1

Revised Draft Analysis of U.S. Commercial 

Supermarket Refrigeration Systems

Prepared by ICF Consulting for 

U.S. EPA’s Stratospheric Protection Division

November 30, 2005
2

Table of Contents

1. Executive Summary............................................................................................................................3

2. Introduction.........................................................................................................................................4

3. Direct Expansion (DX) Systems.........................................................................................................7

3.1. Description...................................................................................................................................7

3.2. Penetration of Technology ...........................................................................................................7

3.3. Refrigerant Type and Charge Size ...............................................................................................8

3.4. Typical Leak Rates and Direct Emissions ...................................................................................8

3.5. Energy Consumption....................................................................................................................9

3.6. Capital and Installation Costs.......................................................................................................9

4. Secondary Loop Systems....................................................................................................................9

4.1. Description...................................................................................................................................9

4.2. Penetration of Technology .........................................................................................................10

4.3. Refrigerant Type and Charge Size .............................................................................................10

4.4. Typical Leak Rates and Direct Emissions .................................................................................11

4.5. Energy Consumption..................................................................................................................12

4.6. Capital and Installation Costs.....................................................................................................14

5. Distributed Systems..........................................................................................................................15

5.1. Description.................................................................................................................................15

5.2. Penetration of Technology .........................................................................................................16

5.3. Refrigerant Type and Charge Size .............................................................................................16

5.4. Typical Leak Rates and Direct Emissions .................................................................................17

5.5. Energy Consumption..................................................................................................................18

5.6. Capital and Installation Costs.....................................................................................................18

6. Low-Charge Multiplex Systems ......................................................................................................18

6.1. Description.................................................................................................................................18

6.2. Penetration of Technology .........................................................................................................20

6.3. Refrigerant Type and Charge Size .............................................................................................20

6.4. Typical Leak Rate and Direct Emissions...................................................................................20

6.5. Energy Consumption..................................................................................................................21

6.6. Capital and Installation Costs.....................................................................................................21

7. Advanced Self-Contained Systems..................................................................................................21

7.1. Description.................................................................................................................................21

7.2. Penetration of Technology .........................................................................................................22

7.3. Refrigerant Type and Charge Size .............................................................................................22

7.4. Typical Leak Rate and Direct Emissions...................................................................................22

7.5. Energy Consumption..................................................................................................................22

7.6. Capital and Installation Costs.....................................................................................................23

8. Total Equivalent Warming Impact (TEWI)...................................................................................23

8.1. TEWI Comparisons....................................................................................................................23

9. Retrofitting R-22 Supermarket Equipment ...................................................................................28

9.1. System Efficiency ......................................................................................................................28

9.2. Retrofit Cost...............................................................................................................................29

9.3. Retrofit Procedures ....................................................................................................................29

10. References..........................................................................................................................................30

Appendix A: Best Practices for Retrofitting R-22 Equipment..............................................................33
3

1. Executive Summary

This report presents a wide range of data collected on five types of supermarket refrigeration systems:

direct expansion, secondary loops, distributed, low-charge multiplex, and advanced self-contained 

systems. In many cases, varying or even conflicting information was obtained from the published

literature and/or industry experts. Table ES-1, below, summarizes the results of this data analysis. 

Table ES-1. Summary of Key Attributes of Supermarket Systems, Based on ICF Analysis

Baseline Alternative Technologies

Direct Expansion 

(DX)

Secondary Loop Distributed Low-Charge 

Multiplex

Advanced SelfContained

Estimated 

Penetration of 

Technology into 

New/ Remodeled

U.S. 

Supermarkets

60% to 80%

(~70%)

3% to 5%

(~4%)

18% to 35%

(~26%)

Minimal Minimal

Common 

Refrigerants

R-22, R-502, R404A, R-507AR-404A, R-507A R-22, R-404A, R507AR-404A, R-507A R-134a, R-404A,

R-507A

Average Leak 

Rates During 

Use

15% to 35%

(Old systems: 25%;

New systems: 

15%)

< 2% to 15%

(Literature: <2% to 

5%; 

Industry: 10% to 

15%)

5% to 25% 25% Literature: 1%;

Industry: 10%

Comparison of Alternatives to Baseline (DX)

Typical Charge 

Size 

10% to 50% 12% to 60% 30% to 60% 5% to 10%

Change in Direct 

Emission 

Reduction 

- 44% to -99%

(HFCs);

-100% 

(ammonia, HCs)

- 75% to -95% NA NA

Change in 

Energy 

Consumption 

- 5% to +15%;

0% to +20%

- 8% to +16%;

0% to +10%

- 12% +7%

Change in 

Capital Cost 

+10% to +25%

(capital costs are 

on the higher end 

of this range for 

systems using 

natural refrigerants)

0% to +33% 0% 0%

Change in 

Installation Cost 

-4% to +10% -25% to +15% 0% 0% to +15%

TEWI Reduction 42% to 61% 38% to 60% 24% to 44% 56%

NA = Not available.
4

2. Introduction

Supermarkets are defined as retail food stores with sales greater than $2 million. In 2004, the Chain Store 

Guide estimated that there were over 31,000 supermarkets in the United States. The top 20 supermarket

chains, with 18,276 stores, hold 77% of total retail groceries sales in the U.S (Chain Store Guide, 2004). 

Published estimates of the average supermarket size in the United States vary widely. UNEP (2003) 

estimated that the average supermarket in the United States is 43,000 ft2; more recent industry estimates 

concur, indicating that the average store size is currently about 45,000 ft2. However, a 2002 study by

Arthur D. Little (ADL) estimated that newly constructed supermarkets in the United States are 60,000 ft2, 

and this will be the average size of all supermarkets in 8 to 10 years. 

Annual energy use in supermarkets ranges from 100,000 kWh/year to 1.5 million kWh/year, depending

on store size. Refrigeration energy consumption in a typical supermarket is estimated to comprise 30% to 

50% of total energy consumption, or up to 65% for small supermarkets (ADL, 2002; Baxter and Walker,

2003; IPCC/TEAP, 2005). According to IEA (2003), compressors and condensers account for 60% to

70% of refrigeration energy consumption, while display and storage cooler fans, display case lighting,

evaporator defrosting, and anti-sweat heaters account for the remainder (IEA, 2003). 

Figure 1, below, presents the typical layout of a supermarket with the refrigerated display cases and

storage areas located around the store’s perimeter.

Figure 1. Typical Supermarket Layout

Source: ADL (1996).

Approximately 4,000 new supermarket refrigeration systems are purchased each year, with about 60%

being for new store applications and 40% for remodels (Humphrey, 2000). One industry expert estimated 

that of his company’s sales of DX systems, 70% of sales are for new store applications, while 30% are for 

remodels. Depending on the supermarket chain, supermarket remodeling occurs every seven to ten years

(Humphrey, 2000), although the life span of refrigeration equipment is estimated to be between 10 and 20 

years (IPCC/TEAP, 2005). The trends for new supermarket construction and remodeling in the United 

States over the last several years are presented in Figure 2, below.
5

Figure 2. U.S. Trends for New Supermarket Stores and Remodels

600

800

1000

1200

1400

1600

1800

2000

2200

2001 2002 2003 2004

(projected) Year

Number of Stores

Remodels

Openings

Source: Chain Store Guide (2001, 2002, 2003, 2004).

Currently, nearly all supermarket refrigeration equipment in use contains either HCFCs (R-22) or HFCs

(R-404A and R-507A). The estimated market breakout by refrigerant type, as provided by two U.S. 

industry sources, is presented in Figure 3.

Figure 3. Estimated Breakout of In-Use Supermarket Equipment, By Refrigerant Type

Refrigerant Percent of In-Use Equipment

Manufacturer A Manufacturer B

CFCs 5% 0%

HCFC-22 65% 40%

HFCsa 30% 60%

a

 Includes R-404A and R-507A. According to industry estimates, R-404a is used in a larger portion of systems than R-507A.

There are many types of refrigeration systems in use in U.S. supermarkets, many of which are customized 

to fit particular stores’ needs. These systems vary in many aspects, including store layout, refrigerant

type, and refrigerant charge size. 

This paper describes the most common, conventional type of supermarket refrigeration systems in use—

the direct expansion (DX) system—as well as four alternative technologies that are still being improved 

upon and, increasingly, penetrating the U.S. market. These systems provide the potential to reduce

consumption and emissions of ozone depleting substance (ODS) or greenhouse gases (GHGs) and, in

some cases, energy consumption. These four technologies include:

• Secondary loop systems;

• Distributed systems;

• Low-charge multiplex systems; and

• Advanced self-contained systems.
6

These systems are often able to operate with a lower refrigerant charge and non- ODS refrigerants. Other 

innovations in these systems, described in later sections of this paper, can also help to reduce refrigerant

emissions.

