ANSI/NFRC 100-2023[E0A0]

Procedure for Determining

Fenestration Product U-factors

An American National Standard

© 2013, 2023 National Fenestration
Rating Council, Inc.

Prepared by:
Swin
National Fenestration Rating Council
6305 Ivy Lane, Suite 410
Greenbelt, MD 20770
P: 301-589-1776
F: 301-589-3884
E: info@nfrc.org
W: www.nfrc.org

ANSI/NFRC 100-2023[E0A0] Page

© 2013, 2023. National Fenestration Rating Council Incorporated (NFRC). All rights reserved.
 FOREWORD
The National Fenestration Rating Council, Incorporated (NFRC) has developed and
operates a uniform rating system for energy and energy-related performance of
fenestration products. The Rating System determines the U-factor, Solar Heat Gain
Coefficient (SHGC) and Visible Transmittance (VT) of a product, which are mandatory
ratings for labeling NFRC certified products, are mandatory ratings for inclusion on label
certificates, and are supplemented by procedures for voluntary ratings of products for Air
Leakage (AL), and Condensation Resistance. Together, these rating procedures, as set
forth in documents published by NFRC, are known as the NFRC Rating System.
The NFRC Rating System employs computer simulation and physical testing by NFRC-
accredited laboratories to establish energy and related performance ratings for
fenestration product types. The NFRC Rating System is reinforced by a certification
program under which NFRC-licensed responsible parties claiming NFRC product
certification shall label and certify fenestration products to indicate those energy and
related performance ratings, provided the ratings are authorized for certification by an
NFRC-licensed certification and Inspection Agency (IA).
The requirements of the rating, certification, and labeling program (Certification Program)
are set forth in the most recent versions of the following as amended, updated, or
interpreted from time to time:
• NFRC 700 Product Certification Program (PCP).
• NFRC 705 Component Modeling Approach (CMA), Product Certification Program
(CMA-PCP).
Through the Certification Program and the most recent versions of its companion
programs as amended, updated, or interpreted from time to time:
• The laboratory accreditation program (Accreditation Program), as set forth in the
NFRC 701 Laboratory Accreditation Program (LAP).
• The IA licensing program (IA Program), as set forth in NFRC 702 Certification
Agency Program (CAP).
• The CMA Approved Calculation Entity (ACE) licensing program (ACE Program), as
set forth in the NFRC 708 Calculation Entity Approval Program (CEAP).

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© 2013, 2023. National Fenestration Rating Council Incorporated (NFRC). All rights reserved.
 NFRC intends to ensure the integrity and uniformity of NFRC ratings, certification, and
labeling by ensuring that responsible parties, testing and simulation laboratories, and IAs
adhere to strict NFRC requirements.
In order to participate in the Certification Program, a Manufacturer/Responsible Party
shall rate a product whose energy and energy-related performance characteristics are to
be certified in accordance with mandatory NFRC rating procedures. At present, a
Manufacturer/Responsible Party may elect to rate products for U-factor, SHGC, VT, AL,
Condensation Resistance, or any other procedure adopted by NFRC, and to include
those ratings on the NFRC temporary label affixed to its products, or on the NFRC Label
Certificate. U-factor, SHGC and VT, AL, and Condensation Resistance rating reports
shall be obtained from a laboratory that has been accredited by NFRC in accordance
with the requirements of the NFRC 701.
The rating shall then be reviewed by an IA which has been licensed by NFRC in
accordance with the requirements of the NFRC 702. NFRC-licensed IAs also review
label format and content, conduct in-plant inspections for quality assurance in
accordance with the requirements of the NFRC 702, and issue a product Certification
Authorization Report (CAR), or approve for issuance an NFRC Label Certificate for site-
built or CMA products and attachment products. The IA is also responsible for the
investigation of potential violations (prohibited activities) as set forth in the NFRC 707
Compliance and Monitoring Program (CAMP).
Ratings for products that are labeled with the NFRC Temporary and Permanent Label, or
products that are listed on an NFRC Label Certificate in accordance with NFRC
requirements, are considered to be NFRC-certified. NFRC maintains a Certified Products
Directory (CPD), listing product lines and individual products selected by the
manufacturer/responsible party for which certification authorization has been granted.
NFRC manages the Rating System and regulates the Product Certification Program
(PCP), Laboratory Accreditation Program (LAP) and Certification Agency Program (CAP)
in accordance with the NFRC 700 (PCP), the NFRC 701 (LAP), the NFRC 702 (CAP),
the NFRC 705 (CMA-PCP), and the NFRC 708 (CEAP) procedures, and conducts
compliance activities under all these programs as well as the NFRC 707 (CAMP). NFRC
continues to develop the Rating System and each of the programs.
NFRC owns all rights in and to each of the NFRC 700, NFRC 701, NFRC 702, NFRC
705, NFRC 707, NFRC 708 and each procedure, which is a component of the Rating
System, as well as each of its registration marks, trade names, and other intellectual
property.
The structure of the NFRC program and relationships among participants are shown in
Figure 1, Figure 2, and Figure 3. For additional information on the roles of the IAs and
laboratories and operation of the IA Program and Accreditation Program, see the NFRC
700 (PCP), NFRC 701 (LAP), and NFRC 702 (CAP) respectively.

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© 2013, 2023. National Fenestration Rating Council Incorporated (NFRC). All rights reserved.
 Figure 1

Figure 2

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© 2013, 2023. National Fenestration Rating Council Incorporated (NFRC). All rights reserved.
 Figure 3

Questions on the use of this procedure should be addressed to:

National Fenestration Rating

Council
6305 Ivy Lane, Suite 410
Greenbelt, MD 20770
Voice: (301) 589-1776
Fax: (301) 589-3884
Email: info@nfrc.org
Website: www.nfrc.org

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© 2013, 2023. National Fenestration Rating Council Incorporated (NFRC). All rights reserved.
 DISCLAIMER
NFRC certification is the authorized act of a Manufacturer/Responsible Party in: (a) labeling
a fenestration or related attachment product with an NFRC Permanent Label and NFRC
Temporary Label, or (b) generating a site built or CMA label certificate, either of which
bears one or more energy performance ratings reported by NFRC-accredited simulation
and testing laboratories and authorized for certification by an NFRC-licensed IA. Each of
these participants acts independently to report, authorize certification, and certify the
energy-related ratings of fenestration and related attachment products.
NFRC does not certify a product and certification does not constitute a warranty of NFRC
regarding any characteristic of a fenestration or fenestration-related attachment product.
Certification is not an endorsement of or recommendation for any product or product line or
any attribute of a product or product line. NFRC is not a merchant in the business of selling
fenestration products or fenestration-related products, and therefore cannot warrant
products as to their merchantability or fitness for a particular use.
NFRC THEREFORE DISCLAIMS ANY AND ALL LIABILITY THAT MAY ARISE FROM OR
IN CONNECTION WITH SERVICES PROVIDED BY, DECISIONS MADE BY OR
REPORTS OR CERTIFICATIONS ISSUED OR GRANTED BY ANY NFRC-ACCREDITED
LABORATORY, NFRC-LICENSED IA OR ANY PRODUCT MANUFACTURER/
RESPONSIBLE PARTY; RELIANCE ON ANY NFRC PRODUCT DESCRIPTION,
SPECIFICATION, RATING, TEST OR CERTIFICATION, WHETHER APPEARING IN A
REPORT, A PRODUCT CERTIFICATION AUTHORIZATION OR A PRINTED OR
ELECTRONIC DIRECTORY, OR ON A LABEL, OR ON A LABEL CERTIFICATE; OR THE
SALE OR USE OF ANY NFRC-RATED OR CERTIFIED PRODUCT OR PRODUCT LINE;
INCLUDING BUT NOT LIMITED TO DAMAGES FOR PERSONAL OR OTHER INJURY,
LOST PROFITS, LOST SAVINGS OR OTHER CONSEQUENTIAL OR INCIDENTAL
DAMAGES.
NFRC program participants are required to indemnify NFRC from and against such liability.

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© 2013, 2023. National Fenestration Rating Council Incorporated (NFRC). All rights reserved.
 This standard is maintained by the Continuous Maintenance Process.
Approval of ANSI / NFRC 100 as an American National Standard is
maintained using the continuous maintenance process. Comments or
proposals for revisions on any part of this standard may be submitted to the
National Fenestration Rating Council at any time. Written comments or
proposals must be in writing and be submitted to the NFRC Accredited
Standards Developer at standards@nfrc.org.
Any written comments or proposals submitted to NFRC as provided above
shall be submitted by NFRC to its consensus body for consideration within a
reasonable timeframe not to exceed one year. The submitter will be notified
by NFRC of the expected time frame for consideration of the proposal or
comments. NFRC shall apply for reaffirmation of this standard regardless of
any comment or proposals every three years.

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© 2013, 2023. National Fenestration Rating Council Incorporated (NFRC). All rights reserved.
 Table of Contents
Foreword ................................................................................................................... i
Disclaimer ................................................................................................................. v
Table of Contents................................................................................................... vii
1. Purpose .......................................................................................................... 1
2. Scope ............................................................................................................. 1
2.1 PRODUCTS AND EFFECTS COVERED ......................................................... 1
2.2 PRODUCTS AND EFFECTS NOT COVERED ................................................. 2
3. Definitions...................................................................................................... 2
4. General ......................................................................................................... 19
4.1 COMPLIANCE ........................................................................................ 19
4.1.1 Product Line Simulation and Testing ....................................... 19
4.1.2 Testing Alternative ................................................................... 20
4.1.3 Custom Product Rating ............................................................ 21
4.1.4 Dynamic Glazing Product Rating ............................................. 21
Table 4-1 Standardized Slat Stacked Height ...................................... 22
4.2 PRODUCT LINES AND INDIVIDUAL PRODUCTS ........................................... 22
4.2.1 Product Lines ........................................................................... 22
4.2.2 Individual Products .................................................................. 25
4.2.3 Validation Test Matrix .............................................................. 26
4.2.3.1 Same Product Type .................................................. 26
4.2.3.2 Multi-Purpose Products ............................................. 27
4.2.4 Grouping of Products ............................................................... 28
4.2.4.1 Center-of-Glazing Grouping ...................................... 28
4.2.4.2 Shading Systems between Glazing Layers Grouping 30
4.2.4.3 Frame/Sash Grouping ............................................... 30
4.2.4.4 Spacer Grouping ....................................................... 31
4.2.4.5 Sightline Grouping .................................................... 31
4.2.5 General Simulation Rules ........................................................ 32
4.2.6 General Testing Rules ............................................................. 33

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 4.2.7 General Rating Rules .............................................................. 33
4.2.8 Additions to the Product Line ................................................... 34
4.3 STANDARD CONDITIONS ........................................................................ 34
4.3.1 Simulation ................................................................................ 34
NFRC Simulation Conditions: ............................................................. 36
Table 4-2 – Boundary Conditions ....................................................... 37
4.3.2 Testing ..................................................................................... 37
4.3.2.1 Total Fenestration Product Test Procedure .............. 37
4.3.2.2 Center-of-Glazing Component Test Procedure ......... 38
4.3.2.3 Component Substitution ............................................ 38
4.4 MODEL SIZES AND CONFIGURATIONS ..................................................... 39
Table 4-3 – Product Types and Model Sizes ...................................... 39
4.5 SIMULATION PROCEDURES .................................................................... 40
4.5.1 Total Fenestration Product U-factors for Model Sizes ............. 40
4.5.2 Total Fenestration Product....................................................... 40
4.5.3 Component .............................................................................. 41
4.5.3.1 Approved Center-of-Glazing Simulation Programs ... 41
4.5.3.2 Approved 2-D Heat Transfer Simulation Programs ... 41
4.6 TEST PROCEDURES .............................................................................. 41
4.6.1 Total Fenestration Product....................................................... 42
4.6.2 Component .............................................................................. 42
4.6.2.1 Glazing Component Test Procedure ......................... 42
4.6.3 Calculation Procedure ............................................................. 43
4.6.4 Reporting of Ratings ................................................................ 44
4.7 VALIDATION .......................................................................................... 44
4.7.1 Equivalence ............................................................................. 44
Table 4-4 -- Equivalence .................................................................... 44
4.8 FIGURES .............................................................................................. 45
Figure 4-1 – Fenestration Product Schematic – Vertical Elevation ..... 45
Figure 4-2 – Fenestration Product Schematic – Vertical Section ....... 46
Figure 4-3 – Divider Height and Divider Width ................................... 47
Figure 4-4 – Sightline Examples ......................................................... 48
5. Variations from the General Requirements .............................................. 49
5.1 WINDOWS AND SLIDING GLASS DOORS .................................................. 49
5.1.1 Scope ...................................................................................... 49
5.1.2 Variations from Standard Product Lines .................................. 49
5.1.3 Variations from Standard Individual Products .......................... 49
5.1.4 Variations from Standard Simulation and Test Conditions ....... 49
5.1.5 Calculation of Total Product Rating ......................................... 49
5.1.6 Figures ..................................................................................... 50
5.2 SIDE-HINGED EXTERIOR DOORS AND SIDELITES...................................... 50
5.2.1 Scope ...................................................................................... 50
5.2.1.1 Simplified Door Rating (SDR) Method ...................... 50
5.2.1.2 Detailed Door Rating (DDR) Method ......................... 51
5.2.2 Variations from Standard Product Lines .................................. 51

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 5.2.3 Variations from Standard Individual Products .......................... 52
5.2.4 Variations from Standard Simulation and Test Conditions ....... 53
5.2.5 Calculation of Total Product Rating ......................................... 55
5.2.5.1 Simplified Door Rating (SDR) Method ...................... 55
5.2.5.2 Modeling using the Detailed Door Rating (DDR)
Method .......................................................................... 57
5.2.6 Baseline Product...................................................................... 58
Table 5-1 – Glazing and Divider Patterns for Doors ........................... 59
5.2.7 Figures ..................................................................................... 60
Figure 5-1a – Exterior Steel/Composite Door System – Vertical
Elevation in Steel Frame .......................................................... 60
Figure 5-1b – Exterior Steel/Composite Door System – Vertical
Elevation in Wood Frame ........................................................ 61
Figure 5-2 – Exterior Wood Door System – Vertical Elevation ........... 62
Figure 5-3 – Typical 6-Panel Layout ................................................... 63
Figure 5-4 – Common Pressed-Steel Frame – Single Unit Type
Pressed-Steel Frame ............................................................... 64
Figure 5-5 – Frame Cross Section...................................................... 65
Pressed Steel Frame Specification..................................................... 65
Figure 5-6 – Wood Default ................................................................. 66
Figure 5-7 – Default Wood Door Head Jamb and Side Jamb ............. 66
Figure 5-8a – Default Thermally Broken Aluminum Door Sill ............. 67
Figure 5-8b – Default Non-Thermal Door Sill ..................................... 68
Figure 5-9 – Default Door Lite Frame ................................................. 68
Figure 5-10 – SDR Configurations of Single Door or Sidelights ......... 69
Figure 5-11 – Commercial Door Example in a Glazed Wall System .. 70
Figure 5-12 – Door Inside Glazed Wall System .................................. 71
Figure 5-13 – Door Inside Glazed Wall System .................................. 72
5.3 SKYLIGHTS ........................................................................................... 73
5.3.1 Scope ...................................................................................... 73
5.3.2 Variations from Standard Product Lines .................................. 73
5.3.3 Variations from Standard Individual Products .......................... 73
5.3.4 Variations from Standard Simulation and Test Conditions ....... 73
5.3.4.1 Curb .......................................................................... 74
5.3.5 Calculation of Total Product Rating ......................................... 74
5.3.6 Figures ..................................................................................... 74
5.4 TUBULAR DAYLIGHTING DEVICES (TDD) ................................................. 74
5.4.1 Scope ...................................................................................... 74
5.4.2 Variations from Standard Product Lines .................................. 74
5.4.3 Variations from Standard Individual Products .......................... 74
5.4.4 Variations from Standard Simulation and Test Conditions ....... 74

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 5.4.4.1Orientation ................................................................ 74
5.4.4.1.1 Insulation at Ceiling Configuration .............. 74
5.4.4.1.2 Insulation at Roof Configuration ................. 75
5.4.4.2 Sizes ......................................................................... 75
5.4.4.3 Tubular Daylighting Device Area ............................... 75
5.4.4.4 Standard Testing Conditions ..................................... 75
5.4.4.4.1 Insulation at Ceiling Configuration .............. 75
5.4.4.4.2 Insulation at Roof Configuration ................. 76
5.4.4.5 Calculation of Total Product Rating ........................... 76
5.4.5 Figures ..................................................................................... 76
Figure 5-14a – Tubular Daylighting Device Product Schematic –
Vertical Elevation ..................................................................... 76
Figure 5-14b – Hybrid Tubular Daylighting Device Product Schematic –
Vertical Elevation ..................................................................... 77
5.5 VEHICULAR ACCESS (GARAGE) DOORS .................................................. 77
5.5.1 Scope ...................................................................................... 77
5.5.2 Variations from Standard Product Lines .................................. 77
5.5.3 Variations from Standard Individual Products .......................... 78
5.5.4 Variations from Standard Simulation and Test Conditions ....... 78
5.5.5 Total Product Rating ................................................................ 78
5.5.6 Figures ..................................................................................... 80
Figure 5-15 – Garage Door U-factor Area Weighting, Sectional ......... 81
Figure 5-16 – Garage Door U-factor Area Weighting, Front Elevation
View 82
Figure 5-17 – Garage Door Front Elevation View and Perimeter Details
83
5.6 NON-RESIDENTIAL PRODUCTS ............................................................... 84
5.6.1 Scope ...................................................................................... 84
5.6.1.1 Products and Systems Covered................................ 84
5.6.2 Variations from Standard Product Lines .................................. 84
5.6.3 Variations from Standard Individual Products .......................... 84
5.6.4 Variations from Standard Simulation and Test Conditions ....... 85
5.6.4.1 Rating Configuration for Glazed Wall and Sloped
Glazing Systems ........................................................... 85
5.6.4.2 Unspecified Product Sample Validation Criteria ........ 85
5.6.4.3 Determining the Thermal Transmittance for
Solarium/Sunroom Systems.......................................... 86
5.6.5 Calculation of Total Product Rating ......................................... 87
5.6.6 Figures ..................................................................................... 87
5.7 DYNAMIC ATTACHMENT FOR SWINGING DOOR PRODUCTS (DASD) .......... 87
5.7.1 Scope ...................................................................................... 87
5.7.2 Methodology ............................................................................ 87
5.7.3 Approved Computational Program ........................................... 88
Table 5-2 – Reference Swinging Doors .............................................. 88
5.7.4 Figures ..................................................................................... 88
Figure 5-18 – Reference Swinging Door Details ................................ 89

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 Figure 5-19 – Reference Swinging Door Details ................................ 90
5.8 ROLLING DOORS ................................................................................... 91
5.8.1 Scope ...................................................................................... 91
5.8.2 Variations from Standard Product Lines .................................. 91
5.8.3 Variations from Standard Individual Products .......................... 91
5.8.4 Variations from Standard Simulation and Test Conditions ....... 91
5.8.5 Total Product Rating ................................................................ 92
5.8.6 Figures ..................................................................................... 94
Figure 5-20 – Rolling Door U-factor Area Weighting - Sectional View 94
Figure 5-21 – Rolling Door U-factor Area Weighting – Front Elevation
View 94
Figure 5-22 – Rolling Door Front Elevation View and Perimeter Details
95
5.9 COMPONENT MODELING APPROACH (CMA) FOR NON-RESIDENTIAL
PRODUCTS ........................................................................................... 96
5.9.1 Scope ...................................................................................... 96
5.9.2 Products and Systems Covered .............................................. 96
5.9.3 Standard Simulation and Testing ............................................. 96
5.9.3.1 Simulation ................................................................. 96
5.9.3.1.1 Definition of the Low and High (L/H) Options
................................................................... 96
5.9.3.1.2 Reporting Simulation Results ..................... 98
5.9.3.1.3 Total Product U-factor Calculation.............. 98
5.9.3.2 Testing ...................................................................... 99
5.9.4 Validation Testing .................................................................... 99
5.9.5 Simplifications ........................................................................ 100
5.9.5.1 Simplifications to Spacer Components ................... 100
Table 5-4 – Generic Sealant and Desiccant Material Values ........... 101
5.9.5.2 Simplifications to Frame Component ...................... 102
Table 5-5 – Frame Group Leader for all Metallic, Aluminum, Thermally-
Improved Aluminum, and Thermally-Broken Aluminum Frames
104
Table 5-6 – Frame Group Leader for Vinyl, Fiberglass, and Composite
Frames .................................................................................. 104
Table 5-7 – Frame Group Leader for Wood Frames (either with or
without Cladding) ................................................................... 105
5.9.5.3 Modification of Approved Framing Components and
Addition of New Framing Components........................ 105
5.9.6 Total Product Rating .............................................................. 105

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 5.9.6.1 Reporting of Ratings ............................................... 105
5.9.6.2 Determining Thermal Transmittance (U-factor) for
Sloped Glazing Systems ............................................. 106
5.9.6.3 Complex Product Rating ......................................... 106
5.9.6.3.1 Spandrel Panel System ............................ 106
5.9.6.3.2 Combination Products .............................. 106
5.9.6.3.3 Composite Products ................................. 107
5.10 APPLIED FILMS ................................................................................... 107
5.10.1 Scope .................................................................................... 107
5.10.2 Variations from Standard Product Lines ................................ 107
5.10.3 Variations from Standard Individual Products ........................ 107
5.10.4 Variations from Standard Simulation and Test Conditions ..... 107
5.10.4.1 Approved Center-of-Glazing Computational Program
107
5.10.5 Calculation of Total Product Rating ....................................... 108
5.10.5.1 Reference Fenestration Products ........................... 108
Figure 5-23 – Residential Fixed Window Reference Product ........... 109
Figure 5-24 – Non-Residential Window-Wall Reference Product ..... 110
5.10.5.2 Total Fenestration Product U-factor ........................ 112
Table 5-8 – Center-of-Glazing Values Uc ......................................... 112
5.10.6 Testing ................................................................................... 113
5.10.6.1 Center-of-Glazing Component Test Procedure ....... 113
5.10.6.2 Total Fenestration Product Test Procedure ............ 113
5.11 TRENDLINE APPROACH ........................................................................ 114
5.11.1 Scope .................................................................................... 114
5.11.2 Products and Systems Covered ............................................ 114
5.11.3 Variations from Standard Product Lines ................................ 114
5.11.4 Variations from Standard Simulation and Test Conditions ..... 114
5.11.4.1 Trendlines ............................................................... 114
5.11.4.1.1 Categorizing Product Options for a Trendline
................................................................. 115
5.11.4.1.2 Establishing Trendline Endpoints ............. 115
5.11.4.1.3 Development of a Trendline ..................... 116
5.11.5 Total Fenestration Product U-factor Rating............................ 117
5.11.6 Validation ............................................................................... 117
5.11.7 Adding Individual Product Options to Existing Trendlines ...... 117
6. References ................................................................................................. 118
Appendix A (Non-Mandatory Information) ......................................................... 120
A.1 DETERMINATION OF PROJECT-SPECIFIC U-FACTORS ............................. 120
A.2 DETERMINATION OF U-FACTORS AT NON-STANDARD SIZES .................... 120
Table A-1 – Example U-factor Size Matrix........................................ 121
Example Only – Widths, Heights, and U-factors ............................... 121
A.3 DETERMINATION OF SKYLIGHT U-FACTORS AT NON-STANDARD SLOPES . 122
Table A-2: Convective Surface Heat Transfer Coefficients, hc, in for

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 Skylights at Different Incidence Angles (W/m2∙ºK) ................. 122
Table A-3: Convective Surface Heat Transfer Coefficients, hc, in for
Skylights at Different Incidence Angles (Btu/hr2∙ft2∙ºF)........... 123
Table A-4: Skylight U-factors Slope Table (Example Only) .............. 123
A.4 DETERMINATION OF U-FACTORS FOR DYNAMIC GLAZING PRODUCTS AT
ADDITIONAL SLAT ANGLES .................................................................... 124

Index .................................................................................................................... 125

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1. PURPOSE
To specify a method of determining fenestration product U-factor (thermal
transmittance).

