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Walk-In Coolers and Walk-In 

Freezers Test Procedure 

Notice of Proposed 

Rulemaking Public Meeting 

The U.S. Department of Energy (DOE) is 

publishing a Notice of Proposed Rulemaking 

(NOPR) for the test procedure rulemaking for 

walk-in coolers and walk-in freezers (WICF). 

The NOPR is the first document to be 

published in the test procedure rulemaking 

process. It will be followed by a final rule. At 

the NOPR stage, DOE proposes the 

procedures to be used to test WICF 

equipment for certification, compliance, and 

enforcement of the energy conservation 

standards. Interested parties are invited to 

review the NOPR, attend public meetings, and 

submit comments on DOE's approach. 

The following documents are available as 

Adobe Acrobat PDFs. Download Adobe 

Reader. 

Meeting Materials 

z Energy Conservation Program: Test 

Procedures for Walk-In Coolers and 

Walk-In Freezers, Proposed 

Rule, Federal Register, 75 FR 186, 

January 4, 2010 (PDF 564 KB) 

z Energy Conservation Program: Public 

EERE Information Center

Programs and Offices 

DATE: March 24, 2010 

TIME: 9:00 a.m. – 5:00 p.m. EST 

LOCATION:

U.S. Department of Energy 

Forrestal Building 

1000 Independence Avenue, SW 

Room 8E-089 

Washington, DC 20585 

Appliances and Commercial Equipment Standards: Walk-In Coolers and Walk-In Freezer... Page 1 of 3

http://www1.eere.energy.gov/buildings/appliance_standards/commercial/wicf_test_procedu... 4/2/2010

EERE2008-BT-TP-0014 DOC ID 1.2.009
Meeting and Availability of the Notice 

of Proposed Rulemaking for Walk-In 

Coolers and Walk-in Freezers; Date 

Change, Federal Register 75FR 9120, 

March 1, 2010 (PDF 72 KB) 

z Agenda (PDF 26 KB) 

z Presentation (PDF 1.1 MB) 

z Transcript. A transcript will be 

available on this Web site after the 

meeting, and will also be available for 

public inspection in the Building 

Technologies Program Reading Room, 

between 9:00 a.m. and 4:00 p.m., 

Monday through Friday, except 

Federal Holidays. To schedule an 

appointment or to purchase the 

transcript, contact: 

Brenda Edwards 

U.S. Department of Energy 

Building Technologies Program 

950 L'Enfant Plaza, 6th Floor 

Washington, DC 20024 

Telephone: 202-586-2945 

How to Submit Comments 

Interested parties may submit comments 

electronically, by mail, or by hand delivery 

or courier. Comments should clearly identify 

docket number EERE-2008-BT-TP-0014. 

The deadline for submitting comments is 

March 31, 2010. 

Wherever possible, comments in the 

electronic format should carry the electronic 

signature of the author. Absent an electronic 

signature, comments submitted 

electronically must be followed and 

authenticated by submitting the signed 

original paper document. 

z E-mail: 

wicf-2008-tp-0014@ee.doe.gov

Include Docket Number EERE-2008-

BT-TP-0014 and/or RIN 1904-

AB85 in the subject line of the 

message. 

z Postal Mail: 

Brenda Edwards 

U.S. Department of Energy 

Building Technologies Program 

1000 Independence Avenue, SW 

Mailstop EE-2J 

Washington, DC 20585 

Appliances and Commercial Equipment Standards: Walk-In Coolers and Walk-In Freezer... Page 2 of 3

http://www1.eere.energy.gov/buildings/appliance_standards/commercial/wicf_test_procedu... 4/2/2010

EERE2008-BT-TP-0014 DOC ID 1.2.009
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Content Last Updated: 04/01/2010 

Please include a signed original. 

z Hand Delivery or Courier: 

Brenda Edwards 

U.S. Department of Energy 

Building Technologies Program 

950 L'Enfant Plaza, 6th Floor 

Washington, DC 20024 

Telephone: 202-586-2945 

Please include a signed original. 

Contact Information 

Charles Llenza

Project Manager 

202-586-2192 

Printable Version 

Appliances and Commercial Equipment Standards: Walk-In Coolers and Walk-In Freezer... Page 3 of 3

http://www1.eere.energy.gov/buildings/appliance_standards/commercial/wicf_test_procedu... 4/2/2010

EERE2008-BT-TP-0014 DOC ID 1.2.009
1 | Program Name or Ancillary Text eere.energy.gov

Building Technologies Program

Test Procedures for 

Walk-in Coolers and Freezers 

Notice of Proposed Rulemaking

March 24, 2010

2 | Building Technologies Program eere.energy.gov

Table of Contents

2 Background & Approach

3 Basic Model

4 Proposed Test Procedure – Envelope 

5 Proposed Test Procedure – Refrigeration System 

6 Impacts on Small Businesses

7 Others Issues/Closing Discussion

1 Overview of Public Meeting

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Table of Contents

2 Background & Approach

3 Basic Model

4 Proposed Test Procedure – Envelope 

5 Proposed Test Procedure – Refrigeration System 

6 Impacts on Small Businesses

7 Others Issues/Closing Discussion

1 Overview of Public Meeting

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Overview >> Welcome 

Welcome

• Introductions

• Role of the Facilitator

• Ground Rules (norms)

– Listen as an ally

– Use short, succinct statements/keep to the point

– Hold sidebar conversations outside the room

– One person speaks at a time (raise hand to be recognized; state your name for the 

record)

– Set cell phones to silent/vibrate

• Housekeeping Items

• Agenda Review

• Opening Remarks

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9:00 – 9:15 am Welcome and Introductions 

9:15 – 9:30 am Rulemaking Overview

9:30 – 10:00 am Opening Remarks from Interested Parties

10:00 – 11:00 am Test Procedures Approach

11:00 – 11:15 am Break

11:15 – 12:30 pm Proposed Envelope Test Procedure

12:30 – 1:30 pm Lunch

1:30 – 3:15 pm Proposed Envelope Test Procedure, continued

3:15 – 3:30 pm Break

3:30 – 4:30 pm Proposed Refrigeration System Test Procedure

4:30 – 4:45 pm Discussion of Small Business Impacts

4:45 – 5:00 pm Other Issues; Questions & Comments; Closing Remarks

5:00 pm Adjourn

Overview >> Agenda

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EPCA Provision Authority Effective Date Details

Prescriptive 

Standards Congress January 1, 2009

DOE does not have the 

authority to alter these 

prescriptive standards.

Test Procedures DOE

30 Days After Test 

Procedure Final Rule 

Publication

This is the subject of today‘s 

rulemaking.

Energy 

Conservation 

Standards

DOE 3 Years After Standards 

Final Rule Publication

This is being addressed in a 

separate DOE rulemaking.

EPCA Provision Authority Effective Date Details

Prescriptive 

Standards Congress January 1, 2009

DOE does not have the 

authority to alter these 

prescriptive standards.

Test Procedures DOE

30 Days After Test 

Procedure Final Rule 

Publication

This is the subject of today‘s 

rulemaking.

Energy 

Conservation 

Standards

DOE 3 Years After Standards 

Final Rule Publication

This is being addressed in a 

separate DOE rulemaking.

Background & Approach >> Overview

 Test procedures and energy conservation standards set by 

DOE are separate from the prescriptive standards set by EPCA.

DOE is conducting this rulemaking as required by law. 

• The Energy Independence and Security Act of 2007 (EISA 2007) amended the 

Energy Policy and Conservation Act (EPCA) to add provisions for WICF.

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Background & Approach >> Overview

The test procedure and standards rulemakings are currently at 

different stages.

The test procedure NOPR is the subject of this public meeting. 

NOPR Final

Rule

Test 

Procedure 

Milestones

Framework Prelim. 

Analysis NOPR Final 

Rule

Standards 

Milestones

The energy conservation standards rulemaking is in the preliminary analysis stage. 

The standards preliminary analysis results will be presented in a separate public 

meeting.

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Major Milestones

NOPR Final

Rule

• NOPR published: January 4, 2010 (75 FR 186).

• NOPR public meeting: March 24, 2010 (today).

• NOPR comments due: March 31, 2010 (one week from today).

– Transcript records oral comments from today‘s public meeting.

– Written comments.

