 2.80 $44,166

3.20 $7,562 3.10 $31,279 3.00 $59,357

3.40 $6,125 3.30 $42,040 3.20 $79,771
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Table 3.4.3 Price-Efficiency Points for Water-Cooled Computer Room Air Conditioners 

with a Fluid Economizer

Small (<65,000 Btu/h) Large (≥65,000 Btu/h and 

<240,000 Btu/h)

Very Large (≥240,000 Btu/h 

and <760,000 Btu/h

Efficiency 

Level (SCOP)

Price Efficiency 

Level (SCOP)

Price Efficiency 

Level (SCOP)

Price

2.55 $15,062 2.45 $13,633 2.35 $25,878

2.75 $12,199 2.65 $18,324 2.55 $34,778

2.95 $9,881 2.85 $24,628 2.75 $46,739

3.15 $8,003 3.05 $33,101 2.95 $62,814

3.35 $6,482 3.25 $44,489 3.15 $84,417

Table 3.4.4 Price-Efficiency Points for Glycol-Cooled Computer Room Air Conditioners

Small (<65,000 Btu/h) Large (≥65,000 Btu/h and 

<240,000 Btu/h)

Very Large (≥240,000 Btu/h 

and <760,000 Btu/h

Efficiency 

Level (SCOP)

Price Efficiency 

Level (SCOP)

Price Efficiency 

Level (SCOP)

Price

2.50 $14,233 2.15 $12,870 2.10 $24,453

2.70 $11,528 2.35 $17,297 2.30 $32,864

2.90 $9,337 2.55 $23,245 2.50 $44,166

3.10 $7,562 2.75 $31,240 2.70 $59,357

3.30 $6,125 2.95 $41,985 2.90 $79,771

Table 3.4.5 Price-Efficiency Points for Glycol-Cooled Computer Room Air Conditioners 

with a Fluid Economizer

Small (<65,000 Btu/h) Large (≥65,000 Btu/h and 

<240,000 Btu/h)

Very Large (≥240,000 Btu/h 

and <760,000 Btu/h

Efficiency 

Level (SCOP)

Price Efficiency 

Level (SCOP)

Price Efficiency 

Level (SCOP)

Price

2.45 $15,062 2.10 $13,620 2.05 $25,878

2.65 $12,199 2.30 $18,304 2.25 $34,778

2.85 $9,881 2.50 $24,599 2.45 $46,739

3.05 $8,003 2.70 $33,060 2.65 $62,814

3.25 $6,482 2.90 $44,430 2.85 $84,417

These results represent the average industry price for achieving certain efficiency levels 

and do not take into account the cost for specific design improvements. The prices in the tables 

above do not represent any single manufacturer. DOE found that among individual 

manufacturers there was no discernable relationship between pricing and efficiency; however, 

when manufacturer prices were aggregated, trends between price and efficiency appeared. 
3-14

Namely, the aggregate data indicated that there are manufacturers who sell lower price, less

efficient units and manufacturers who sell higher price, more efficient units.

DOE observed that the results for small water-cooled computer room air conditioners 

with and without a fluid economizer and small glycol-cooled computer room air conditioners 

with and without a fluid economizer have a negative correlation between price and efficiency

(i.e., as the efficiency of the unit increases, the price for that unit decreases). This result is 

counter-intuitive because DOE typically finds that an increase in efficiency will also result in an 

increase in manufacturer costs, which are then reflected in increased customer prices. DOE 

believes that more data points could reveal a different trend than resulted from its pricing 

analysis.

DOE also found no common trend when looking at results from individual manufacturers 

within each product class. Oftentimes, the most efficient unit offered by a particular 

manufacturer also happened to be the manufacturer’s least expensive model. DOE believes that it 

is likely that manufacturers base the pricing of their units on factors other than energy efficiency. 

For example, factors such as how competitive the market is for certain equipment could cause 

manufacturers to apply different markups to different product lines. As a result, more-popular 

equipment might have a lower price (either due to lower markup or higher manufacturing 

volumes) and less-popular equipment might be more expensive. Additionally, manufacturers 

may charge a premium for other factors that are unrelated to efficiency, such as longer 

warranties, improved user controls, or a myriad of other factors. Accordingly, it follows that an 

alternative approach, such as a reverse-engineering or design option approach which estimates

the equipment cost at the point of manufacturer (rather than the purchase price from the 

distributor) might yield different results from those presented in this analysis.