The remainder of this report is structured as follows:

• Section 3 discusses traditional DX systems;

• Section 4 details secondary loop systems;

• Section 5 provides information on distributed systems;

• Section 6 presents information on low-charge multiplex systems; 

• Section 7 discusses advanced self-contained systems; 

• Section 8 presents a TEWI analysis, comparing the direct and indirect warming impacts of each

of the supermarket systems for which quantitative data is available;

• Section 9 presents the information on efficiency and cost penalties associated with R-22 

supermarket retrofits; 

• Section 10 provides the references used in this report; and

• Appendix A provides best practices for performing R-22 retrofits.

In each of the technology discussions (Section 3 through 7), brief system descriptions are provided, as are 

estimates of the systems’ market penetrations in the United States, common refrigerants, typical charge 

sizes and leak rates, direct emissions, energy consumption, and capital and installation costs.
7

3. Direct Expansion (DX) Systems

3.1. Description

In a direct expansion (DX) system, the compressors are mounted together and share suction and discharge 

refrigeration lines that run throughout the store feeding cases and coolers. The compressors and

condensers are located in a separate machine room, either in the back of the store or on its roof, to reduce 

noise and regulate heat rejection. These multiple compressor racks operate at various suction pressures to 

support display cases operating at different temperatures (Baxter and Walker, 2003; Powell, 2003). The

hot gas from the compressors is piped to the condenser and converted to liquid. The liquid refrigerant is

then piped to the receiver and distributed to the cases and coolers by the liquid manifold. After cycling

through the cases, the refrigerant returns to the suction manifold and the compressors (Southern 

California Edison and Foster-Miller, Inc., 2004). Figure 4, below, presents the layout of a typical DX

system in a supermarket. 

Figure 4. Direct Expansion (DX) Refrigeration System

Source: IEA (2003).

3.2. Penetration of Technology

DX systems have traditionally been the most commonly used commercial refrigeration systems in the

United States. In 2002, Powell estimated that DX systems were installed in 90% of supermarkets

(Powell, 2002). In 2005, one equipment manufacturer estimated that 79% of new commercial 

refrigeration systems sold by his company are DX systems, while another manufacturer provided a lower 

estimate of 60%. Thus, DX systems represent an estimated 60% to 80% of new market sales in the

United States.
8

3.3. Refrigerant Type and Charge Size 

R-22 has been the most commonly used refrigerant in DX systems, with R-502 often used for lowtemperature applications. However, R-404A and R-507A are increasingly penetrating the U.S. market as 

an alternative for both R-22 and R-502 (IPCC/TEAP, 2005; Powell, 2001; Powell, 2002). As shown in

Figure 5, U.S. equipment manufacturers provided varying estimates of the breakout of refrigerant types

that are used in DX systems sold today.

Figure 5. Estimated Breakout of Refrigerant Types Used in New DX Systems Sold Todaya

Source Refrigerant

HCFC-22 HFC-404A HFC-507A

Manufacturer A 10% 60% 30%

Manufacturer B 33% 33% 33%b

Manufacturer C 50% 50% 0%

a These estimates are provided for each individual manufacturer, not for the U.S. market as a whole.

b

 Use of R-507A is reportedly increasing the fastest.

Charge size depends not only on store size, but also on the specific equipment and applications used (e.g., 

number of racks, low/medium/high temperature applications), which varies from store to store. Estimated 

charge sizes of DX systems, based on published literature and industry information obtained for this

report, are shown in Figure 6. 

Figure 6. Estimated Charge of DX Systems 

As a Percent 

of Floor Area

Store 

Size

(ft2)

Charge Size of 

a DX System

(lbs)

Comments Source

4% 45,000 2,000 Using only medium-temperature equipment Manufacturer A

6% 60,000 3,600 ADL (2002)

6% - 7% 45,000 2,866 to 3,086 Manufacturer C

7.5% - 10% 60,000 4,500 to 6,000 Using 3 racks Manufacturer B

8% - 14% 35,000 3,000 to 5,000

Southern California 

Edison and Foster-Miller, 

Inc. (2004)

According to the above sources, DX charge sizes can range between 4% and 14% of supermarket square 

footage. 

3.4. Typical Leak Rates and Direct Emissions

Figure 7, below, presents estimated leak rates provided in published literature and by industry sources

contacted for this report. As shown, leak rates can vary widely; the reduction in leakage from DX

systems can be explained by a number of steps taken by equipment manufacturers and users to minimize 

leakage, including: designing the system for tightness, practicing maintenance procedures for early

detection and leakage repairs; training personnel; and recovering refrigerant at end-of-life (IPCC/TEAP,

2005). 
9

Figure 7. Estimated Annual Leak Rates of DX Systems

Annual Leak 

Rates

Comments Source

5% to 10% Based on two studies performed in Germany Birndt et al. (2000), Haaf and Heinbokel (2002)

3% - 22% 

(18% average)

Based on a sample of 1,700 supermarket systems 

in the U.S. and several European countries IPCC/TEAP (2005)

12.4% Based on a field test Southern California Edison and Foster-Miller, Inc. 

(2004)

15% Newer equipment IEA (2003)

15% - 35% Multiple factors for such a high leak rate were cited, 

including poor installation and maintenance Manufacturer B

20% - 35% Bivens and Gage (2004)

25% After equipment has been in service for several 

years

Manufacturer A, Manufacturer B, Manufacturer C

> 30% Older equipment IEA (2003)

Estimates of annual leak rates for DX systems range from 3% to 35% for in-use equipment, with the

higher annual leak rates (25%) being more characteristic of older equipment and the lower ones (15%)

being more characteristic of newer equipment. 

3.5. Energy Consumption

DX systems consume significant amounts of energy due to the long pipe runs between the display cases

and compressor racks, which result in pressure drops and suction gas heating. In addition, compressor

run times are increased, increasing compressor energy consumption (Southern California Edison and

Foster-Miller, Inc., 2004). However, DX systems have less thermal resistance, and no separate fluid

pumping equipment, giving them an efficiency and cost advantage compared to alternative systems

(IPCC/TEAP, 2005). According to ADL (2002), a typical DX system in a 60,000 ft2 supermarket is

estimated to consume approximately 1.2 million kWh/year. According to an industry expert, a 45,000 ft2

store will consume 1.45 million kWh/year. 

3.6. Capital and Installation Costs

One U.S. equipment manufacturer estimated that, for a store that is 60,000 ft2, where 3 racks are required, 

total capital cost is about $165,000 (i.e., $55,000 per rack). The cost of food cases would be in additional 

to this. According to another equipment manufacturer, the installation cost of a DX system in a 30,000 ft2

store is approximately $130,000, or $4.33/ft2. In addition, the cost of DX systems will depend on the type 

of refrigerant used; currently, the initial cost of an HFC DX system is estimated to be two to three times

more than the cost of an R-22 system.

4. Secondary Loop Systems

4.1. Description

In secondary loop systems, two liquids are used. The first is a cold fluid, often a brine solution, which is 

pumped throughout the store to remove heat from the display equipment. The second is a refrigerant that 

is isolated from the equipment cooled and passes through a heat exchanger to be cooled (EPA, 2004). 

Secondary loop systems can operate with two to four separate loops and chiller systems depending on the 

temperatures needed for the display cases. Secondary loop systems may use either reciprocating or screw 

compressors, although high-efficiency screw compressors have greater energy savings potential (Southern 

California Edison and Foster-Miller, Inc., 2004).
10

The two main disadvantages associated with secondary loop systems are a loss of energy efficiency and

higher capital costs (EPA, 2004; IEA, 2003). One benefit to secondary loop systems is that they have

improved temperature control compared to conventional direct expansion systems. This is an important

advantage in the United States, which has recently tightened its regulations on temperature control for

refrigerated products such as meat, poultry, and fish (EPA, 2004; IEA, 2003). 

Figure 8 presents a diagram of a secondary loop refrigeration system.

Figure 8. Secondary Loop Refrigeration System

Source: Southern California Edison and Foster-Miller, Inc. (2004).

4.2. Penetration of Technology 

One U.S. equipment manufacturer estimated that approximately 5% of its new supermarket sales are

secondary loop systems.1 Another manufacturer estimated that sales of secondary loop systems represent 

only about 3% of its new supermarket sales. Based on this data, the total market penetration of secondary 

loop systems into new or remodeled stores is estimated to range from 3% to 5% in the United States.

4.3. Refrigerant Type and Charge Size 

According to U.S. equipment manufacturers interviewed for this report, secondary loop systems use

primarily R-404A (about two-thirds) and R-507A (about one-third). No secondary loop systems are 

known to have been sold with R-22 or ammonia within the United States.