• DOE reviews and considers all comments.

Overview >> Rulemaking Milestones

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Following publication of the notice of proposed rulemaking 

(NOPR), DOE is holding this public meeting: 

Overview >> Purpose of the Public Meeting

• To present DOE‘s proposed test procedures for walk-in 

coolers and freezers (WICF or walk-ins).

• To clarify any questions about DOE‘s proposed approach.

• To seek comment from participants on the proposed test 

procedure.

• To describe the next steps for the rulemaking.

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1. Background & Approach

1. Separate Test Procedures for Envelope & Refrigeration System

2. Testing Responsibilities*

3. Definition of Envelope

4. Definition of Refrigeration System

2. Basic Model

1. Basic Model of Envelope

2. Daily Energy Consumption Coefficients

3. Basic Model of Refrigeration System

4. Definition of Basic Model for Refrigeration System*

3. Proposed Test Procedure – Envelope

1. Normalization Factor

2. Proposed Test Method for Conditioning of Foam

3. Impact of Water on Foam*

4. Efficacy of Skins

5. Floorless Cooler Heat Transfer

6. Freezer Floor R-Values

7. Insulated Floor Surface Temperature Assumptions

8. Performance Data for Glass Products

9. Glass Door Energy Calculation

10. Steady-State Infiltration and Reduction Device Effectiveness

11. Calculations for Door-Opening Events

12. Infiltration Reduction Device Effectiveness

13. Electrical Duty Cycle

14. Nominal Energy Efficiency Ratio

Major issues for public comment are detailed in this presentation and in Section 

V.E of the NOPR. 

Overview >> Issues for Public Comment

(Continued on Next Slide)

* Did not appear in 

Section V.E of the 

NOPR

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4. Refrigeration Test Procedure

1. Proposed Test Procedure

2. Calculation Methodology

3. Reporting Requirements

5. Impacts on Small Businesses

1. Number of Small Entities Regulated

2. Differential Impacts on Small Manufacturers

Continued: Major issues for public comment

Overview >> Issues for Public Comment

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Issue Box: DOE welcomes comments, data, and information concerning 

this proposed test procedure on walk-in coolers and freezers. Throughout 

this presentation, issues are provided in boxes like this one for discussion in 

the public meeting. While these are specific issues that DOE identified for 

review, comments are welcome on any part of DOE’s proposed rule.

Overview >> Issues for Public Comment

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Interested parties who contacted DOE to request an 

opportunity to make an opening statement should speak now.

Overview >> Opening Statements

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Table of Contents

1 Overview of Public Meeting

3 Basic Model

4 Proposed Test Procedure – Envelope 

5 Proposed Test Procedure – Refrigeration System 

6 Impacts on Small Businesses

7 Others Issues/Closing Discussion

2 Background & Approach

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EPCA specifies which equipment is covered by the test procedure. 

Background & Approach >> Overview

Statutory Definition of Walk-in Coolers and Freezers:

• ―The terms  ̳walk-in cooler‘ and  ̳walk-in freezer‘ mean an enclosed storage 

space refrigerated to temperatures, respectively, above, and at or below 32 

degrees Fahrenheit that can be walked into, and has a total chilled storage area 

of less than 3,000 square feet.‖ 42 U.S.C. 6311(20)(A) 

Walk-in Type Description of EPCA Requirement

All Has a total chilled storage area of less than 3,000 square 

feet.

Coolers Above 32°F

Freezers At or below 32°F

Exceptions

The definition specifically excludes ―products designed and 

marketed exclusively for medical, scientific, or research 

purposes.‖ (42 U.S.C. 6311(20)(B))

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 DOE proposes to develop separate test procedures for the 

envelope & refrigeration system.

DOE initially considered a single test procedure but changed its 

approach after receiving input from interested parties. 

Background & Approach >> Separate Test Procedures

• There are TWO components of a walk-in cooler or walk-in freezer: 

– Envelope in which items are stored.

– Refrigeration system that chills the space inside the envelope.

• Feedback from Interested Parties (Standards Framework Public Meeting) indicated 

that using a single test procedure was not a viable approach because:

– Could be burdensome to perform the test.

– Envelope & refrigeration system typically manufactured separately.

– Assembler or installer could be required to demonstrate compliance – not DOE‘s 

typical approach.

– Difficult to enforce testing requirements if the walk-in is assembled in the field.

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Background & Approach >> Separate Test Procedures

 The purpose of the proposed test procedure is to quantitatively 

capture energy use in WICF as fully and accurately as possible.

Separated into its distinct systems – envelope and refrigeration 

system – the proposed WICF test procedure follows this structure.

PROPOSED TEST PROCEDURE

Walk-in Coolers and Freezers

Refrigeration Equipment 

Test Procedure

[Annual Energy Use]

Net 

Refrigeration 

Capacity

Annual 

Walk-in Energy 

Factor (AWEF)

Envelope Test Procedure

[Daily Energy Load]

Conduction 

Load

Infiltration 

Load

Electrical 

Load

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Background & Approach >> Manufacturer Requirements

 “Manufacturer” refers to either the envelope manufacturer or 

the refrigeration system manufacturer.

DOE proposes to assign testing responsibilities to the 

manufacturers of the envelope and refrigeration system.

• Envelope manufacturer would be responsible for testing the envelope according to 

the envelope test procedure.

• Refrigeration system manufacturer would be responsible for testing the 

refrigeration system according to the refrigeration system test procedure. 

• Purpose of this provision:

– Accurately reflect the structure of the walk-in market.

– Assign testing responsibilities to the appropriate equipment manufacturers. 

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Background & Approach

Issue 1-1: Separate Test Procedures for Envelope & Refrigeration System

DOE invites comments on its proposal for separate test procedures for the insulated 

envelopes and refrigeration systems of walk-in coolers and freezers. See Section 

III.C.1. for details.

Issue 1-2: Testing Responsibilities

DOE invites comments on its proposal to consider the envelope and refrigeration 

manufacturers responsible for the envelope and refrigeration system test, respectively.

20 | Building Technologies Program eere.energy.gov

DOE proposes that the definition of “envelope” include the box, 

its components, and some electrical equipment.

Background & Approach >> Envelope

Issue 1-3: Definition of Envelope

DOE invites comments on its proposed definition for the envelope of walk-in coolers 

and freezers. See Section III.B.1. for details.

• ―Envelope means (1) the portion of a walk-in cooler or walk-in freezer that isolates 

the interior, refrigerated environment from the ambient, external environment; and 

(2) all energy-consuming components of the walk-in cooler or walk-in freezer that 

are not part of its refrigeration system.‖

• Examples:

(1) insulated panels, windows, gasketing, doors (passage & display), etc.

(2) lighting, anti-sweat door heaters, etc.

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In the NOPR, DOE proposed the following definition for 

“refrigeration system:”

Background & Approach >> Refrigeration

―Refrigeration system means the mechanism used to create the refrigerated 

environment in the interior of a walk-in cooler or freezer, consisting of an integrated 

single package refrigeration unit, or a split system with separate unit cooler and 

condensing unit sections, or a unit cooler that is connected to a central rack system; 

and including all controls and other components integral to the operation of this 

mechanism.‖

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DOE is interested in commenter feedback regarding the proposed 

definition of “refrigeration system.”

Background & Approach >> Refrigeration

REVISED DEFINITION WOULD READ AS FOLLOWS: ―Refrigeration system 

means the mechanism used to create the refrigerated environment in the 

interior of a walk-in cooler or freezer, consisting of a packaged system where 

the unit cooler and condensing unit are integrated into a single piece of 

equipment, or a split system with separate unit cooler and condensing unit 

sections, or a unit cooler that is connected to a multiplex condensing system; 

and including all controls and other components integral to the operation of this 

mechanism.‖

Revisions to the definition may include the following: 

• Substituting ―integrated single package refrigeration unit,‖ with ―a packaged 

system where the unit cooler and condensing unit are integrated into a single 

piece of equipment‖ in order to clarify the term.

• Substituting ―central rack system,‖ with ―multiplex condensing system,‖ because 

the latter is a more inclusive term and may be more technically accurate.

