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CHAPTER 3. ENGINEERING ANALYSIS

TABLE OF CONTENTS

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

3.2 EQUIPMENT CLASSES ANALYZED.......................................................................... 3-2

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 Pricing Data ......................................................................................................... 3-5

3.3.4 Construction of Price-Efficiency Curves............................................................. 3-6

3.3.5 Selection of Baseline Efficiency Levels.............................................................. 3-9

3.3.6 Identification of Efficiency Levels for Analysis................................................ 3-10

3.4 ENGINEERING ANALYSIS SUMMARY OF RESULTS.......................................... 3-11

LIST OF TABLES

Table 3.3.1 Equipment Classes Analyzed in the Engineering Analysis and Their Representative 

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

Table 3.3.2 Baseline SCOP Efficiency Levels for Computer Room Air Conditioners............... 3-9

Table 3.3.3 Efficiency Levels for Analysis of Computer Room Air Conditioners ................... 3-10

Table 3.4.1 Price-Efficiency Points for Air-Cooled Computer Room Air Conditioners .......... 3-11

Table 3.4.2 Price-Efficiency Points for Water-Cooled Computer Room Air Conditioners...... 3-11

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

Fluid Economizer....................................................................................................................... 3-12

Table 3.4.4 Price-Efficiency Points for Glycol-Cooled Computer Room Air Conditioners..... 3-12

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

Fluid Economizer....................................................................................................................... 3-12

LIST OF FIGURES

Figure 3.3.1 Flow Chart of the Extrapolation of the Price-Efficiency Curves............................ 3-8
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3.1 INTRODUCTION

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

efficiency of computer room air conditioners. This relationship serves as the basis for costbenefit 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.

In the NODA, DOE performed a potential energy savings analysis on all six classes 

water-cooled air conditioners (small (<65,000 Btu/h) with no heating or electric resistance 

heating, small with other types of heating, large (≥65,000 Btu/h and <240,000 Btu/h) with no 

heating or electric resistance heating, large with other types of heating, very large (≥240,000 

Btu/h and <760,000 Btu/h) with no heating or electric resistance heating, and very large with 

other types of heating) and on two very large evaporatively-cooled air conditioners (with either 

no heating or electric resistance heating and with other types of heating). For small and large 

evaporatively-cooled air conditioners, DOE could not find any models on the market and could 

not perform a potential energy savings analysis or an engineering analysis for this class. As 

discussed in the NOPR, where DOE did perform a potential energy savings analysis, DOE 

determined that the potential energy savings were very low and that more stringent standards 

than ASHRAE Standard 90.1-2010 were not warranted; therefore, DOE did not perform an 

engineering analysis on this equipment. For water-source VRF heat pumps, DOE could not find 

any models on the market with a cooling capacity <17,000 Btu/h and, therefore, also could not 

perform a potential energy savings analysis on this equipment. DOE performed a potential 

energy savings analysis on this equipment with a cooling capacity ≥135,000 Btu/h and also 

determined that the potential energy savings were very low and that more stringent standards 

than ASHRAE were not justified. Thus, DOE did not perform an engineering analysis for watersource VRF heat pumps.

However, DOE did perform an engineering analysis on computer room air conditioners

which is the subject of this chapter. To develop the engineering analysis for computer room air 

conditioners, DOE used an efficiency-level 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-
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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. ASHRAE Standard 90.1-2010 

separates computer room air conditioners into 30 equipment classes based upon its heat 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 and 

a small number of models 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 largest 

number of models on the market and extrapolated that analysis to the other equipment classes.