 

1

 Supporting this estimate, one supermarket chain in the U.S. reported that 5% of its systems are secondary loop

systems (Godwin, 2005).
11

In Europe, however, ammonia secondary loop systems are in use. In addition, CO2 has also been gaining 

market share as a secondary coolant (IPCC/TEAP, 2005). Although one industry expert noted that CO2

has lots of potential for use in low-temperature applications, currently, safety issues prevent the

widespread use of CO2 in the United States (Beeton, 2005).

Because the primary refrigerant does not need to circulate throughout the store, secondary loop systems

can operate with a significantly lower refrigerant charge than DX systems. Thus, the charge size of a

secondary loop system is estimated to be 10% to 25% of the charge in a DX system (ADL, 2002; Bivens 

and Gage, 2004; IPCC/TEAP, 2005; IEA, 2003) while other estimates range from 30% to 50% of the

charge size of a DX system (Godwin, 2005; Southern California Edison and Foster-Miller, Inc., 2004). 

Figure 9, below, presents a summary of the estimated charge size estimates for secondary loop systems

provided by various sources. Variations in charge size estimates are likely associated with differences in 

secondary loop equipment and, potentially, different baseline comparisons (i.e., differences in the size of

“conventional” DX systems).

Figure 9: Charge Size of a Secondary Loop System as a Percentage of the Charge Size of a DX System

Charge Size

as a 

Percentage of 

DX Systems

Store 

Size

(ft2)

Actual 

Charge 

Size

(lbs)

Comments Source

1% -1.5% 35,000 300 to 500

Based on theoretical calculations made in 

preparation for field study. Field study required 

additional charge to provide heat reclaim for hot 

water and space heat.

Southern California 

Edison and Foster-Miller, 

Inc. (2004)

10% - 15% NA NA IEA (2003)

11% 60,000 396 ADL (2002)

15% - 25% NA NA Based on a sample of 1,700 supermarket systems in 

the U.S. and several European countries IPCC/TEAP (2005)

30% - 40% NA NA Based on a case study of a chain store in North 

America Godwin (2005)

40%a 45,000 1,200 Manufacturer A

~50% 42,000 1,400 Based on a case study of a supermarket in California

Southern California 

Edison and Foster-Miller, 

Inc. (2004)

NA=Not Available

aMedium temperature only.

Based on the data presented above, although theoretical calculations indicate that secondary loop systems 

could require a charge of as little as 1% of DX systems, according to several case studies, secondary loop 

systems actually require a charge of between 10% and 50% of DX systems. 

4.4. Typical Leak Rates and Direct Emissions

Secondary loop systems have lower annual leak rates than DX systems because they have a reduced 

number of connecting joints where leaks can occur (Bivens and Gage, 2004; EPA, 2004). In addition, 

secondary loop systems use pre-manufactured pipes that are often made of plastic instead of copper;

therefore, they do not require brazing (EPA, 2004). Estimates of annual leak rates for secondary loop

systems ranged from less than 2% to 15%, as presented by Figure 10. Based on the more recent data 

available from U.S. systems, this range may be closer to 10% to 15% in the United States.
12

Figure 10. Estimated Annual Leak Rates of Secondary Loop Systems

Annual Leak Rate Comments Source

U.S. Data

2% - 5% ADL (2002)

5% IPCC/TEAP (2005)

10% Manufacturer A

12%

This system uses glycol (ethylene or propylene) as 

cooling fluid to remove heat from food products in 

cases.

Manufacturer B

14.8% Southern California Edison and FosterMiller, Inc. (2004)

International Data

< 2% Based on a study of supermarkets in Sweden. Engsten and Lindh (2004)

The combination of these reduced leak rates and the lower charge sizes results in significant direct

emission reductions (Bivens and Gage, 2004; EPA, 2004). Indeed, secondary loop systems are estimated 

to experience total direct emissions reductions of 44% to 99% relative to DX systems (see Figure 11).

Figure 11. Estimated Direct Emissions of Secondary Loop Systems Relative to DX Systems

Direct Emissions 

Relative to DX 

Systems

Comments Source

- 44%

This estimate is based on a comparison field study of a secondary 

loop system with an annual leak rate of 14.8% (compared to 12.4% 

for DX), and a charge size equal to 11% of a DX system. 

Southern California Edison and 

Foster-Miller, Inc. (2004)

- 50% to -90% Based on a sample of 1,700 supermarket systems in the U.S. and 

several European countries IPCC/TEAP (2005)

- 75% Godwin (2005)

- 98.5% Assumes a 2% to 5% reduction in annual leak rate (compared to 

15% for DX) and that the charge size is equal to 11% of a DX 

system.

ADL (2002)

4.5. Energy Consumption

Most studies have found that secondary loop systems require more energy than conventional DX systems. 

Reasons for increased energy use include (Southern California Edison and Foster-Miller, Inc., 2004):

• The use of display cases containing evaporators designed for DX systems. The evaporator coils

have heat transfer characteristics that are not appropriate for use with a secondary fluid.

• Operation of the refrigeration system reducing the efficiency of the refrigeration compressors.

• The viscosity of the glycol-water mixture used in many secondary loop systems, which is much

higher than that of water alone, increasing the fluid friction and pumping power.

Estimates of the energy consumption of secondary loop systems relative to DX systems are shown in

Figure 12.
13

Figure 12. Estimated Energy Consumption of Secondary Loop Systems Relative to DX Systems

Energy Consumption 

Relative to DX System

Store Size

(ft2)

Comments Source

0% to +20% NA

Estimates are for secondary loop systems with 

ammonia, hydrocarbons, or HFCs

Estimate is based on a sample of 1,700 

supermarket systems in the U.S. and several 

European countries

IPCC/TEAP (2005)

+5% to +20% NA Data reported from 77 supermarkets with 

secondary loop systems in Germany Haaf and Heinbokel (2002)

+10% to +15% NA UNEP (2003)

+15% to +20% 45,000 Manufacturer B

+17% 60,000 ADL (2002)

NA = Not Available

Based on this data, average secondary loop systems in use consume 0% to 20% more energy than DX

systems. 

However, energy savings are possible with advanced secondary loop systems. For example, the 

following design features can lead to energy savings:

• Close coupling between the chiller evaporator and the compressor suction to reduce pressure drop 

and refrigerant gas overheating (Southern California Edison and Foster-Miller, Inc., 2004);

• Improved pump capacity control and use of a low viscosity secondary fluid to reduce the energy

use involved in circulating the secondary fluid (Southern California Edison and Foster-Miller, 

Inc., 2004);

• Design of display cases and fixtures for secondary loop systems to reduce heat transfer penalties

(Southern California Edison and Foster-Miller, Inc., 2004); 

• Subcooling of the primary refrigerant with the secondary fluid and then use of the secondary fluid 

to defrost the heat exchangers in display cases (IEA, 2003).

• More efficient defrost (IPCC/TEAP, 2005);

• Better part load characteristics (IPCC/TEAP, 2005);

• Improved expansion device performance (IPCC/TEAP, 2005); and

• Use of high-efficiency evaporative condensers (IEA, 2003).

Using these improved design features, secondary loop systems can lead to energy savings of 5% to more

than 15% compared to DX systems, as presented by Figure 13.
14

Figure 13. Estimated Energy Consumption of Advanced Secondary Loop Systems Relative to DX Systems

Energy Consumption 

Relative to DX Systems

Store Size

(ft2)

Comments Source

- 4.9% 42,000 Achieved in a field test of an advanced 

secondary loop system

Southern California Edison and 

Foster-Miller, Inc. (2004)

-10% 40,000 Compared to a DX system with an air-cooled 

condenser; Baxter (2003)

> -14.9% 42,000 Energy Prediction made by Southern 

California Edison and Foster-Miller, Inc., 2004

Southern California Edison and 

Foster-Miller, Inc. (2004)

4.6. Capital and Installation Costs

Capital and installation costs of secondary loop systems vary widely depending on the types of primary

and secondary refrigerants used, as shown in Figure 14.