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Issue 1-4: Definition of “Refrigeration System”

DOE invites comments on the proposed definition for the refrigeration system of 

walk-in coolers and freezers, and the suggested modifications to the proposed 

definition. DOE seeks comment on other possible modifications to the definition 

to help improve its clarity. See Section III.C.1 for details.

Background & Approach >> Refrigeration

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Table of Contents

1 Overview of Public Meeting

2 Background & Approach

4 Proposed Test Procedure – Envelope 

5 Proposed Test Procedure – Refrigeration System 

6 Impacts on Small Businesses

7 Others Issues/Closing Discussion

3 Basic Model

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 In the NOPR, DOE proposed using this approach for both the 

envelope and the refrigeration system.

DOE is considering allowing manufacturers to group similar walkin equipment under a single “Basic Model.”

Basic Model >> Concepts & Definitions

• Under this proposal, DOE is considering:

– Allowing manufacturers to group equipment with essentially identical 

characteristics with regard to energy consumption under a single Basic 

Model.

– For envelopes, this approach would include adopting a calculation 

methodology for determining the energy consumption of units within the 

Basic Model.

• The purpose of using Basic Models is to reduce testing burden. The 

proposed Basic Model approach enables manufacturers to group equipment 

with respect to energy consumption characteristics and test only one unit within 

a Basic Model.

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Basic Model >> Concepts & Definitions

 DOE believes this approach ensures compliance with a future 

standard while reducing testing burden.

The Basic Model concept provides a way for manufacturers to 

rate their equipment without testing every unit.

• Manufacturers must rate the energy consumption of every unit of walk-in 

equipment that they manufacture.

• Manufacturers are required to test at least one unit of each Basic Model to 

determine its energy consumption.

• For envelopes, the manufacturers may use a calculation methodology to 

rate every other unit in the Basic Model based on the test results from the 

tested unit.

– DOE proposes a calculation methodology for rating envelopes within a 

Basic Model because every envelope a manufacturer makes could be 

unique.

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The underlying rationale for the Basic Model is the Daily Energy 

Consumption Coefficient (DECC), a scaling factor that allows for 

the calculation of energy consumption for some components.

Basic Model >> Envelope

DECC Parameters

Wall surface area

Non-glass door surface area

Glass display door surface area

Glass wall and inset window surface area

Opening of doors (and effectiveness of infiltration reduction devices)

Electrical energy consumption due to devices including, but not limited to: 

lights, anti-sweat heaters, and motors to drive air mixing fans

 DECCs provide a linear expression of the energy consumption of any 

envelope of the same Basic Model as the tested envelope.

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 DECCs are a scaling methodology that manufacturers would 

use to rate their equipment.

• In the standards framework document, DOE proposed to allow manufacturers to 

develop Alternative Efficiency Determination Methods (AEDMs) for calculating energy 

consumption of units.

– The AEDMs would be substantiated with test data and verified by DOE.

Basic Model >> Envelope

DOE developed the DECC to replace a previously proposed 

approach that stakeholder feedback indicated was not appropriate.

• Interested Parties (Standards Framework Public Meeting) objected to the idea of 

allowing manufacturers to develop AEDMs for these reasons:

– Could be expensive and time-consuming for manufacturers to develop.

– Could benefit some manufacturers unfairly.

– May not provide consistent information to end users. 

• Therefore, DOE created a single, consistent calculation methodology based on Daily 

Energy Consumption Coefficients (DECCs).

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Feature Sample change How addressed? New Rating? New Basic Model?

Temperature Cooler vs. Freezer

Testing Yes Yes

Insulation Material • Foam (e.g., urethane, styrene)

• Blowing agent (e.g., HFC 245fa)

Infiltration Devices Strip or air curtains

Assembly System

• Panel locking system (e.g., 

camlock)

• Gasketing, door sweep

• Material

Doors

Materials

• Number of doors

• Door type

Calculation Yes No Dimensions of 

Envelope Size of envelope

Electrical Load • Anti-sweat heaters

• Lighting — interior, door

Miscellaneous

• Paint color, type

• Type of metal (e.g., galvanized)

• Shelving

No action 

required No No

Basic Model >> Envelope

Which changes necessitate a separate Basic Model?

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 Different Basic Models would be required because a trigger 

parameter is met.

These WICF belong to different Basic Models.

Basic Model >> Envelope

Different Basic Models? Rationale

Yes  Different insulation material

Polyurethane Polystyrene

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 However, these models would be RATED differently using 

DECCs, owing to their dimensional differences.

These WICF belong to the same Basic Model.

Different Basic Models? Rationale

No

 Same temperature

 Same materials

 Same assembly systems

Cooler

Basic Model >> Envelope

Cooler

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Example calculation for this Basic Model: the two units differ only 

in their surface area.

DECC = Energy Load / Exterior Surface Area

Surface AreaBasic Model Unit = 400 ft2

Energy LoadBasic Model Unit (as tested) = 5,126 Watt-hours (Wh) / day

THEREFORE, the DECCBasic Model = 12.815 Wh / day-ft2

Basic Model >> Envelope

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Example calculation for this Basic Model: the units differ only in 

their surface area.

Basic Model >> Envelope

DECCBasic Model = 12.815 Wh / day-ft2(from previous slide)

Exterior Surface Area Calculated Unit = 1,200 ft2

Energy LoadCalculated Unit = DECCBasic Model X Exterior Surface AreaCalculated Unit

THEREFORE, the calculated Energy LoadCalculated Unit = 15.4 kWh / day

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Taking these ideas into consideration, DOE proposes the 

following definition of Basic Model for envelopes:

―Basic Model means all units of a given type of walk-in equipment manufactured 

by a single manufacturer, and—with respect to envelopes, which do not have any 

differing construction methods, materials, components, or other characteristics 

that significantly affect the energy consumption characteristics.‖ 

Issue 2-1: Basic Model of Envelope

DOE invites comments on the approach of grouping walk-in envelopes into Basic 

Models and on the proposed definition of Basic Model for envelopes.

Issue 2-2: Daily Energy Consumption Coefficients

DOE invites comments on the approach of using DECCs to calculate energy 

consumption of units with a Basic Model.

Basic Model >> Envelope

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Basic Model >> Refrigeration System

 DOE is considering applying the Basic Model concept to 

refrigeration systems to reduce testing burden.

The Basic Model concept could also apply to refrigeration 

systems.

• Refrigeration systems may be virtually identical but may have different design 

characteristics, either electrical (e.g. voltage), or physical (e.g. exterior finish), that would 

change the energy consumption either very minimally or not at all.

• The purpose of using a Basic Model would be reducing the testing burden on 

manufacturers by allowing them to group similar models of refrigeration systems into a 

single Basic Model.

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Basic Model >> Refrigeration System

 DOE is considering an additional approach to the Basic Model 

definition and concept originally described in the NOPR.

DOE is considering the following options for testing refrigeration 

systems:

Option Description Implications

1

Basic Model approach proposed 

in the NOPR

• Manufacturers may group several models into a 

single Basic Model, consisting of units that may differ 

in energy consumption but not significantly. 

• It may be difficult to determine what constitutes a 

―significant‖ difference.

2

Basic Model approach used for 

other equipment in the 

appliance standards program

• Manufacturers may group several models into a 

single Basic Model, consisting of models that do not

differ in energy consumption. 

• Purely cosmetic changes, e.g. those to the exterior 

finish, would not necessitate a new test.

3 No provision for Basic Model • Manufacturers must test one of every model of 

refrigeration system they manufacture

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Basic Model >> Refrigeration System

 In this approach, differences that impact energy consumption 

in a minimal way would not trigger a new Basic Model.

DOE is considering how best to define the term Basic Model for 

refrigeration systems, if a Basic Model were used for this 

equipment.

• As defined in the NOPR, refrigeration systems in one Basic Model 

could include design changes that do affect energy 

consumption, though minimally. (Option 1 on the previous slide)

• Original definition proposed in NOPR that DOE is considering:

―Basic Model means all units of a given type of walk-in equipment 

manufactured by a single manufacturer, and—With respect to refrigeration 

systems, which do not have any differing electrical, physical, or functional 

characteristics that significantly affect energy consumption.‖

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 In this approach, any difference that impacts energy 

consumption in any way would trigger a new Basic Model.

DOE is considering how best to define the term Basic Model for 

refrigeration systems, if a Basic Model were used for this 

equipment.