2. SCOPE

2.1 Products and Effects Covered

The following products and effects are within the scope of ANSI/NFRC 100
and shall be permitted to be rated in accordance with this procedure.
A. Products of all types as defined in Table 4-3;
B. Products of all frame materials, including (but not limited to)
aluminum, steel, thermally broken aluminum, wood, vinyl, reinforced
vinyl, fiberglass, and plastic, used singularly or in combination, or
products utilizing foam as a core material;
C. Products of all glazing materials, tints, and types, including (but not
limited to) clear glass, tinted glass, laminated glass (diffuse or
specular), stained glass, fritted glazing, etched glazing, sandblasted
glazing, glass block, silicone coated glazing, thin plastic films
(internally suspended, internally applied, or externally applied, diffuse
or specular), rigid plastics (diffuse or specular), and translucent
fiberglass with or without any solar control, low-E, or any other
partially transparent coating, and products with manufactured
decorative opaque insulated glazing panels, designed for
interchangeability with other glazing options;
D. Products with any or no gap width between glazing layers;
E. Products with any spacer or spacer system between glazings,
including (but not limited to) metallic, non-metallic, or composite
spacers;
F. Products utilizing any and all glazing dividers, including (but not
limited to) interior, exterior or between glazing grilles, muntin bars,
true divided lites, or simulated divided lites;
G. Products with any gas-fill between glazing layers, including (but not
limited to) air, argon, krypton, or mixes of these gases;
H. Products utilizing shading systems, diffusing systems, or dynamic
glazing that are an integral part of the product as shipped from the
manufacturer;

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 I. Vacuum insulating glass (VIG); and
J. Dynamic Attachment for Swinging Doors.

2.2 Products and Effects Not Covered

The following products and effects are beyond the scope of ANSI/NFRC
100 and shall not be rated in accordance with this procedure.
A. Fenestration products with shading and/or diffusing systems other
than those listed in Section 2.1;
B. Thermal performance changes of a fenestration product over the
course of time, i.e., long-term energy performance;
C. Issues related to water tightness, structural capacity, and air leakage;
D. Pet doors; and
E. Permanently attached louvers.

3. DEFINITIONS

Air Leakage, AL:

The volume of air flowing per unit time per unit area through a fenestration system due
to air pressure or temperature difference between the outdoor and indoor environment.

Architectural Skylight Systems:

A multiple-lite glazed system used as a roofing element, with glazing at a slope greater
than 30º from the vertical plane, excluding unit skylights and roof windows. This category
encompasses all types of skylights including but not limited to: Single Pitch Skylight,
Single Pitch Skylight with Vertical Ends, Double Pitch Ridge Skylight, Double Pitch
Ridge Skylight with Vertical Ends, Double Pitch Ridge Skylight with Hipped Ends,
Pyramid Skylight, Polygonal Skylight, Continuous Vaulted Skylight and Continuous
Vaulted Skylight with Vertical End Walls. These products shall be rated as sloped
glazing products.

Areas:
Center of glazing Area (Ac):
All glazing areas except those within 63.5 mm (2.5 in) of any part of a primary sash,
and/or frame, and/or divider; or any part of a primary door, and/or frame, and/or
divider. See Figures 4-1, 4-2, 5-11, 5-12, 5-13, 5-14, 5-15, 5-19, and 5-20.

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 Divider Area (Ad):
The projected area in the plane(s) parallel to the fenestration product’s glazing of all
interior or exterior applied non-removable dividers, true dividers, and simulated
dividers or between glazing dividers. See Figures 4-1 and 4-2.

Door Core Area (Adc):

The projected area of the door less the frame, edge-of-frame, lite glazing frame,
edge-of-glazing, center-of-glazing, edge-of-divider, divider, edge-of-panel and panel
areas. See Figures 4-3, 5-1, 5-2, 5-11, 5-12, 5-13, 5-16, 5-17, and 5-18.

Edge-of-divider Area (Ade):

All glazed vision areas within 63.5 mm (2.5 in) of any part of a divider area. The
edge-of-divider area shall exclude any edge-of-glazing area. See Figures 4-1 and 4-
2.

Edge-of-glazing Area (Aeg):

All glazed vision areas within 63.5 mm (2.5 in) of any part of the frame and sash or of
the door lite frame sight line, excluding any divider or edge of divider. See Figures 4-
1, 4-2, 5-11, 5-12.

Edge-of-panel Area (Aep):

The projected area extending from the point 25 mm (1 in) of uniform thickness on the
panel, to the point which includes 25 mm (1 in) of door core material from the
interface of any decorative bead or from the interface of the panel cutout and the
door core. See Figures 4-3, 5-1, 5-2, 5-11, 5-12.

End Stile Area (Aes):

The projected area of the end stile in the plane(s) parallel to the garage door surface.
See Figures 5-11, 5-12, 5-17.

Frame Area (Af):

The projected area of frame and sash in the plane(s) parallel to the glazing surface,
except for doors, which shall include the projected areas of the door jambs, header,
threshold, door bottom sweep and the peripheral structural elements of the door slab,
in a plane parallel to the door core surface. See Figures 4-1, 4-2, 5-1, 5-2, 5-11, 5-
16, 5-17, 5-19, and 5-20.

Exterior Door System Area:

The total door system that includes all frame, lite frame, divider, edge-of-divider,
edge-of-glazing, center-of-glazing, door core, edge-of-panel, and panel areas; the
door, slab, or slab door together with the surrounding frame, weatherstrip, sill, and
sweep.

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 Lite Frame Area (Alf):
Specific to doors, the projected area extending from the sight line of the lite frame
into the surrounding homogeneous door core surface for a distance of 25 mm (1 in)
beyond the outer edge of the lite frame and parallel to the door core surface. See
Figures 5-11 and 5-12.

Panel Area (Ap):

The projected area of all decorative panels of uniform thickness and extending from
a point 25 mm (1 in) of uniform thickness, in a plane parallel to the door core surface.
See Figures 4-1, 4-2, 5-1, 5-2, 5-11, and 5-12.

Projected Fenestration Product Area (Apf):

The area of the rough opening in the wall or roof, for the fenestration product, less
installation clearance.

Note: Where a fenestration product has glazed surfaces facing in only one direction
(typical products), the sum of the edge-of-divider area, the edge-of-glazing area, the
divider area, the center-of-glazing area, and the frame area will equal the total
projected fenestration product area (Apf). Where a fenestration product has glazed
surfaces in more than one direction (e.g., greenhouse/garden, bay/bow windows) the
sum of the areas will exceed the projected fenestration product area.

Total Fenestration Product Area (A):

The area of the total fenestration product that includes all frame, divider, edge-of-
glazing, edge-of-divider, and center-of-glazing areas.

Awning Window:
A window with one (or more) sash that rotates about its top hinge and projects outward.

Base Profile:
Primary structural member of a fenestration product line which forms the basis for
comparison, such as groupings.

Baseline Product:
Within a product line, the individual product selected for validation testing. To verify door
glazing and lite frame simulations, the baseline product for door, sidelite, and garage
(vehicular access) door product lines which include glazed options, shall include glazing.

Basement Window:
A window usually with one sash that projects inward and is intended to be used at or
below grade; rated as the appropriate product type.

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 Bay Window:
A combination assembly which is composed of two or more individual windows joined
side by side and which projects away from the wall on which it is installed. Center
windows, if used, are parallel to the wall on which the bay is installed. The two side
windows are angled with respect to the center window(s). Common angles are 30º and
45º, although other angles are sometimes employed. Individual windows are rated as
the appropriate product type.

Bead:
(1) A strip used around the periphery of the glazing to secure it in a frame or sash (also
referred to as a “stop”); (2) S strip of sealant, such as caulking or glazing compound.

Blackbody:
A perfect emitter and absorber of thermal radiation. A blackbody emits radiant energy at
each wavelength at the maximum rate possible as a consequence of its temperature
and absorbs all incident radiant flux.

Bow Window:
A rounded bay window that projects from a wall in the shape of an arc. Individual
windows rated as the appropriate product type.

Breather/Capillary Tube:
A tube providing an intentional breach of the IG seals to allow for pressure equalization.

Caming:
Material that divides and holds pieces of glazing together to form a single decorative
glazing panel.

Casement Window:
A window containing one (or more) sash, hinged to open from the side, that project
outward or inward from the plane of the window in a vertical plane. A conventional
casement window has a sash that projects outward.

Certification:
The affixing by a licensed Responsible Party of an NFRC label on a fenestration
product, or on a box/packaging containing an attachment product, or the distribution of
an NFRC Label Certificate for which Certification Authorization has been granted.

Certified Simulator:
Any individual that has attended at least one NFRC-sanctioned Simulation Training
Workshop, completed and satisfactorily passed all necessary examinations, participated

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 in NFRC simulation round robins, and is approved by NFRC to use at least one NFRC-
approved simulation software tool.

Cladding:
An applied rigid or semi-rigid roll-formed or extruded covering that is placed over or is
attached to and follows the contour of the interior or exterior framing member for the
primary purpose of protection from environmental elements and/or aesthetics. Cladding
adds no structural integrity to the framing member.

Combination Assembly:
An assembly formed by a combination of two or more separate fenestration.

Composite Assembly (Unit):

A window, door, or skylight unit consisting of two or more sash, leaves, lites, or sliding
door panels within a single frame utilizing an integral mullion. (Not to be confused with
products made from composite materials.)

Computer Simulation:
The process by which a product is analyzed for energy performance characteristics
utilizing NFRC-approved computer software and manufacturer supplied product
specifications and drawings, in accordance with the requirements of the NFRC Rating
System.

Convective Film Coefficient (h):

The time rate of convection heat transfer from a unit area of a surface to its
surroundings, induced by a unit temperature difference between the surface and the
environment.

Curtain Wall:
A non-load-bearing exterior wall, comprised of multiple fenestration elements, with
vertical framing members which are designed to run past the face of the floor slabs,
which is secured to and supported by the structural members of the building.

Daylight Opening Size:

The glazing infill dimension measured from the glazing sightline, also known as the
vision area.

Decorative Panel/Panel Insert:

A decorative raised molding that is inserted into a cut-out in an insulated door slab.
Decorative panels are typically molded from a composite material. The gap between the
two halves of the panel may be filled with an insulating material.

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 Detailed Door Rating (DDR) Method:
A modeling procedure that combines opaque Door or Sidelite slab simulations with
various glass simulations projected into the opaque unit(s) to determine a total product
U-factor.

Diffuse (adj.):
Referring to radiometric quantities, indicates that flux propagates in many directions, as
opposed to a direct beam, which refers to quasi-collimated flux from the sun, whose
angular diameter is approximately 0.5O. When referring to reflectance, it is the
directional hemispherical reflectance less the specular reflectance. Diffuse has been
used in the past to refer to hemispherical collection (including the specular component).
This use is deprecated in favor of the more precise term hemispherical.

Diffuser:
A translucent glazing layer or fenestration product accessory designed to transmit direct-
beam radiation diffusely, i.e. many directions.

Divider:
Any vertical or horizontal bar used to separate glazing into multiple lites or placed in the
gap between sheets of glazing. Dividers may be external or internal, may be removable
or non-removable, and may be real (true) or simulated. Dividers may also be called
grids, grilles, or muntins.

Doorglass Assembly Area (DGAA):

Sum of the Lite-Frame-Area (Alf), Edge-of-Glazing Area (Aeg), Center-of-Glazing Area
(Ac), Edge-of-Divider-Area (Aed), Divider Area (Ad)

Slab:
For an operable door or sidelite system, the swinging portion of the system, whose
primary function is to allow human egress/ingress or ventilation. A slab may also be
included as part of a non-operable door or sidelite system. Sometimes referred to as a
leaf in the industry.

Composite (material) Slab:

A door manufactured from skins molded from plastics, fiberglass compounds,
compressed composites, or other non-metallic materials. The door slab may or may
not incorporate a structural perimeter constructed from materials, including (but not
limited to) wood, wood products, composites, or other reinforcing materials. The core
of the door slab may be filled with materials including, but not limited to insulating
polyurethanes, styrenes, or honeycombs.

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 Steel Door:
A door manufactured from steel skins, which may be coated with paint, plastic, wood
veneers, or other finishes. The door leaf may or may not incorporate a structural
perimeter, including (but not limited to) materials of wood, wood products,
composites, or other reinforcing materials. The core of the door leaf may be hollow or
filled with material, including (but not limited to) insulating polyurethanes, styrenes, or
honeycombs.

Wood Slab:
A door manufactured from solid wood, wood veneers, wood laminates, or a
combination thereof. Such doors are generally assembled from stiles, rails, and
raised panels, but may also be wood flush doors of solid or hollow core construction.

Aluminum Slab:
A door manufactured from aluminum extrusions for the vertical stiles and horizontal
rails with glazed panel area. Aluminum doors may also be flush doors manufactured
with aluminum skins (exterior and interior sides) applied over the aluminum stiles and
rails with an insulating core.

Door Panel:
The portion of a sliding glass door or exterior bi-fold door that is installed in a frame and
includes the glazing, stiles, and rails. A panel may be operable or non-operable.

Dual Action Window:

A window that operates into two different ways. Typically, the window consists of a sash
that tilts from the top and swings inward from the side.

Dynamic Attachment:
Any Fenestration Attachment that incorporates Dynamic Glazing.

Dynamic Glazing Product:

Any Fenestration Product that incorporates Dynamic Glazing.

Embossed/Raised Panel:
Decorative areas on a door slab. On a steel door these may be pressed into the steel
skin or achieved by the application of plastics or other trim materials. On composite
(material) doors these are usually molded into the door skin or may be achieved by the
use of surface applied trim. Wood doors usually incorporate thinner wood sections
assembled into the stiles and rails. [Note: See Figure 5-3 for typical 6-panel layout.]

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 Emissivity (ε):
The relative ability of a surface to reflect or emit heat by radiation. Emissivity ranges
from 0.00 to 1.00 (Blackbody emissivity is 1.0).

Energy Panel:
A glazed Fenestration Attachment designed to be mounted to the interior or exterior of a
primary fenestration product such that a gap is created between the glazing systems of
the attachment and the primary fenestration product. This includes, but it not limited to,
storm windows, storm doors, and storm panels. Also see “Fenestration Attachment.”

Exterior Bi-Fold Doors (aka Folding Walls, Bi-Fold Glass Wall System):
A door with two or more panels, typically fully-glazed, where each panel folds on top of
the adjacent panel to open. These are classified as Side-Hinged Exterior Door and shall
be rated and tested as either single or double door products.

Film:
Fenestration attachment products that consist of a flexible adhesive-backed polymer film
which may be applied to the interior or exterior surface of an existing glazing system.
See Fenestration Attachment.

Finish:
The final treatment or coating of a surface.

Fixed Window:
A window designed to be non-operable.

Frame:
The enclosing structure of a window, door, or skylight which fits into the wall or roof
opening and receives either, glazing, sash, or vents.

Fully CLOSED Position:

The orientation or condition of a Dynamic Glazing Product with a shading system, or a
shade/blind fenestration attachment product, that allows the minimum Visible
Transmittance (VT) within the design limitations of the product.

Fully OFF Position:

The orientation or condition of a Dynamic Glazing Product, such as chromogenic
glazing, where the glazing is de-energized, de-activated, or otherwise “OFF.”

Fully ON Position:
The orientation or condition of a Dynamic Glazing Product, such as chromogenic
glazing, where the glazing is energized, activated, or otherwise “ON.”

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 Fully OPEN Position:
The orientation or condition of a Dynamic Glazing Product with a shading system, or a
shade/blind fenestration attachment product, that allows the maximum Visible
Transmittance (VT) within the design limitations of the product.

Gap Width:
The distance between two adjacent glazing surfaces.

Gas-fill:
The process of adding a gas between glazing panes. Term typically used to indicate
gases other than air, such as argon and krypton.

Glass:
An inorganic, amorphous substance, usually transparent, composed of silica (sand),
soda (sodium carbonate), and lime (calcium carbonate) with small quantities of other
materials.

Glazed Wall:
A collective term used to describe any system which meets the definition of curtain wall
or window wall.

Glazing System/Glazing In-fill:

A generic term used to describe an in-fill material, such as glass, plastic, or other
transparent or translucent material, or assembly of glazing material, spacer, and
desiccant, used to enclose openings in a building created by a specific framing system.

Glazing System:
The assembly of the glazing, spacer, and desiccant combined to be placed in the
opening in a window, skylight, door, or sidelite.

Greenhouse/Garden Window:
A window unit that consists of a three-dimensional, five-sided structure generally
protruding from the wall in which it is installed. Operable sash may or may not be
included.

Grid(s):
See “Divider.”

Group Leader:
The single option defined as representing all other options in that group for purposes of
grouping.

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 Grouping:
The process of reducing the number of individual options by selecting the worst
performing option as representative.

Horizontal Sliding Window:

A window that contains one or more operable sash(es) that slide horizontally within a
common frame. Operable sash (X) and a non-operable sash/lite (O) comprising a unit is
termed a single slider (XO or OX). When two operable sashes are separated by a non-
operable sash/lite, the unit is termed a picture slide (XOX) or end vent. When an
operable sash separates two non-operable sash/lites, the unit is termed a center slide
(OXO). When two bi-parting sashes are located at the center of the unit with the non-
operable sash/lites at each end, the unit is termed a bi-part center slide (OXXO). When
adjacent sashes bypass one another, the unit is termed a double slide (XX or XXO) or a
double slide and vent (XXX).

Hybrid Tubular Daylighting Device (HTDD):

The HTDD category has been retired and all products have been placed in the TDD
category.

Individual Product:
Any one specific fenestration product within a product line, specific to weather seals,
glazing method, hardware, operable/non-operable configurations, ventilators, weep
systems, and sills.

Inset Mount:
An installation type where a skylight is mounted directly into the roof deck (as opposed
to a curb mount.)

Insulating Glass Unit (IGU), Sealed Insulating Glass Unit:

A preassembled unit comprising lites of glass, which are sealed at the edges and
separated by dehydrated space(s). The unit is normally used for windows, window walls,
picture windows, sliding doors, patio doors, or other types of fenestration.

Label:
Permanent and/or temporary marker or device applied to a fenestration product, listing
rating information and indicating compliance with certification requirements.

Label Certificate:
A document used in lieu of an NFRC Temporary Label specific to certain products that
have received certification authorization (see NFRC 705).

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 Lite:
Another term for glazing used in a fenestration product. Frequently spelled “lite” in
industry literature to avoid confusion with “light,” as in “visible light.”

Low-E Coating:
Microscopically thin metal, metal oxide, or multilayer coating deposited on a glazing
surface to reduce its thermal infrared emittance.

Model Size:
The size listed in Table 4-3 that is used to rate a fenestration product.

Mullion:
A structural member connecting two or more products. Mullions may be of the following
types:

Combination Mullion:
A member formed by joining two or more individual fenestration products together
with or without an additional reinforcing member (mullion stiffener).

Integral Mullion:
A member bound at both ends by crossing frame members.

Mullion Stiffener:
An additional reinforcing member used in a reinforcing mullion. Mullion stiffeners may
be designed to carry the total load or may share the load with the adjacent framing
members.

Reinforcing Mullion:
A member with an added continuous mullion stiffener joining two or more individual
fenestration products along the sides of the mullion stiffener.

Nail Flange, Nailing Fin:

An extension of a fenestration product frame that generally laps over the conventional
stud construction and through which fasteners are used to secure the frame in place.

Obscure Glazing:
Glazing layer that fully or partially obscures or distorts the image through the layer.
Including but not limited to acid-etched, imaged, fritted, silicone coated, embossed,
patterned, textured, wired, and stained glass. Also included are products with privacy
applied films and light-scattering interlayers.

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 Opaque In-fill Systems:
Fenestration systems that include opaque elements. See “Spandrel.”

Outdoor Air Ventilator Assembly (OAVA):

A device, other than a sash unit, for the purpose of controlling the passage of air though
a fenestration product. An OAVA shall not allow outside air access to cavities within the
cross-sectional boundaries of the sash, frame, or glazing.

Product Line:
A series of individual fenestration products of the same operator type manufactured from
the same profiles. Individual variations such as glazing, spacer, or small variations in
frame profiles are considered individual products within product lines.

Product Type:
A designation used to distinguish between fenestration products based on non-operable
and operable sash and frame members. [Note: Referred to as operator type in previous
versions.]

Radiation:
The transfer of heat in the form of electromagnetic waves or photons from one body to
another.

Rating:
Performance values obtained using NFRC-approved procedures used for comparative
purposes only (i.e., U-factor, SHGC, VT, etc.).

Rating System:
A system that consists of NFRC simulation and test procedures for determining
comparative fenestration product energy performance characteristics, as supported by
the Certification Program.

Reference Fenestration Product:

The fenestration product that an attachment is combined with for the purposes of rating.
A reference fenestration product comprises a reference glazing system and a reference
frame with a specified construction.

Reference Frame:
The frame of the reference fenestration product. This may or may not correspond to an
actual frame type available commercially.

Reference Glazing System:

The glazing system in the reference fenestration product.

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 Representative Size:
The actual size of a specimen used for validation testing.

Roof Window:
See "Unit Skylight/Roof Window."

Rough Opening:
The framed opening in a wall or roof where a fenestration product is to be installed.

Sash:
The portion of a fenestration assembly that is installed in a frame and includes the
glazing, stiles, and rails. A sash may be operable or non-operable.

Sealant:
A flexible material placed between two or more parts of a structure, with adhesion to the
joining surfaces, to prevent the passage of certain elements such as air, moisture, water,
dust, and other matter.

Side-Hinged Exterior Door: A non-operable and/or operable exterior door system. An

operable door system shall have at a minimum, a slab and a frame, and hinge attachment of any
type between a slab and jamb, mullion, or edge of another slab (e.g. bi-fold doors) or shall have
a single, fixed vertical axis (swinging/pivoted) about which the slab rotates between open and
closed positions. A non-operable door system shall have at a minimum a slab and a frame.

Shading System:
A device that is integral to a fenestration system or integral to a glazing system which
has the fully reversible ability to affect the Solar Heat Gain Coefficient (SHGC) or the
Visible Transmittance (VT) of the fenestration system or glazing system.

Sidelite
A fenestration product that is used as a companion product installed on one or both
sides of a door system. Sidelites may consist of a glazed frame, sash or slab within a
frame.

Sightline:
The line formed by the highest opaque member (frame, sash, spacer, divider, or shading
system) that is interior, exterior, or within the glazing system cavity of the fenestration
cross-section and the glazing in a plane perpendicular to the surface. A change in
sightline will result in a change in the projected frame dimension (PFD) between frame
cross-sectional profiles of individual products within a product line (see Figure 4-4).

Simplified Door Rating (SDR) Method:

A modeling procedure allowing component simulations to be conducted by separate
entities and re-assembled by an authorized end-user to calculate a total U-factor.

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 Component U-factor and corresponding areas are determined for up to four size
configurations of doorglass assemblies and up to five panel/door core/frame-sill
configurations for each glass option.