Figure 14. Estimated One-Time Costs of Secondary Loop Systems using HFC Refrigerants Relative to DX Systems

Type of 

Cost

Cost 

Relative to 

DX System

Primary 

Refrigerant

Secondary 

Refrigerant

Comments Source

HFC Secondary Loop Systems

+10% NA NA Based on a study of one 

supermarket chain in North America Godwin (2005)

+10% to 

+25%

HFCs Based on a sample of 1,700 

supermarket systems in the U.S. 

and several European countries

IPCC/TEAP 

Capital (2005)

+17.5% HFC

Not specified 

(secondary 

coolant or brine)

EPA (2004)

+ 6.8% R-404A Glycol Rohrbach 

(2005)

+15%a NA NA UNEP (2003)

+15% R-404A or 

R-507A

Propylene glycol 

or potassium 

formate brines

IEA (2003)

Capital and 

Installation

+15% to 

+35%b

NA NA Based on a study of 77 

supermarkets in Germany 

Bivens and 

Gage (2004)

+10% NA NA Godwin (2005) Installation

-4% NA NA Manufacturer A

-20% R-404A Glycol Rohrbach 

Maintenance (2005)

-40% to 

+50%

NA NA Godwin (2005)

Secondary Loop Systems Using Natural Refrigerants

Capital +25% Ammonia NA EPA (2004)

Capitalc +30% Hydrocarbons NA Based on a sample of 1,700 

supermarket systems in the U.S. 

and several European countries

IPCC/TEAP 

(2005)

NA = Not Available.

a This cost refers to the “initial cost,” which this analysis assumes to include both capital and installation costs.

b This cost refers to the “installed costs,” which this analysis assumes to include both capital and installation costs.

c This cost is assumed to be a capital cost, though the literature is not clear.

The higher capital and/or installation costs associated with secondary loops can be offset by lower 

operating and maintenance costs due to decreased charge sizes, decreased leak rates, faster defrost, lower 
15

maintenance needs, and longer shelf lives, potentially resulting in significant cost-savings over time

(EPA, 2004; IEA, 2003; Southern California Edison and Foster-Miller, Inc., 2004). 

Figure 15, below, compares the maintenance costs associated with repairs to five DX and five secondary 

loop systems in a major Midwest supermarket chain from April 2002 to April 2004. Overall, the

secondary loop systems showed a decrease in the costs of labor, parts, refrigerant, and maintenance

relative to the costs for DX systems. The secondary loop systems did, however, show a 20% increase in

the cost of energy.2

Figure 15. Comparison of the Costs Associated with Repairs to DX and Secondary Loop Systems in a Major

Supermarket Chain (April 2002 – April 2004)

Store # Labor

($)

Parts

($)

Refrigerant

($)

Refrigerant 

(lbs)

Secondary 

Fluid ($)

Secondary 

Fluid (gal)

Energy

($)

Maintenance 

($)

DX Systems (5 Stores)

#1014 16,490 14,080 948 834 322,232 32,352

#1067 17,336 19,236 3,360 4,420 383,729 44,352

#1162 17,420 6,703 1,596 1,275 519,326 26,994

#3039 13,060 5,107 1,968 1,765 432,620 21,900

#4075 18,231 12,534 996 1,410 414,224 33,171

TOTAL 82,537 57,659 8,868 9,704 2,072,131 158,768

Secondary Loop Systems (5 Stores)

#12 19,048 3,814 1,200 200 545 47 515,804 24,854

#1149 17,539 12,271 0 0 9,143 610 503,710 39,562

#1150 10,250 5,600 2,100 350 0 0 524,280 18,299

#1693 19,252 5,503 750 125 417 30 462,358 26,077

#3159 14,878 12,742 2,550 425 321 40 492,175 30,956

TOTAL 80,966 39,929 6,600 1,100 10,426 727 2,498,327 139,747

Change 

Relative 

to DX 

- 1.9% - 30.8% - 25.6% - 88.7% + 20.6% - 12.0%

The total cost to purchase and install secondary loop equipment can range from 6.8% to 35% more than 

DX systems. Capital costs alone can range from 10% to 25% more than DX systems, with capital costs

for systems using natural refrigerants (e.g., ammonia, hydrocarbons) being slightly higher than for HFC

systems. In addition, estimates of installation costs range from 4% less to 10% more than DX systems (for 

both HFC and natural refrigerants). These increased one-time costs can be offset by lower annual costs;

maintenance costs associated with secondary loops is 20% to 50% less than DX systems.

5. Distributed Systems

5.1. Description

Unlike DX systems, which have a central refrigeration room containing multiple compressor racks, 

distributed systems use multiple smaller rooftop units that connect to cases and coolers, using

considerably less piping (Powell, 2003; Baxter and Walker, 2003). The compressors in a distributed

system are located throughout the store near the display cases they serve. Thus, distributed systems

typically use scroll compressors, which have lower noise and vibration levels than other compressors. 

 

2

 Because all the supermarkets used in the study are in the same geographical region, this analysis assumes that per 

unit costs of labor, parts, refrigerant, and energy are equal. However, data is currently unavailable on the size of

each of these supermarkets, which could undermine the comparability of these data.
16

The compressors are connected by a water loop to the cooling units on the roof or outside of the store

(EPA, 2004). Figure 16 presents the layout of a distributed system.

Figure 16. Distributed System Layout

Source: IEA (2003)

5.2. Penetration of Technology

UNEP (2003) noted that, although distributed systems had been developed about 5 years prior, they still 

did not constitute a significant share of the global market. However, recent information indicates that

distributed systems are gaining an important share in the United States’ market. Indeed, according to two 

U.S. equipment manufacturers, distributed systems account for 18% of one company’s sales and 35% of

the other’s sales. Thus market penetration of distributed systems is estimated to range from 18% to 35%.

5.3. Refrigerant Type and Charge Size 

Distributed systems use R-22, R-404A and R-507A (ADL, 2002; IPCC/TEAP, 2005). Figure 17 presents 

estimated market percentages of each refrigerant used in distributed systems, as estimated by two U.S. 

equipment manufacturers.
17

Figure 17. Estimated Breakout of Refrigerant Types Used in New Distributed Systems Sold Todaya

Refrigerant

HCFC-22 HFC-404A HFC-507A

Manufacturer B 0% 75% 25%

Manufacturer A 10% 60% 30%

a Estimates shown are for individual manufacturers, not for the U.S. market as a whole.

Because distributed systems require less piping than DX systems, less refrigerant is needed (Powell,

2003; Baxter and Walker, 2003). Estimates of the charge size of distributed systems range from 12% to

60% of conventional DX systems, as presented in Figure 18.

Figure 18. Estimated Charge Size of Distributed Systems as a Percentage of DX Systems

Charge Size 

as a

Percentage of 

DX Systems

Store 

Size

(ft2)

Estimated 

Charge 

Size

(lbs)

Comments Source

12% 60,000 600 Using water-cooled condensers Manufacturer B

19% 60,000 960 Using air-cooled condensers Manufacturer B

25% 42,000 900 ADL (2002)

25% 35,000 300 to 500

Based on a sample of 1,700 supermarket 

systems in the U.S. and several European 

countries

IPCC/TEAP (2005)

33% NA NA

High-efficiency scroll compressors are able to 

operate at lower condensing temperatures than 

conventional reciprocating compressors; tests 

performed by the Department of Energy’s Oak 

Ridge National Laboratory (ORNL)

ACHR (1999)

30% - 35% NA NA IEA (2003)

50% - 60% NA NA Using separate rooftop condensers for each 

cabinet IEA (2003)

NA = Not Available

5.4. Typical Leak Rates and Direct Emissions

The use of distributed systems in place of DX systems can potentially reduce ODS emissions because

smaller refrigeration units are distributed among the refrigerated and frozen food display cases. Through 

this set-up, distributed systems significantly reduce the refrigerant inventory and minimize the length of

refrigerant tubing and the number of fittings that are installed in direct expansion systems, further 

reducing refrigerant leakage. 

Available data indicate that annual leak rates for distributed systems can range from 5% to 25%, as

presented in Figure 19.

Figure 19. Estimated Annual Leak Rate of Distributed Systems

Annual Leak Rate Source

<5% ADL (2002)

5% -7% IPCC/TEAP (2005)

<8% Manufacturer B

25% Manufacturer A

When changes in both annual leakage and charge size are considered, as well as emission reductions at

end of life, estimates of direct emission reductions associated with distributed systems can range from

75% to 90% compared to DX systems. This lower bound estimate of 75% is based on the draft

IPCC/TEAP report (2005), while the upper bound estimate of 90% is based on ADL (2002).
18

5.5. Energy Consumption

The amount of energy used by a distributed system depends on what type of compressor is installed in the 

system. Scroll compressors are generally less efficient at the evaporating and condensing temperatures

needed in commercial refrigeration. However, scroll compressors, unlike reciprocating compressors, do

not have valves. Thus, they can operate at lower condensing temperatures, increasing their efficiency and 

reducing energy consumption (Powell, 2003; Baxter and Walker, 2003). 

Literature sources disagree on the energy impact of distributed systems relative to DX systems. As 

presented in Figure 20, distributed systems have been found to be more energy efficient (by about 8% to

16%) in some cases, but less efficient (by 0% to 10%) in others.

Figure 20. Estimated Energy Consumption of Distributed Systems Relative to DX Systems

Energy Consumption Relative to DX Systems Source

-8% ADL (2002)

10% to -16% ACHR (1999)

0% to +10% IPCC/TEAP (2005)

5.6. Capital and Installation Costs

The capital costs of distributed systems are estimated to be from 0% to 33% higher than DX systems, as

shown in Figure 21.