Basic Model >> Refrigeration System

• DOE is considering a revised definition: refrigeration systems in one 

Basic Model could not include design changes that affect energy 

consumption. (Option 2)

• Revised definition that DOE is considering:

―Basic Model means all units of a given type of walk-in equipment manufactured by a 

single manufacturer, and—With respect to refrigeration systems, which have 

electrical characteristics that are essentially identical, and which do not have any 

differing electrical, physical, or functional characteristics that affect energy 

consumption.‖

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Basic Model >> Refrigeration System

DOE may decide to reject both Option 1 and Option 2, leaving the 

default of no provision for Basic Model (Option 3).

• DOE may decide that manufacturers cannot use either Basic Model approach.

• In this case, manufacturers would have to test one of every model of 

refrigeration system they manufacture.

• This would ensure that every model would be rated accurately and could be 

certified to comply with a future energy conservation standard. 

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Issue 2-3: Basic Model of Refrigeration Systems

DOE invites comments on these options and whether a Basic Model approach is 

necessary or appropriate for refrigeration systems. DOE asks interested parties 

to suggest additional options that DOE should consider. 

Issue 2-4: Definition of Basic Model for Refrigeration Systems

DOE invites comments on the definitions of Basic Model as proposed in the NOPR 

and as outlined in this presentation. For purposes of defining Basic Model, DOE 

also requests comment on what might constitute a ―significant difference‖ in 

energy consumption that would make a new Basic Model necessary.

Basic Model >> Refrigeration System

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Table of Contents

1 Overview of Public Meeting

2 Background & Approach

3 Basic Model

5 Proposed Test Procedure – Refrigeration System 

6 Impacts on Small Businesses

7 Others Issues/Closing Discussion

4 Proposed Test Procedure – Envelope 

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Envelope energy load depends on a variety of components.

Envelope >> Overview

Doors

Lights

Heater Wire

Metal Skin & Insulated Panels

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Conduction, infiltration, and electric use determine envelope 

energy load.

Envelope >> Overview

Conduction 

Load

Surfaces

(Non-glass)

Foam 

Insulation

Surfaces

(Glass)

Glass 

Systems

Infiltration Load

Doors

Electrical Load & 

Electrical Heat Load

Performance 

Test

Envelope Test 

Procedure

Steadystate 

infiltration

Infiltration 

Reduction 

Devices

Energy Use of WICF Envelope

Envelope Electrical 

Devices

44 | Building Technologies Program eere.energy.gov

Envelope >> Overview

 As in this example for glass doors, various components may impact 

energy load through more than one of the three primary mechanisms.

The purpose of the envelope test procedure is to accurately and 

fully capture the energy load of the envelope. 

Conduction 

Load Infiltration Load Electrical Load & Electrical Heat Load

Energy Load

of WICF Envelope

Glass Door Heater Wire

EERE2008-BT-TP-0014 DOC ID 1.2.009
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 Energy associated with the envelope will be normalized by 

external surface area (ft2)

Stakeholder comments suggested that WICF should be 

normalized by a parameter related to the size of the walk-in.

Envelope >> Overview > Normalization

WICF Normalization Factor: External Area and Glass Area Ratio

• DOE believes that the external surface area of the envelope is an 

appropriate normalization factor

– Surface area is the key geometric characteristic related to both 

conduction and infiltration

– Glass surface area in particular has a major impact on energy use.

• Therefore, DOE proposes to normalize the energy use by an external 

surface area corrected by the ratio of glass to non-glass area of the WICF.

46 | Building Technologies Program eere.energy.gov

Equation 3-34 describes the energy normalization and correction 

by surface area and glass to non-glass ratio, respectively.

Envelope >> Overview > Normalization

Issue 3-1: Normalization Factor

DOE invites comments on its proposal to normalize the energy consumption using 

surface area. See Section III.B.3.e for details.

non glass tot glass tot

tot EER

non glass tot glass tot

non glass tot

tot non glass A A

Q

A A

A

E

, ,

,

, ,

,

,

Eq. 3-34

E = Energy (kWh/day-ft2)

A = Area (ft2)

Q = Heat load (kWh/day)

EERE2008-BT-TP-0014 DOC ID 1.2.009
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Conduction refers to the transfer of heat through a material and is 

a key mechanism of heat gain. 

Envelope >> Conduction

Conduction Load

Surfaces 

(Non-glass)

Foam 

Insulation

Surfaces

(Glass)

Glass Door 

Systems

Measured 

by R-value

Infiltration Load Electrical Load & 

Electrical Heat Load

Performance 

Test

Envelope Test 

Procedure

48 | Building Technologies Program eere.energy.gov

Envelope >> Conduction > Foam R-Value

 Foam R-Value has a major impact on WICF conduction losses.

“R-Value” is typically used to describe the performance of a 

thermally insulating material.

R-Value, ft2-F-h/Btu

• R-Value is a measure of resistance to thermal conductivity.

• The greater the R-Value, the greater the thermal resistance.

• Foam is the most common insulating material used in walk-in cooler and 

freezer construction.

@ 4” thickness

• Steel R-Value: 0.16 ft2-F-h/Btu

• Foam R-Value: 16.00-32.00 ft2-F-h/Btu

• Vacuum Insulated Panel R-value: 120-200 ft2-F-h/Btu

EERE2008-BT-TP-0014 DOC ID 1.2.009
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Envelope >> Conduction > Foam R-Value

Heat transfer through insulation is easily calculated. The 

calculation requires known area, R-value, thickness, and ΔT.

T2 ( ̊F)

T1

( ̊F)

h (ft)

w (ft)

t (in)

R (ft2-F-hr/Btu) 

A h w

hr

( ) Btu 2 1

R t

A T T

Qheat

50 | Building Technologies Program eere.energy.gov

Envelope >> Conduction > Foam R-Value

 There are two key mechanisms of R-value decline: the diffusion 

of gases and moisture infiltration.

At the framework public meeting, DOE received numerous 

comments regarding the diminishing R-Value of insulating foams.

1. Diffusion of gases, which typically occurs within 2-3 years 

after manufacture.

2. Moisture infiltration, which may occur over time due to 

environmental conditions inherent in refrigerated boxes and 

WICF design, such as but not limited to differences in 

temperature and relative humidity.

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DOE found that diffusion and water absorption may affect the Rvalue of foam insulation.

Envelope >> Conduction > Foam R-Value

Conduction Load

Surfaces 

(Non-glass)

Foam 

Insulation

Surfaces

(Glass)

Glass Door 

Systems

Measured 

by R-Value

Infiltration Load

Issue: Diffusion

Issue: Water Absorption

Electrical Load & 

Electrical Heat Load

Performance 

Test

Envelope Test 

Procedure

52 | Building Technologies Program eere.energy.gov

 Although the cells are called “closed,” they are permeable.

The insulating performance of foam depends both on the plastic 

polymer and on the gas trapped within its cells.

Foam Insulation

Closed Cells Filled 

with blowing agent

WICF Panel Foam Cells

Envelope >> Conduction > Foam R-Value

EERE2008-BT-TP-0014 DOC ID 1.2.009
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 The rate of diffusion of gases decays exponentially. 

Initially, foam cells are filled with high concentration of blowing 

agent. Over time, the concentration of blowing agent decreases.

Envelope >> Conduction > Foam R-Value

Primary mechanism

1. Air (nitrogen and oxygen) diffuses 

into the cells.

2. The air reduces the concentration of 

blowing agent and therefore 

reduces the thermal resistivity of the 

foam.

Secondary mechanism

1. Blowing agent diffuses out of the 

foam into the atmosphere.

2. This further reduces the 

concentration of blowing agent 

and reduces thermal resistivity.

= Air

= Blowing Agent

Individual Cell

54 | Building Technologies Program eere.energy.gov

 The change in concentration of blowing agent over time 

reduces insulating performance.

First, air diffuses into the foam cells, and then the blowing agent 

diffuses out of the foam.

Envelope >> Conduction > Foam R-Value

After manufacture Primary Diffusion Secondary Diffusion

= Air = Blowing Agent

EERE2008-BT-TP-0014 DOC ID 1.2.009
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DOE believes that thin slicing is the best option for conditioning 

insulating foams.