Simulation Software:
Any computer software used for Computer Simulation.

Site-Built Products:
Fenestration products that are designed to be field glazed or field assembled and are
comprised of specified framing and glazing components.

Skylight:
See “Unit Skylight/Roof Window”

Sliding Glass Door:

Sliding glass doors contain one or more operable panels that slide horizontally within a
common frame. Operable panel (X) and a non-operable lite/panel (O) comprising a unit
is termed a single slider (XO or OX). When two operable panels are separated by a non-
operable lite/panel, the unit is termed a picture slide (XOX) or end vent. When an
operable panel separates two non-operable lites/panels, the unit is termed a center slide
(OXO). When two bi-parting panels are located at the center of the unit with the non-
operable lites/panels at each end, the unit is termed a bi-part center slide (OXXO).
When adjacent panels by-pass one another, the unit is termed a double slide (XX or
XXO) or a double slide and end vent (XXX).

Sloped Glazing:
A multiple-lite glazed system (similar to a curtain wall) that is mounted at a slope greater
than 30º from the vertical plane, excluding unit skylights and roof windows.

Spandrel Panel System:

A non-vision application of a fenestration product; typically used to hide or obscure
features of the building structure or used for visual effect. A spandrel panel system
consists of an exterior exposed glazing layer with an interior insulated opaque panel.

Spectral (adj):
Indicating that the property or quantity was evaluated at a specific wavelength (), within
a small wavelength interval ( about ). Usually indicated by placing the wavelength
symbol , as a subscript following the symbol for the quantity, as with E , thereby
indicating that the flux-related quantity is a concentration of flux at the indicated
wavelength, or it may be placed inside parentheses following the symbol for the material
property, as with  (λ). It is permissible to indicate the wavelength dependence of a flux
quantity as follows: E ().

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 Structurally Glazed Framing:
A method of glazing where framing members are generally not exposed to the exterior
(i.e., two-sided or four-sided structural glazed).

Sunroom/Solarium:
A glazed envelope system that has one wall (or a portion thereof) that opens to a
primary structure and remaining walls which may include a number of fenestration
systems, such as windows, doors, skylights, kneewalls, etc., in varying percentages per
the design of the system.

Surface Heat Transfer Coefficient, Surface Conductance, Film Coefficient (h):

The time rate of heat flow between a surface and its surroundings per unit area and per
unit temperature difference.

Thermal Break:
A material of low thermal conductivity that is inserted between members of high
conductivity in order to reduce the heat transfer. Thermal barrier material conductivity
shall not be more than 0.52 W/mK (3.60 Btu·in/h·ft2·ºF).

Thermal Bridge:

A path of high thermal conductance from the exterior to interior surfaces of a system that
has lower thermal conductance in all other areas. An example would be a metal
fastener penetrating an insulating wall or thermally broken frame.
Thermal Opening Area:
The area of the TDD/HTDD product at the interior-most plane of the building’s thermal
envelope.

Thermally Broken Members (TB):

System members with a minimum of 5.30 mm (0.210 in) separation provided by a low
conductance material (where thermal conductivity ≤ 0.5 W/mK, (≤ 3.6 Btu·in/h·ft2·ºF) or
open-air space between the interior and exterior surfaces. Examples of such systems
include (but are not limited to) pour and debridged urethane systems, crimped-in-place
plastic isolator systems, and pressure glazed systems with intermittent fasteners.

Note: Intermittent fasteners shall be manufacturer’s standard. Nominal spacing of

fasteners shall be 150 mm (6 in) apart or greater.

Thermally Improved Members (TI):

System members with a separation ≥ 1.60 mm (0.062 in) separation provided by a
material [where thermal conductivity ≤ 0.5 W/mK, (≤ 3.6 Btu·in/h·ft2·ºF)] or open-air

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 space between the interior and exterior surfaces. Such systems include members with
exposed interior or exterior trim attached with clips and all skip/debridged systems.

Transom:
A non-operable fenestration product that is used as a companion product installed
above another fenestration product. Transoms may consist of a glazed frame or a non-
operable sash within a frame. A transom may be rated as either a fixed window or a
transom at the discretion of the manufacturer. An operable transom product shall be
rated as the appropriate operator type.

Tubular Daylighting Device (TDD):

A non-operable device primarily designed to transmit daylight from a roof surface to an
interior ceiling surface via a tubular conduit. The device consists of an exterior glazed
weathering surface, a light transmitting tube with a reflective inside surface and an
interior sealing device, such as a translucent ceiling panel. See also “Hybrid Tubular
Daylighting Device.”

U-factor, Thermal Transmittance (U):

The heat transfer per time per area and per degree of temperature difference. The U-
factor multiplied by the interior-exterior temperature difference and by the projected
fenestration product area yields the total heat transfer through the fenestration product
due to conduction, convection, and long-wave infra-red radiation.

Center-of-glazing U-factor (Uc):

The U-factor representative of the center-of-glazing area.

Divider U-factor (Ud):

The U-factor representative of the divider area.

Door Core U-factor (Udc):

The U-factor representative of the door core area.

Edge-of-divider U-factor (Ude):

The U-factor representative of the edge-of-divider area.

Edge-of-glazing U-factor (Ue):

The U-factor representative of the edge-of-glazing area.

Edge-of-panel U-factor (Uep):

The U-factor representative of the edge-of-panel area.

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 End Stile U-factor (Ues):
The U-factor representative of the garage door end stile area.

Frame U-factor (Uf):

The U-factor representative of the frame and sash area.

Lite Frame U-factor (Ulf):

The U-factor representative of the lite frame area.

Panel U-factor (Up):

The U-factor representative of the panel area.

Total Fenestration Product U-factor (Ut):

The U-factor representative of the total system.

Unit Skylight/Roof Window:

A window designed for sloped or horizontal application, the primary purpose of which is
to provide daylighting and/or ventilation. Typically, the term “roof window” is not used for
horizontal applications.

Vacuum Insulating Glass (VIG): an assembly with an evacuated gap between glass
lites which are sealed at the edges and separated by a pillar array or other system
designed to maintain spacing between glass lites.

Validation Matrix:
Two or more product lines whose U-factor can be validated by a single test.

Vehicular Access (Garage Door):

A door that is used for vehicular traffic at entrances of buildings (such as garages,
loading docks, parking lots, factories, and industrial plants) that is not generally used for
pedestrian traffic. The garage door includes vertical jamb tracks, all divider, edge-of-
divider, edge-of-glazing, center-of-glazing, door panel core, edge-of-panel, and stile (end
cap) areas.

Vertical Sliding Window:

A window that contains at least one operable sash that slides vertically within a common
frame. Operable sash (X) and a non-operable sash/lite (O) comprising a unit are called
single hung windows and units with two operable sash (X/X) are called double hung
windows.

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 Weatherstrip:
A flexible component used to reduce air leakage, water penetration, or both between the
sash or panels and/or sash or panels and frame.

Window Wall:
A non-load-bearing fenestration system, comprised of multiple fenestration elements,
with vertical framing members which are designed to span from the top of a floor slab to
the underside of the next higher floor slab or roof. Also referred to as a "storefront",
“strip window” or “horizontal ribbon window system.”

4. GENERAL

4.1 Compliance
Fenestration product ratings shall be determined following the procedures
outlined in Section 4.1.1, in accordance with the criteria specified in
Sections 4.2 through 4.8, as modified by applicable portions of Section 5.

4.1.1 Product Line Simulation and Testing

A. Determine the representative size matrix of U-factors. List all
individual products and associated representative sizes (see
Section 4.4) within a product line. The representative size
matrix or list of U-factors for a product line is given as follows:
Representative Size Matrix of U-factors
Product ID List U-factor for Model Size
Individual Product #1
Individual Product #2
Individual Product #XX
Individual Product #Last

B. Compute the total fenestration product U-factor for the

baseline product in the representative size matrix of U-factors.
Using the approved total fenestration product U-factor
calculation procedure (see Section 4.3.1), compute the U-
factor for the baseline product (see Section 4.2.6).
Note: Compute as many U-factors in this representative size
matrix as is necessary to definitely determine the baseline
product.

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 C. Test the baseline fenestration product using the approved total
fenestration product U-factor test procedure in Section 4.3.2.1.
D. Validation of the simulation procedure: if the simulated and
tested U-factors for the baseline product are equivalent (as
defined in Section 4.7.1), then the computational procedure
presented in Section 4.3.1 shall be considered validated for all
the products in the product line. The approved total
fenestration product U-factor calculation procedure presented
in Section 4.3.1 shall then be used to determine U-factors for
the model size matrix of U-factors of Section 4.5.1. These are
the values that shall be reported. If the simulated and tested
U-factors for the baseline product are not equivalent (as
defined in Section 4.7.1), then the alternative test procedure
presented in Section 4.1.2 may be used for all products within
the product line—with written permission from NFRC.

4.1.2 Testing Alternative

If an individual product listed in Section 2.1 cannot be simulated in
accordance with Section 4.3.1, the test procedure found in Section
4.3.2.1 shall be used to determine the U-factors of the individual
fenestration product(s) for the size defined in Table 4-3.
Currently the following products cannot be simulated:
A. Non-planar products including but not limited to:
i. Greenhouse/garden windows
ii. Tubular daylighting devices
iii. Domed skylights without frames or flashing
B. Complex glazed products other than the following:
i. Vertical products with between-glass venetian blinds
ii. Products with outdoor woven shades
iii. Products with fritted glazing
The test specimen size shall be the size with the lowest deviation
determined from Equation 4-2. If the test specimen cannot be
fabricated at the Table 4-3 size, the tested U-factor shall be adjusted
to the model size using the following, unless other provisions for
specific products have been made in ANSI/NFRC 100:

(𝑈𝑟𝑒𝑝 𝐴𝑟𝑒𝑝 )
𝑈𝑚𝑜𝑑 =
𝐴𝑚𝑜𝑑
Equation 4-1

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 Where:

Umod = U-factor at model size

Urep = U-factor at representative size (test size)
Arep = Area at representative size
Amod = Area of model size

4.1.3 Custom Product Rating

A custom product is an NFRC individual product which meets all of
the following criteria:
A. A custom product shall be composed of unique frame/sash
components not covered within an existing standard product
line's U-factor matrix;
B. The specific configuration of a custom product shall not be
offered publicly in a manufacturer's catalog or similar
literature; and
C. Fewer than 500 units shall be produced annually or shall be
produced as part of one purchase order.
U-factors for custom products (which meet the criteria above) may be
represented by U-factor ratings generated for a similar stock
individual product made of the same product type and materials. A
simulation analysis from an NFRC-certified simulator employed by an
NFRC-accredited simulation laboratory, confirming that the custom
product's
U-factor is equal to or lower than the stock product, shall be provided
to the NFRC or NFRC’s designated representative.

4.1.4 Dynamic Glazing Product Rating

Products meeting the definition of a Dynamic Glazing Product shall
be rated at their Fully ON/CLOSED and Fully OFF/OPEN Positions.
The manufacturer shall specify the appropriate procedure to achieve
the stated positions. Rating procedures for these positions shall be
the same as for non-Dynamic Glazing Products, as outlined in
Section 4.1.1 or Section 4.1.2 as appropriate.
When rating Dynamic Glazing Products with slatted blinds between
glass in the Fully OFF/OPEN position, the standardized slat stack
heights of Table 4.2 shall be used.

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 Table 4-1 Standardized Slat Stacked Height
Product Overall
Blind Stack Height (Dim A)
Product Types Covered Height
mm mm in
Windows
Awning, Door Transom 600 20 0.8
Vertical Slider 1500 27 1.1
Horizontal Slider 1200 45 1.8
Fixed, Casement, Dual Action 1500 57 2.2
Sliding Glass Doors
Sliding Glass Doors 2000 77 3.0
Swinging Door and Door Sidelites
Typical overall height of door is 2090mm
Swinging Doors and Door Typical Door
Blind Stack Height (Dim A)
Sidelites Lite IG Height
mm (in) mm in
¼ Lite (Doors Only) 457 (18) 19 0.7
½ Lite 889 (35) 36 1.4
¾ Lite 1194 (47) 48 1.9
Full Lite 1600 (63) 65 2.6

4.2 Product Lines and Individual Products

U-factors shall be determined for all individual products within a product line,
except as allowed in Section 4.2.4. All product lines shall be simulated
separately.

4.2.1 Product Lines

A product line is a series of fenestration products of the same product
type (as listed in Table 4-3) manufactured from the same profiles and
components. The following changes are the only allowable
exceptions within a product line:
A. Overall fenestration product size;
B. Center-of-glazing and edge-of-glazing characteristics such as
glazing types and thicknesses, glazing coatings, tints and
obscurity, gas-fills, gap widths, shading systems between
glazing layers, dividers, and spacers;

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 C. Operable/non-operable configurations, as defined in Table 4-
3;
i. Product types defined as operable that have a non-
operable version (Casement-Single, Dual-Action,
Pivoted (Horizontal Axis), Pivoted (Vertical Axis) and
Projecting/Awning-Single) may be included in the same
product line, at the manufacturer’s discretion, as long
as the changes to render the product non-operable
comply with Section 4.2. If there is no operable version
of the product, it shall be classified as a Fixed Window.
ii. Product types defined as either operable or non-
operable (Greenhouse/Garden, Skylight/Roof Window)
may be included in the same product line, at the
manufacturer’s discretion, as long as the changes to
render the product non-operable comply with Section
4.2. If the changes do not comply with Section 4.2, the
product shall be treated as two separate product lines.
D. Changes to accommodate glazing unit variations, limited to
changes of geometry, number, or material type to stops,
beads, adhesives, or gaskets designed to retain the glazing.
Changes to frame and sash profiles are allowed to
accommodate glazing unit variations. This provision does not
allow for interior and exterior glazed products to be in the
same product line;
E. Frame/sash modifications made to accommodate operating
hardware and reinforcement for the purpose of addressing
higher/lower loads and stresses: limited to changes that do not
change the exterior perimeter shape of the assembled cross
section;
NOTE: "Exterior perimeter" is defined as the perimeter of the
entire assembled cross-section (Interior, Adiabatic, and
Exterior boundaries of the frame and sash).
F. Frame or sash changes where one component is replaced by
another component of the same physical shape with a thermal
conductivity that does not differ by more than 10 times the
thermal conductivity of the original material;
G. Products with and without cladding can be incorporated into
one product line, provided that the only changes made to the
unclad product are notches or grooves to accommodate the
cladding, or removal of the frame/sash material up to the
depth of the cladding;

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 H. Changes to the frame/sash profiles to allow for different
installations, limited to the following:
i. Any changes to interior/exterior appendages added to
the main web of the frame that are removable or not
exposed after product installation, i.e., nailing fins,
ii. Changes in the width (dimension perpendicular to the
plane of the glazing) of the main frame or main frame
components to allow for installation in different wall
thicknesses, i.e., lengthening, shortening, and the
addition of extruded or pultruded walls within a hollow
cavity (web walls),
iii. Door products manufactured in both in-swing and out-
swing options when only the frame is modified,
iv. Any changes to the exterior beyond the plane of the
nailing fin, J-channel, the exterior plane of the wall, or
interior most point of exterior accessory groove, i.e.
screen tracks, varying shapes of brickmold, J-channels,
or stucco bars formed in (integral) or applied to the
frame and that do not change the sightline,
v. Any changes or additions to accessory grooves or
decorative flanges, i.e., lengthening, shortening, and
the addition of reinforcing web wall(s);
vi. Any changes to trim/stops due to an application of a
screen system that cover or hold the screen. The
product offered without a screen system shall be used
to represent this product and minor frame changes to
accommodate the screen system are permitted.
I. Any sightline changes due to:
i. Lengthening or shortening of existing walls,
ii. Components added or replaced for equal and unequal
lite configuration options,
iii. For the installation of an outside air ventilator assembly
(OAVA), or
iv. Changes to the frame profiles to allow for different
installations including pocket or sloped-sill configuration
options and sill height modifications;
v. Sightline changes that occur due to any situation in
4.2.1 shall also be allowed. For example, the sightline
change due to a change in the glazing bead shall be
allowed per Section 4.2.1 (D).

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 NOTE: A change in sightline will result in a change in
the projected frame dimension (PFD) between frame
profiles of individual products within a product line.
J. Changes to the following are deemed minor revisions made to
the profiles:
i. Limited to changes in the size and shape of snap
beads, stops, jamb extensions, dividers (including
simulated and true divider lites), weather strip sockets
and kerfs, exterior trim caps on curtain walls, window
walls, and sloped glazing,
NOTE: The term “stop” above refers to any stop and
not just glazing stops.
ii. Decorative elements such as grooves, beads, or
brickmolds or exterior trim components and/or casings
formed in or applied to the frame or sash are also
allowed,
iii. Addition, removal, or modification of pull/lift handles
utilized on the interior side of the product, whether it is
an integral extrusion of the sash/glazing bead or
mechanically fastened, or
iv. Addition, removal, or replacement of a snap-in
extrusion (in which the thermal conductivity does not
differ by more than 10 times of the original material) for
sealing and /or interlocking purposes;
K. Addition, deletion, or changes in hardware and reinforcement
(may include reinforcing web walls);
L. Changes to interior or exterior finishes or coatings;
M. Sealing characteristic variables and elements: limited to
changes in gaskets, sealants, adhesives, weather strips, or
the addition/removal of drip-caps, in the same profile (profile
changes to accommodate seal changes shall be allowed); and
N. Vinyl caps attached to the interior.

4.2.2 Individual Products

An individual product is any one specific combination of the product
line variables (singularly or in combination) allowed in Section 4.2.1.
All individual products shall be simulated except as allowed in
Section 4.2.1.
The following changes are the only allowable exceptions to an
individual product:

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 A. Variations in frame or sash interior/exterior finish, paint,
varnish, or stain shall not constitute different individual
products provided that each of these variations does not
change the surface emittance by more than 0.1 or overall
thickness by more than 0.400 mm (0.016 in);
B. Products with different variations in glazing divider patterns do
not need to be treated as different individual products:
i. The manufacturer shall be permitted to define a
standard glazing divider pattern (which shall be a
standard product offering) which uses glazing dividers
305 mm (12 in) on-center or less,
ii. A glazing divider pattern with an on-center spacing
closest to but not greater than 305 mm (12 in) shall be
designated as the glazing divider pattern, or
iii. The overall window dimension shall be used to
determine the number of dividers;
C. Fenestration products that include an outdoor air ventilator
assembly (OAVA) shall be considered the same individual
product if the OAVA projected dimension (including any
components to facilitate installation of the OAVA) is less than
or equal to 45 mm (1.75 in). If this dimension exceeds 45 mm
(1.75 in) it shall be simulated as an individual product; and
D. Dynamic glazing products shipped with integral or attached
shading systems shall be considered individual products within
the product line.

4.2.3 Validation Test Matrix

A validation test matrix of multiple product lines of the same product
type or multi-purpose products of different product types shall be
permitted to be created.

4.2.3.1 Same Product Type

When the changes listed below are made, two or more
product lines of the same product type (as listed in Table 4-
3) shall be permitted to be included within the same
validation test matrix if the overall U-factor difference
between the product lines is ± 0.06 W/m2K (0.01
Btu/h·ft2·ºF) or less when simulated with the lowest center-
of-glazing option.
A. Changes to shift the location of the glazing relative
to the sash or frame – exterior to interior;

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 B. Changes (to sash profiles only) to accommodate
interior and exterior glazed products;
C. Product lines fabricated with both pocket and sloped
sill options;
D. Changes to installation orientation of a product
where the product has been designed to function
when installed facing into or out of the room; or
E. Changes to accommodate in-swing and out-swing
product lines with nearly identical frame/sash base
profiles. Minor changes to profiles to accommodate
the in-swing and out-swing operation change are
allowed, but are limited to: (a) movement, addition,
or deletion of specific elements (i.e. walls &
cavities), (b) weather-stripping and associated
sealing characteristics, and (c) any component
changes that occur as a direct result of any
hardware changes.

4.2.3.2 Multi-Purpose Products

Multi-purpose products incorporating nearly identical
frame/sash base profiles shall be permitted to be within
one validation matrix provided that the differences between
the base profiles are limited to minor changes to
accommodate different product types. The minor changes
allowed are:
A. The movement or addition of specific elements (i.e.
walls and cavities) to accommodate the differing
operating hardware;
B. Adding or deleting components to adapt a
channeled frame to use a tilt sash;
C. The use of the hung window sash stiles as the
bottom rail;
D. Deleting of the roller track of the horizontal slider;
E. The addition of sash balance covers; or
F. Any other component changes that occur as a direct
result of the hardware changes.
Any elements added to the profile to accommodate
operating hardware shall be of the same material types
used in the original profile.

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 4.2.4 Grouping of Products
This section presents rules that shall be permitted to reduce the
number of simulations for individual products that represent a product
line. If this approach is used, the total fenestration product U-factor
for the group leader shall be used to represent the total fenestration
product U-factors for all individual products within that group. These
grouping rules shall not be used to group individual products from
different product lines into one product line.
To ensure consistent ratings, groupings shall be done in the following
order:
Center-of-glazing (includes dividers) Section 4.2.4.1
Shading systems between glazing layers Section 4.2.4.2
Frame/Sash Section 4.2.4.3
Spacer Section 4.2.4.4
Sightline Grouping Section 4.2.4.5
Any combination of groupings shall be done in the order established
above. All grouping comparisons shall be based on three significant
digits.

4.2.4.1 Center-of-Glazing Grouping

For the purpose of determining U-factors, center-of-glazing
groups shall consist only of variations in glazing thickness,
gap width, gas fill, low-E coatings, and the presence or
absence of internal grids. Once all center-of-glazing
options have been identified within a product line, the
center-of-glazing U-factor shall be simulated for each
option. Then these products shall be permitted to be
grouped, with each group represented by the center-of-
glazing group leader (which shall be the center-of-glazing
option with the highest center-of-glazing U-factor):
A. Glazing options with different numbers of glazing
layers shall not be grouped together;
B. Glazing options with clear glazing in all layers shall
not be grouped with glazing options with one or
more low-E layers (E is less than or equal to 0.50);
and
C. Only individual products that contain the same
mixture of gases shall be permitted to be grouped.
Variable concentrations of the same mixture of
gases shall be permitted to be grouped as a center-
of-glazing grouping as long as the total gas

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 concentration, other than air, is more than 60% and
does not vary by more than ± 10% from the group
leader.
D. For the purpose of determining U-factors, divider
groups shall consist only of variations in divider
materials and shapes. After all divider options have
been identified within a product line the divider heat
loss shall be simulated for each divider option using
the glazing option with the lowest center-of-glazing
U-factor in the product line. These products shall be
permitted to be grouped with each group
represented by the divider group leader, which shall
be the divider option with the highest divider frame
heat loss. If this approach is used, the total
fenestration product U-factor for the divider group
leader shall be used to represent the total
fenestration product U-factors for all individual
products within that divider group.
i. For glazing matrix consisting of both double
pane and triple pane glazing configurations,
dividers can be grouped by simulating each
divider option in the appropriate glazing
category (double pane or triple pane) with the
lowest center-of-glazing U-factor in the
glazing category. Divider group leaders for
double pane and triple pane configurations
shall represent the double pane group and
triple pane group, respectively.
ii. Products with glazing dividers, or decorative
tape-applied caming bars between layers of
an insulated glass (IG) unit shall be permitted
to be assumed to have the same U-factors as
identical products without such dividers,
providing the following:
(a) For dividers, there is at least 3.00 mm
(0.118 in.) air/gas space between the
divider and both adjacent glazing
surfaces.
(b) For simulated caming bars applied
with decorative tape, there shall be a
minimum airspace of 9.5mm (0.375
in.) between the caming bar and
adjacent glazing surface.