Figure 21. Estimated Capital Costs of Distributed Systems Relative to DX Systems

Costs Relative to DX Systems Comments Source

0% to +10% Based on a sample of 1,700 supermarket systems 

in the U.S. and several European countries

IPCC/TEAP (2005)

+8% to +10% Manufacturer B

+33% EPA (2004)

The installation costs of distributed systems have been found to range significantly based on published

literature and industry estimates. As shown in Figure 23, installation costs have been found to be from

25% lower to 15% higher than DX systems.

Figure 22. Estimated Installation Costs of Distributed Systems Relative to DX Systems

Costs Relative to DX 

Systems

Comments Source

+15% “Installed cost”aIEA (2003)

- 8% to +10% Installation costs are less, primarily because less refrigerant 

is needed. Manufacturer B

-25% Less piping is required, resulting in reduced costs for 

materials, time, and labor. Powell (2003)

a This analysis assumes that this cost includes both capital and installation costs.

6. Low-Charge Multiplex Systems

6.1. Description

Low-charge multiplex refrigeration systems can use several different control systems to reduce the

amount of refrigerant charge needed and the amount of energy required to operate the system. In one

type of control system, a control valve that operates a bypass from the condenser liquid line maintains a

constant differential between the high and low pressures of the system. This limits the refrigerant charge 

to the amount needed to service all display case evaporators with no additional charge needed for the

receiver, as presented in Figure 23 (Baxter and Walker, 2003; IEA, 2003). A mixture of vapor and liquid 
19

refrigerant is sent to each display case lineup and storage room, controlled by the compressor rack. The

evaporators are operated by valves that control refrigerant flow and evaporation (IEA, 2003). The 

refrigerant liquid bypassed by the valve is expanded and evaporated through heat exchange using the

discharge manifold. This vapor is then piped to the suction manifold to be recompressed and returned to

the compressor (Baxter and Walker, 2003).

Figure 23. Low-Charge Multiplex System

Source: IEA (2003).

In another type of control system, the refrigerant charge is reduced by minimizing the refrigerant

contained in the receiver during operation (see Figure 24). The control valve and ambient temperature

sensor act together to maintain a constant temperature difference between the condenser outlet liquid and 

the ambient air. After the liquid refrigerant passes through the control valve, it is vaporized via heat

exchange with the discharge manifold. The receiver stores any liquid refrigerant that is not vaporized

(IEA, 2003).
20

Figure 24. Low-Charge Multiplex System

Source: IEA (2003).

6.2. Penetration of Technology

According to one U.S. equipment manufacturer, very few of these systems have been sold in the U.S.,

thus they comprise a negligible portion of new supermarket system sales. 

6.3. Refrigerant Type and Charge Size

One U.S. equipment manufacturer that produces low-charge multiplex systems for the Canadian market,

estimated that approximately two-thirds of the low-charge multiplex systems it sells contain R-404A, 

while the remaining third contain R-507A. According to this manufacturer, only a few of these systems

have been sold in the U.S.

Regarding charge size, available estimates suggest that low-charge multiplex systems require only

between 30% and 66% of that of DX systems, as shown in Figure 25. 

Figure 25. Estimated Charge Size of Low-Charge Multiplex Systems Relative to DX Systems

Charge Size as a 

Percentage of DX 

Systems

Comments Source

~30% In systems where charge is reduced to the minimum amount needed 

by the evaporators IEA (2003)

66% In systems where the refrigerant inventory is minimized in the receiver Baxter (2003), IEA (2003)

6.4. Typical Leak Rate and Direct Emissions

According to one industry contact, low-charge multiplex systems have an annual leak rate of 25%, similar 

to that of DX systems. No leak rate or direct emissions estimates for these systems were found in the

literature reviewed.
21

6.5. Energy Consumption

A field study performed by Oak Ridge National Laboratory (ORNL) estimated that the low-charge 

multiplex system used 11.6% less energy than the DX system (Baxter, 2003). The control option that

minimizes charge for the system evaporators is estimated to be as energy efficient as traditional DX

systems. Moreover, the control option that minimizes refrigerant inventory in the receiver can produce

some energy savings because the system compressors are able to operate at lower condensing

temperatures than normal (IEA, 2003).

The use of a bypass control valve allows compressors to operate at very low head pressures, offering 

some energy-saving potential. Because the condenser fans can consume all the compressor energy

savings in order to maintain the low head pressure, a “fan control strategy” is very important. Variablespeed condenser fans are recommended to achieve the lowest fan energy consumption while maintaining

the desired low head pressures (Baxter and Walker, 2003). 

6.6. Capital and Installation Costs

Low-charge multiplex systems using either control option are estimated to have the same installation

costs as DX systems (IEA, 2003).

7. Advanced Self-Contained Systems

7.1. Description

Equipment considered to be self-contained includes beverage vending machines, beverage merchandisers, 

beer coolers, undercounter refrigerators, refrigerators for commercial food service, ice machines, and

drinking water coolers (ADL, 2002). In advanced self-contained refrigeration systems, the refrigeration

compressors and water-cooled condensers are located in the display cases. A glycol loop rejects heat

from the display cases and carries it to the store’s exterior. The recent introduction of horizontal scroll

compressors into the market (vertical scroll compressors were not suitable for use in display cases) permit 

more widespread use of self-contained systems (Baxter and Walker, 2003). Foam insulation is used in

most equipment to keep temperatures inside the equipment low (ADL, 2002). Figure 26 depicts the

typical refrigeration circuit in a self-contained unit.
22

Figure 26. Diagram of a Self-Contained Refrigeration Circuit

Source: ADL (1996).

7.2. Penetration of Technology

Due to the high upfront costs associated with manufacturing self-contained systems, there are currently

very few supermarkets comprised entirely of self-contained equipment in use in the United States. One 

equipment manufacturer noted that his company has only produced a few of these systems, and estimated 

that there were less than 10 in operation throughout the entire United States. Therefore, U.S. penetration 

of this technology is assumed to be minimal (<1%).

7.3. Refrigerant Type and Charge Size 

Although self-contained equipment has historically contained R-22, today, advanced self-contained 

refrigeration systems used internationally typically use R-404A and R-134a (IPCC/TEAP, 2005).

Total charge size in a given supermarket could be as low as 5% to 10% of the charge size of a DX system,

if self-contained systems are used for all refrigeration needs (IEA, 2003). For individual types of

equipment, charge size can range from 0.3 kg to several kilograms (ADL, 2002). 

7.4. Typical Leak Rate and Direct Emissions

Refrigerant emissions in advanced self-contained equipment are minimized by the use of brazed joints

connecting the refrigerant tubing and refrigeration system components (ADL, 2002). It is estimated that

advanced self-contained systems have a leak rate of approximately 1% (Baxter, 2003; Bivens and Gage,

2004). In addition, according to ADL (2002), because all the components are in the same unit, there is a

minimal amount of tubing, further reducing refrigerant emissions. However, more recent information

obtained from a U.S. industry contacts suggests that average in-use leak rates of these systems are much

higher—about 10% annually. 

7.5. Energy Consumption

Much of the energy consumption of self-contained equipment is related to frequent door openings, large

beverage cool down loads, and ice maker throughput. A study performed by ORNL indicated that
23

advanced self-contained systems consume 7.3% more energy than do traditional DX systems (Baxter,

2003). Self-contained systems are often less energy efficient per kW of cooling power than centralized

systems as they usually reject heat into the store, which then increases the store’s demand for airconditioning and, in turn, increases total energy costs (IPCC/TEAP, 2005).

To reduce energy consumption of these systems, a study performed by ADL (2002) recommended the 

integration of heat reduction from individual units in a water circuit (IPCC/TEAP, 2005). In addition, the 

following measures are suggested to improve system efficiency (Baxter and Walker, 2003):

• Maintain the capacity control of the compressor. 

• Regulate the condensing temperature to maintain a limited range. 

• Ensure that the compressor capacity does not surpass the required refrigeration load to avoid

excessive compressor cycling. 

• Ensure a close link between the compressor and the case evaporator to reduce the pressure drop at 

the compressor suction and limit the heat gain to the suction gas.

7.6. Capital and Installation Costs

A study conducted by IEA (2003) estimates that a store that uses only self-contained equipment is

associated with approximately the same capital cost as a DX system, but with installation costs that are up 

to 15% higher. In contrast, one U.S. industry representative claimed that there are “very high” upfront

costs associated with self-contained systems, although no quantitative estimates were provided.

8. Total Equivalent Warming Impact (TEWI)

The use of supermarket refrigeration equipment generates “indirect” emissions of greenhouse gases

(primarily carbon dioxide) from the generation of power required to operate the equipment. These

indirect emissions can significantly reduce—if not, outweigh—the direct emission savings that can result

from some alternative technologies. Hence, energy efficiency has a major impact on the total greenhouse 

gas emissions of an application. 