Envelope >> Conduction > Foam R-Value

Overview of ASTM C1303-08 test procedure

1. Slice the full thickness foam sample.

2. Allow time to pass (time determined based on slice thickness).

3. Measure the R-Value of the stack of slices using ASTM C518-04.

Benefits

• Results from thin slicing are used to predict an average R-value over a 15 year 

life. 

• The U.S. building industry recognizes that initial R-values decline over time and 

therefore uses conditioned R-values on labeling of insulating foams.

• Since 2001, Canada has required industries using insulating foams to use a thin

slicing method to accelerate conditioning. 

56 | Building Technologies Program eere.energy.gov

Issue 3-2: Proposed Test Method for Conditioning of Foam

DOE invites comment on the proposal to require the use of ASTM C1303-08, 

―Standard Test Method for Predicting Long-Term Thermal Resistance of Closed-Cell 

Foam Insulation,‖ as a standard conditioning method for insulating foams used in walkin coolers and freezers prior to testing these foams with ASTM C518-04 as required by 

EPCA. See Section III.B.2.a. for details.

Envelope >> Conduction > Foam R-Value

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Conduction Load

Surfaces

(Non-glass)

Foam 

Insulation

Surfaces

(Glass)

Glass Door 

Systems

Measured 

by R-Value

Infiltration Load

Issue: Diffusion

Issue: Water Absorption

Oral and written comments submitted by interested parties 

requested that DOE investigate the impact of water absorption on 

the R-Value of foams.

Envelope >> Conduction > Foam R-Value

Electrical Load & 

Electrical Heat Load

Performance 

Test

Envelope Test 

Procedure

58 | Building Technologies Program eere.energy.gov

DOE believes that water impacts the R-Value of foam insulation. 

No test procedure is currently available and DOE has not 

developed one.

Envelope >> Conduction > Foam R-Value

Summary of Water Issues

1. There are limited or nonexistent industry-accepted measurement 

procedures for this issue. 

2. Limited research conducted by academic, government, or industry 

has focused on issues specific to the building industry rather than 

WICF.

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Issue 3-3: Impact of Water on Foam

DOE invites comments on this issue. See Section III.B.2.ii for details. 

Envelope >> Conduction > Foam R-Value

60 | Building Technologies Program eere.energy.gov

Conduction Load

Surfaces

(Non-glass)

Foam 

Insulation

Surfaces

(Glass)

Glass Door 

Systems

Measured 

by R-Value

Infiltration Load

Issue: Diffusion

Issue: Water Absorption

Oral and written comments submitted by interested parties 

regarding diffusion and water absorption referenced the topic of 

permeability of “skins”.

Envelope >> Conduction > Foam R-Value

Electrical Load & 

Electrical Heat Load

Performance 

Test

Envelope Test 

Procedure

Issue: Skins

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Many manufacturers seek to prevent or delay diffusion and 

moisture infiltration.

Envelope >> Conduction > Foam R-Value

DOE received conflicting comments on this issue

1. Whether WICF walls can be made fully impermeable using metal skins;

-OR2. Whether full impermeability cannot be achieved due to:

• Lack of or imperfect sealing at panel joints;

• Imperfect adherence of foam to metal skins during or after 

manufacture; and/or

• Deliberate punctures for fixtures and shelving and/or inadvertent 

punctures that typically occur in the field. 

62 | Building Technologies Program eere.energy.gov

Issue 3-4: Efficacy of Skins

DOE invites comments on skins used to reduce moisture and air permeance 

through insulating materials. DOE invites the submission of test results regarding 

the impact of impermeable skins on long-term R-value, specifically peer-reviewed, 

published data pertaining to the efficacy of skins in preventing or delaying R-value 

decline. See Section III.B.2.a for details.

Envelope >> Conduction > Foam R-Value

EERE2008-BT-TP-0014 DOC ID 1.2.009
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 The proposed correction is available on the following slide.

DOE is considering a correction to the method used to calculate 

heat transfer through floorless coolers. 

Envelope >> Conduction > Floor

Floorless Coolers: Correction to NOPR

• In the published NOPR, DOE proposed the use of a method for 

calculating heat transfer through uninsulated cooler floors.

• Subsequent modeling has demonstrated that the previously 

published approach could be improved. 

64 | Building Technologies Program eere.energy.gov

DOE is considering an improved approach to calculating the heat 

transfer ONLY through floorless coolers. 

Envelope >> Conduction > Floor

Floorless Coolers: Proposed Correction

• DOE performed computational simulations of walk-in coolers of various 

sizes.

• The result is an equation that is a function of floor area.

• A = floor area of the walk-in cooler [ft2]

• qfloor= Average floor heat flux [Btu/h-ft2]

If A ≤ 750 ft2, qfloor = 33.153 x A-0.364

If A > 750 ft2, qfloor = 0.0002 x A + 2.84

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Comparison of original and new equations from the published 

NOPR:

Envelope >> Conduction > Floor

Original Eq. 3-10

(except floorless coolers)

New Eq. 3-10a

(for floorless coolers only)

k j

floor k i

i

Ti q T T

1 1 non-glass,wall, j

non-glass,doors,j

non-glass,ceil, k

ceiling,k

floor

1 non-glass,wall,i

walls,i

cond-non-glass R

A

R

A

A

R

A

Q

i l

l

k

k

j

Ti Tj T T

1 1 non-glass,door, l

non-glass doors,l

1 non-glass,ceil, k

ceiling,k

1 non-glass,floor, j

floor, j

non-glass,wall,i

walls,i

cond-non-glass R

A

Δ

R

A

Δ

R

A

Δ

R

A

Q Δ

Issue 3-5: Floorless Cooler Heat Transfer

DOE invites comment on its proposed correction for floorless coolers.

66 | Building Technologies Program eere.energy.gov

DOE is considering conditional requirements for heat transfer 

calculations through insulated freezer floors.

Envelope >> Conduction > Floor

Issue 3-6: Freezer Floor R-Values

DOE invites comment on freezer floor R-values. See Section III.B.3.b for details.

Freezers: R-28 Floor Assumption

If the manufacturer does not provide any additional insulating 

surface:

• DOE will require the use of an R-value of 28 [ft2-F-h/Btu] for 

freezers for the purposes of calculating the energy loss 

through walk-in freezer floors.

• This reflects the R-value minimum prescribed by EPCA for 

freezer floors.

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DOE proposes a correction to the floor temperature assumption 

for insulated floors in WICF.

Envelope >> Conduction > Floor

Floor Surface Temperature Assumption

• In the NOPR, DOE specified that 55 ̊F be used in heat transfer calculations for 

both freezers and coolers. 

• DOE proposes replacing 55 ̊F with separate assumptions:

1. Freezers: 60 ̊F

2. Coolers: 65 ̊F

Issue 3-7: Insulated Floor Surface Temperature Assumptions

DOE invites comment on floor surface temperature assumptions. 

68 | Building Technologies Program eere.energy.gov

Conduction refers to the transfer of heat through a material and is 

a key mechanism of heat gain. 

Envelope >> Conduction > Glass U-Factor

Conduction Load

Surfaces

(Non-glass)

Foam 

Insulation

Surfaces

(Glass)

Glass Door 

Systems

Measured 

by U-Factor

Infiltration Load Electrical Load & 

Electrical Heat Load

Performance 

Test

Envelope Test 

Procedure

EERE2008-BT-TP-0014 DOC ID 1.2.009
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In addition to panes, the inert gas fill, emissivity coating, and 

pane separation distance have an impact on door performance.

Envelope >> Conduction > Glass U-Factor

Variables That Impact U-Factor 

Include:

• Number of glass panes

• Glass coatings

• Inert gas fill

• Inter-pane spacing

• Frame materials

• Gasket materials

Gas Fill

Pane Spacing

Glass Pane Frame

Coatings

WICF cooler R-Value

Walls = 20-30 [ft2-F-h/Btu]

Glass Doors = 2-3 [ft2-Fh/Btu]

U-Factor = 1 / R-Value

70 | Building Technologies Program eere.energy.gov

 Manufacturers may use Window 5.2 method 

only if an NFRC label is not available.

DOE proposes that manufacturers account for the energy use of 

their glass components with the NFRC component label.