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 4.2.4.2 Shading Systems between Glazing Layers Grouping
When rating dynamic glazing products with shading
systems between glazing layers, it shall be permitted to
group combinations of shading systems and glazing layers.
For purposes of determining U-factors, the shading system
and glazing layers comprising each group leader shall be
determined as follows:
A. Glazing layers within a group, and the
corresponding glazing layers used in the group
leader, shall be determined in accordance with the
center-of-glazing grouping rules of Section 4.2.4.1.
B. Shading systems within a group may vary by color,
material, finish, rise (i.e., the arc in the case of
venetian blind slats), and thickness of the shading
systems. ; and
i. Grouping by color shall adhere to one of the
two options per ANSI/NFRC 200, Section
4.2.3.C.i; or
ii. Grouping by the default venetian blind slat
material shall use aluminum alloy (k=160
W/mK) as the material and the finish (i.e.,
surface emittance) per ANSI/NFRC 200,
Section 4.2.3.C.ii.
iii. The venetian slat rise of 0mm shall be
permitted to represent all offered rises.

4.2.4.3 Frame/Sash Grouping

A. For the purpose of determining U-factors, frame
groups shall consist only of frame/sash base profile
variations consistent with the definition of a product
line. After all frame options have been identified
within a product line, the frame and edge-of-glazing
heat loss shall be simulated for each option with the
lowest center-of-glazing U-factor in the product line.
The frame group leader shall be identified as the set
of frame options within the highest whole product
heat loss. If this approach is used, the total
fenestration product U-factor for the frame group
leader shall be used to represent the total
fenestration product U-factors for all individual
products within that group.

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 B. To determine the frame group leader the spacer
used in simulation shall be a spacer used by the
manufacturer. If more than one spacer is available,
the spacer used shall be selected from the list below
in the following order:
Group 1 – Spacer containing aluminum
Group 2 – Spacer containing mild steel (i.e.
galvanized steel, tin-plated steel)
Group 3 – Spacer containing stainless steel
Group 4 – Spacer containing all non-metallic
materials

4.2.4.4 Spacer Grouping

For the purpose of determining U-factors, spacer groups
shall consist only of variations in spacer assembly
materials and shapes. After all spacer options have been
identified within a product line, the frame and edge-of-
glazing heat loss shall be simulated for each spacer option
with the lowest center-of-glazing U-factor and the frame
group leader in the product line. These products shall be
permitted to be grouped with each group represented by
the spacer group leader (which shall be the option with the
highest whole product heat loss). If this approach is used,
the total fenestration product U-factor for the spacer group
leader shall be used to represent the total fenestration
product U-factors for all individual products within that
group.
For glazing matrix consisting of both double pane and triple
pane glazing configurations, spacers can be grouped by
simulating each spacer option in the appropriate glazing
category (double pane or triple pane) with the lowest
center-of-glazing U-factor in the glazing category. Spacer
group leaders for double pane and triple pane
configurations shall represent the double pane group and
triple pane group, respectively.

4.2.4.5 Sightline Grouping

Sightline groups shall consist only of individual products
with sightline differences due to frame/sash base profile
variations. These products shall be permitted to be
grouped with each group represented by the sightline
group leader, which shall be the sightline option within the
group with the highest total fenestration product U-factor.

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 Since sightline changes may be in small size increments,
the determination of the highest total fenestration product
U-factor for each sightline group shall be determined for
the frame/sash with the greatest and least daylight opening
areas, using the lowest center-of-glazing U-factor option
and the model size for the product type per Table 4-3.

4.2.5 General Simulation Rules

A. If a nail flange is not removable and is identified as such by
the manufacturer, the product shall be simulated and tested
with the nail flange covered with a nominal 1 in x 4 in fir trim. If
a nail flange is removable, the product shall be simulated and
tested without the nail flange;
B. Products with integral appendages that extend beyond the
rough opening and are not exposed after installation shall be
permitted to be assumed to have the same U-factors as
identical products without such appendages;
C. Products with elements added to the outer surface of the
framing so as to expand the frame in the direction parallel to
the plane of installation and allow for different installations,
shall be permitted to have the same U-factors as identical
products without such added elements:
Examples of such elements include, but are not limited to,
subsills and frame expanders;
D. Nominal glass thickness shall be permitted to be used for
determining U-factor provided the emissivity of the glass is
taken from the approved NFRC Spectral data file and the air
gap dimension is maintained at the dimensions specified by
the manufacturer. The nominal glass thickness to be used
shall be listed in ASTM C 1036 [Reference 6]. If the glass
thickness does not fall within the nominal thickness ranges,
the actual thickness shall be used;
E. An infill system with a “Center-of-Glazing Component Test”
that utilizes an adaptor between the infill and frame which
allows for direct replacement of the standard glazing shall be
considered an individual product in the same product line with
the standard glazing, as long as all components (including the
adaptor) are included in the simulation for the infill glazing
system;
F. Non-rectangular fenestration products shall be rated as
rectangular fenestration products per the standard size in
Table 4-3 (develop a product line with the same frame cross
sections as the non-rectangular fenestration product); and

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 G. IG units manufactured with breather or capillary tubes
designed to remain closed after manufacturing shall be
simulated as having the same gas content; IG units
manufactured with breather tubes intended to be opened at
some point after manufacturing shall be simulated as air-filled
IG units:
H. For the purpose of determining U-factors, only glazing tint
and/or obscurity (including obscure glass) shall be permitted to
be assumed to have the same U-factor as the clear glass and
does not need to be simulated separately unless this change
is associated with a change in coating properties. This option
can be used as an alternative to obtaining product properties
using the measurement procedure defined in NFRC 301 for
diffuse products; and
I. Products with removable or non-removable dividers (e.g. SDL)
or decorative tapes that are applied to glazing to simulate the
appearance of dividers applied to the room side and/or
exterior side glazing surface shall be permitted to be assumed
to have the same U-factors as identical products without such
dividers. However, any component (shadow bar) of an SDL
that is within the cavity of the IGU shall be treated as a normal
internal divider. At the discretion of the manufacturer, a
simulator shall be permitted to model a SDL in accordance
with Section 8.3.2 of the NFRC Simulation Manual.

4.2.6 General Testing Rules

The baseline product shall be the individual product selected for
validation testing (see Section 4.1.1). The individual product selected
as the baseline product shall have a simulated U-factor within 0.60
W/m2K (0.10 Btu/h·ft2·ºF) or 20% of the lowest simulated U-factor,
whichever is greater. Size variations shall be limited to the
representative size as defined in Section 4.6.1 for the product type. If
more than one product type is being validated with a single test, then
the baseline product shall be selected from the product lines in the
validation test matrix.

4.2.7 General Rating Rules

A. Combination products shall not be rated in combination.
B. Sash kits, sliding door panels, and side hinged door slabs
shall be rated using one of two options:
Option1: Simulate and test (if required) in a frame of similar
material and design as the proposed installation.
Manufacturers of sash kits, sliding door panels, and side

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 hinged door slabs shall provide information on the intended
installations for those products. (See Figure 5-6 for an
example of a default double hung frame when a sash kit is
intended to be installed in a wood double hung window.)
Option 2: Sash kits, sliding door panels, and side hinged door
slabs that are identical in material and design as a
manufacturer’s rated product line may use the same ratings.
The manufacturer shall verify the rated frame meets the
requirements of Option 1.

4.2.8 Additions to the Product Line

The product line validated simulation procedure (see Section 4.1.1)
may be used to determine U-factors of additions to a validated
product line if the simulated U-factor for the additional product(s) is
either higher than the previously computed baseline product U-factor,
or not more than 0.60 W/m2K (0.10 Btu/h·ft2·ºF) or 20% (whichever is
greater) lower than a previously simulated baseline product U-factor.
If the simulated U-factor of the addition to the product line is outside
these bounds, a new baseline product shall be established and
validated by testing.
If a manufacturer introduces a new individual product into multiple
product lines (see Section 4.2.6 for an example of glazing or spacer
options) that has simulated U-factor more than 0.60 W/m2K
(0.10 Btu/h·ft2·ºF) or 20% lower than the simulated baseline product
U-factor, only one product line with a new individual product shall be
tested. If the simulation of the new baseline product validates, then
all other product lines using this option shall be validated and those
new individual products shall be permitted to be simulated to obtain
U-factors.

4.3 Standard Conditions

This section presents standard simulations, tests, and calculations for
determining total or component fenestration product U-factors.

4.3.1 Simulation
The requirements of Reference 2 (NFRC Simulation Manual) and of
Section 4.3.2.1 shall be used to determine total fenestration product
U-factors.
Skylights and other sloped glazing products shall be simulated and
rated at a slope of 20o above the horizontal. Until accurate simulation
software is available, tubular daylighting devices (TDDs) shall be
tested and rated with the tube in a vertical orientation (Figures 5-14a

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 and b). All other products shall be simulated and rated in the vertical
position.
Spandrel panel systems shall be simulated with 254mm (10 in.) of
“Edge” assigned to the spandrel panel system instead of the required
63.5mm (2.5 in.) as noted in Section 4.3.1.A below.
All calculations shall be based on computer simulations using the
latest approved software (which shall be in compliance with ISO
15099), with the following exceptions:
A. For calculating the overall U-factor (per ISO 15099), the area-
weighted method as described in Section 4.1.4 of ISO 15099
shall be the only method permitted, with the exception of
opaque spandrel panel systems which shall use 254mm (10
in.) of edge-of-glazing dimension;
B. Thermophysical properties of materials shall be determined in
accordance with NFRC 101;
C. For fenestration products incorporating venetian blinds:
i. Include models for venetian blinds slats (See
References 13 and 14);
ii. Thermal radiation from venetian blinds shall be
calculated using directional diffuse radiation (See
References 13 and 14);
D. Include models for fritted, etched, sand-blasted glazing, and
other light-scattering products that can be measured according
to NFRC 301 (See Reference 14 and 15);
i. Glazing layers that are partially covered with a light-
scattering element shall be simulated using the
properties of the fully covered layer and properties of
the non-scattering layer, and the final result is the area-
weighted mix of the different areas. This could be done
for any number of different areas.
ii. Using data according to NFRC 301 for light-scattering
products is an alternative to using a clear glazing as
approximation as described in 4.2.5 H;
E. Include models for fenestration products incorporating vacuum
insulating glass (VIG) (See Reference 16 and 17)
F. Section 8.2 in ISO 15099 addresses environmental conditions.
The following conditions shall be used for the determination of
U-factor: 0 W/m2 (0 Btu/h·ft2)

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 NFRC Simulation Conditions:
Tin = interior ambient temperature of 21.0º C (69.8º F)
Tout = exterior ambient temperature of -18.0º C (-0.4º F)
V = wind speed of 5.5 m/s (12.3 mph)
Trm,out = Tout
Trm,in = Tin
Is = 0 W/m2 (0 Btu/h·ft2)
G. Section 8.3 in ISO 15099 addresses convective film
coefficients on the interior and exterior of the fenestration
product;
H. The indoor side convective heat transfer coefficient shall be
based on the center of glass temperature and the entire
fenestration product height; this film coefficient shall be used
on all glass and edge of glass indoor surfaces with the
exception of spandrel panel systems. The spandrel panel
shall be assigned a boundary condition as noted in Table 4-2
below.
I. Frame section indoor convective film coefficients shall be
constants, which depend on frame material type; these values
are listed in Table 4-2;
J. The outdoor side convective heat transfer coefficient shall be
calculated based on wind speed (as defined under 4.3.1.E)
and shall be applied to all of outdoor surface, glass and frame.
Standard values for outdoor convective surface heat transfer
coefficients is listed in Table 4-2;
K. On the indoor side of a fenestration product, detailed radiation
model, based on gray body radiation model as described in
Section 8.4.2.1 in ISO 15099, shall be used for all products.
This model applies to both glass and frame surfaces;
L. The use of detailed radiation model on indoor fenestration
surfaces makes the use of “slightly or partially ventilated
cavities” on the indoor frame surfaces redundant (see Section
6.7.1 of ISO 15099). The standard frame convective film
coefficients (hc) shown in Table 4-2 and detailed radiation
model referenced above shall thus be applied to all interior
frame surfaces;
M. On the outdoor side of a fenestration product, black body
radiation model (as defined in ISO 15099) shall be used. This
model applies to both glass and frame surfaces; and

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 N. All cross-sections shall include 150 mm (6 in) of glazing
section from the sightline to the end of the glazing section,
while maintaining a 63.5 mm (2.5 in) edge-of-glazing
dimension. The exception is with spandrel panel systems
which shall be 406mm (16 in.) of spandrel panel section while
maintaining a 254mm (10 in.) edge dimension.

Table 4-2 – Boundary Conditions

Convective Film Coefficient Boundary
Radiation
Boundary Condition Tilt = 90o Tilt = 20o
Model 2 2
W/m K (Btu/h·ft ·ºF) W/m K (Btu/h·ft2·ºF)
2

NFRC 100-2010 Exterior Blackbody 26.00 (4.578) 26.00 (4.578)

Interior Aluminum Frame Automatic 3.29 (0.579) 4.65 (0.819)
(convection only) Enclosure Model
Interior Thermally Broken Automatic 3.00 (0.528) 4.09 (0.720)
Frame (convection only) Enclosure Model
Interior Thermally Automatic 3.12 (0.549) 4.32 (0.761)
Improved Frame Enclosure Model
(convection only)
Interior Wood/Vinyl Automatic 2.44 (0.429) 3.09 (0.544)
Frame (convection only) Enclosure Model
Interior Glazing System Automatic Depends on the WINDOW calculations for the
boundary condition Enclosure Model imported glazing system
Steel Skin Door Slabs Automatic Non-Metal Edge of Door Slab shall use
Enclosure Model “Wood/Vinyl Frame”
Steel or Aluminum Edge of Door Slab shall use
“Thermally-Improved”
Interior Insulated Opaque Automatic Shall use the interior boundary condition from
Spandrel Panel Enclosure Model above that is equivalent to the glazed wall
system’s intermediate frame type

4.3.2 Testing

4.3.2.1 Total Fenestration Product Test Procedure

NFRC 102 [Reference 1], shall be used to determine
tested total fenestration product U-factors. The following
conditions also apply:
C. Test specimen size tested shall be in accordance
with Section 4.6.1;
D. All test specimens shall be tested without screens,
removable grilles and trims, or any other applied
devices;

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 E. All test specimens shall be tested in the vertical
position, except tubular daylighting devices (TDDs).
TDDs shall be tested and rated with the tube in a
vertical orientation (see Figures 5-10a and b). For
determining validation of the baseline product only,
skylights and other sloped glazing products shall be
simulated in a vertical position; and
F. The test specimen shall not be modified by the
testing laboratory, except as allowed in Reference 1
for sealing against air leakage and as required in
this section.

4.3.2.2 Center-of-Glazing Component Test Procedure

If the U-factor for the product cannot be simulated in
accordance with Section 4.3.1, the test methods in ASTM
C1363-97 (or later versions) using NFRC environmental
conditions, shall be used to determine the conductance of
the center-of-glazing. The conductance value shall be used
to determine an effective conductivity at the thickness of
the glazing/frame insert which can be used to build a
glazing layer in WINDOW.
The specimen shall be 1000 mm x 1000 mm (39 in x 39 in)
or closest deviation as determined using Section 4.6. This
size represents all product types in Table 4-3.
For a product that consists of a glazing panel only (without
frame), the tested U-factor per this section, standardized in
accordance with NFRC 102, shall be the U-factor of the
product.
Obscure and tinted versions of a clear glazing tested using
this procedure may be represented by the clear glazing
results as long as the product emissivity does not change.

4.3.2.3 Component Substitution

Component substitutions may be made if using approved
NFRC simulation tools to verify the performance
equivalence to three significant digits. The original certified
U-factors shall be used to represent the new product.
For products certified under the testing alternative method
(Section 4.1.2), component substitution shall apply only if
the simulation laboratory states in the simulation report that
the simulation tools are appropriate for the simulation of
the components being substituted.

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 A. For spacer substitutions, only the spacer shall be
modeled, or
B. For glazing system changes, only the center-of-
glazing shall be modeled.

4.4 Model Sizes and Configurations

For each individual product, total fenestration product U-factors shall be
reported for the specified configuration at the model size as shown in Table
4-3.
For products that, when area-weighted at the standard NFRC size, have
less than 63.5 mm (2.5 in) edge-of-glazing area or edge-of-divider area, the
overall product dimensions shall be increased as needed to restore the
standard 63.5 mm (2.5 in) of edge-of-glazing for each section (including
dividers). The increase in size shall result in zero center-of-glass area.

Table 4-3 – Product Types and Model Sizes

Product Type Model Size Operable (X)
Width x Height, mm (in) Non-operable (O)
Windows
Casement – Single 600 x 1500 (24 x 59) X
Casement – Double 1200 x 1500 (47 x 59) XX, XO
Dual-Action 1200 x 1500 (47 x 59) X
Fixed 1200 x 1500 (47 x 59) O
Greenhouse/Garden 1500 x 1200 (59 x 47) X, O
Horizontal Slider 1500 x 1200 (59 x 47) XX, XO
Pivoted 1200 x 1500 (47 x 59) X
Projecting (Awning – Single) 1500 x 600 (59 x 24) X
Vertical Slider 1200 x 1500 (47 x 59) XX, XO
Doors and Door Related
Side-Hinged Exterior Door 960 x 2090 (38 x 82) X, O
Side-Hinged Exterior Door (Double) 1920 x 2090 (76 x 82) XX, XO
Sliding Glass Door 2000 x 2000 (79 x 79) XX, XO
Sidelite 960 x 2090 (38 x 82) X, O
Transom 2000 x 600 (79 x 24) O
Garage (Vehicular Access)/Rolling Door 2134 x 2134 (84 x 84) X
Skylights
Skylight/Roof Window 1200 x 1200 (47 x 47) X, O
Tubular Daylighting Device 350 (14) Diameter O
Glazed Wall Systems
Curtain Wall 2000 x 2000 (79 x 79) OO
Window Wall 2000 x 2000 (79 x 79) OO
Sloped Glazing 2000 x 2000 (79 x 79) OO
Spandrel Panel System 2000 x 2000 (79 x 79) OO

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 4.5 Simulation Procedures

4.5.1 Total Fenestration Product U-factors for Model Sizes

For a given product line, list all individual products and the associated
model size U-factors (see Section 4.4). The model size matrix of U-
factors for a given product line shall be outlined as shown in Section
4.1.1.A.
This matrix shall include all individual products within a product line
that are available from the manufacturer, including but not limited to
the number of glazing layers, glazing types, glazing coatings, gas
fills, gap widths, spacer types, and use of dividers. See Section 4.2.1
for the definition of a product line and Section 4.2.2 for the definition
of an individual product.
In order to determine total fenestration product U-factors for all of the
entries in this matrix, use the product line validated simulation
procedure, presented in Section 4.1.1. The testing alternative,
presented in Section 4.1.2, may only be used to determine the U-
factor for an individual product(s) within a product line if that
individual product(s) cannot be simulated in accordance with Section
4.3.1.
Thus, the only time a product line may contain tested as well as
simulated total fenestration product U-factors shall be when an
accredited simulation laboratory states in the simulation report that it
cannot simulate an individual product(s) to a reasonable accuracy. In
addition, the written permission of NFRC shall be required.

4.5.2 Total Fenestration Product

The U-factor of a fenestration product may vary by size, depending
upon the component materials and the glazing. To simplify the
system, ratings are based on a specific model size. The U-factor for
the model size in Table 4-3 for all single-lite products shall be
representative of all variations in configuration with one or more lites
(operable/non-operable)for the product type. The U-factor for the
model size in Table 4-3 for all dual-lite products shall be
representative of all variations in configuration with two or more lites
for the product type. Casement and Exterior Door products shall be
rated as dual-lite types only when a single-lite version is not
produced. The U-factor for the model size shall be representative of
all variations in size and factory assembled operable and non-
operable units in a common frame.

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 For gas fills other than air, the gas fill concentration percentages
represent the initial nominal design value. The maximum gas
concentration used in the simulations shall not exceed the following
values:
Evacuated Chamber Filling 97% for any gas type
Two-Probe filling with concentration sensor 95% for Argon
90% for any other
Single-Probe Timed Filling 90% for any gas type
Non-continuous elements including (but not limited to: screws and
bolts in sloped glazing and poured and debridged thermal barriers
that are not fully debridged), shall be simulated as indicated in
Reference 2.
The total fenestration product U-factor calculation procedure can be
found in the applicable fenestration product section, see Sections 5.1
to 5.10.

4.5.3 Component

4.5.3.1 Approved Center-of-Glazing Simulation Programs

Approved center-of-glazing software shall be used. NFRC
approved software is listed in Reference 3.

4.5.3.2 Approved 2-D Heat Transfer Simulation Programs

Approved 2-D heat transfer software shall be used. NFRC
approved software is listed in Reference 3.

4.6 Test Procedures

There are two different test procedures used in ANSI/NFRC 100:
Total Fenestration 4.6.1
Glazing 4.6.2.1
Section 4.3.2.1 defines the total fenestration product test procedure, its
standard conditions and requirements. The total fenestration product test
procedure shall be used to validate the product line simulations (see Section
4.1.1) and shall be used under the testing alternative (see Section 4.1.2),
which shall be used only if the U-factor for the product cannot be simulated
in accordance with Section 4.3.1. Section 4.3.2.2 defines a glazing
component test procedure, which may be used only if the U-factor for the
center-of-glazing cannot be simulated in accordance with Section 4.3.1.
Since the glazing system may include non-homogeneous elements (e.g.
spacers, thermal bridges, etc.), an average conductance shall be assigned
to the whole glazing system. Insertion of such a glazing system in the 2-D

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 heat transfer program shall be done as a continuous slab of material with
the conductivity equal to the average conductivity of the glazing system.

4.6.1 Total Fenestration Product

For the purposes of testing (see Section 4.3.2), production line units
and sizes shall be used. The test specimen size shall be the
production line size with the least deviation (D) from the model size
(see Table 4-3) as defined by Equation 4-2:

𝐷 = √(𝑊𝑝 − 𝑊𝑚 )2 + (𝐻𝑝 − 𝐻𝑚 )2
Equation 4-2

Where

D = Deviation in mm (in)
Wp, Hp = Width, height of production size in mm (in)
Wm, Hm = Width, height of model size in mm (in)
For rectangular fenestration products, the representative sizes
reported by the simulation laboratory shall not vary by more than 13.0
mm (0.5 in) in width or 13.0 mm (0.5 in) in height (25 mm [1 in] for
doors) from the reported sizes of the tested specimens.
For non-rectangular products, the simulated product area shall meet
the following relationship with the tested specimen area:

𝐴𝑡𝑒𝑠𝑡 − 𝐶(𝑊𝑚 + 𝐻𝑚 ) ≤ 𝐴𝑠𝑖𝑚 ≤ 𝐴𝑡𝑒𝑠𝑡 + 𝐶(𝑊𝑚 + 𝐻𝑚 )

Equation 4-3
Where
Asim = Area of product simulated in mm2 (in2)
Atest = Area of specimen tested in mm2 (in2)
C = A constant, 25 mm (1 in)
Wm, Hm = Width, height of model size in mm (in)

4.6.2 Component

4.6.2.1 Glazing Component Test Procedure

The test methods in Reference 6, using NFRC
environmental conditions, shall be used to determine the
average conductivity of the glazing. The test results are
applicable only to the unit tested, with no variations in
shape or material allowed.