Total Equivalent Warming Impact (TEWI) measures the environmental impact of greenhouse gases

resulting from operation, service and end-of-life disposal of the equipment. It combines the effects of

both the direct emissions of refrigerants and the indirect emissions resulting from energy consumption by 

the burning of fossil fuels and the generation of electricity for cooling. The calculation of TEWI is based 

on the global warming potentials (GWPs), developed by the Intergovernmental Panel on Climate Change 

(IPCC), which use CO2 as a reference gas (Sand et al., 1997). 

8.1. TEWI Comparisons

Eight TEWI studies have been reviewed and assessed for this report: 

1. Arnemann, M., D. Gebhardt, and H. Kruse. 1995. “Experiementelle Bewertung neuer

Kältemittelgemische als Ersatz für R-22 und R-502 [Experimental assessment of new refrigerant

mixes as substitutes for R-22 and R-502].” Die Kälte- und Klimatechnik (2): 66. As cited in

Kruse, Horst, 2000. “Refrigerant Use in Europe.” ASHRAE Journal. 

2. Sand, James R., Steven K. Fischer, and Van D. Baxter. 1997. “Energy and Global Warming

Impacts of HFC Refrigerants and Emerging Technologies.” U.S. Department of Energy and

Alternative Fluorocarbons Environmental Acceptability Study. 
24

3. International Energy Agency. 2003. “IEA Annex 26: Advanced Supermarket Refrigeration/Heat

Recovery Systems, Final Report Volume 1- Executive Summary.” Compiled by Van D. Baxter,

Oak Ridge National Laboratory. April.

4. EPA. 2004. “Analysis of Costs to Abate International Ozone-Depleting Substance Substitute

Emissions.” Office of Air and Radiation (6205J), EPA 430-R-04-006. June. [Note: this analysis

is based on data from ADL (2002).]

5. Baxter, Van D. 2003. “Advances in Supermarket Refrigeration Systems.” U.S. Department of

Energy, Oak Ridge National Laboratory, Oak Ridge, TN. 

6. Baxter, Van D. and David H. Walker. 2002. “Field Testing of an Advanced Low-Charge 

Supermarket Refrigeration System.” Paper presented at the New Technologies in Commercial

Refrigeration Conference, University of Illinois at Urbana-Champaign, Urbana, IL. 22-23 July.

7. Bivens, Donald and Cynthia Gage. 2004. “Commercial Refrigeration Systems Emissions.” Paper

Presented at the 15th Annual Earth Technology Forum, Washington, DC. 13-15 April.

8. Intergovernmental Panel on Climate Change/Technology and Economic Assessment Panel. 

2005. Draft of IPCC/TEAP Special Report on Ozone and Climate, Chapter 4: Refrigeration. 

These studies, each of which is discussed below, have demonstrated that, although indirect emissions can 

significantly reduce the net environmental benefit associated with alternative systems used in supermarket 

refrigeration, alternative systems still represent net greenhouse gas improvements over conventional DX 

systems.

The study conducted at the Research Centre for Refrigeration and Heat Pumps in Hanover, Germany

using R-404A, R-407A, R-407B, R-407C, R-507A, R-410A, and R-290 (propane), determined that only

R-410 and R-290 have an improved TEWI compared to R-22, with similar performance in terms of

energy efficiency. The other refrigerants were shown to have a 5% to 15% higher energy consumption. 

Figure 27 presents the results of this study (Arnemann et al., 1995, as cited in Kruse, 2000).

Figure 27: TEWI Comparison of R-22 and its Substitutes

Source: Kruse (2000).

Figure 28 presents the results of a study conducted by Sand et al. (1997) (also discussed in the IEA (2003) 

report), comparing DX, secondary loop, and distributed systems, each with a variety of different

refrigerants in North America, including ammonia (R-717) in secondary loop systems. As shown, both

secondary loop and distributed systems offer considerable TEWI reductions compared to the DX systems, 
25

especially when careful attention is paid to optimizing design and operational efficiency. The large

refrigerant charge and high direct emission rate of DX systems result in high TEWI values, with direct

refrigerant loss accounting for about half of the total emissions (IEA, 2003).

Figure 28: TEWI Analysis of Low Temperature Supermarket Refrigeration Systems Reported by Sand et al. (1997)

Source: IEA (2003).

EPA (2004) includes a TEWI analysis comparing distributed, HFC secondary loop, and ammonia

secondary loop systems to a conventional DX system, based on data provided in ADL (2002). As shown 

in Figure 29, all alternative systems were found to result in net emission savings compared to

conventional DX systems, with the distributed option resulting in the lowest net emissions, due to its

lower energy consumption (despite larger charge size and leak rate compared to the secondary loop

systems).

Similar results for distributed and HFC secondary loop systems are reported by Baxter (2003) (as also

cited in IEA (2003)). Baxter (2003) compared not only distributed and secondary loop systems, but also

low-charge multiplex and advanced self-contained systems, all of which were tested in a Washington, DC 

location, assuming a 15-year service life. As shown in Figure 30, the analysis indicates that alternative

systems can reduce net greenhouse gas emissions by 20% to more than 60% compared to the baseline DX 

system. Of all alternatives, secondary loop systems with evaporative condensers were found to achieve

the greatest emission reduction, even when using fluorocarbon refrigerants. In addition, although selfcontained systems have the smallest leak rates, their higher energy use leads to higher net emissions than 

secondary loop and distributed systems. However, Baxter (2003) found that self-contained systems could 

potentially achieve the same TEWI reductions as distributed systems, if more efficient, small compressors 

and/or other improved system components are developed to help reduce system energy use. (Baxter,

2003) 
26

Figure 29: TEWI Results for 60,000 ft2 Supermarket, as Reported in EPA (2004) and Based on ADL (2002)

Centralized 

Direct Expansion 

System (Base)

Distributed 

System

Ammonia 

Secondary Loop 

System

HFC Secondary 

Loop System

Charge Size (kg)a

(% change)

1,633 408

(- 75%)

180

(- 89%)

180

(- 89%)

HFC Leak Rate (% of charge/yr)a 15% 4% 0% 2%

Direct Emissions (kg/yr) 245 16 0 4

Change in Direct Emissions (kg/yr) N/A (229) (245) (241)

Change in Direct Emissions (TCE/yr)c N/A (204) (218) (214)

Energy Consumption- kWh/yra

(% change)

1,200,000 1,100,000

(- 8%)

1,400,000d

(+ 17%)

1,400,000d

(+ 17%)

Indirect Emissions (TCE/yr)e 198 182 231 231

Change in Indirect Emissions 

(TCE/yr)

N/A (17) 33 33

Change in Indirect Emissions 

(TCE/yr) per ton of cooling capacityb

N/A (0.02) 0.05 0.05

Change in Net Emissions (TCE/yr) N/A (221) (185) (181)

Net Electricity Cost ($/yr)f N/A ($4,000) $8,000 $8,000

Note: Totals may not sum due to independent rounding.

N/A = not applicable. 

a Based on ADL (2002).

b Assumes that conventional direct expansion systems require 5 pounds (or 2.27 kg) of refrigerant per ton of cooling capacity 

(EPA, 2004). For a 60,000 sq. ft. store using 3,600 lbs refrigerant (ADL, 2002), this translates to 720 tons of cooling capacity

c

 Assumes the refrigerant is R-404A (ADL, 2002).

d Recent technological advances on secondary loop refrigeration systems for supermarkets suggest that, with the use of improved 

technological features and design/manufacturing/contractor experience, these systems can lead to significant reductions in energy 

consumption (Baxter, 2003; EPA, 2004); however, these reductions are not assumed in this analysis.

e Assumes a national average emissions factor of 0.606 kg CO2

/kWh (EPA, 2004). 

f Assumes average energy costs for United States between 1994-1999 (of approximately $0.04/kWh) based on EPA (2004). 

Source: EPA (2004).