Envelope >> Conduction > Glass U-Factor

Primary Option: 

National Fenestration Rating 

Council (NFRC) Label

If WICF door suppliers

participate in the NFRC rating

program, the performance of 

the door shall be simply read 

from its label and used for 

calculations in this test 

procedure. 

Alternative Option: 

Window 5.2 Calculation

If a glass door does not have an 

NFRC rating, then DOE 

proposes to require 

manufacturers to use Lawrence 

Berkeley National Laboratory‘s 

(LBNL) publicly available 

Window 5.2 software package to 

calculate glass door 

performance. 

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LBNL’s Window 5.2 software (available for free online) has been 

thoroughly verified with years of use and empirical test data. 

Envelope >> Conduction > Glass U-Factor

Use of Window 5.2 Software

• The WICF manufacturer must fully document the glass door model and all 

specifications/inputs used calculate the U-Factor in Window 5.2 such as 

the size of the door, number of panes of glass, gas fill between panes, 

pane spacing etc. 

• This will help ensure that inputs used to calculate overall door 

performance are not being manipulated since any of the results should be 

reproducible and inputs can be directly compared to shipped products.

Issue 3-8: Performance Data of Glass Products 

DOE seeks comment on the availability of performance data on glass products used in 

walk-in applications, glass component manufacturers‘ participation in third-party 

certification programs such as NFRC, and the proposed method for predicting the 

thermal performance of glass components using Window 5.2.

72 | Building Technologies Program eere.energy.gov

NOPR Clarification: energy calculation for display-type WICF sold 

with and without glass doors

Envelope >> Conduction > Glass U-Factor

Display-Type Walk-in Sold 

Without Display Doors

For the purposes of calculating the 

energy use associated with 

display doors:

- EPCA maximum whole door 

U-Factors: 0.43* and 0.3* 

[Btu/hr-ft2-F] for coolers 

and freezers, respectively

Display-Type Walk-in Sold 

With Display Doors

For the purposes of calculating the 

energy use associated with 

display doors:

- The rating of the glass 

doors sold with the walk-in 

shall be used.

Issue 3-9: Glass Door Energy Calculation

DOE seeks comment on the use of using EPCA maximum U-Factor for glass door 

energy calculations and their related assumed values.

*Calculated using Window 5.2: 2-pane argon gas fill and 3-pane 

argon gas fill for coolers and freezers (no low e-coatings).

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Infiltration refers to air leakage into WICF and is a key pathway for 

envelope energy losses.

Envelope >> Infiltration > Steady-State

Infiltration Test

Doors

Steadystate 

Infiltration

Infiltration 

Reduction 

Devices

Envelope

Infiltration Load Electrical Load & 

Electrical Heat Load Conduction Load

Performance 

Test

Envelope Test 

Procedure

74 | Building Technologies Program eere.energy.gov

 Air exchange accounts for a large portion of WICF energy use.

DOE proposes to account for steady-state air infiltration in the 

envelope test procedure.

Envelope >> Infiltration > Steady-State

Door

Threshold

Panels Panel-to-Panel

Interface

Pressure Relief 

Valve

Steady-state infiltration may occur through:

- Panels

- Panel-to-panel interfaces

- Door threshold

- Bi-directional pressure relief valves

(freezers)

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DOE identified the Gas Tracer Method as a good method for 

measuring air infiltration in WICF.

Envelope >> Infiltration > Steady-State

WICF Envelope Step 1 Step 2

= Tracer Gas

Step 3 Step 4

Time = 0

Time > 0

1. Inject tracer gas

2. Measure gas concentration

3. Let time pass (air exchange 

occurs)

4. Measure gas concentration

5. Calculate infiltration rate 

(change in concentration over 

time)

76 | Building Technologies Program eere.energy.gov

DOE proposes the use of ASTM E741-06 to measure steady-state 

infiltration and the effectiveness of infiltration reduction devices.

Envelope >> Infiltration > Steady-State

Issue 3-10: Steady-State Infiltration Measurement

DOE invites comments on the proposed test method for measuring steady-state 

infiltration. See Section III.B.2.b for details on the proposed analytical methods.

• ASTM E741-06: ―Standard Test Method for Determining Air Change in a Single 

Zone by Means of a Tracer Gas Dilution‖ 

• Also referred to as the Gas Tracer Method

• The Gas Tracer Method is NOT used for calculation of air infiltration related to 

door-opening events. (An analytical approach is used instead to calculate air 

exchange due to door opening events).

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Infiltration refers to air leakage into WICF and is a key pathway for 

envelope energy losses.

Envelope >> Infiltration > Door Opening

Door Opening 

Events 

(calculation)

Doors

Steadystate 

infiltration

Infiltration 

Reduction 

Devices

Envelope

Infiltration Load Electrical Load & 

Electrical Heat Load Conduction Load

Performance 

Test

Envelope Test 

Procedure

78 | Building Technologies Program eere.energy.gov

Envelope >> Infiltration > Door Opening

 Door opening air exchange accounts for a large portion of 

WICF energy use.

Hot air enters through the top of the passage as cold dense air 

flows through the bottom.

Open 

Door

Cold Air

Hot, Humid Air

Factors that impact energy lost during air infiltration:

1. Door size

2. Air properties (relative humidity and temperature)

3. Door opening frequency

4. Door opening duration

5. Infiltration reduction device effectiveness

WICF 

Side 

View

WICF 

Front 

View

The energy associated with door 

infiltration is calculated using 

ASHRAE defined equations (as 

described in the NOPR).

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DOE proposes the use of an analytical method to calculate 

infiltration due to door-opening events.

Envelope >> Infiltration > Door Opening

Issue 3-11: Calculations for Door-Opening Events 

DOE invites input and feedback on the calculations proposed for determining 

infiltration from door-opening events. See Section III.B.2.b for details on the 

proposed analytical methods.

• The DOE approach uses equations described in ASHRAE Fundamentals as 

well as assumed door-opening frequency, duration, and the measured 

infiltration barrier effectiveness to calculate the air infiltration associated with 

each door. 

• This method avoids the burden of individual infiltration measurements for each 

unique door.

80 | Building Technologies Program eere.energy.gov

Infiltration refers to air leakage into WICF and is a key pathway for 

envelope energy losses.

Envelope >> Infiltration > Door Opening

Reduction 

Effectiveness 

Test

Doors

Steadystate 

infiltration

Infiltration 

Reduction 

Devices

Envelope

Infiltration Load Electrical Load & 

Electrical Heat Load Conduction Load

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 IRD performance is measured in terms of device effectiveness.

Infiltration Reduction Devices (IRD) can reduce air exchange 

associated with door opening events.

Envelope >> Infiltration > Door Opening

Strip 

Curtain

IRDs include:

- Strip Curtains

- Air Curtains

- Automated curtain 

doors

Source: DOE

Air 

Curtain

82 | Building Technologies Program eere.energy.gov

Infiltration Reduction Device effectiveness is measured using the 

gas tracer test.

Envelope >> Infiltration > Door Opening

With IRD

1. Measure 

Infiltration

Open

Doorway

WICF 

Front 

View

Without IRD

2. Measure 

Infiltration

Device Effectiveness =

Issue 3-12: Infiltration Reduction Device Effectiveness

DOE invites input and feedback on the IRD effectiveness test. See section 

III.B.2.b.iii for details.

IRD

Open

Doorway

Infiltration w/ IRD

Infiltration w/o IRD

1-

Correction to 

NOPR

EERE2008-BT-TP-0014 DOC ID 1.2.009
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Electricity use is another form of energy consumption in the 

envelope. Electricity is used for devices like heater wires and 

lighting.

Envelope >> Electrical

Infiltration Load Electrical Load & 

Electrical Heat Load Conduction Load

Electrical 

Devices

Percent Time Off 

and name plate 

capacity

(calculation)

84 | Building Technologies Program eere.energy.gov

 This will provide a uniform means of comparison.

DOE examined the energy use of electrical components sited 

within the envelope.

Envelope >> Electrical

Electrical Device Calculations

• DOE recommends calculating the electricity consumption of lights, 

sensors, and other miscellaneous electrical devices not considered part of 

the refrigeration equipment using name-plate rating and an assumed 

daily operation. 

• DOE incorporates assumed duty cycles of lights, anti-sweat heaters, and 

other devices based on whether they are controlled by a preset control 

system. 