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 4.6.3 Calculation Procedure
The total fenestration product U-factor shall be calculated as outlined
below:
A. Determine all of the following, as applicable:
i. Center-of-glazing U-factor per the total product height
procedure (as defined in Reference 2) using an
approved center-of-glazing simulation program or the
approved glazing test procedure given in Section
4.3.2.2,
ii. Edge-of-glazing U-factor, using an approved 2-D heat
transfer simulation program. In the case that center-of-
glass thermal performance is simulated, this center-of-
glass configuration shall be inserted into the frame and
spacer assembly shall be added. In the case that the
glazing component test procedure had to be utilized,
entire glazing system shall be represented as a
homogenous slab of material with conductivity equal to
average conductivity of the measured specimen. For
mullions and meeting rails, two glazing systems shall
be inserted on each end and the reported U-factor shall
be the average of the two edge-of-glass U-factors,
iii. Divider U-factor, using an approved 2-D heat transfer
simulation program. Divider shall be simulated with two
glazing systems pointing in opposite directions,
simulated in a vertical orientation,
iv. Edge-of-divider U-factor, using an approved 2-D heat
transfer simulation program. Edge-of-divider U-factor
shall be the average of the two edge-of-glass section U-
factors,
v. Frame U-factor using an approved 2-D heat transfer
simulation program. Frame U-factor is always
calculated on the exposed indoor side of frame, starting
at the bottom of the frame and ending at the indoor
sight line. For mullion and meeting rail cross-sections,
frame surface is counted from one indoor sight line to
another,
vi. The component areas of:
(a) Center-of-glazing area,
(b) Edge-of-glazing area,
(c) Divider area,
(d) Edge-of-divider,

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 (e) Frame area, and
(f) Projected fenestration product area;
B. Perform the following calculations as explained:
i. Multiply the center-of-glazing, edge-of-glazing, divider,
edge-of-divider, and frame U-factors by their
corresponding areas,
ii. Total these quantities, and
iii. Divide this total by the projected fenestration product
area to produce simulated total fenestration product U-
factors for all the fenestration products in the matrix of
required U-factors.

4.6.4 Reporting of Ratings

The full floating-point accuracy of any software shall be used for all
calculations. The final U-factor shall be reported in IP units
(BTU/hr∙ft2∙ºF) and rounded to two digits following the decimal point
after truncating the full precision result to six decimal places. If the
U-factor is to be reported in SI units as well as IP units, the SI U-
factor shall be converted from the IP U-factor following the procedure
outlined in NFRC 700, Section 6.5.I.iii.

4.7 Validation

4.7.1 Equivalence
Simulated and tested U-factors for a given total fenestration product
shall be considered equivalent if the agreement between the two
numbers is within the ranges in Table 4-4.

Table 4-4 -- Equivalence

Simulated U-factor Accepted Difference Between Tested
and Simulated U-factor
1.7 W/m2K 0.17 W/m2K
(0.3 Btu/h·ft2·ºF) or less (0.03 Btu/h·ft2·ºF) or less
Greater than 1.7 W/m2K 10% of Simulated U-factor
(0.3 Btu/h·ft2·ºF)

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 4.8 Figures
Figure 4-1 – Fenestration Product Schematic – Vertical Elevation

LEGEND
C Center-of-Glazing
E Edge-of-Glazing
F Frame
D Divider
DE Edge-of-Divider

Center-of-glazing, edge-of-glazing, divider, edge-of-divider, and frame areas for a

typical fenestration product. Edge-of-glazing and edge-of-divider are 63.5 mm (2.5
in) wide (with exception of Spandrel Panel Systems which shall be 254mm (10 in)).
The sum of these component areas equals the total projected fenestration product
area.

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 Figure 4-2 – Fenestration Product Schematic – Vertical Section

Installation Clearance

Frame

Edge-of-glazing

Center-of-glazing

Edge-of-divider

Divider
Projected Rough
Edge-of-divider
Area Opening

Center-of-glazing

Edge-of-glazing

Frame

Exterior Interior

Center-of-glazing, edge-of-glazing, divider, edge-of-divider, and frame areas for a

typical fenestration product. Edge-of-glazing and edge-of-divider are 63.5 mm (2.5
in) wide. The projected fenestration product area is the rough opening less
installation clearances.

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 Figure 4-3 – Divider Height and Divider Width

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 Figure 4-4 – Sightline Examples

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5. VARIATIONS FROM THE GENERAL REQUIREMENTS
This section presents and references methods for determining specific product
system heat transfer properties or quantities used in the determination of these
properties. At this time, the scope of these properties is limited to total product
system U-factor.

5.1 Windows and Sliding Glass Doors

5.1.1 Scope
This section presents additional details specific to windows and
sliding glass doors.
This section presents and references methods for determining
windows and sliding glass doors product system heat transfer
properties or quantities used in the determination of these properties.
The scope of these properties is limited to windows and sliding glass
doors total product system U-factor.

5.1.2 Variations from Standard Product Lines

None

5.1.3 Variations from Standard Individual Products

None

5.1.4 Variations from Standard Simulation and Test Conditions

None

5.1.5 Calculation of Total Product Rating

The total fenestration product U-factor shall be calculated as per
Section 4.6.3. Perform the following calculation to determine total
product rating.

[Σ(𝑈𝑓 𝐴𝑓 ) + Σ(𝑈𝑑 𝐴𝑑 ) + Σ(𝑈𝑒 𝐴𝑒 ) + Σ(𝑈𝑑𝑒 𝐴𝑑𝑒 ) + Σ(𝑈𝑐 𝐴𝑐 )]

𝑈𝑡 =
𝐴𝑝𝑓
Equation 5-1
Where:
Ut = Total product U-factor
Apf = Projected fenestration product area
Uf = Frame U-factor
Af = Frame area

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 Ud = Divider U-factor
Ad = Divider area
Ue = Edge-of-glazing U-factor
Ae = Edge-of-glazing area
Ude = Edge-of-divider U-factor
Ade = Edge-of-divider area
Uc = Center-of-glazing U-factor
Ac = Center-of-glazing area

5.1.6 Figures
None

5.2 Side-Hinged Exterior Doors and Sidelites

5.2.1 Scope
This section presents additional details specific to side-hinged
exterior doors, sidelites, and exterior bi-fold doors (a.k.a. folding wall)
to determine a total product U-factor.
This section presents and references methods for determining
specific heat transfer properties and areas used in the determination
of these properties for exterior doors, sidelites, and exterior bi-fold
doors. These values shall be determined using one of three methods
as listed below. Manufacturers may choose to perform their
simulations using any of the techniques applicable to their specific
product.

5.2.1.1 Simplified Door Rating (SDR) Method

The Simplified Door Rating (SDR) method is described in
detail in Section 5.2.5.1 and shown in Figure 5-10.
Products Eligible for the SDR Method:
A. Skinned slabs with a foam, wood, or other core;
B. Wood stile and rail doors;
C. Composite assemblies comprised of a side-hinged
exterior door slab with a sidelite slab within a single
frame (see Composite Assembly definition in
Section 3). If the side-hinged exterior door or
sidelite are not offered as individual products, the
SDR methodology may be used to determine the U-
factor of the side-hinged exterior door slab with a
default or proprietary frame/sill;

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 D. Slab sidelites within a proprietary and/or default
frame/sill.

5.2.1.2 Detailed Door Rating (DDR) Method

The Detailed Door Rating method utilizes basic NFRC
techniques and is described in detail in Section 5.2.5.2.
A side-hinged exterior door system which is configured to
only support a full-lite option, shall be permitted to be
modeled using the standard techniques (as for windows)
described in Section 5.1 or Section 5.11. Product Line
Grouping and simplifications that are allowed in Sections
5.2.2 through 5.2.4 may be applied to these
systems. These systems typically use extruded or
moulded profiles (aluminum, fiberglass, vinyl, wood, etc.)
and can only support the glass size dictated by the profiles.
Adding embossed/raised panels to an existing factory
assembled full-lite product line does not require re-
simulation of the full-lite option; however, the SDR or DDR
method shall be used to simulate and calculate U-factors
for the opaque, 1/4, 1/2, and 3/4 lite options, as applicable
(e.g. manufacturer is adding a 1/2 lite option so they are
only required to simulate the 1/2 lite).

5.2.2 Variations from Standard Product Lines

A given series of side-hinged exterior door or sidelite assemblies is
defined by skin material, core material, and edge-of-door construction
that are allowed to differ by:
A. Size;
B. Embossed/raised panel and cut out configurations;
C. Products with multiple slab thickness;
D. Products with multiple embossed/raised panel thickness (i.e.
different thicknesses of wood panels, or different depth of
embossments);
E. The replacement of core and/or embossed/raised panel area
with glazing system;
F. Center-of-lite characteristics and edge-of-lite characteristics,
such as glazing types, gap widths, glazing lite areas, use of
dividers, use of spacers, glazing coatings, gas fills;
G. Operable/non-operable configurations, e.g. X, O, XX, XO,
OXXO etc.;

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 H. In-swing or out-swing operation;
I. Door slab changes where one component of the same
physical shape with a thermal conductivity that does not differ
by more than a factor of 10;
J. Frame components, e.g. headers, jambs and threshold; and
K. Variations in frame and/or door interior/exterior finish, paint,
varnish, or stain do not constitute different product lines
provided that each of these variations does not change the
surface emittance by more than 0.10.

5.2.3 Variations from Standard Individual Products

A. Products with a pre-installed storm door from the manufacturer
shall be rated with the storm door and associated parts
removed from the assembly, or be rated as Test Only for each
storm door with side-hinged exterior door embossed/raised
panel/glazing configuration;
Exception: full-lite swinging door with a pre-installed full-lite
storm door may be rated using simulation;
B. Doors which are designed to be installed in a variety of glazed
wall systems shall be rated in the glazed wall system framing
in which it is installed.
If the door utilizes an additional frame which is inserted into
the glazing pocket of the glazed wall system (typically termed
an insert frame), the door shall be rated using only the insert
frame and shall not include the primary glazed wall framing in
which the insert frame is installed (See Figures 5-11 through
5-13).
C. A door or sidelite slab without a frame shall be rated using
default frame components. However, products with the same
slab and different proprietary frames shall be treated as
individual products within one product line. All frame options
shall be individually modeled or grouped.
D. Products with multiple sill options, where the sill design
changes to accommodate different installation requirements,
made of the same materials type shall be different individual
products within the same product line.

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 5.2.4 Variations from Standard Simulation and Test Conditions
This section presents rules that may be used to reduce the number of
simulations of individual products necessary to represent a product
line. These rules may be used either with the product line validated
simulation procedure (see Section 4.1.1) or with the testing
alternative (see Section 4.1.2).
A door offered with one or more door slabs shall be rated in the
configuration with the least number of slabs (i.e. single door) of the
same style or model. If a door is not offered in a single or double
unit, a representative double unit shall be rated, incorporating the two
end most slabs and a representative intermediate vertical member,
as determined and reported by the simulator.
For opaque doors with flat, raised, or embossed panels, a 6-panel
layout shall be representative of all panel doors (regardless of the
number of panels). This layout may also be considered
representative of flush doors. See Figure 5-3 for a typical 6-panel
layout. A specific 6-panel layout which is required for the SDR
method and may be used as a default pattern in any other case is
shown in Figure 5-10.
When simulating U-factors where a decorative lite (continuous or
non-continuous) is used, the decorative lite glass shall be assumed
to have the same properties as clear glass of the same glass
thickness and each decorative lite caming pattern shall be
considered to be a different individual option or the optional caming
pattern as shown in the Table 5-1 may be used to represent all
decorative lite caming patterns. The default caming profile may be
used to represent any caming profile.
Default and/or proprietary components may be used at the
manufacturer’s discretion for door slab and/or slab sidelites. These
can be used to represent proprietary frames (with the limitations
noted below). (See Reference 2 for drawings):
A. Default Frame Components (Head and Jambs)
i. Default Wood Frame: (Representative of any wood,
vinyl, or composite material frame) 115 mm (4.56 in)
softwood single rabbeted frame of 8% to 12% moisture
content, with a specific gravity of 0.35 to 0.45, with a
dual durometer plastic compression weatherstrip and
flexible sweep. The default door sill shall be a standard
combination wood/aluminum sill (where the aluminum
does not extend to the interior) that performs as well or
better than the default door sill illustrated in Figure 5-8a;

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 ii. Default Steel Frame: (Representative of any steel
frame, or other metal of equal or lower conductivity) 145
mm (5.75 in) - 16 Ga. pressed painted steel frame with
a minimum 120 mm (4.75 in) throat depth, applied
weather-strip. Frame shall consist of a head jamb,
hinge jamb, lock jamb, and reinforcement for hinges
and locks. See Figure 5-4 and Figure 5-5;
B. Default Sill Components
i. Default Thermally Broken Aluminum Sill
(Representative of any thermally broken aluminum sill
with similar construction or non-metal sill): A standard
combination wood/aluminum sill as illustrated in Figure
5-8a;
ii. Default Non-Thermal Sill (Representative of any non-
thermally broken metal sill): A standard aluminum non-
thermally broken sill with a sill wall thickness of 1.4 mm
to 1.6 mm (0.055 in to 0.065 in) and no substrate as
illustrated in Figure 5-8b;
C. Default Door Lite Frame (Representative of any non-metal
door lite frame). A polypropylene door lite frame as illustrated
in Figure 5-9;
D. Default Caming Profile (See Reference 2).
E. Default SDR foam and wood materials used around the
perimeter shall be as follows:
i. Polyurethane Foam Insulation: 0.024 W/mK (0.166
Btuin/hrft2F);
ii. Expanded Polystyrene: 0.038 W/mK (0.263
Btuin/hrft2F);
iii. Hardwood: 0.160 W/mK (1.109 Btuin/hrft2F)
F. Allowable SDR door slab dimensions:
i. Door slabs thickness shall be 44mm ± 2mm (1.75”
±0.079”)
ii. Steel Skin thickness shall be no greater than 0.6mm
(0.024”)
iii. Fiberglass skin thickness shall be no greater than
1.9mm (0.075”)

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 Add-Ons
If a manufacturer wishes to simulate a door or sidelite slab in multiple
frames, either proprietary or default the manufacturer may either
simulate all individual products in the matrix or develop an add-on for
the additional frames. To develop the frame add-on, all the individual
products in the matrix shall be simulated in the best performing
framing system. The best performing product in the best performing
framing system shall then be simulated in the additional frame
options. The difference between these two U-factors shall be the
frame add-on. The U-factor for the products in the additional frame
shall be the U-factor for that product in the best performing frame
plus the frame add-on.
For manufacturers offering multiple sill options:
A. Sill systems that meet the requirement of a thermally broken
member shall use the product values for the NFRC default sill
system;
B. Sill systems that are metal and do not meet the requirement of
a thermally broken member may be given total product U-
factor of 0.10 W/m2K (0.02 BTU/hrft2F) higher than the same
door system option with the NFRC default sill system.

5.2.5 Calculation of Total Product Rating

Total fenestration product U-factors for model sizes and
configurations shall be calculated in accordance with Section 5.2.5.1
for the Simplified Door Rating (SDR) method and with Section 5.2.5.2
for the Detailed Door Rating (DDR) method.
To reduce the number of individual products necessary to represent
a product line, refer to the guidelines prescribed in Sections 4.2.4,
5.2.2, 5.2.3 and 5.2.4.

5.2.5.1 Simplified Door Rating (SDR) Method

A. Modeling of opaque side-hinged exterior doors or
sidelites is based on using a six-panel or flush
configuration door product area.
i. Modeling of glazed side-hinged exterior doors
will consist of two elements, the door opaque
area (slab, frame, and sill); plus, the Door
Glass Assembly Area (DGAA);
ii. The opaque door area (that is, the area
outside the DGAA, including door frame and
sill) shall be simulated in five configurations,

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 calculated per Equation 5-2, for the opaque,
¼ lite, ½ lite, ¾ lite, and full-lite opaque
areas;
iii. The DGAA of the door shall be simulated
using 4 configurations, calculated per
Equation 5-3, at the ¼ lite, ½ lite, ¾ lite and
full-lite sizes (See Figure 5-10 of door slab
with various panel sizes);
iv.
B. The total product U-factor will be calculated, per
Equation 5-4, by adding the product of the glazed
assembly (UDGAAADGAA), and the product of the
remaining opaque door or sidelite slab assembly
(UsdAsd) divided by the total product area, where:

𝑈𝑠𝑑 𝐴𝑠𝑑 = [(𝑈𝑓 𝐴𝑓 ) + (𝑈𝑑𝑐 𝐴𝑑𝑐 ) + (𝑈𝑝 𝐴𝑝 ) + (𝑈𝑒𝑝 𝐴𝑒𝑝 )]

Equation 5-2

𝑈𝐷𝐺𝐴𝐴 𝐴𝐷𝐺𝐴𝐴 = [(𝑈𝑙𝑓 𝐴𝑙𝑓 ) + (𝑈𝑑 𝐴𝑑 ) + (𝑈𝑑𝑒 𝐴𝑑𝑒 ) + (𝑈𝑒𝑔 𝐴𝑒𝑔 ) + (𝑈𝑐 𝐴𝑐 )]
Equation 5-3
Note: UDGAA and ADGAA shall be determined using WINDOW.

[(𝑈𝑠𝑑 𝐴𝑠𝑑 ) + (𝑈𝐷𝐺𝐴𝐴 𝐴𝐷𝐺𝐴𝐴 )]

𝑈𝑡 =
𝐴𝑡
Equation 5-4

Where
Uf = Frame U-factor
Af = Frame area
Ulf = Lite frame U-factor
Alf = Lite frame area
Ud = Divider U-factor
Ad = Divider area
Ude = Edge-of-divider U-factor
Ade = Edge-of-divider area
Ueg = Edge-of-lite U-factor
Aeg = Edge-of-lite area

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 Uc = Center-of-lite U-factor
Ac = Center-of-lite area
Udc = Door or Sidelite core U-factor
Adc = Door or Sidelite core area
Up = Panel U-factor
Ap = Panel area
Uep = Edge-of-panel U-factor
Aep = Edge-of-panel area
UDGAA = Doorglass Assembly Area U factor
ADGAA = Doorglass Assembly Area at ¼ Lite, ½ Lite, ¾ Lite,
Full-Lite
Usd = U-factor of Door Slab & Frame/Sill Opaque area
Asd = Opaque Area of NFRC Model Size Swinging Door, or
Sidelite, for 1/4 lite, 1/2 lite, 3/4 lite, full-lite and
complete opaque configurations
Ut = Total Product U-factor
At = Total area

5.2.5.2 Modeling using the Detailed Door Rating (DDR) Method

The Detailed Door Rating Method total door system U-
factor shall be calculated as outlined below:
A. Determine all of the following, as applicable, using
the approved 2-D heat transfer computational
program for all frame, panel, and core modeling and
WINDOW for the center-of-lite U-factor:
i. Panel(s) U-factor;
ii. Edge-of-panel U-factor;
iii. Door core U-factor;
iv. Center-of-lite U-factor using WINDOW;
v. Lite frame U-factor;
vi. Edge-of-lite U-factor;
vii. Divider U-factor;
viii. Edge-of-divider U-factor;
ix. Frame U-factor;
x. The component areas of:
(a) Frame area
(b) Lite frame area
(c) Divider area

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 (d) Edge-of-divider area
(e) Edge-of-lite area
(f) Center-of-lite area
(g) Door core area
(h) Panel area
(i) Edge-of-panel area
(j) Projected total door system area
B. Perform the following calculations as shown in
Equation 5-5:
i. Multiply the center-of-lite, divider, edge-of-lite,
edge-of-divider, panel, door core, lite frame,
edge-of-panel, and frame U-factors by their
corresponding areas;
ii. Total these nine quantities; and
iii. Divide this total by the projected total exterior
door system area to produce computed total
door system product U-factors for all the door
systems in the matrix of required U-factors.

(𝑈𝑓 𝐴𝑓 ) + (𝑈𝑙𝑓 𝐴𝑙𝑓 ) + (𝑈𝑑 𝐴𝑑 ) + (𝑈𝑑𝑒 𝐴𝑑𝑒 ) + (𝑈𝑒𝑔 𝐴𝑒𝑔 ) + (𝑈𝑐 𝐴𝑐 ) +

[ ]
(𝑈𝑑𝑐 𝐴𝑑𝑐 ) + (𝑈𝑝 𝐴𝑝 ) + (𝑈𝑒𝑝 𝐴𝑒𝑝 )
𝑈𝑡 =
𝐴𝑡
Equation 5-5
Where the variables are defined in Section 5.2.5.1 above.

5.2.6 Baseline Product

A. The simulation report shall include simulation results for the
exact option as tested.
B. For representative production line specimens; doors, sidelites,
and transoms of the complete system (slab, frame, and sill)
shall be within ± 25 mm (1 in) of the appropriate model size
listed in Table 4-3.
C. For door and sidelite product lines which include glazed
options, the baseline product shall be a 1/2 Lite product with a
height/width tolerance of the glazing to be within +/- 13mm
(0.5 in) of the dimension listed in Figure 5-10.

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 Table 5-1 – Glazing and Divider Patterns for Doors
Individual For Doors with1 For Sidelites Simulate or Optional
Product with1 Test with Caming
Daylight Pattern
Opening Size
1/4 glazing < 0.265 m2 glazing < 0.042 534 mm x 457 5 vertical
glazing (411 in2) m2 mm 1 horizontal
(65 in2) (21 in x 18 in)

1/2 0.265 m2 ≥ glazing < 0.042 m2 ≥ 534 mm x 889 5 vertical

glazing 0.581 m2 (411-901 glazing < 0.181 mm 8 horizontal
in2) m2 (65-281 in2) (21 in x 35 in)
3/4 2
0.581 m ≥ glazing < 0.181 m2 ≥ 534 mm x 1194 5 vertical
glazing 0.710 m2 (901-1101 glazing < 0.252 mm 10 horizontal
in2) m2 (281-391 in2) (21 in x 47 in)
Full glazing ≥ 0.710 m2 glazing ≥ 0.252 534 mm x 1600 5 vertical
glazing (1101 in2) m2 mm 13 horizontal
(391 in2) (21 in x 63 in)
1Designated glazing areas are for the daylight opening size in the actual product
and are not based on the model sizes from Table 4-3.

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 5.2.7 Figures
Figure 5-1a – Exterior Steel/Composite Door System – Vertical Elevation in Steel
Frame

The projected door area is the rough opening area less installation clearances. Sidelite
area schematic may be identical or similar without perimeter weatherstrip and bottom
sweep.

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 Figure 5-1b – Exterior Steel/Composite Door System – Vertical Elevation in Wood
Frame

The projected door area is the rough opening area less installation clearances.
Sidelite area schematic may be identical or similar without perimeter weatherstrip
and bottom sweep.

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 Figure 5-2 – Exterior Wood Door System – Vertical Elevation

The projected door area is the rough opening area less installation clearances.
Sidelite area schematic may be identical or similar without perimeter weatherstrip
and bottom sweep.

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 Figure 5-3 – Typical 6-Panel Layout

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Figure 5-4 – Common Pressed-Steel Frame – Single Unit Type Pressed-Steel Frame

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 Figure 5-5 – Frame Cross Section

146.00mm (5.75")

Variable Weatherstrip
16.00mm (0.63")

1.27mm (0.05") 51mm (2")

12.5mm (0.5") 12.5mm (0.5")

Pressed Steel Frame Specification (16 G)

Pressed Steel Frame Specification

Single-unit type pressed steel frames shall consist of a head, a sill and two jamb
pieces, hinge reinforcements, a strike plate reinforcement, and base and wall
anchors
The wall anchors provided shall be adjustable or fixed masonry anchors, bolts with
expansion shells, channel clips, “Z” clips, wood stud anchors, or steel anchors.
The head and jamb pieces shall be constructed, as shown in Figure 5-4.