In the market assessment analysis, 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 literature. 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 both orientations have the same major 

components and that the prices and incremental costs for increasing efficiency for both 

orientations would be nearly the same. Therefore, DOE only analyzed downflow units in the 

engineering analysis, where more data was available. Since the downflow results would have 

been similar to the upflow results, 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: 

small (i.e., sensible capacity <65,000 Btu/h) air-cooled, large (i.e., sensible capacity ≥65,000 

Btu/h and <240,000 Btu/h) air-cooled, small (i.e., sensible capacity <65,000 Btu/h) water-cooled, 

and large (i.e., sensible capacity ≥65,000 Btu/h and <240,000 Btu/h) water-cooled. For the other 

11 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. To start its analysis DOE gathered as much 

information possible about small (<65,000 Btu/h)1, large (≥65,000 Btu/h and <240,000 Btu/h), 

 

1 The small and large definitions for computer room air conditioners in ASHRAE Standard 90.1-2010 are slightly 

different from the definitions of small and large commercial package air conditioning and heating equipment in 
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very large (≥240,000 Btu/h and <760,000 Btu/h) air-cooled, water-cooled, and glycol-cooled

computer room air conditioners currently available on the market, which is discussed in chapter 

2 of this TSD (Market Assessment). The information obtained in the market assessment 

informed decisions made for the engineering analysis and other downstream analyses.

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 

particular design options used to achieve such increases; and/or (3) the reverse engineering or 

cost-assessment 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 this rulemaking, DOE used an efficiency-level approach with a pricing survey in 

order to estimate the cost of achieving different 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 analysis. DOE obtained pricing data from equipment distributors of 

three2 major computer room air conditioner manufacturers, which was used to develop the priceefficiency relationship for computer room air conditioners.

 

EPCA, which defines small equipment as having cooling capacities <135,000 Btu/h and large equipment as having 

cooling capacities ≥135,000 Btu/h and <240,000 Btu/h. 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.
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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 for 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 class, rounded to the nearest ton of 

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

that contained the highest number of models with efficiency information for that equipment 

class.

For air-cooled, water-cooled, and glycol-cooled computer room air conditioners with a 

sensible cooling capacity less than 65,000 Btu/h, DOE selected 36,000 Btu/h (3 tons) as the 

representative capacity for analysis. For air-cooled, water-cooled, and glycol-cooled computer 

room air conditioners with a sensible cooling capacity greater than 65,000 Btu/h and less than 

240,000 Btu/h, DOE selected 132,000 Btu/h (11 tons) as the representative capacity for analysis.

For air-cooled, water-cooled, and glycol-cooled computer room air conditioners with a sensible 

cooling capacity greater than 240,000 Btu/h, DOE selected 288,000 Btu/h (24 tons) as the 

representative capacity for analysis. 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, 

DOE collected data for all five of the units with efficiency data in these equipment classes.

(These were the only units in the database that had efficiency information at this size.) For the 

equipment classes with fluid economizers, DOE selected the same representative capacities as 

the equipment classes without the fluid economizer. 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 

below. Also, DOE extrapolated the analysis for the glycol-cooled equipment class from the 

water-cooled equipment class.

Table 3.3.1 shows the computer room equipment classes and the representative sensible 

cooling capacities at which DOE collected information for the engineering analysis.
3-5

Table 3.3.1 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

<65,000 36,000 

≥65,000 and <240,000 132,000 

>240,000 288,000 

Water-Cooled

<65,000 36,000 

≥65,000 and <240,000 132,000 

>240,000 288,000 

Water-Cooled with a 

Fluid Economizer

<65,000 36,000 

≥65,000 and <240,000 132,000 

>240,000 288,000 

Glycol Cooled

<65,000 36,000

≥65,000 and <240,000 132,000 

>240,000 288,000 

Glycol Cooled with a 

Fluid Economizer

<65,000 36,000

≥65,000 and <240,000 132,000 

>240,000 288,000 

3.3.3 Pricing Data

After selecting the representative capacity for each equipment class, DOE selected units 

for which it would obtain pricing information. The units selected represented a variety of 

technologies and SCOP ratings. The selections were limited to models for which DOE had 

SCOP information. Due to the limited amount of data available, 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 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 for the units plus 

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 total: 6 small air-cooled 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 the pricing information along with the estimated SCOP 

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

equipment classes, DOE extrapolated the analysis based on the results, SCOP differences in 

ASHRAE, and price differences from the four primary equipment classes. DOE decided to use 

the SCOP differences in ASHRAE because there wasn’t 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 approximate the industry average SCOP 

differences between equipment classes.