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DOE assumed certain values for the daily operation of electrical 

components.

Envelope >> Electrical

Percent Time Off (PTO) Assumptions

Lights

• PTO value of 25% for systems without timers or other 

auto shut-off systems.

• PTO value of 50% for systems with timers or other auto 

shut-off systems installed.

Anti-sweat 

heaters

• PTO value of 0% for all systems without direct or 

indirect relative humidity sensing controls. 

• DOE further proposes that 75% be used for walk-in 

coolers and 50% for walk-in freezers with these 

controls. 

86 | Building Technologies Program eere.energy.gov

DOE assumed certain values for the daily operation of electrical 

components.

Envelope >> Electrical

Percent Time Off (PTO) Assumptions

Powered 

infiltration 

reduction devices

• For devices not actively controlled based on door open 

or closed positions, DOE proposes a PTO value of 25%.

• For devices actively controlled based on door open or 

closed position for display doors, DOE proposes 99.33%.

• For devices actively controlled based on door open or 

closed position for all other doors, DOE proposes 

99.17%.

All other devices

• DOE proposes a PTO value of 0%, unless the walk-in 

manufacturer can demonstrate that the device is controlled 

by a preset control system. 

• If this can be demonstrated, DOE proposes 25% for the 

device in question.

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Envelope >> Electrical

Issue 3-13: Percent Time Off (PTO) Assumptions

DOE invites comments on the assumed PTO for the purposes of calculating 

electrical load of the envelope. See Section III.B.3.d for details.

88 | Building Technologies Program eere.energy.gov

 All electrical devices sited inside a WICF increase the amount 

of heat that must be removed by the refrigeration equipment.

DOE examined the energy impact of door anti-sweat heaters and 

lights (power use and heat generation).

Glass Door with 

Anti-sweat Heating

Envelope >> Electrical

WICF

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Evaluating the conduction, infiltration, and energy consumption 

of electrical devices yields values of heat gain. 

Envelope >> Electrical

 A means for translating the thermal properties of the envelope 

into a quantifiable energy consumption value is needed.

Energy Consumption Associated with the Envelope

• A single metric, in units of kWh/day, is preferred.

• The heat gains related to the envelope are expressed in units of 

[Btu/h].

- For these reasons, a method is needed to express these thermal 

gain values into heat removed by the refrigeration system [i.e. 

convert Btu/h to kWh/day]

90 | Building Technologies Program eere.energy.gov

DOE proposes the use of Energy Efficiency Ratios (EER) to 

“convert” the envelope-related thermal energy into kWh/day of 

electrical energy consumption.

Envelope >> EER

• EERs represent the relative system efficiencies of walk-in refrigeration 

equipment; i.e. a measure of how many units of heat are removed per unit 

electrical energy input into the refrigeration equipment.

• Proposed nominal values: DOE is considering the use of an EER of 12.4 and 

6.3 (Btu/W-h) for coolers and freezers, respectively (AHRI 1250-2009).

Issue 3-14: Nominal Energy Efficiency Ratio

DOE invites comments on the use of EERs for the refrigeration system to 

determine the energy consumption associated with heat gain through the 

envelope due to conduction, infiltration and electric devices. See Section III.B.3.a 

for details.

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In summary, conduction, infiltration, and electric use determine 

envelope energy load.

Envelope >> Overview

Conduction 

Load

Surfaces

(Non-glass)

Foam 

Insulation

Surfaces

(Glass)

Glass 

Systems

Infiltration Load

Doors

Electrical Load & 

Electrical Heat Load

Performance 

Test

Envelope Test 

Procedure

Steadystate 

infiltration

Infiltration 

Reduction 

Devices

Energy Use of WICF Envelope

Envelope Electrical 

Devices

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Table of Contents

1 Overview of Public Meeting

2 Background & Approach

3 Basic Model

4 Proposed Test Procedure – Envelope 

6 Impacts on Small Businesses

7 Others Issues/Closing Discussion

5 Proposed Test Procedure – Refrigeration System 

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DOE proposes to adopt Air-Conditioning, Heating and Refrigeration 

Institute (AHRI) Standard 1250, published in 2009.

Refrigeration >> Overview

• In 2009, AHRI developed a new rating method 

for refrigeration systems of walk-in coolers and 

freezers.

• DOE proposes to incorporate AHRI 1250 as the 

DOE test procedure for walk-in refrigeration 

systems.

– This test procedure measures Annual Walkin Energy Factor (AWEF), a measure of 

efficiency.

– DOE proposes to add calculations to derive 

the energy consumption as required by 

EPCA.

94 | Building Technologies Program eere.energy.gov

A refrigeration system consists primarily of a compressor, 

condenser, unit cooler and other miscellaneous components.

Refrigeration >> Overview

Unit Cooler

Condenser

Compressor

Expansion 

valve Fan

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Refrigeration systems come in three general configurations:

Refrigeration >> Overview

1. Packaged System 2. Split System 3. Unit Cooler Connected to a 

Multiplex System

Unit Cooler

Unit Cooler Unit Cooler

Compressor & 

Condenser

Compressor & 

Condenser

These systems have a dedicated compressor and 

condenser. The compressor and condenser are included in 

the test.

This system does not have a dedicated 

compressor and condenser. The multiplex 

system is not included in the test.

Multiplex 

System

96 | Building Technologies Program eere.energy.gov

AHRI 1250 accounts for three different types of equipment 

systems.

Refrigeration >> AHRI 1250

 The following slides summarize the tests for each system type.

1. Matched system: Unit cooler paired with a condensing unit and tested 

together as a complete system.

2. Mix-match system: Unit cooler and condensing unit are tested separately; 

their efficiency when they are paired together is calculated from the test 

results.

3. Unit cooler paired with a multiplex system: Unit cooler is tested alone. The 

efficiency is calculated using a nominal EER value for the multiplex system 

that depends on the suction dew point temperature. 

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Summary of tests for a matched system.

Matched 

System

On-cycle Steady 

State System 

Test

On-cycle 

power 

consumption

Net 

refrigeration 

capacity

Off-cycle 

Evaporator Fan 

Power Test

Off-cycle evap. 

fan power 

consumption

Mandatory 

Defrost Test 

(freezer only)

Energy input 

for defrost 

cycle

Duration of 

defrost cycle

Optional Defrost 

Test (freezer 

only)

Time interval 

between 

defrosts

Refrigeration >> AHRI 1250

Mix-Match 

System

Unit 

Cooler 

(paired with 

multiplex 

system)

98 | Building Technologies Program eere.energy.gov

Summary of tests for a mix-match system.

Refrigeration >> AHRI 1250

Mix-Match 

System

Unit Cooler 

Test

Capacity test at 

2 different 

suction 

temperatures

Net Refrigeration 

Capacity

Off-cycle 

Evaporator Fan 

Power Test

Off-cycle Evap. Fan 

Power Consumption

Mandatory 

Defrost Test 

(freezer only)

Energy Input for 

Defrost Cycle

Duration of Defrost 

Cycle

Optional Defrost 

Test (freezer 

only)

Time Interval Between 

Defrosts

Condensing 

Unit Test

On-cycle test

On-cycle Power 

Consumption 

Gross Refrigeration 

Capacity

Matched 

System

Unit 

Cooler 

(paired with 

multiplex 

system)

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Summary of tests for a unit cooler paired with a multiplex system.

Refrigeration >> AHRI 1250

Unit Cooler 

(paired with 

multiplex 

system)

Unit Cooler 

Test

Capacity Test

Net Refrigeration 

Capacity

Off-cycle 

Evaporator Fan 

Power Test

Off-cycle Evap. 

Fan Power 

Consumption

Mandatory 

Defrost Test 

(freezer only)

Energy Input For 

Defrost Cycle

Duration Of 

Defrost Cycle

Optional 

Defrost Test 

(freezer only) Time Interval 

Between Defrosts

Mix-Match 

System

Matched 

System

100 | Building Technologies Program eere.energy.gov

The test procedure specifies test conditions for various 

parameters to give credit for energy-saving technologies.