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 Figure 5-6 – Wood Default
115mm (4.56 in.)

Head

115mm (4.56 in.) Jambs

Sill

Figure 5-7 – Default Wood Door Head Jamb and Side Jamb

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 Figure 5-8a – Default Thermally Broken Aluminum Door Sill

TOLERANCE:
DECIMAL: STANDARD TOLERANCE PER "THE ALUMINUM ASSOCATION"
MANUAL. USE THE STANDARD TOLERANCE TABLE UNLESS
OTHERWISE NOTED AT THE DIMENSION.

ANGLES: +/- 1/2 DEG. UNLESS OTHERWISE NOTED.

0.250"(5)

0.247"

0.015" RAD.
0.223" 0.302"

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 Figure 5-8b – Default Non-Thermal Door Sill

Figure 5-9 – Default Door Lite Frame

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 Figure 5-10 – SDR Configurations of Single Door or Sidelights

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 Figure 5-11 – Commercial Door Example in a Glazed Wall System

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 Figure 5-12 – Door Inside Glazed Wall System

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 Figure 5-13 – Door Inside Glazed Wall System

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 5.3 Skylights

5.3.1 Scope
This section presents additional details specific to skylights.
This section presents and references methods for determining
specific skylight system heat transfer properties or quantities used in
the determination of these properties. At this time, the scope of these
properties is limited to total skylight system U-factor. For additional
simulation parameters see Reference 2.

5.3.2 Variations from Standard Product Lines

If a skylight can be installed using more than one of the installation
methods listed below, the skylight product line shall include all of the
pertinent options as individual products. The method in which
skylights are mounted will affect the U-factor of the skylight. Mounting
variations include:
A. Inset mount where the curb of the skylight extends into the
rough opening in the roof;
B. Curb mount where the outside of the curb is equal to the rough
opening in the roof; and
C. Curb mount where the inside of the curb is equal to the rough
opening in the roof.
Variations of each mounting type may occur.
A skylight with an interior diffuser is rated with the interior tube and/or
diffuser removed from the assembly. Any solar tracking devices or
other auxiliary elements shall also be removed for rating purposes.

5.3.3 Variations from Standard Individual Products

None

5.3.4 Variations from Standard Simulation and Test Conditions

Skylights and other sloped glazing products shall be simulated and
rated at a slope of 20º above the horizontal. For determining
validation of the baseline product only, skylights and other sloped
glazing products shall be simulated and tested in a vertical position.
Ratings for test only products shall be converted to the 20º slope
from the vertical position by multiplying the tested value at vertical by
1.20.

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 5.3.4.1 Curb
Curb mounted skylights that do not have an attached
integral curb when manufactured shall be simulated and
tested installed on a nominal 2 in x 4 in wood curb made
from douglas fir (with no knots).

5.3.5 Calculation of Total Product Rating

The total fenestration product U-factor shall be calculated as outlined
in Section 5.1.5.

5.3.6 Figures
None

5.4 Tubular Daylighting Devices (TDD)

5.4.1 Scope
This section presents and references methods for determining
specific TDD system heat transfer properties or quantities used in the
determination of these properties. At this time, these products can
only be rated using the testing alternative procedure (Section 4.1.2).
The specific details for testing TDDs are outlined in Appendix 3 of
NFRC 102.

5.4.2 Variations from Standard Product Lines

A TDD product line shall only consist of individual products of the
same tube material, exterior dome material, and interior diffuser
material.

5.4.3 Variations from Standard Individual Products

None

5.4.4 Variations from Standard Simulation and Test Conditions

5.4.4.1 Orientation
U- TDDs shall be rated with the tube in a vertical
orientation (see Figures 5-14a and 5-14b). Therefore, the
heat flow shall be in the vertical direction. Standardized
rating conditions are defined in Section 5.4.4.4.

5.4.4.1.1 Insulation at Ceiling Configuration

The diffuser is attached to the insulated ceiling.
The tubular section is located in the attic space
connecting the interior diffuser to the exterior

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 dome. The exterior dome/flashing assembly is
mounted to the roof deck.

5.4.4.1.2 Insulation at Roof Configuration

The diffuser is attached to the tubular section
which is located in the interior space. The
tubular section is connected to the exterior
dome. The exterior dome/flashing assembly is
mounted to the insulated roof deck.

5.4.4.2 Sizes
The standard TDD size listed in Table 4-3 is based on the
Thermal Opening Area, as defined in Section 3. For the
purpose of testing, this is the interior side of the 254 mm
(10 in.) foam panel. The standard TDD size is 350 mm +/-
30mm (14 in +/- 1 in) diameter tube opening. The closest
production size to the standard size shall be tested. In the
event that the device is not manufactured in the standard
model size, the production size with the closest area (as
defined in 5.4.4.3) shall be used and the result for that unit
shall be the product’s rating. For TDD products with non-
circular Thermal Opening Area, the product shall use an
opening area equivalent to the actual size of the
manufactured product as tested. Equation 4-1 shall not be
used to adjust the results to model size.

5.4.4.3 Tubular Daylighting Device Area

The U-factor for all TDDs shall be based on the Thermal
Opening Area, as defined in Section 3. This area shall be
used when calculating the total product U-factor.

5.4.4.4 Standard Testing Conditions

5.4.4.4.1 Insulation at Ceiling Configuration

750 mm (30 in) shift length (interior ceiling
line to exterior roof line);
Ceiling insulation shall be represented by
a surround panel, 250mm (10 in) in depth;
An exterior 13 mm (0.5 in) thick plywood
roof deck, painted to limit moisture
transfer;
ASHRAE attic space boundary conditions
on the exposed surface of the vertical

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 shaft material, from the top of the
insulation material to the underside of the
13 mm (0.5 in) plywood roof deck;
Exterior boundary conditions applied to
the exposed surface of the dome; and
Bottom of the tubular skylight covered
with a light diffusing plate (manufacturer
specific).

5.4.4.4.2 Insulation at Roof Configuration

750 mm (30 in) shaft length (from the
exterior roof line to the top of the diffuser);
Roof insulation shall be represented by a
surround panel, 250mm (10 in) in depth;
Exterior boundary conditions applied to
the exposed surface of the dome; and
Bottom of the tubular skylight covered
with a light diffusing plate (manufacturer
specific).

5.4.4.5 Calculation of Total Product Rating

The total TDD system U-factor shall be determined as
noted in Appendix A3 of NFRC 102.

5.4.5 Figures
Figure 5-14a – Tubular Daylighting Device Product Schematic – Vertical Elevation

INSULATION AT CEILING INSULATION AT ROOF

UNINSULATED
ROOF DECK

SURROUND
PANEL
TUBULAR
DAYLIGHTING
DEVICE

762mm
TUBULAR
762mm
(30 in.)
(30 in.) DAYLIGHTING
SURROUND DEVICE
PANEL

See Reference 12 for a more detailed drawing of the rough opening and diffuser
plate attachment.

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 Figure 5-14b – Hybrid Tubular Daylighting Device Product Schematic – Vertical
Elevation

5.5 Vehicular Access (Garage) Doors

5.5.1 Scope
This section presents and references methods for determining
specific garage door system heat transfer properties or quantities
used in the determination of these properties. At this time, the scope
of these properties is limited to total garage door system U-factor. For
additional simulation parameters, see Reference 2.

5.5.2 Variations from Standard Product Lines

A given series of garage door systems defined by skin material, core
material, and edge of garage door construction that differ only in:
A. Size;
B. Solid panel and panel cut-out configurations;
C. The replacement of core or a panel area with a glazing
system;
D. Center-of-glazing characteristics and edge-of-glazing
characteristics, such as glazing types, gap widths, glazing
areas, use of dividers, use of spacers, glazing coatings, and/or
gas fills;

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 E. Panel changes where one component of the same physical
shape has a thermal conductivity that differs by more than a
factor of 10;
F. Jamb track and/or hardware components, variations in panel
interior/exterior finish, paint, varnish, or stain; and
G. Variations in end stile design, intermediate stile design, and
door bottom edge design.

5.5.3 Variations from Standard Individual Products

An individual product, in a product line, shall be those products that
comply with the requirements per Section 5.5.2.

5.5.4 Variations from Standard Simulation and Test Conditions

A. In accordance with validation testing for simulated garage door
products, sectional garage doors shall have the U-factor
determined using a specimen to fill a 2.13 m (7 ft) wide by
2.13 m (7 ft) tall opening (the aperture is smaller than the test
specimen).
B. For doors with glazing options, the glazing shall be per the
manufacturer’s design. If grids or dividers are normally used in
garage door glazing, those grids and dividers shall be included
for modeling purposes when glazing is included. The glazed
garage door option which meets the validation sample
requirement shall be chosen for testing.
C. Door opening framing and sill shall be included in simulation
calculations. The framing (nominal 2 in x 4 in) and the sill
(nominal 2 in x 6 in) shall consist of 38 mm (1 1/2 in) wood
surrounding the perimeter of the door (See Figures 5-11
through 5-13).

5.5.5 Total Product Rating

The total garage door system U-factor shall be calculated as outlined
below:
A. Determine all of the following, as applicable:
i. Top rail (i.e., top edge of door) U-factor using the
approved 2-D computational program, including the
wood framing in the surround panel,
ii. Bottom rail (i.e., bottom edge of door) U-factor using the
approved 2-D computational program, including the
wood sill in the surround panel,

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 iii. End stile (i.e., side edge of door) U-factor using the
approved 2-D computational program, including the
wood framing in the surround panel,
iv. Meeting rail (i.e. section interface between door panels)
U-factor using the approved 2-D computational
program,
v. Door panel core U-factor using the approved 2-D
computational program (this will only include portions of
those top, intermediate, and bottom panels that are not
glazed),
vi. Edge-of-glazing U-factor, including the glazing frame,
using the approved 2-D computational program,
vii. Center-of-glazing U-factor per the total product height
procedure as defined in Reference 2 using the
approved center-of-glazing computational program, with
input as needed from the approved center-of-glazing
conductance test procedure given in Section 4.5.3, and
viii. The component areas in square feet, to the nearest
0.001 m2 (0.010 ft2) of:
(a) Top rail area, which includes the greater of 63
mm (2.5 in) or 25 mm (1 in) into a homogeneous
area of the door core, measured from the top
edge of the wood opening framing,
(b) Bottom rail area, which includes the greater of 63
mm (2.5 in) or 25 mm (1 in) into a homogeneous
area of the door core, measured from the bottom
edge of the wood opening sill,
(c) End stile area, which includes the greater of 63
mm (2.5 in) or 25 mm (1 in) into a homogeneous
area of the door core, measured from the outside
edge of the wood opening framing,
(d) Meeting rail area, which for each door panel
includes the greater of 63 mm (2.5 in) or 25 mm
(1 in) into a homogeneous area of the door core,
measured from the interface of the door panels,
(e) Door panel core area,
(f) Edge-of-glazing area,
(g) Center-of-glazing area, and
(h) Projected total exterior door system area
(including framing and sill areas);

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 B. Perform the following calculations as shown in Equation 5-3:
i. Multiply the top rail, bottom rail, end stile, meeting rail,
door panel core, edge-of-glazing, and center-of-glazing
area U-factors by their corresponding areas,
ii. Total these seven quantities, and
iii. Divide this total by the projected total exterior garage
door system area to produce computed total garage
door system product U-factors for all the door systems
in the matrix of required U-factors.

𝑈𝑡 = [(𝑈𝑡𝑟 𝐴𝑡𝑟 ) + (𝑈𝑏𝑟 𝐴𝑏𝑟 ) + (𝑈𝑒𝑠 𝐴𝑒𝑠 ) + (𝑈𝑚𝑟 𝐴𝑚𝑟 ) + (𝑈𝑑𝑝𝑐 𝐴𝑑𝑝𝑐 ) + (𝑈𝑒𝑔 𝐴𝑒𝑔 ) + (𝑈𝑐𝑔 𝐴𝑐𝑔 )]/𝐴𝑝𝑡
Equation 5-3
Where

Ut = Total door system U-factor

Utr = Top rail U-factor
Atr = Top rail area
Ubr = Bottom rail U-factor
Abr = Bottom rail area
Ues = End stile U-factor
Aes = End stile area
Umr = Meeting rail U-factor
Amr = Meeting rail area
Udpc = Door panel core U-factor
Adpc = Door panel core area
Ueg = Edge-of glazing U-factor
Aeg = Edge-of-glazing area
Ucg = Center-of-glazing U-factor
Acg = Center-of-glazing area
Apt = Projected total door system area

5.5.6 Figures

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 Figure 5-15 – Garage Door U-factor Area Weighting, Sectional

Legend 1

1 Top Rail* 4
2 Bottom Rail*
3 Meeting Rail*
3
4 Door Panel Core 4
5 Edge-of-Glazing; 63 mm (2.5 in.) 5
around perimeter, including glazing 6
5
framing
4
6 Center-of-Glazing 3

*greater of 63 mm (2.5 in.) or 25 mm (1 in.) into a

homogeneous area 4

Notes 3

1. Glazing is optional.
4
2. Number of glazing lites may
vary.
2
3. Glazing locations may vary.

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 Figure 5-16 – Garage Door U-factor Area Weighting, Front Elevation View

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 Nominal 2 x 6

Figure 5-17 – Garage Door Front Elevation View and Perimeter Details
EXTERIOR ELEVATION
Nominal 2 x 4 N.T.S.
Nominal 2 x 4 4 Panel Door
4" Surround Panel 4 Panel Door
4" Surround Panel

EXT.
Nominal 2 x 4 Nominal 2 x 4
Nominal 2 x 4 Nominal 2 x 4

GARAGE DOOR
ASSEMBLY
ATTACHED TO
WOOD JAMBS
Nominal 2 x 6

INT.
Nominal 2 x 6

SECTION A-A
EXTERIOR ELEVATION EXTERIOR ELEVATION N.T.S.

N.T.S. N.T.S.

4" Surround Panel

EXT.
EXT.

EXT. INT.

GARAGE DOOR
ASSEMBLY
ATTACHED TO
WOOD HEADER

GARAGE DOOR GARAGE DOOR

ASSEMBLY ASSEMBLY
ATTACHED TO ATTACHED TO
WOOD JAMBS WOOD JAMBS
INT.
INT.

4" Surround Panel

SECTION A-A SECTION A-A

N.T.S. N.T.S.

SECTION B-B
N.T.S.

4" Surround Panel 4" Surround Panel

EXT. EXT.
INT. INT.

GARAGE DOOR GARAGE DOOR

ASSEMBLY ASSEMBLY
ATTACHED TO ATTACHED TO
WOOD HEADER WOOD HEADER

4" Surround Panel 4" Surround Panel

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SECTION B-B SECTION B-B
© 2013, 2023. National Fenestration
N.T.S. Rating Council Incorporated
N.T.S. (NFRC). All rights reserved
 5.6 Non-Residential Products

5.6.1 Scope
Non-residential fenestration systems covered by this method include
products that are designed to be field glazed or field assembled units
comprised of specified framing and glazing components, including
but not limited to:

5.6.1.1 Products and Systems Covered

Transparent and translucent wall systems where the
glazing material is glass, plastic, or other light-transmitting
panels (including opaque spandrel panels within the
system), except those products where no testing or
calculation procedure exists
A. Glazed wall support and framing systems;
B. Products of any size and design;
C. Products with single or multiple glazing layers;
D. Products with spacer systems between glazings;
E. Horizontal, vertical and sloped systems;
F. Products that, by design, may have multiple framing
components and/or glazing combinations;
G. Fenestration systems using unitized construction,
where a system is field assembled from factory
assembled sub-units; and
H. Dynamic glazing products.

5.6.2 Variations from Standard Product Lines

If a glazed wall system meets the definition of a curtain wall system, it
shall be rated as a curtain wall system, regardless of application. If a
glazed wall system meets the definition of a window wall system, it
shall be rated as a window wall system, regardless of application.

5.6.3 Variations from Standard Individual Products

None

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 5.6.4 Variations from Standard Simulation and Test Conditions

5.6.4.1 Rating Configuration for Glazed Wall and Sloped Glazing

Systems
These systems are rated using two lites with a single
vertical mullion.
A. Curtain Walls shall be simulated and tested with
intermediate verticals as jambs and intermediate
horizontals as head/sill frame members. Area
weight intermediate members based on centerline
dimensions.
B. Window walls shall be simulated and tested with
intermediate verticals as jambs and standard head
and sill members. Area weight intermediate
members based on centerline dimensions.
C. Sloped glazing may also be rated based on the
centerline dimensions if utilized like a curtain or
window wall, except for solariums and sunrooms.
D. Sloped glazing of solariums and sunrooms shall be
simulated and tested with standard jamb, head, and
sill members (see Section 5.6.4.3).
E. Other sloped glazing, as identified under the
"Architectural Skylight Systems" definition, shall also
be rated as sloped glazing products based on
centerline dimensions. These products shall be
simulated and tested with purlins as head and sill
and rafters as jambs and vertical mullion.
F. Spandrel panel systems are utilized within glazed
walls and therefore shall be simulated with the same
modeling rules as indicated in this section for the
appropriate product type.

5.6.4.2 Unspecified Product Sample Validation Criteria

If the product to be used for validation purposes is not
specified, then the individual product used for validation
purposes shall be simulated and tested using the following
criteria: The test specimen shall be constructed in such a
manner as to be identical to the individual product
simulated and have outside dimensions measuring 2000
mm x 2000 mm (79 in x 79 in), having one vertical mullion
and two glazed lites. The glazing system configuration for
the validation testing shall be nominal 25 mm (1 in) outside
dimension insulating glass utilizing two lites of 6 mm (1/4

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 in) clear (uncoated glass), a typical dual-sealed aluminum
spacer system, and air-filled. There shall be no insulation
of any type applied to the test specimen during validation
testing. Validation will be achieved per Section 4.7.1
This section is to be used only in those instances where
the representative sample for validation purposes has not
been prescribed by a specifying authority, such as an
architect, project manager, engineering firm, building
owner, etc.
For simulating and testing of all other fenestration operator
types other than glazed wall systems, sloped glazing, and
solarium/sunroom systems model sizes shall be consistent
with the sizes listed in Table 4-3 of this standard.

5.6.4.3 Determining the Thermal Transmittance for

Solarium/Sunroom Systems
Note: This procedure is to be used when the solarium is
glazed on-site. If manufactured window or door systems
are used to create the glazed walls in a solarium, the
thermal transmittance shall be determined in accordance
with Section 4 of this standard.
A. The thermal transmittance of solarium/sunroom
systems shall be determined in accordance with
Section 4.1 of this standard;
B. For simulating and testing site-built vertical glazed
wall sections of solarium/sunroom systems, each
product line shall have one baseline product
validated in accordance with Section 4.1.1 and
4.3.1, with the following exception--the individual
product used for validation purposes shall be
simulated and tested using the following criteria: the
test specimen shall be constructed in such a
manner as to be identical to the individual product
simulated and have outside dimensions measuring
2000 mm x 2000 mm (79 in x 79 in), having one
vertical mullion and two glazed lites; the glazing
system configuration for the validation testing shall
be nominal 25 mm (1 in) outside dimension
insulating glass utilizing two lites of 3 mm (1/8 in)
clear (uncoated glass), a typical dual-sealed
aluminum spacer system, and air-filled; and there
shall be no insulation of any type applied to the test
specimen during validation testing. Validation will be
achieved per Section 4.1.1;

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 C. Sloped glazing systems shall be rated in
accordance with Section 4.1 utilizing sample
construction as described in Section 5.6.4.3.B; and
D. For simulating and testing all other fenestration
operator types other than glazed wall systems and
sloped glazing systems, model sizes shall be
consistent with the sizes listed in Table 4-3 of this
standard with glazing in accordance with Section
5.6.4.3.B.

5.6.5 Calculation of Total Product Rating

Calculation of U-factor of an opaque spandrel panel system cannot
be conducted using Berkeley Lab WINDOW. Opaque spandrel panel
systems require a 254mm (10 in.) edge-of-glass (panel) U-factor
surface tag. Therefore, a specialized spreadsheet shall be used to
conduct the proper product area-weighting using equation 5-1
whereas the center-of-glazing is the spandrel system
(glass/air/insulated panel) for the variables Uc (derived from THERM)
and Ac

5.6.6 Figures
None

5.7 Dynamic Attachment for Swinging Door Products (DASD)

Rating procedures for full and half lite glazed swinging doors shall be used
with the dynamic attachment in the “fully open” and “fully closed” positions.

5.7.1 Scope
This section presents additional details specific to DASD. This
section presents and references methods for determining specific
dynamic attachments for swinging doors U-factor rating.

5.7.2 Methodology
Methodology for rating full and half lite swinging doors can be found
in Section 5.2. DASD products will be rated using Reference
Swinging Doors (see Table 5-2 and Figures 5-18 and 5-19).
The dynamic attachment for swinging door shall be simulated with
the attachment in the “fully open” position.
The DASD shall be tested as a whole product system (attachment
and reference door) in the “fully closed” position. Center-of-glazing
tests are not acceptable for this purpose.

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 Individual product ratings shall be determined for each of the four
configurations.

5.7.3 Approved Computational Program

The DASD product U-factor shall be determined using approved
glazed swinging door simulation. The DASD shall be modeled on the
following reference swinging doors.
Table 5-2 – Reference Swinging Doors
3068; Steel skin; wood edge; EPS core door ½” IG Full and Half
Lite
See Figure 5-18
3068; Fiberglass skin; wood edge; urethane core door ½” IG
Full and Half Lite
See Figure 5-19
Reference Swinging Door Glazing Detail
The glazing system shall consist of two panes of 3 mm (1/8 in) clear
glass with a 1/4 in air gap separated by an aluminum spacer system.
For simulation purposes, the 3 mm (1/8 in) clear glass shall be the
generic 3mm clear glass file (ID#102) from the approved NFRC
spectral data files with the International Glazing Database (IGDB).

5.7.4 Figures

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 Figure 5-18 – Reference Swinging Door Details

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 Figure 5-19 – Reference Swinging Door Details

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 5.8 Rolling Doors

5.8.1 Scope
This section presents and references methods for determining
specific rolling door system heat transfer properties or quantities
used in the determination of these properties. At this time, the scope
of these properties is limited to total rolling door system U-factor. For
additional simulation parameters see Reference 2.

5.8.2 Variations from Standard Product Lines

A given series of rolling door systems defined by skin material, core
material, and edge of rolling door construction that differ only in:
A. Size,
B. Slat changes where one component of the same physical
shape has a thermal conductivity that differs by more than a
factor of 10,
C. Jamb guide components,
D. Variations in slat ends and guide configurations,
E. Variations in slat interior/exterior finish that changes the
surface emittance by more than 0.10, and
F. Variations in top slat and bottom slat/bottom bar designs.

5.8.3 Variations from Standard Individual Products

An individual product, in a product line, shall be those products that
comply with the requirements per Section 5.8.2.