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 water-cooled equipment classes. For very 

large air-cooled equipment, DOE shifted the large 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 difference in price between 

large and very large units in the same model line in order to determine the average percent 

difference in price between the large and very large air-cooled equipment class. DOE found that 

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

for the very large air-cooled equipment class as compared to 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 very 

large water-cooled equipment, DOE shifted the large price-efficiency curve down by 0.10 SCOP 

(the difference in SCOP as noted by ASHRAE Standard 90.1-2010). Then, DOE calculated the 
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average percent difference in price between a large and very large unit in the same water-cooled 

model line, which DOE found to be 90 percent. DOE multiplied the prices in the large watercooled 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 based on the information from the watercooled equipment class. DOE found that in both of the instances where DOE had pricing 

information for a model that was optionally water-cooled or glycol-cooled, 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.) Based on this 

information, DOE modeled the glycol units as having the same prices as water-cooled units at 

the same representative capacity; but DOE shifted the SCOP 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).

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 will require more fan energy and thus have a lower 

SCOP rating then those models without a fluid economizer. Thus, DOE shifted the priceefficiency 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. DOE was only able to 

collect pricing data for one unit with a fluid economizer (a very large glycol-cooled unit). DOE 

compared the price of the unit with the fluid economizer to the price of the same unit without a 

fluid economizer to determine the price increase associated with the addition of a fluid 

economizer. DOE found that the percentage difference of 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 price-efficiency 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 
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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. 

Figure 3.3.1 Flow Chart of the Extrapolation of the Price-Efficiency Curves

Small Air-Cooled 

Computer Room 

AC

Large Air-Cooled 

Computer Room 

AC

Very Large AirCooled Computer 

Room AC

Very Larger WaterCooled Computer 

Room AC

Large WaterCooled Computer 

Room AC

Small WaterCooled Computer 

Room AC

Small WaterCooled Computer 

Room AC with a 

Fluid Economizer

Large WaterCooled Computer 

Room AC with a 

Fluid Economizer

Very Large WaterCooled Computer 

Room AC with a 

Fluid Economizer

Very Large GlycolCooled Computer 

Room AC

Large GlycolCooled Computer 

Room AC

Small GlycolCooled Computer 

Room AC

Small GlycolCooled Computer 

Room AC with a 

Fluid Economizer

Large GlycolCooled Computer 

Room AC with a 

Fluid Economizer

Very Large GlycolCooled Computer 

Room AC 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

SCOP 

– 0.35

SCOP 

– 0.30
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3.3.5 Selection of Baseline Efficiency Levels

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. Also, 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 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. The baseline model in each 

equipment class generally contains the typical features and technologies of equipment in that 

class. Table 3.3.2 shows the baseline efficiency level for each equipment class of computer room 

air conditioners.

Table 3.3.2 Baseline SCOP Efficiency Levels for Computer Room Air Conditioners

Equipment Class 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 1.9

Water-Cooled

<65,000 2.6

≥65,000 and <240,000 2.5

>240,000 2.4

Water-Cooled with a 

Fluid Economizer

<65,000 2.55

≥65,000 and <240,000 2.45

>240,000 2.35

Glycol Cooled

<65,000 2.5

≥65,000 and <240,000 2.15

>240,000 2.1

Glycol Cooled with a 

Fluid Economizer

<65,000 2.45

≥65,000 and <240,000 2.1

>240,000 2.05 1 As noted in Section 3.2, DOE focused its analysis on downflow only models.
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3.3.6 Identification of Efficiency Levels for Analysis

In the engineering analysis, DOE identified efficiency levels for each equipment class 

based on an extensive review of the database 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 SCOP, the new 

efficiency metric used in the updated ASHRAE 127-2007 test procedure. ASHRAE 127-2007 

contains a “rule of thumb” formula to convert from the ASHRAE 127-2001 EER rating to the 

ASHRAE 127-2007 SCOP rating, which DOE used to estimate SCOP ratings, as described in 

chapter 2 of this TSD. As previously noted, DOE only had enough data to directly analyze four 

equipment classes, small air-cooled, large air-cooled, small water-cooled, and large watercooled. For each of these four equipment classes, DOE identified the baseline efficiency level (as 

noted in the previous section) and the max tech efficiency level and chose three additional evenly 

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

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

DOE selected efficiency levels based on the efficiency differences 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 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 models database. 