Figure 30: TEWI Analysis on Supermarket Refrigeration Conducted by Baxter (2003) 

Baseline 

(DX)

Low-Charge 

Multiplex

Distributed Secondary Loop Advanced SelfContained

Condensing 

Type

Air-Cooled Evaporative WaterCooled, 

Evaporative

Evaporative WaterCooled, 

Evaporative

Water-cooled, 

evaporative

Charge -

kg/kW

(% change)

4.15 2.77

(- 33%)

1.24

(- 70%)

0.69

(- 83%)

0.27

(- 93%)

0.14

(- 97%)

Primary 

Refrigerant

R-404A/

R-22a

R404A/

R-22a

R-404A R-507Ab R-507Ab R-404A

Leak Rate 30% 30% 15% 5% 10% 5% 5% 2% 1%

Energy UsekWh/year

(% change)

976,800 863,600

(- 12%)

866,100

(- 11%)

875,200

(- 10%)

959,700

(- 2%)

1,048,300

(+ 7%)

TEWI 

Reductionc

24% 44% 59% 58% 61% 57% 58% 56%

a 1/3 R-404A (low temperature), GWP = 3260; 2/3 R-22 (medium temperature), GWP = 1700.

b R-507A, GWP = 3300.

c Relative to baseline. 
27

Baxter and Walker (2002) compared a distributed system using R-404A to a DX system using both R-22 

and R-404A (for different racks), and determined that the distributed system achieved a TEWI reduction

of 38% over the baseline DX system. In addition, the distributed system consumed 12% less energy than 

DX system. 

Bivens and Gage (2004) found that distributed systems can lead to even greater TEWI reductions

compared to DX systems—achieving a 47% reduction. However, unlike previous studies, this analysis

found that distributed systems consume the same amount of energy as DX systems—not less. Bivens and 

Gage (2004) also compare secondary loop and low-charge multiplex systems to DX systems, and

conclude that secondary loop systems can achieve TEWI reductions of between 42% and 47%, and lowcharge multiplex systems can achieve reductions of 46%.

Similar to Bivens and Gage (2004), the IPCC/TEAP draft report (2005) also reports that the energy

consumption of distributed systems is equal to or greater than conventional DX systems. Figure 31

presents a comparison of the direct emission reductions, and energy usage of alternative supermarket

refrigeration systems, as compared to the baseline DX system, as provided in the draft IPCC/TEAP 

report. 

Figure 31: TEWI Data Reported in Draft IPCC/TEAP Report (2005) 

Baseline (DX) HFC Secondary 

Loop 

Ammonia 

Secondary Loop

Distributed (HFC)

Refrigerant R-22 R-404A Ammonia R-404A

Direct Emission 

Reduction

50% to 90% 100% 75%

Change in Energy 

Usage

0% to +20% 0% to + 20% 0% to +10%

TEWI Reduction

Relative to DX

35% to 60%

Additional data may be available in the near future; one manufacturer and a supermarket chain are

conducting a study comparing the costs of DX and secondary loop systems. Another manufacturer is also 

developing a TEWI analysis and expects to have results available in several months. 
28

9. Retrofitting R-22 Supermarket Equipment 

9.1. System Efficiency

In addition to replacing ODS refrigeration equipment with alternative technologies, alternative

refrigerants can also be used to retrofit or “convert” existing ODS (e.g., R-22) systems. However, many

ozone-friendly substitutes for R-22 result in a reduction in cooling performance and energy efficiency,

which represents a major economic barrier to ODS alternatives. For example, Spletzer and Rolotti (2004) 

conducted a performance study of R-22 retrofits converted to R-404A, R-407C, R-417A, and R-507A for 

use in medium-temperature refrigeration loop, and found that:

• R-417A produced the largest losses in refrigerating capacity of any of the retrofits.

• R-407C produced a better capacity match and had the closest capacity of any of the alternatives at 

the 30oF box temperature condition. It also produced the highest efficiencies of the retrofit 

refrigerants.

• R-404A and R-507A performed similarly and produced the highest capacities, on average, of the 

retrofits.

Honeywell (Gartland, 2005) also conducted a performance study of R-22 systems converted to R-404A, 

R-407C, R-422A, and R-417A (medium-temperature only). The study found that:

• All refrigerants showed efficiency loss at high ambient temperature in the medium-temperature 

application.

• Only R-404A showed a capacity increase in the medium-temperature application.

• All refrigerants showed a slight decrease in efficiency in the low-temperature application.

• R-404A had the best capacity in the low-temperature application.

The results of this study are summarized in Figure 32.

Figure 32: Results of Performance Study of R-22 Systems Retrofitted with HFC Refrigerants, Conducted by Honeywell

(Gartland, 2005)

R-404A R-507A R-407C R-417A R-422A

Capacity 

(relative to R-22) Similar Similar

Lower capacity at 

lower 

temperatures

Considerably 

lower capacity

~10% decrease at 

low temperatures

Mass Flow 

(relative to R-22) ~45% higher ~45% higher 55% higher

Temperature 

Glide Very low Very low 8 -12°F 5 -8°F 2 - 4°F

Pressure ~20% higher ~20% higher ~10% higher ~20% higher

Lubricant Used Synthetic 

lubricants

Synthetic 

lubricants

Synthetic 

lubricants

Oil return issues 

with mineral oil 

use

Reduced oil 

return when used 

with mineral oil

Beeton (2005) noted that, while R-422A (One Shot® refrigerant) may be a viable alternative, R-404A is 

currently the most efficient retrofit refrigerant for R-22. One large supermarket chain (Bigg’s) has 

performed two retrofits, converting a low-temperature rack and a medium-temperature rack from R-22 to 

R-422A. The low-temperature rack ran between 70% and 95% of capacity on R-22, and between 60% 

and 90% of capacity with extended periods below 50% of capacity after being retrofitted with R-422A. 

The medium-temperature rack ran between 50% and 80% of capacity when using R-22 and consistently 

below 50% with R-422A. Due to the reduction in capacity, the number of compressors needed to 
29

maintain the suction pressure target is reduced, which in turn will lead to lower energy costs associated 

with compressor operation (ACHR News, 2005). 

9.2. Retrofit Cost

According to one industry expert, costs to retrofit R-22 retail food equipment to ODS alternatives can run 

very high: 

• Retrofitting R-22 to R-407c/R-417a: $20,000-$60,000, depending on store size

• Retrofitting R-22 to R-404a/R-507A: $40,000-$90,000, depending on store size (requires up to 

200 expansion valve changes)

The above cost estimates were supported by one U.S. equipment manufacturer who estimates R-22 

retrofit costs for a store of 30,000 ft2 to be between $50,000 and $70,000. However, another U.S.

equipment manufacturer estimated retrofit costs for a larger supermarket (between 60,000 ft2and 65,000 

ft2) to be above this range—between $85,000 and $105,000.

9.3. Retrofit Procedures

Appendix A provides a checklist for conducting equipment retrofits.
30

10. References

Air Conditioning, Heating & Refrigeration (ACHR) News. 2005. “Retrofitting R-22 supermarket 

systems.” Air Conditioning, Heating & Refrigeration News 226(1): 12-14. 5 September.

Air Conditioning, Heating & Refrigeration (ACHR) News. 1999. “DOE sponsors advanced supermarket 

refrigeration and hvac systems field air conditioning.” Air Conditioning, Heating & Refrigeration News

208(3): 13. 20 September.

Arnemann, M., D. Gebhardt, and H. Kruse, 1995. “Experiementelle Bewertung neuer 

Kältemittelgemische als Ersatz für R-22 und R-502 [Experimental assessment of new refrigerant mixes as 

substitutes for R-22 and R-502].” Die Kälte- und Klimatechnik (2): 66. As cited in Kruse, Horst, 2000. 

“Refrigerant Use in Europe.” ASHRAE Journal. Available at

http://www.usgbc.org/Docs/LEED_tsac/Energy/ASHRAE%20Journal%2009-

00%20Refrigerant%20Use%20in%20Europe.pdf.

Arthur D. Little, Inc. (ADL). 2002. “Global Comparative Analysis of HFC and Alternative Technologies 

for Refrigeration, Air Conditioning, Foam, Solvent, Aerosol Propellant, and Fire Protection 

Applications.” Final Report to the Alliance for Responsible Atmospheric Policy. Available at 

http://www.arap.org/adlittle/HFCstudy3-22JD.pdf.

Arthur D. Little, Inc. (ADL). 1996. “Energy Savings Potential for Commercial Refrigeration Equipment.” 

Available at http://www.eere.energy.gov/buildings/info/documents/pdfs/comm_refridg_equip.pdf

Baxter, Van D. and David H. Walker. 2003. “Analysis of advanced low-charge refrigeration for 

supermarkets.” ASHRAE Transactions. 1 January.

Baxter, Van D. and David H. Walker. 2002. “Field Testing of an Advanced Low-Charge Supermarket 

Refrigeration System.” Paper presented at the New Technologies in Commercial Refrigeration 

Conference, University of Illinois at Urbana-Champaign, Urbana, IL. 22-23 July.

Baxter, Van D. 2003. “Advances in Supermarket Refrigeration Systems.” U.S. Department of Energy, 

Oak Ridge National Laboratory, Oak Ridge, TN.

Beeton, Warren. 2005. Copeland Refrigeration. “Future Trends in Refrigerants.” Presented at the 2005 

Food Marketing Institute Energy & Technical Services Conference, Montreal, Quebec. 18-21 September.