5.8.4 Variations from Standard Simulation and Test Conditions

A. In accordance with validation testing for simulated rolling door
products, rolling doors shall have the U-factor determined
using a specimen to fill a 2.13 m (7 ft) wide by 2.13 m (7 ft) tall
opening (the aperture is smaller than the test specimen);
B. Slat height shall be per the manufacturer’s drawing (the
bottom slat, the top slat, and the intermediate slats shall be
modeled per manufacturer drawings);
C. Slat ends and guide configurations shall be per the
manufacturer’s drawing;
D. Rolling door simulations shall not include components and
hardware above the top of the opening, e.g. hood, barrel,
operator, etc.; and

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 E. Door opening framing and sill shall be included in simulation
calculations. The framing (nominal 2 in x 4 in) and the sill
(nominal 2 in x 6 in) shall consist of 38 mm (1.5 in) thick wood
surrounding the perimeter of the door (See Figures 5-15
through 5-17).

5.8.5 Total Product Rating

The total rolling door system U-factor shall be calculated as outlined
below:
A. Determine all of the following, as applicable:
i. Top rail (i.e., top edge of door) U-factor using the
approved 2-D computational program, including the
wood framing in the surround panel,
ii. Bottom rail (i.e., bottom edge of door) U-factor using the
approved 2-D computational program, including the
wood sill in the surround panel,
iii. End stile (i.e., side edge of door) U-factor using the
approved 2-D computational program, including the
wood framing in the surround panel,
iv. Door core U-factor using the approved 2-D
computational program, and
v. The component areas in square feet, to the nearest
0.001 m2 (0.010 ft2) of:
(a) Top rail area, which includes the greater of 63
mm (2.5 in) or 25 mm (1 in) into a homogeneous
area of the door core, measured from the top
edge of the wood opening framing,
(b) Bottom rail area, which includes the greater of 63
mm (2.5 in) or 25 mm (1 in) into a homogeneous
area of the door core, measured from the bottom
edge of the wood opening sill,
(c) End stile area, which includes the greater of 63
mm (2.5 in) or 25 mm (1 inch) into a
homogeneous area of the door core, measured
from the outside edge of the wood opening
framing,
(d) Door core area, using three slats as the basis for
computation, and
(e) Projected total exterior door system area
(including framing and sill);

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 B. Perform the following calculations as shown in Equation 5-4:
i. Multiply the top rail, bottom rail, end stile, and door core
U-factors by their corresponding areas,
ii. Total these four quantities, and
iii. Divide this total by the projected total exterior rolling
door system area to produce computed total rolling
door system product U-factors for all the door systems
in the matrix of required U-factors.

𝑈𝑡 = [(𝑈𝑡𝑟 𝐴𝑡𝑟 ) + (𝑈𝑏𝑟 𝐴𝑏𝑟 ) + (𝑈𝑒𝑠 𝐴𝑒𝑠 ) + (𝑈𝑑𝑐 𝐴𝑑𝑐 )]/𝐴𝑝𝑡

Equation 5-4

Where

Ut = Total door system U-factor

Utr = Top rail U-factor
Atr = Top rail area
Ubr = Bottom rail U-factor
Abr = Bottom rail area
Ues = End stile U-factor
Aes = End stile area
Udc = Door core U-factor
Adc = Door core area
Apt = Projected total door system area

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 5.8.6 Figures

Figure 5-20 – Rolling Door U-factor Area Weighting - Sectional View

Top Rail*

Door Core

Bottom Rail*

*greater of 63 mm (2.5 in.) or 25 mm (1 in.)

into a homogeneous area

Figure 5-21 – Rolling Door U-factor Area Weighting – Front Elevation View
Top Rail*

Door Core

End Stile* End Stile*

Bottom Rail*

* greater of 63 mm (2.5 in.) or 25 mm (1 in.) into a

homogeneous area

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 Figure 5-22 – Rolling Door Front Elevation View and Perimeter Details

Nominal 2 x 4

4" Surround
Panel

Nominal 2 x 4 Nominal 2 x 4

Nominal 2 x 4

7'-0"
4" Surround
Panel

Nominal 2 x 4 Nominal 2 x 4
7'-0"
Nominal 2 x 4

4" Surround
Panel
7'-0"

Nominal 2 x 4 Nominal 2 x 4
Nominal 2 x 6
EXT.
7'-0"
7'-0"

EXTERIOR ELEVATION 4" Surround Panel

7'-0" Door not shown Nominal

N.T.S.2 x 6
EXT. INT.

4" Surround Panel

EXTERIOR ELEVATION Nominal 2 x 6
Door not shown N.T.S. EXT. INT.
EXT.

ROLLING DOOR
CURTAIN
EXTERIOR ELEVATION ATTACHED TO
WOOD HEADER
Door not shown N.T.S.
ROLLING DOOR
EXT.

CURTAIN
ATTACHED TO
WOOD HEADER
4" Surround Panel 4" Surround Panel
EXT.

4" Surround Panel 4" Surround Panel

4" Surround Panel

ROLLING DOOR
INT.

4" Surround Panel 4" Surround Panel

CURTAIN
ATTACHED TO 4" Surround Panel
ROLLING DOOR WOOD JAMBS
INT.

CURTAIN
ATTACHED TO
SEC
ROLLING DOOR
INT.

WOOD JAMBS
CURTAIN
ATTACHED TO
SECTION A-A SECTION B-B
WOOD JAMBS N.T.S. N.T.S.
SECTION A-A SECTION B-B
N.T.S. N.T.S.
SECTION A-A
N.T.S.

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 5.9 Component Modeling Approach (CMA) for Non-Residential Products

5.9.1 Scope
This section covers methods for determining fenestration product U-
factor (thermal transmittance) for fenestration products using
Component Modeling Approach (CMA).

5.9.2 Products and Systems Covered

A. All products listed in Table 4-3 except;
i. Garage Doors;
ii. Greenhouse/garden;
iii. Hybrid tubular;
iv. Jal/jal awning;
v. Tubular daylighting devices
vi. Tropical awning
B. Combination products;
C. Composite products

5.9.3 Standard Simulation and Testing

5.9.3.1 Simulation
All simulations shall be based on computer simulations that
comply with Section 4.3.1 and are further based on the
CMA modeling procedure (Reference 10).
The CMA procedure is based on modeling frame cross-
sections with generic low and high (L/H) conductance
center-of-glazing assemblies (L/H COGA) and low and
high conductance spacer edge seal assemblies (L/H
SESA), collectively known as L/H options. The following
are definitions of L/H options.

5.9.3.1.1 Definition of the Low and High (L/H) Options

A total of four configurations are used in the
definition of L/H options for insulated
glazing. For products without SESA, only
two center of glazing assembly
configurations are defined for two L/H
options. These configurations are
assembled from the extreme ends of thermal
performance for both COGA and SESA.

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 Insulating glazing: The following thermal
performance is used for insulating glazing
options:
i. Low glazing – Double glazed, low-
E, with the invented gas fill
properties that produces R12.5
insulation value – Ucog = 0.45
W/m2-K (0.08 Btu/hr-ft2-F)
ii. High glazing – Double glazed clear
air
iii. Ucog = 2.684 W/m2-K (0.473
Btu/hr-ft2-F)
Single glazing: The following thermal
performance is used for single glazing
options:
i. Low glazing – Low-E single glass,
with low-E facing indoor side –
Ucog = 3.24 W/m2-K (0.57 Btu/hr-
ft2-F)
ii. High glazing Ucog = 5.82 W/m2-K
(1.03 Btu/hr-ft2-F)
Glazing for dual window or door and
glazing for products with secondary sash
or panel, energy panel, or storm panel:
i. Low glazing – Use a combination
of low-E coated glass and invented
gas fill from above
ii. High glazing – Use clear glass
(non-coated) for all panes with all
glazing cavity with air
If the original configuration has any
combination of insulated glazings and/or
single glazings, low and high glazing
configuration should duplicate that;
If a product includes SESA, the following
low and high spacer details should be
used:
i. Low spacer – generic low
conductivity spacer – Keff = 0.01
W/m-K (0.006 Btu/hr-ft-F)

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 ii. High spacer – generic high
conductivity spacer – Keff = 10.0
W/(m-K) (5.8 Btu/hr-ft-F)
SESA height is standardized to 12.7 mm
(0.5 in), spacer width is variable in order
to match the gap width of L/H COGA;
SESA is not applicable to single glazing
systems; and
Glass thickness is standardized to 3 mm
(1/8 in) for residential products and 6 mm
(1/4 in) for commercial products. Overall
(nominal) thickness of L/H glazing
systems should match nominal thickness
(± tolerance) of the real glazing systems
(i.e. 19.1 mm (3/4 in); 22.2 mm (7/8 in); 25
mm (1 in), etc.) that the simulated product
is designed for.

5.9.3.1.2 Reporting Simulation Results

See NFRC 701.03 – Reporting Requirements,
Section 1.2.

5.9.3.1.3 Total Product U-factor Calculation

Total product U-factor calculation requires
the U-factors for frame components frame
U-factor (Uf) and edge-of-glass U-factor
(Ue), for their representative Low and High
options. In addition, projected frame depth
(pfd) is required;
The following additional calculation results
are required for total product U-Factor
calculation and these shall be reported for
the whole product:
COGA: Uc = W/m2-K (Btu/hr-ft2-ºF)
SESA: Keff = W/m-K (Btu/hr-ft-ºF)
The calculation of total product U-factor
for products with a SESA is done using
the procedure detailed in Reference 10.
For products without a SESA, total
product U-factor is calculated by
excluding the equations that involve the
SESA; and

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 The NFRC-approved CMA Software Tool
(CMAST) shall be used to determine total
product U-factor for standard model size..
U-factor ratings for sizes other than
standard model size can be calculated for
informational purposes when applicable.

5.9.3.2 Testing
There is no separate CMA testing procedure for frame
components. Testing is done for the whole product, which
is the baseline product for the purposes of validation
testing and is done to validate a Framing Product Line
(FPL).

5.9.4 Validation Testing

Each FPL will require validation testing on a standard baseline
product representing the framing product line, using NFRC 102. The
following conditions apply:
A. Test specimen size and configuration shall be as defined in
Table 4-3 and Section 5.9.6
B. All test specimens shall be tested without removable screens,
removable grilles and trims, or any other applied devices;
C. All test specimens shall be tested in the vertical position. For
determining validation of the baseline product only, skylights,
and other sloped glazing products shall be simulated in a
vertical position;
D. The test specimen shall not be modified by the testing
laboratory, except as allowed in Reference 1 for sealing
against air leakage and as required by this section;
E. The product selected as the baseline product shall have an
insulating glass unit(s) with a maximum center-of-glazing U-
factor of 0.35, unless the product is not designed for use with
insulating glass (i.e. domes, glass block, translucent panels,
single glazing, etc.); and
F. The framing product line is validated if the baseline product
has a tested U-factor which meets the equivalence criteria in
Table 4-4 when simulated in accordance with Section 5.9.3.

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 5.9.5 Simplifications

5.9.5.1 Simplifications to Spacer Components

A. For the purpose of the CMA methodology, each
SESA performance shall be provided in terms of its
effective conductivity, Keff;
B. The SESA consists of the spacer component,
desiccant, and any applicable sealants. Three
different paths are provided for the definition of the
spacer component and corresponding SESA; and
C. Each spacer component can be submitted by the
spacer manufacturer and later made available for
SESA under only one path.
Path I – Generic Spacer: (Default Spacer, Default
Sealant, Default Geometry)
The Keff is defined based on simple review of spacer
drawings.
Group 1 – Spacer containing aluminum
If the spacer uses any aluminum in the design, it shall be
assigned a spacer system Keff of 8.0 W/mC (4.622 Btu/hr-
ft-F).
Group 2 – Spacer containing mild steel (i.e. galvanized
steel, tin-plated steel)
If the spacer uses any mild steel in the design, it shall be
assigned a spacer system Keff of 3.0 W/mC (1.733 Btu/hr-
ft-F).
Group 3 – Spacer containing stainless steel
If the spacer uses any stainless steel in the design, it shall
be assigned a spacer system Keff of 1.0 W/mC (0.578
Btu/hr-ft-F).
Group 4 – Spacer containing all non-metallic materials
If the spacer uses only non-metallic materials in the design,
it shall be assigned a spacer system Keff of 0.5 W/mC
(0.289 Btu/hr-ft-F). If the spacer design incorporates any
metal, it shall fall into either Group 1, 2, or 3.
In the event a spacer contains two metals, the higher
conductivity metal shall be used in specifying the spacer
group, regardless of the amount of that metal present in
the spacer.

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 Path II – Specific Spacer, Default Sealants (Specific
Spacer, Default Sealants, Limited Geometry):
The Keff of the spacer edge-seal assembly is defined
based on simulation from spacer bar drawings.
A. The spacer manufacturer shall submit drawings to
an NFRC-accredited simulator to be evaluated and
modeled;
B. The spacer component shall be evaluated by the
certified simulator working for an accredited lab and
shall be based on the drawings and the bill of
materials supplied by the spacer manufacturer;
C. The spacer component is evaluated for each width
available for the spacer series, to which spacer
component belongs, based on the drawings
supplied by the spacer manufacturer at the
maximum spacer height available for the spacer
series;
D. Modeling of desiccant is applicable to only those
spacer systems which separately add desiccant to
the spacer bar;
E. The spacer edge seal assembly that is generated
from this spacer component shall be evaluated
using generic sealant and desiccant materials to
cover all sealant and desiccant materials (see table
below); and
F. The spacer edge seal assembly with the highest
Keff value shall be used to represent all spacer
components for this spacer series. Only one Keff
for the spacer edge-seal assembly is submitted for
inclusion in the CMA database to represent all
spacer components for the spacer series.
Table 5-4 – Generic Sealant and Desiccant Material Values
Generic Materials k (W/m-K) k(Btu/hr-ft-F)
Generic Primary Sealant 0.25 0.144
Generic Secondary Sealant 0.40 0.231
Generic Desiccated Matrix 0.29 0.168
Generic Desiccant Bead 0.03 0.017

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 Path III – Specific Spacer, Specific Sealants: (Specific
Spacer, Specific Sealant, Detailed Spacer Edge-Seal
Assembly Geometry)
The Keff of the spacer edge-seal assembly is defined
based on simulation from spacer drawings, any applicable
desiccant, and any applicable sealants.
A. The spacer manufacturer shall submit drawings to
an NFRC-accredited simulator to be evaluated and
modeled;
B. The spacer component shall be evaluated by the
certified simulator working for an accredited lab and
shall be based on the drawings and the bill of
materials supplied by the spacer manufacturer;
C. Each spacer component has a unique width and
height;
D. The spacer edge-seal assembly, consisting of the
spacer component, desiccant, and any sealants, as
appropriate, is generated when the spacer edge-
seal assembly composition and geometry is known;
E. The effective conductivity of such spacer edge-seal
assembly is calculated on demand using the specific
spacer component, generic values for desiccant
from the Table 5.6.2 and specific values for the
primary and secondary sealants, as appropriate,
and shall be used in the whole fenestration product
calculation; and
F. As an option, the product may be evaluated and
modeled with the generic sealant materials defined
under Path II to limit the number of system
configurations. However, specific sealant geometry
shall be used.

5.9.5.2 Simplifications to Frame Component

FPL are not grouped; grouping is done on the basis of
frame components (i.e., head cross-sections are compared
to head cross-sections, etc.). All applicable frame
components shall be members of the same FPL.
Membership in the FPL is based on the comparison with
the approved framing components used in the standard
framing system product.
This section presents additional product line simplification
rules specific to frame components.

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 Frame Grouping
i. All grouping rules contained in Section 4 shall
be permitted to be utilized with the calculation
procedures of Section 5.9,
ii. In addition, this section presents additional
frame grouping rules that shall be permitted
to reduce the number of simulations by
grouping individual frame components. If this
approach is used, the frame U-factors (Uf)
calculated in accordance with Section 5.9.5
for the frame group leader shall be used to
represent the frame U-factors (Uf) for all
individual frame components within that
group,
iii. Individual frame components may be
grouped based upon the variations listed
below; when more than one of these
variations is being used for grouping, the
priority for determining the frame group
leader shall be in the order listed below:
(a) Change in frame length in the direction
perpendicular to the fenestration
plane,
(b) Emissivity of external and internal
frame surfaces,
(c) Glazing inset relative to the exterior,
(d) Projected frame depth (PFD),
(e) Material wall thickness, or
(f) Addition of internal frame web(s) to
create additional frame cavities.
iv. The frame group leader shall be determined
in accordance with Tables 5-5 to 5-7 based
upon the dominant frame material.

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 Table 5-5 – Frame Group Leader for all Metallic, Aluminum, Thermally-Improved
Aluminum, and Thermally-Broken Aluminum Frames

Variation
Group Leader

Change in frame length in the

direction perpendicular to the Maximum length
fenestration plane

Surface emissivity Highest emissivity

Glazing inset relative to the Glazing location closest

exterior to the outside

Change in PFD Highest PFD

Material wall thickness Highest wall thickness

Addition of internal frame web(s) to Maximum number of

create additional frame cavities webs

Table 5-6 – Frame Group Leader for Vinyl, Fiberglass, and Composite Frames

Variation Group Leader

Change in frame length in the

direction perpendicular to the Maximum length
fenestration plane

Glazing inset relative to the Glazing location closest

exterior to the outside

Change in PFD Highest PFD

Material wall thickness Highest/thickest wall

Addition of internal frame web(s) to Minimum number of

create additional frame cavities webs

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Table 5-7 – Frame Group Leader for Wood Frames (either with or without Cladding)

Variation Group Leader

Change in frame length in the

direction perpendicular to the Minimum length
fenestration plane

Glazing inset relative to the Glazing location closest

exterior to the outside

Change in PFD Highest PFD

5.9.5.3 Modification of Approved Framing Components and

Addition of New Framing Components
A. If a framing component within an approved FPL is
modified, the modified component becomes a new
member of the approved FPL without additional
validation testing if the modification is consistent
with the definition of framing product line.
B. A new framing component may be added to an
approved FPL without additional validation testing if
the new framing component is consistent with the
definition of FPL.

5.9.6 Total Product Rating

The U-factor of a fenestration product may vary by size. In order to
provide a uniform rating procedure for the comparison of fenestration
systems, total product U-factor rating is calculated for the model
(standard) size per Table 4-3 and Table 5-9.
A U-factor rating for sizes other than standard model size can be
calculated for informational purposes.

5.9.6.1 Reporting of Ratings

The final U-factor shall be reported in IP units
(BTU/hr∙ft2∙ºF) and rounded to two digits following the
decimal point. All variables used in the formula shall be
expressed to at least three significant decimal places. If
the U-factor is to be reported in SI units as well as IP units,
the SI U-factor shall be converted from the IP U-factor
following the procedure outlined in NFRC 700, Section
6.5.I.iii.

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 5.9.6.2 Determining Thermal Transmittance (U-factor) for
Sloped Glazing Systems
A. All sloped glazing systems shall be rated for thermal
performance characteristics at a slope of 20o above
the horizontal (See Section 5.3 [Skylights] for more
information); and
B. Sloped glazing systems are validated at vertical
position.

5.9.6.3 Complex Product Rating

This section provides the details of additional non-
residential product types and their model (standard) sizes
for rating purposes.

5.9.6.3.1 Spandrel Panel System

Spandrel panel systems shall be rated for U-
factor at the size specified in Table 4-3 if the
system can be represented by an approved
glazing layer or a # sign glass layer entry from
the International Glazing Database (IGDB).
Validation of Spandrel Panel System Products.
If the frame components of the spandrel
panel system, with limitation as noted in
Section 5.9.6.3.1 above have been
validated for any framing product line, no
additional validation is required. It is
treated as an additional glazing option.

5.9.6.3.2 Combination Products

Individual fenestration products forming the
combination product, which can be identified as
a product/operator type listed in Table 4-3, will
get separate NFRC rating for their individual
model (standard) sizes.
No separate validation is required for
combination products. Frame components of
individual units forming the combination product
shall be part of a validated Framing Product Line
(FPL).

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 5.9.6.3.3 Composite Products
Individual units forming the composite product,
which can be identified as a product/operator
type listed in Table 4-3, will be rated at their
NFRC standard size. Centerline of integral
mullion will be used to determine the actual sizes
of these individual units.
No separate validation is required for composite
products. Frame components of individual units
forming the composite product shall be part of a
validated Framing Product Line (FPL).

5.10 Applied Films

Note: Applied films factory-applied to glazing prior to fenestration product
fabrication and installation are already covered as glazing options by
ANSI/NFRC 100 and shall not be rated according to the procedure of
Section 5.10 below.

5.10.1 Scope
This section presents additional details specific to applied films. This
section presents and references methods for determining specific
applied films U-factor rating.

5.10.2 Variations from Standard Product Lines

None

5.10.3 Variations from Standard Individual Products

None

5.10.4 Variations from Standard Simulation and Test Conditions

5.10.4.1 Approved Center-of-Glazing Computational Program

Approved center-of-glazing software shall be used to
determine U-factor. Applied films shall be from the
approved NFRC spectral data files with the International
Glazing Database (IGDB). Glazing/applied film assembly
shall be constructed in accordance with NFRC 304
procedure.
The following reference glazing systems shall be simulated
with and without the film installed:

A. Single 3 mm (1/8 in) Clear;

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 B. Single 6 mm (1/4 in) Clear;
C. Single 6 mm (1/4 in) Grey;
D. Double 3 mm (1/8 in) Clear/3 mm (1/8 in) Clear: 7
mm (1/4 in) air gap;
E. Double 6mm (1/4 in) Clear/ 6 mm (1/4 in) Clear:
12.7 mm (1/2 in) air gap; and
F. Double 6 mm (1/4 in) Grey/ 6mm (1/4 in) Clear: 12.7
mm (1/2 in) air gap.
The position (surface number) of the film when installed on
the glazing system shall be documented (i.e., #1 to #4).
This will yield the matrix in Table 5-8 for each applied film
and applied film position.

5.10.5 Calculation of Total Product Rating

The reference fenestration product with applied film U-factor shall be
calculated as outlined below.

5.10.5.1 Reference Fenestration Products

Calculate the total fenestration product U-factor for each
reference fenestration product with the corresponding
applied film according to Section 5.10.5.2. U-factors for
reference products are pre-calculated based on the
illustrations in Figures 5-23 and 5-24. This will result in the
matrix in Table 5-9 for each film product.

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 Figure 5-23 – Residential Fixed Window Reference Product

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 Figure 5-24 – Non-Residential Window-Wall Reference Product

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ANSI/NFRC 100-2023[E0A0] Page 111
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 5.10.5.2 Total Fenestration Product U-factor
Calculate the total fenestration product U-factor for each
reference fenestration product and corresponding
reference product with applied film using the following
equation:
𝑈𝑡 = [𝛴(𝑈𝑓 𝐴𝑓 ) + 𝛴(𝑈𝑒 𝐴𝑒 ) + 𝛴(𝑈𝑐′ 𝐴𝑐 )]/𝐴𝑝𝑓 Equation 5-5

Where:

Ut = Total product U-factor, W/m2K, (Btu/hr-ft2-ºF)

Apf = Projected fenestration product area, m2 (ft2)
Uf = Frame U-factor, W/m2K , (Btu/hr-ft2-ºF)
Af = Frame area, m2 (ft2)
Ue = Edge-of-glazing U-factor, W/m2K, (Btu/hr-ft2-ºF)
Ae = Edge-of-glazing area, m2 (ft2)
Uc = Center-of-glazing U-factor, W/m2K, (Btu/hr-ft2-ºF)
Ac = Center-of-glazing area in ft2 (m2)
To three significant figures

Table 5-8 – Center-of-Glazing Values Uc

Without
With Film
Film

Uc Film Uc*
Reference Glazing Btu/h·ft2·ºF Position Btu/h·ft2·ºF
System
3 mm (1/8 in) clear 1.04 Interior
6 mm (1/4 in) clear 1.02 Interior
6 mm (1/4 in) grey 1.02 Interior
3 mm (1/8 in) clear
3 mm (1/8 in) clear 0.55 Interior
7mm (1/4 in) gap
6 mm (1/4 in) clear
6 mm (1/4 in) clear 0.47 Interior
12.7mm (1/2 in) gap
6mm (1/4 in) grey
6 mm (1/4 in) clear 0.47 Interior
12.7mm (1/2 in) gap
* Uc ‘with Film’ shall be calculated using reference glazing with film to be rated.