Table 3.3.3 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

Air-Cooled, ≥65,000 Btu/h and <240,000 Btu/h 2.10 2.35 2.60 2.85 3.10

Air-Cooled, ≥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

Water-Cooled, ≥65,000 Btu/h and <240,000 Btu/h 2.50 2.70 2.90 3.10 3.30

Water-Cooled, ≥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

Water-Cooled with a Fluid Economizer, ≥65,000 

Btu/h and <240,000 Btu/h

2.45 2.65 2.85 3.05 3.25

Water-Cooled with a Fluid Economizer, ≥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

Glycol-Cooled, ≥65,000 Btu/h and <240,000 Btu/h 2.15 2.35 2.55 2.75 2.95

Glycol-Cooled, ≥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

Glycol-Cooled with a Fluid Economizer, ≥65,000 2.10 2.30 2.50 2.70 2.90
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Btu/h and <240,000 Btu/h

Glycol-Cooled with a Fluid Economizer, ≥240,000 

Btu/h and <760,000 Btu/h

2.05 2.25 2.45 2.65 2.85

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 $6,681.09 2.10 $22,621.45 1.90 $32,574.89

2.40 $7,853.51 2.35 $24,383.30 2.15 $35,111.96

2.60 $9,231.68 2.60 $26,282.38 2.40 $37,846.62

2.80 $10,851.69 2.85 $28,329.36 2.65 $40,794.28

3.00 $12,755.99 3.10 $30,535.77 2.90 $43,971.50

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 $14,232.84 2.50 $12,883.01 2.40 $24,453.25

2.80 $11,527.69 2.70 $17,315.28 2.60 $32,863.52

3.00 $9,336.69 2.90 $23,272.43 2.80 $44,166.35

3.20 $7,562.12 3.10 $31,279.07 3.00 $59,356.59

3.40 $6,124.84 3.30 $42,040.32 3.20 $79,771.25
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Table 3.4.3 Price-Efficiency Points 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 $15,061.82 2.45 $13,633.37 2.35 $25,877.51

2.75 $12,199.11 2.65 $18,323.79 2.55 $34,777.62

2.95 $9,880.50 2.85 $24,627.91 2.75 $46,738.77

3.15 $8,002.57 3.05 $33,100.89 2.95 $62,813.76

3.35 $6,481.57 3.25 $44,488.92 3.15 $84,417.45

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 $14,232.84 2.15 $12,870.13 2.10 $24,453.25

2.70 $11,527.69 2.35 $17,296.59 2.30 $32,863.52

2.90 $9,336.69 2.55 $23,245.45 2.50 $44,166.35

3.10 $7,562.12 2.75 $31,240.31 2.70 $59,356.59

3.30 $6,124.84 2.95 $41,984.87 2.90 $79,771.25

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 $15,061.82 2.10 $13,619.74 2.05 $25,877.51

2.65 $12,199.11 2.30 $18,304.01 2.25 $34,777.62

2.85 $9,880.50 2.50 $24,599.36 2.45 $46,738.77

3.05 $8,002.57 2.70 $33,059.87 2.65 $62,813.76

3.25 $6,481.57 2.90 $44,430.24 2.85 $84,417.45

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. The 
3-13

data collected by DOE indicated that there are manufacturers who sell lower price, less efficient

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

DOE notes 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 other similar equipment which DOE has analyzed have previously shown 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 their different product lines. As a result, morepopular 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 

attempts to estimate the equipment cost at the point of manufacturer (rather than the purchase 

price from the distributor) might yield different results from those discovered in this analysis.