ASTM E1423 - 14

    Standard Practice for Determining Steady State Thermal Transmittance of Fenestration Systems

    Active Standard ASTM E1423 | Developed by Subcommittee: E06.51

    Book of Standards Volume: 04.11


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    Significance and Use

    4.1 This practice details the test specimen sizes and test conditions, namely, the room-side and weather-side air temperatures, and the surface heat transfer coefficients for both sides of the test specimen, when testing fenestration products in accordance with Test Method C1199.

    4.2 The thermal transmittance and conductance of a specimen are affected by its size and three-dimensional geometry. Tests should therefore be conducted using the specimen sizes recommended in 5.1. Should the specimen size differ from those given in 5.1, the actual size shall be reported in the test report.

    4.3 Many factors can affect the thermal performance of a fenestration system, including deflections of sealed glazing units. Care should be exercised to maintain the original physical condition of the fenestration system and while installing it in the surround panel.

    4.4 The thermal transmittance and conductance results obtained do not, and are not intended, to reflect performances expected from field installations since they do not account for solar radiation and air leakage effects. The thermal transmittance and conductance results are taken from specified laboratory conditions and are to be used only for fenestration product comparisons and as input to thermal performance analyses that also include solar and air leakage effects.

    1. Scope

    1.1 This practice covers standard test specimen sizes and test conditions as well as the calculation and presentation of the thermal transmittance and conductance data measured in accordance with Test Method C1199. The standard sizes and conditions are to be used for fenestration product comparison purposes. The specifier may choose other sizes and conditions for product development or research purposes.

    1.2 This practice deals with the determination of the thermal properties of a fenestration system installed vertically without the influences of solar heat gain and air leakage effects.

    Note 1To determine air leakage effects of fenestration systems, Test Method E283 or E1424 should be referenced.
    Note 2See Appendix Appendix X1 regarding garage doors and rolling doors.

    1.3 This practice specifies the procedure for determining the standardized thermal transmittance of a fenestration test specimen using specified values of the room-side and weather-side surface heat transfer coefficients, hh and hc, respectively.

    1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

    1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    C168 Terminology Relating to Thermal Insulation

    C1199 Test Method for Measuring the Steady-State Thermal Transmittance of Fenestration Systems Using Hot Box Methods

    C1363 Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus

    E283 Test Method for Determining Rate of Air Leakage Through Exterior Windows, Curtain Walls, and Doors Under Specified Pressure Differences Across the Specimen

    E631 Terminology of Building Constructions

    E783 Test Method for Field Measurement of Air Leakage Through Installed Exterior Windows and Doors

    E1424 Test Method for Determining the Rate of Air Leakage Through Exterior Windows, Curtain Walls, and Doors Under Specified Pressure and Temperature Differences Across the Specimen

    Other Documents

    NFRC102-2002 Available from National Fenestration Rating Council, 1300 Spring Street, Suite 500, Silver Spring, MD 20910.


    ICS Code

    ICS Number Code 91.060.50 (Doors and windows); 91.120.10 (Thermal insulation of buildings)

    UNSPSC Code

    UNSPSC Code 30140000(Insulation)


    DOI: 10.1520/E1423

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