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 Table 5-9 – Values of U-factor for Reference and Applied Films
U-factor
Reference Product Btu/h·ft2·ºF
Operator Type Reference Reference Glazing no film with film*
Frame
Residential Fixed Aluminum 3mm (1/8 in) clear 1.081

Non-Residential 6mm (1/4 in) clear 1.021

Aluminum
Window-wall 6mm (1/4 in) grey 1.021

3mm (1/8 in) clear

Residential Fixed Aluminum 3mm (1/8 in) clear 0.700
7mm (9/32 in) gap

6mm (1/4 in) clear

6mm (1/4 in) clear 0.588
12.7mm (1/2 in) gap
Non-Residential
Aluminum
Window-wall 6mm (1/4 in) grey
6mm (1/4 in) clear 0.588
12.7mm (1/2 in) gap
* ‘with film’ shall be calculated using reference glazing with film to be rated.

5.10.6 Testing
If a reference product with applied film cannot be simulated in
accordance with Section 5.10.5, the center-of-glazing test procedure
in Section 5.10.6.1 shall be used to determine the U-factor of the
applied film glazing system.

5.10.6.1 Center-of-Glazing Component Test Procedure

The center-of-glazing U-factor (Uc) for corresponding
reference product glazing system with applied film shall be
tested in accordance with Section 4.6.2.1.

5.10.6.2 Total Fenestration Product Test Procedure

Using center-of-glazing U-factor (Uc) determined in
accordance with Section 5.10.6.1 with applicable reference
product framing system shall be simulated to calculate total
fenestration product U-factor.

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 5.11 Trendline Approach

5.11.1 Scope
This section covers methods for determining fenestration product U-
factor (thermal transmittance) for fenestration products using a
trendline calculation approach.

5.11.2 Products and Systems Covered

Product lines that are comprised of only the following product types:
a fully glazed stile and rail hinged doors, lift and slide doors, folding
doors, and products listed in Table 4-3 except for the following:
A. Garage (Vehicular Access)/Rolling Door;
B. Greenhouse/Garden;
C. Non-full lite Door Sidelite;
D. Non-full lite Side-Hinged Exterior Door;
E. Non-full lite Door Transom; and
F. Tubular Daylighting Device

5.11.3 Variations from Standard Product Lines

None

5.11.4 Variations from Standard Simulation and Test Conditions

5.11.4.1 Trendlines
Grouping criteria referenced in Section 4.2.4 shall be
applied prior to calculating the whole product U-factor
using a trendline calculation. After applying Section 4.2.4
grouping of products, separate trendlines are generated
based on a product’s characteristics.
Each trendline represents a specific categorization of
individual product options for which there is a linear
relationship between the center-of-glass U-factor (Ucog)
and the total product U-factor (Utot). The linear relationship
is used to generate the Utot from any individual product
option’s Ucog that falls within the categorized
specifications.
The accuracy of the trendline relationship is affected by
certain characteristics of the individual product options and
is independent of other characteristics. For example, a
data group containing both argon-filled and krypton-filled
glazings will produce an accurate trendline; whereas,

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 introducing different gaps widths will greatly reduce the
accuracy.
Research has produced a list of known characteristics that
affect trendline accuracy. By categorizing individual
product options per these factors, the result produces
accurate trendlines for any product options that fall within
that category.

5.11.4.1.1 Categorizing Product Options for a Trendline

Available individual product options shall be
separated into product groupings (categories)
per a combination of the characteristics listed
below. A category need only be created for those
options available for a given product line.
A trendline per section 5.11.4.1.2 will be created
for each category of the following characteristics:
IGU characteristics:
glass types – monolithic or laminate
cavity width size;
spacer system;
number of glazing layers;
Interior surface low-e;
grids or true divided lites; and
dynamic glazing products
Frame characteristics
reinforcement material and locations;
frame cavity fill material and locations;
sightline
NOTE: Refer to NFRC RCBC Simulation Manual
to develop trendlines.

5.11.4.1.2 Establishing Trendline Endpoints

The categorization of a trendline per section
5.11.4.1.1 will set the glazing options. The
following explains the process to set the three
points used for a trendline. A category with less
than three glazing options shall not be permitted
to use the trendline methodology.

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 Each trendline shall be established with a
minimum of three (3) points: the two
endpoints and one midpoint.
Glazing (i.e., center-of-glass) options for
the endpoints shall be the best and worst
performing (Uc-min and Uc-max,
respectively) options in the available
category options.
Glazing selection for each trendline COG
midpoint (Uc-mid) shall be the closest
COG of the average of the Uc-min and
Uc-max. For trendlines where there are
only three glazing options, the three
options will be the Uc-min, Uc-mid, and
Uc-max.
The determined Uc-min, Uc-mid, and Uc-
max shall be used to develop trendlines
per Section 5.11.4.1.3.

5.11.4.1.3 Development of a Trendline

For each category established in 5.11.4.1.1, a
trendline shall be created from the three points
selected in 5.11.4.1.2.
Each of the point glazing configurations
shall be simulated with the category frame
and spacer options, per NFRC RCBC
Simulation Manual.
The resulting whole product (Utot) and
COG (Uc) U-factors of each trendline point
shall be plotted as a line graph, as
specified below, using NFRC’s Trendline
Excel file.
The values of Uc are plotted against the
horizontal (X) axis.
The values of Utot are plotted against the
vertical (Y) axis.
The linear equation coefficients, “m” and
“b”, for this category, as well as the R2
value, shall be computed from the
modeling results.

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 The m and b coefficients define the
trendline and are used to calculate Utot
from Uc.
The R2 coefficient of determination is a
measure of the linearity of the trendline
points. Its value shall be greater than
0.990.
If the trendline’s R2 evaluation does not
meet linearity standards, the results shall
require the re-simulation of the existing
points or the re-categorization of the
trendline per 5.11.4.1.1.

5.11.5 Total Fenestration Product U-factor Rating

A. Develop a matrix of all individual product options according to
the trendline category.
B. To determine the total fenestration product U-factors for all
entries in the trendline matrix, use the values from the slope
intercept formula y=mx+b.
i. The “m” is the slope
ii. The “b” is the intercept
iii. The “x” is the individual product option’s center-of-glass
U-factor(cog).
iv. The “y” is the whole product total U-factor(tot).
C. Apply the slope intercept formula representing the “x” for each
corresponding individual product option’s center-of-glass
U-factor(cog) listed in the matrix. The resulting “y” is the
individual product’s total U-factor(tot) rating.

5.11.6 Validation
The baseline product option selected per Section 4.2.6 criteria shall
be modeled and shall be an option in the trendline.

5.11.7 Adding Individual Product Options to Existing Trendlines

A. Addition of new individual product options where the Ucog falls
inside an existing trendline’s endpoint range, shall be
permitted to use that existing trendline.
B. Addition of new individual product options where the Ucog falls
outside an existing trendline’s endpoint range, shall not use
that existing trendline and shall create a new trendline per
section 5.11.4.1 for new individual product options.

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6. REFERENCES

1) NFRC 102-2023: Procedure for Measuring the Steady-State Thermal

Transmittance of Fenestration Systems. National Fenestration Rating Council:
Greenbelt, MD; 2014. 197Hwww.nfrc.org.
2) NFRC THERM7 / WINDOW7 Simulation Manual. National Fenestration Rating
Council: Greenbelt, MD. www.nfrc.org.198H

3) List of Approved Simulation Computer Programs. National Fenestration Rating

Council: Greenbelt, MD. www.nfrc.org.19H

4) ASTM Standard C 1363, 2019, “Standard Test Method for the Thermal
Performance of Building Assemblies by Means of a Hot Box Apparatus,” ASTM
International, West Conshohocken, PA, 2005, DOI: 10.1520/C1363-11,
www.astm.org.
20H

5) ASTM SI10 – 02 IEEE, 2002, “American National Standard for use of the
International System of Units (SI): The Modern Metric System. (Replaces ASTM E
380), ASTM International, West Conshohocken, PA, 2002. www.astm.org.

6) ASTM Standard C 1036, 2006. “Standard Specification for Flat Glass,” ASTM
International, West Conshohocken, PA, 2006, DOI: 10.1520/C1036-06.
www.astm.org.
H

7) ASHRAE Handbook—Fundamentals American Society of Heating, Refrigerating,

and Air-Conditioning Engineers: Atlanta, GA, 2009. www.astm.org. 2

8) ANSI/DASMA 105-2017. Test Method for Thermal Transmittance and Air

Infiltration of Garage Doors. American National Standards Institute: West
Conshohocken, PA; Door & Access Systems Manufacturers’ Association:
Cleveland, OH, 2004. www.dasma.com www.ansi.org
203H 204H

9) ISO 15099. Thermal Performance of Windows, Doors and Shading Device-–

Detailed Calculations. International Organization for Standardization: Geneva,
Switzerland. www.iso.org. 2003.
205H

10) Curcija DC, Bhandari MS, Manteghi M, Shah BV. “Component Modeling
Methodology for Predicting Thermal Performance of Non-Residential Fenestration
Systems,” Thermal Performance of Building Envelopes IX, Clearwater, FL.
December 2004.

ANSI/NFRC 100-2023[E0A0] Page 118

© 2013, 2023. National Fenestration Rating Council Incorporated (NFRC). All rights reserved
11) NFRC 304-2023: Creating an Applied Film Layer in Optics for NFRC Certification.
National Fenestration Rating Council: Greenbelt, MD. www.nfrc.org. 206H

12) Curcija DC. “Proposed Methodology for Modeling Tubular Skylights for NFRC
Rating Purposes.” CEERE Technical Report. Center for Energy Efficiency &
Renewable Energy, University of Massachusetts Amherst. June 2001.
207Hwww.ceere.org

13) LBNL. Calculation of Optical Properties for a Venetian Blind Type of Shading
Device, October 20, 2006. Lawrence Berkeley National Laboratory, Berkeley, CA.
http://windows.lbl.gov/software/window/6/TechnicalDocs.html

14) LBNL. TARCOG: Mathematical Models for Calculation of Thermal Performance of

Glazing Systems with or without Shading Devices, October 17, 2006. Lawrence
Berkeley National Laboratory, Berkeley, CA.
http://windows.lbl.gov/software/window/6/TechnicalDocs.html

15) Vidanovic, S.; Kohler, C.J.; Curcija, D.C. "Optical Model of Fritted Glazing". LBNL
Technical Report. January 25, 2012. Berkeley, CA.
http://windows.lbl.gov/software/window/6/TechnicalDocs.html

16) Curcija, D.C.; Hart, R.G. "Modeling Thermal Performance of VIG: WINDOW and
THERM software tools". LBNL Technical Report. Berkeley, CA.
https://windows.lbl.gov/sites/default/files/software/WINDOW/Modeling Thermal
Performance of VIG_with Ref.pdf

17) Hart, R.H.; and Curcija, D.C. 2013. “Modeling of Vacuum Insulating Glazing.”
Proceedings of the Thermal Performance of the Exterior Envelopes of Whole
Buildings XII International Conference, Clearwater Beach, FL. December 2013.

18) NFRC 600: Glossary and Terminology. National Fenestration Rating Council:
Greenbelt, MD; 2014. 197Hwww.nfrc.org.

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APPENDIX A (NON-MANDATORY INFORMATION)
A.1 Determination of Project-Specific U-factors
The system U-factor ratings for project-specific U-factors shall be
determined by an NFRC-accredited simulation laboratory using NFRC-
approved software tools which utilizes components of the NFRC-certified
system, specifically with the frame, edge-of-glazing, and center-of-glazing
U-factors. Each component of the total system shall be assigned
percentages of the total product and the total system U-factor shall be
calculated using the procedures outlined in Section 4.6.3 and if applicable,
Section 5.11.
Note: Reference the contents of Section 5 of this document.

A.2 Determination of U-factors at Non-Standard Sizes

A U-factor-rating matrix that is size specific may be developed in
accordance with ANSI/NFRC 100 procedures and requirements. A matrix
shall only be developed for those product lines and individual products of a
product line that have been submitted to an NFRC-licensed independent
certification and Inspection Agency (IA) for certification authorization
purposes at the product size as defined in Table 4-3. Products that have
previously received certification authorization may also have a matrix
developed. Each matrix shall be specific to an individual product within a
product line.
The matrix shall include the standard rating size and sizes that are defined
by the manufacturer.
The fenestration thermal performance parameter ratings (i.e., U-factor,)
shall be determined by an NFRC-accredited simulation laboratory, using
NFRC-approved software tools, which utilizes components of the NFRC-
certified system, specifically with the frame, edge-of-glazing and center-of-
glazing thermal performance ratings, where applicable. Each component of
the total system shall be assigned percentages of the total product and the
total system thermal performance parameter shall be calculated using the
procedures outlined in Section 4.6.3 and if applicable, Section 5.11.
Note: Until such time that a certification change is made in the NFRC 700:
Product Certification Program, the thermal performance parameters that are
determined at sizes other than the product size in Table 4-3 are for
informational purposes only.

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 Table A-1 – Example U-factor Size Matrix
Example Only – Widths, Heights, and U-factors
Width (in.)

36 48 60 72 80 84 96 108 120

36 0.55 0.52 0.49 0.48 0.47 0.47 0.46 0.45 0.45

H 48 0.53 0.49 0.47 0.46 0.45 0.44 0.44 0.43 0.42
e 60 0.52 0.48 0.46 0.44 0.43 0.43 0.42 0.41 0.41
i 72 0.51 0.47 0.45 0.43 0.42 0.42 0.41 0.40 0.40
g 80 0.51 0.47 0.44 0.43 0.42 0.41 0.41 0.40 0.39
h 84 0.51 0.47 0.44 0.42 0.42 0.41 0.40 0.40 0.39
t 96 0.50 0.46 0.44 0.42 0.41 0.41 0.40 0.39 0.38
(in.) 108 0.50 0.46 0.43 0.42 0.41 0.40 0.39 0.39 0.38
120 0.50 0.46 0.43 0.41 0.40 0.40 0.39 0.38 0.38
Note: U-factor units in matrix above are Btu/hr-ft2-ºF

Shaded area indicates ANSI/NFRC 100 Standard Size for Certification and
Rating Purposes.
The values stated (other than the identified standard size) in the matrix
above are for informational purposes only and have not been authorize for
certification. The standard size rating is also shown on the label certificate to
which this matrix is attached. For additional information, contact the IA
stated on the label certificate.

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 A.3 Determination of Skylight U-factors at Non-Standard Slopes
A U-factor-rating matrix that is slope-specific may be developed in
accordance with ANSI/NFRC 100 procedures and requirements. A matrix
shall only be developed for those product lines and individual products of a
product line that have been submitted to an NFRC-licensed independent
certification and Inspection Agency (IA) for certification authorization
purposes at the standard 20° slope from horizontal. Products that have
previously received certification authorization may also have a matrix
developed. Each matrix shall be specific to an individual product and glazing
type within a product line.
The matrix shall include the standard slope rating and ratings at other
slopes that are defined by the manufacturer.
Calculation shall use the following Convective Surface Heat Transfer
Coefficients, for any of the listed slopes:

Table A-2: Convective Surface Heat Transfer Coefficients, hc, in for Skylights at
Different Incidence Angles (W/m2∙ºK)

Frame Angle of Incidence from Horizontal (degrees)

Type 0 10 15 20 30 45 60 70 85 90
Wood/
Vinyl 3.147 3.147 3.095 3.090 3.042 2.798 2.357 2.405 2.441 2.443
T/B Al 4.147 4.147 4.096 4.091 4.043 3.801 3.088 2.953 2.997 2.999
TI Al 4.373 4.373 4.322 4.317 4.270 4.029 3.316 3.071 3.117 3.120
Al 4.710 4.710 4.659 4.654 4.606 4.366 3.657 3.244 3.292 3.295

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 Table A-3: Convective Surface Heat Transfer Coefficients, hc, in for Skylights at
Different Incidence Angles (Btu/hr2∙ft2∙ºF)

Frame Angle of Incidence from Horizontal (degrees)

Type 0 10 15 20 30 45 60 70 85 90
Wood/
Vinyl 0.554 0.554 0.545 0.544 0.536 0.493 0.415 0.424 0.430 0.430
T/B Al 0.730 0.730 0.721 0.720 0.712 0.670 0.544 0.520 0.528 0.528
TI Al 0.770 0.770 0.761 0.760 0.752 0.710 0.584 0.541 0.549 0.549
Al 0.829 0.829 0.821 0.820 0.811 0.769 0.644 0.571 0.580 0.580
Coefficients for any slopes not listed can be calculated using linear
interpolation between the two closest angles.

Skylights that are approved for use at slopes within 15° of vertical under the
manufacturer’s standard instructions may be entitled to dual U-factor ratings. Consult
with the NFRC-licensed independent certification and Inspection Agency (IA) for further
determination.
Note: Until such time that a certification change is made in the NFRC 700:
Product Certification Program, the thermal performance parameters that are
determined at slopes other than the standard slope are for informational
purposes only.

Table A-4: Skylight U-factors Slope Table (Example Only)

Roof Slope (degrees above horizontal)

0 15 20 40 60 75 85
U-Factor 0.52 0.50 0.49 0.47 0.45 0.43 0.42

Shaded column indicates ANSI/NFRC 100 standard slope ratings for certification
purposes.
The values stated (other than the identified standard ratings) in the matrix above
are for informational purposes only and have not been authorized for certification.
The standard slope ratings are also shown on the label or certificate to which this
matrix is attached. For additional information, contact the IA stated on the label
certificate.

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 A.4 Determination of U-factors for Dynamic Glazing Products at additional
slat angles
Determination of U-factors for Dynamic Glazing Products with slatted blinds
between glass shall be permitted at slat tilt angles other than Fully
ON/CLOSED and Fully OFF/OPEN. Additional slat angles of -45º and +45º
shall also be permitted as optional ratings that may be added to the CPD.
See figure below for angle descriptions.

Outdoor
Indoor

Positive tilt angle shown

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 Door
Composite .................................. 71, 73
INDEX Garage ........................... 100, 101, 103
leaf ................................................... 10
Sliding Glass .................................... 58
Wood .......................................... 75, 80
A dual action window........................... 11
Dynamic Attachment ...................... 108
Accreditation Program ........................ ii
Dynamic Glazing .............................. 26
air .................................................... 16
Dynamic Glazing Product ................ 26
Air Leakage .................................... i, ii
Area............ 59, 94, 100, 101, 116, 117 E
Projected Fenestration Product Area 52 Emissivity ......................................... 12
Assembler ......................................... 6
Attachment ...................................... 95 F
B Fenestration 23, 34, 39, 42, 46, 47, 48,
51, 54, 130, 139, 147
Base Profile ............................... 30, 34 Film ........................................ 138, 146
baseline product ................................ 7 frame................................................ 12
Baseline Product ............................. 42 Frame27, 28, 30, 34, 71, 73, 77, 79, 83,
Bead ................................................ 28 84, 85, 86, 87, 89, 126, 128, 129, 130,
Blackbody.......................................... 7 131, 132
C G
Calibration Transfer Standard ........... 7 glass ................................................ 13
caming............................................... 8 Glass.............................................. 122
Caming ...................................... 33, 34 Glazing28, 34, 47, 48, 69, 70, 109, 130
CAP .................................................... ii Sloped ............................................ 130
CAR.................................................... ii glazing/glazing in-fill ......................... 13
Center-of-Glazing ..32, 34, 43, 47, 132, greenhouse/garden window ............. 14
138, 139, 146, 147 Group Leader ........... 34, 127, 128, 129
Certified Products Directory ............... ii grouping ........................................... 14
cladding ............................................. 8 Grouping .............................. 32, 34, 35
Cladding ........................................ 129
Compliance and Monitoring Program . ii H
Condensation Resistance ................... i Head ................................................ 80
CR ...................................................... ii horizontal sliding window ................. 14
CTS ................................................... 7 Hybrid Tubular Daylighting Device ... 96
Curb ................................................ 92
curtain wall ........................................ 9 I
Curtain Wall................................... 106 IA v
D Independent Certification and Inspection
Agency
decorative panel ................................ 9 IA i, ii
Diffuse ............................................... 9 Individual Product23, 26, 28, 29, 34, 58,
divider.............................................. 10 61, 62, 92, 93, 97, 106, 113, 132, 148
Divider ...................... 34, 37, 56, 69, 70

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Insulating Glass Unit ....................... 37 Representative Size ................... 23, 24
Responsible Party .............................. 8
J
roof window ...................................... 22
Jamb ............................................... 80
S
L
sash ................................................. 17
Laboratory Accreditation Program ... i, ii Sash..................................... 27, 30, 34
LAP .................................................. i, ii Sealant..................................... 17, 125
Lite ............................................ 15, 83 Sidelite
M Slab .................................................. 62
sight line........................................... 18
Model Size ...........................44, 45, 46 Sightline ............................... 28, 41, 49
Mullion Sill .............................................. 62, 81
Integral........................................... 131 site-Built Products ............................ 18
N Slab.................................................. 62
sliding glass door ............................. 18
NFRC Label ................................... ii, 8 sloped glazing .................................. 19
O Spacer ..................................... 35, 123
Spandrel .......................... 45, 120, 130
OAVA .............................................. 16
Sunroom ........................................ 107
obscure glass .................................. 16
sunroom/solarium ............................ 19
opaque in-fill systems ...................... 16
surface heat transfer coefficient ....... 20
Operator Type ........................106, 131
outdoor air ventilator assembly ....... 16 T
P Temporary Label ................................ v
Thermal Conductivity ....................... 20
panel area ......................................... 5
thermal transmittance ...................... 21
panel insert........................................ 9
Thermal Transmittance .......... 107, 130
PCP ................................................. 15
thermally broken (TB) members....... 20
Product Certification Authorization .... 8
thermally improved (TI) members .... 20
Product Certification Program . i, ii, 155
total fenestration product area ........... 6
PCP ................................................. i, ii
transom ............................................ 21
Product Line 16, 23, 26, 28, 30, 34, 39,
tubular daylighting device ................ 21
58, 60, 61, 91, 92, 96, 106, 113, 123,
Tubular Daylighting Device .. 92, 94, 95
130, 131, 132
Product Type ......................30, 45, 130 U
R U-factor
Center-of-glazing .............. 34, 138, 146
Radiation ......................................... 16
Total Fenestration Product 34, 46, 137,
Rating25, 26, 37, 58, 64, 92, 95, 97, 108,
145
114, 130, 131, 134, 151, 154
Rating System ........................... i, ii, 17 V
Reference fenestration product ....... 17 validation matrix ............................... 22
Reference Fenestration Product ... 134 Validation Testing .......................... 123
Reference frame ............................. 17 vertical sliding window ..................... 22
Reference glazing system ............... 17 Visible Transmittance.......................... i
representative size .......................... 17

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 VT .................................................... i, ii Window .......................... 106, 135, 143
Fixed ...................................... 134, 141
W
Wall ................................................ 106
Weatherstrip .................................... 23 Wood ........................... 73, 75, 80, 129

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