Refrigeration >> AHRI 1250

Category Parameter Conditions

Interior WICF Temperature

Cooler At 35 F

Freezer At -10 F

Condenser Location

Indoors At one ambient temperature (90 F)

Outdoors At three ambient temperatures (35 F,

59 F, and 95 F)

Compressor Type

Fixed-capacity At single capacity

Two-capacity At both capacities

Variable-capacity At minimum, maximum, and an 

intermediate capacity

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DOE examined AHRI 1250 and believes that the methods are wellsuited to test WICF refrigeration systems.

Refrigeration >> AHRI 1250

• Based on test methods already used in the industry and shown to be accurate 

and repeatable.

• Developed and approved by industry and published by the industry trade 

association.

• Applicable to the covered equipment because it accounts for the unique 

operating conditions, configurations, and use patterns of WICF refrigeration.

• Gives credit for energy saving technologies such as variable-speed 

evaporator fans and defrost control strategies.

Issue 4-1: Proposed Test Procedure

DOE invites comment on whether AHRI 1250-2009 is an appropriate test procedure for 

refrigeration systems used in walk-ins. See Section III.C.1 for details.

102 | Building Technologies Program eere.energy.gov

After the test data are gathered, the AWEF is calculated.

Refrigeration >> Calculation

• The AWEF is a measure of the efficiency

of the system.

• The refrigeration system is analytically

paired with a theoretical envelope. 

• The test procedure calculates the energy

the refrigeration system would use to

reject the heat load associated with the 

envelope.

total energy consumption of the refrigeration system (Wh)

net heat removed from the walk -in (Btu)*

AWEF

* Does not include heat generated by the refrigeration system.

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 The assumed ambient conditions are consistent across all 

WICF refrigeration systems.

The test procedure calculates the AWEF under assumed ambient 

conditions. 

Refrigeration >> Calculation

Assumptions Regarding 

Ambient Conditions:

1. For indoor units, the ambient 

temperature is assumed to be 

constant at 90 °F.

2. For outdoor units, the ambient 

temperature varies according 

to an assumed temperature 

profile.

The Ambient Conditions Affect:

1. The conduction load on the 

theoretical envelope, which 

contributes to the total heat 

load removed from the 

walk-in.

2. The energy consumption of 

the condensing unit.

104 | Building Technologies Program eere.energy.gov

DOE adapted the AHRI test procedure to fulfill the statutory 

requirement of EPCA. 

Refrigeration >> Calculation

• The AHRI test procedure calculates the AWEF of a refrigeration system, a 

measure of efficiency. 

* Does not include heat generated by the refrigeration system.

• The DOE test procedure derives annual energy use from the AWEF, consistent 

with the EPCA mandate that the test procedure measure ―energy use.‖

* Does not include heat generated by the refrigeration system.

total energy consumption of the refrigeration system [Wh]

net heat removed from the walk -in [Btu]*

AWEF

AWEF [Btu/Wh]

net heat removed from the walk -in [Btu]*

AnnualEnergy Use [Wh]

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DOE derived energy use from measured data and constants.

Refrigeration >> Calculation

Temperature 

profile data 

(outdoor only) 

(tj)

Heat load for each 

ambient temperature

Total annual heat load that 

must be removed by the 

refrigeration system

Total annual 

energy use

AWEF

Net refrigeration 

capacity at test temp 

(qss) [Btu/h]

Measured 

data and 

constants

Hourly temp. 

profile data 

(outdoor only) 

(nj)

Result

106 | Building Technologies Program eere.energy.gov

DOE proposes the following equations in the rule language:

Refrigeration >> Calculation

AWEF

0.30 q 90 F) 8760 hrs/year AnnualEnergy Use

o

ss (

AWEF

0.53 q 90 F) 8760 hrs/year AnnualEnergy Use

o

ss (

AWEF

n

60

q (95 F) (t 35)

0.24 q (95 F) 0.06

AnnualEnergy Use

# bins

j 1

j

j

o

o ss

ss

AWEF

n

105

q 95 F) (t 10)

0.28 q 95 F) 0.25

AnnualEnergy Use

bins

j

j

o

o ss

ss

#

j 1

(

(

Legend: 

q ss = net capacity

AWEF = annual walkin energy factor

tj = temperature j

nj = number of hours 

at temperature j

Indoor units

Coolers:

Freezers:

Outdoor units

Coolers:

Freezers:

Net heat removed

Net heat removed

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The method DOE used to derive these equations appears in the 

NOPR.

Refrigeration >> Calculation

Issue 4-2: Calculation Methodology

DOE invites comments on its proposed method for deriving annual energy 

consumption from the AWEF. See Section III.C.4 for details.

108 | Building Technologies Program eere.energy.gov

DOE anticipates that manufacturers would measure and report 

both the annual energy consumption and the AWEF.

Refrigeration >> Reporting Requirements

Issue 4-3: Reporting Requirements

DOE requests comments on the approach of reporting both energy 

consumption and AWEF. See Section III.C.4 for details.

• DOE does not specify certification and reporting requirements in this test 

procedure.

• DOE will develop future certification requirements in another rulemaking.

• DOE expects that the test procedure will be used to measure compliance with a 

future energy conservation standard.

• Either AWEF or energy consumption could be more useful in developing an 

energy conservation standard.

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Table of Contents

1 Overview of Public Meeting

2 Background & Approach

3 Basic Model

4 Proposed Test Procedure – Envelope 

5 Proposed Test Procedure – Refrigeration System 

7 Others Issues/Closing Discussion

6 Impacts on Small Businesses

110 | Building Technologies Program eere.energy.gov

DOE must consider impacts on small businesses.

Small Business Impacts

• SBA size standard for the commercial and industrial refrigeration manufacturing 

industry: < 750 employees.

• Sources that list businesses in the WICF industry include:

– Regulatory databases

– AHRI‘s listing of commercial refrigeration manufacturer members

– National Sanitation Foundation (NSF) Section 7 database

• DOE found 37 small manufacturers of WICF envelopes and 5 small 

manufacturers of WICF refrigeration systems.

• There could be other small manufacturers than are publicly listed.

Issue 5-1: Number of Small Entities Regulated

DOE invites comments on the number of small entities that may be affected by the 

proposed rule. See Section IV.B.3 for details.

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DOE identified potential impacts and burden-reducing measures 

for walk-in equipment.

Small Business Impacts 

• Impacts are associated with the cost of testing and length of time it takes to 

perform the tests.

• Measures that may reduce burdens include:

– Allowing low-cost testing options; e.g., for ASTM E741-06, DOE specifies 

CO2 as the tracer gas, the lowest-cost option.

– Reducing the number of tests manufacturers need to perform by allowing 

them to group similar models into one Basic Model.

• These apply to all manufacturers but may have a greater impact on small 

business manufacturers.

Issue 5-2: Impacts on Small Manufacturers

DOE invites comments on the expected impact of the rule on small entities and 

whether that impact is expected to be significant. DOE also asks whether small 

manufacturers would be differentially impacted by the proposed test procedures. DOE 

requests comments on any alternatives to the proposed rule and their impacts on small 

manufacturers. See Section IV.B for details.

112 | Building Technologies Program eere.energy.gov

Table of Contents

1 Overview of Public Meeting

2 Background & Approach

3 Basic Model

4 Proposed Test Procedure – Envelope 

5 Proposed Test Procedure – Refrigeration System 

6 Impacts on Small Businesses

7 Others Issues/Closing Discussion

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Closing Remarks

Interested parties who wish to make a closing statement 

should speak now.

114 | Building Technologies Program eere.energy.gov

 Comment period is open until March 31, 2010

How to submit comments:

Closing Remarks >> Comments

Public Meeting – Oral comments will be captured in the transcript and become part of the 

public record.

Written Comments –Reference Docket EERE-2008-TP-0014 and/or RIN 1904-AB85.

Email: WICF-tp-2008-0014@ee.doe.gov

Include EERE-2008-BT-TP-0014 and/or RIN 1904-AB85 in the subject line of your 

message.

Mail: Brenda Edwards

U.S. Department of Energy

Building Technologies Program

1000 Independence Avenue, SW

Mailstop EE-2J

Washington, DC 20585-0121

Courier: Brenda Edwards

U.S. Department of Energy

Building Technologies Program

950 L‘Enfant Plaza, 6th Floor

Washington, DC 20024

Telephone: 202-586-2945

Please include 

one signed 

original paper 

copy.

EERE2008-BT-TP-0014 DOC ID 1.2.009