Birndt, R., Riedel, R., and J. Schenk. 2000. “Tightness of Commercial Refrigeration Systems.” DIE 

KALTE & Klimatchnik. September. As cited in Bivens, Donald and Cynthia Gage. 2004. “Commercial 

Refrigeration Systems Emissions.” Paper Presented at the 15th Annual Earth Technology Forum, 

Washington, DC. 13-15 April.

Bivens, Donald and Cynthia Gage. 2004. “Commercial Refrigeration Systems Emissions.” Paper 

Presented at the 15th Annual Earth Technology Forum, Washington, DC. 13-15 April.

Chain Store Guide. 2004. Directory of Supermarket, Grocery & Convenience Store Chains.

Chain Store Guide. 2003. Directory of Supermarket, Grocery & Convenience Store Chains.

Chain Store Guide. 2002. Directory of Supermarket, Grocery & Convenience Store Chains.

Chain Store Guide. 2001. Directory of Supermarket, Grocery & Convenience Store Chains.
31

Engsten, Karolin and Jenny Lindh. 2004. “Refrigerant Management: The Issue of Minimizing

Refrigerant Emissions – a study of Swedish supermarkets.” Master’s Degree Project, Royal Institute of 

Technology, Sweden.

Gartland, Ted. 2005. Honeywell. “Replacing R-22 in Refrigeration.” Presented at the 2005 Food 

Marketing Institute Energy & Technical Services Conference, Montreal, Quebec. 18-21 September.

Godwin, David. 2005. U.S. EPA. “Using Glycol as a Secondary Coolant.” Presented at the 2005 Food 

Marketing Institute Energy & Technical Services Conference, Montreal, Quebec. 18-21 September.

Haaf, S. and B. Heinbokel. 2002. “Alternative Refrigerants for Supermarket Refrigeration Installations.” 

Proceedings of DKV-Tagungsbericht, 2(2). As cited in Bivens, Donald and Cynthia Gage. 2004. 

“Commercial Refrigeration Systems Emissions.” Paper Presented at the 15th Annual Earth Technology 

Forum, Washington, DC. 13-15 April.

Humphrey, Joe. 2000. “A Truly Super Market.” Engineering Systems. May. Available at 

http://www.esmagazine.com/CDA/ArticleInformation/features/BNP__Features__Item/0,2503,1519,00.ht

ml

International Energy Agency (IEA). 2003. “IEA Annex 26: Advanced Supermarket Refrigeration/Heat 

Recovery Systems, Final Report Volume 1—Executive Summary.” Compiled by Van D. Baxter, Oak 

Ridge National Laboratory. April.

Intergovernmental Panel on Climate Change/Technology and Economic Assessment Panel (IPCC/TEAP). 

2005. Draft of IPCC/TEAP Special Report on Ozone and Climate, Chapter 4: Refrigeration. 

Powell, Peter. 2003. “Report charts supermarket trends.” Air Conditioning, Heating & Refrigeration 

News 220(1): 9-10. 1 September.

Powell, Peter. 2002. “More ways to curb supermarket energy costs.” Air Conditioning, Heating &

Refrigeration News 217(6): 16. 7 October.

Powell, Peter. 2001. “Where refrigerants are, and where they’re going.” Air Conditioning, Heating & 

Refrigeration News 212(8): 1. 19 February.

Rohrbach, Mark. 2005. “Using Glycol as a Secondary Coolant.” Presented at the 2005 Food Marketing 

Institute Energy & Technical Services Conference, Montreal, Quebec. 18-21 September.

Sand, James R., Steven K. Fischer, and Van D. Baxter. 1997. “Energy and Global Warming Impacts of 

HFC Refrigerants and Emerging Technologies.” U.S. Department of Energy Alternative Fluorocarbons 

Environmental Acceptability Study.

Southern California Edison and Foster-Miller, Inc. 2004. “Investigation of Secondary Loop Supermarket 

Refrigeration Systems.” Report prepared for California Energy Commission, Public Interest Energy 

Research Program. March.

Spletzer, Stephen and Gus Rolotti. 2004. “Performance Study of R-22 Refrigeration Retrofits.” Paper 

Presented at the 15th Annual Earth Technology Forum, Washington, DC. 13-15 April.

United Nations Environment Programme (UNEP). 2003. “2002 Report of the Refrigeration, Air 

Conditioning and Heat Pumps Technical Options Committee: 2002 Assessment.” UNEP, Nairobi, 

Kenya. January.
32

U.S. Environmental Protection Agency (EPA). 2004. “Analysis of Costs to Abate International OzoneDepleting Substance Substitute Emissions.” EPA Office of Air and Radiation (6205J), EPA 430-R-04-

006. June. Available at 

http://yosemite.epa.gov/oar/globalwarming.nsf/UniqueKeyLookup/RAMR62ASAF/$File/IMACAll%20Chapters%206-24-04.pdf.
33

Appendix A: Best Practices for Retrofitting R-22 Equipment

A. Checklist

This checklist is intended to be used before conducting a retrofit.

• Conduct preliminary leak check, with special attention to any mechanical joints, valves and fin

surfaces. NOTE: REPAIR ALL LEAKS!

• Record baseline data on original system performance.

• Choose lubricant. NOTE: Because HFC refrigerants are not miscible or soluble with mineral oil

compressor manufacturers require synthetic oils, such as Polyol Ester-POE.

B. Procedure

The following steps should be followed when retrofitting a supermarket refrigeration system from R-22 to 

an HFC refrigerant:

1. Isolate the R-22 refrigerant charge to the receiver.

2. Drain as much of the old lubricant from the system as possible, including from the

compressor sump, oil reservoir, and oil separator. If large amounts of mineral oil remain, it

may clog the system and cause the efficiency of the heat exchangers to decline (Engsten and

Lindh, 2003).

3. Replace oil filters and filter driers when performing oil changes.

4. Measure the amount of oil removed, add back an identical quantity of new oil. NOTE: The

new oil chosen must be approved by the compressor manufacturer.

5. Run the system with R-22 for at least 24 hours. NOTE: Systems running for an extended

period may require fewer oil changes.

6. Repeat steps 1 through 4 until the residual oil is less than 5%, testing using lab analysis or a

refractometer. 

7. Evaluate expansion devices using the process described below in Section C.

8. Recover R-22 in the system.

9. Pull vacuum.

10. Evaluate pressure controls, including high pressure cut-outs, fan cycling controls, and 

pressure relief devices.

11. Recharge system with HFC refrigerant.

12. Check system for leaks.

C. Valve Rebuilds (for systems built before 1995)

Systems built before 1995 will most likely require new gaskets and “o”- rings (elastomers)
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1. Rebuild all Evaporator Pressure Regulators (EPRs);

2. Rebuild all solenoid valves;

3. Rebuild hold back valves;

4. Rebuild heat reclaim valves;

5. Evaluate TXVs and new refrigerant for proper capacity and superheat. Replace whole valve

or power head if necessary. NOTE: Existing R-22 valves may be under-sized for higher mass 

flow refrigerants R-507A, R-404A and R-422A;

6. Replace "o"- rings on the receiver float, and receiver optic switch;

7. Replace nylon gasket on Roto Lock fittings. NOTE: Complete steps 6 and 7 prior to pulling

a vacuum.

D. System “Rack”

1. Replace schraeder caps and schraeder cores on high side. NOTE: All schraeder caps should

be brass.

2. Replace liquid line filters on conversion date.

3. Replace suction felts or cores on conversion date .

4. Use brass sealing caps on ball valves and compressor service valves.

5. Set holdback valves on the condenser drain leg.

6. Set EPRs to manufacturer’s parameters before setting any superheats.

7. Set mechanical sub-coolers to rack manufacturers’ parameters. Verify stable operation 

before setting any superheats.

8. Set TXV superheats to 8o-10o for medium temperature applications and 5o-7o for low

temperature applications. NOTE: With blended refrigerants use DEW values for superheat

measurements.

E. Tips

Keep the following items in mind when performing a retrofit:

• Perform the final oil change on conversion date;

• Run a defrost cycle on all circuits prior to oil changes in order to aid oil removal;

• Replace oil separator filters on conversion date;

• Dispose of used oil properly;

• Recover R-22 and pull vacuum;

• Complete all work outlined under rack system before recharging;
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• Most HFCs have lower densities than R-22 so use proper charge amount; for example, when

using R-404A, 87% of the size of the R-22 charge is required;

• All 400 series refrigerants must be liquid charged; and

• Always use proper personal protection equipment when handling refrigerants and oils.

R-404A requires a higher pressure and many of the systems components must be changed. The

molecules of R-404A are also smaller than those of R-22, so the system must be much tighter to prevent

leaks. In addition, the POE oil that R-404A requires may eat through seals and membranes, leading to

higher leak rates.