ASTM C1363-24
(Test Method)Standard Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus
Standard Test Method for Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus
SIGNIFICANCE AND USE
5.1 A need exists for accurate data on heat transfer through insulated structures at representative test conditions. The data are needed to judge compliance with specifications and regulations, for design guidance, for research evaluations of the effect of changes in materials or constructions, and for verification of, or use in, simulation models. Other ASTM standards such as Test Methods C177 and C518 provide data on homogeneous specimens bounded by temperature controlled flat impervious plates. The hot box test method is more suitable for providing such data for large building elements, usually of a built-up or composite nature, which are exposed to temperature-controlled air on both sides.
5.2 For the results to be representative of a building construction, only representative sections shall be tested. The test specimen shall duplicate the framing geometry, material composition and installation practice, and orientation of construction (see Section 7).
5.3 This test method does not establish test conditions, specimen configuration, or data acquisition details but leaves these choices to be made in a manner consistent with the specific application being considered. Data obtained by the use of this test method is representative of the specimen performance only for the conditions of the test. It is unlikely that the test conditions will exactly duplicate in-use conditions and the user of the test results must be cautioned of possible significant differences. For example, in some specimens, especially those containing empty cavities or cavities open to one surface, the overall resistance or transmittance will depend upon the temperature difference across the test specimen due to internal convection.
5.4 Detailed heat flow analysis shall precede the use of the hot box apparatus for large, complex structures. A structure that contains cavity spaces between adjacent surfaces, for example, an attic section including a ceiling with sloping roof, may be difficult...
SCOPE
1.1 This test method establishes the principles for the design of a hot box apparatus and the minimum requirements for the determination of the steady state thermal performance of building assemblies when exposed to controlled laboratory conditions. This method is also used to measure the thermal performance of a building material at standardized test conditions such as those required in material Specifications C739, C764, C1224 and Practice C1373.
1.2 This test method is used for large homogeneous or non-homogeneous specimens. This test method applies to building structures or composite assemblies of building materials for which it is possible to build a representative specimen that fits the test apparatus. The dimensions of specimen projections or recesses are controlled by the design of the hot box apparatus. Some hot boxes are limited to planar or nearly planar specimens. However, larger hot boxes have been used to characterize projecting skylights and attic sections. See 3.2 for a definition of the test specimen and other terms specific to this method.
Note 1: This test method replaces Test Methods C236, the Guarded Hot Box, and C976, the Calibrated Hot Box which have been withdrawn. Test apparatus designed and operated previously under Test Methods C236 and C976 will require slight modifications to the calibration and operational procedures to meet the requirements of Test Method C1363.2
1.3 A properly designed and operated hot box apparatus is directly analogous to the Test Method C177 guarded hot plate for testing large specimens exposed to air induced temperature differences. The operation of a hot box apparatus requires a significant number of fundamental measurements of temperatures, areas and power. The equipment performing these measurements requires calibration to ensure that the data are accurate. During initial setup and periodic verification testing, each measurement system and sensor is calibrat...
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C1363 − 24
Standard Test Method for
Thermal Performance of Building Materials and Envelope
1
Assemblies by Means of a Hot Box Apparatus
This standard is issued under the fixed designation C1363; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope against a standard traceable to a national standards laboratory.
If the hot box apparatus has been designed, constructed and
1.1 This test method establishes the principles for the design
operated in the ideal manner, no further calibration or adjust-
of a hot box apparatus and the minimum requirements for the
ment would be necessary. As such, the hot box is considered a
determination of the steady state thermal performance of
primary method and the uncertainty of the result is analyzed by
building assemblies when exposed to controlled laboratory
direct evaluation of the component measurement uncertainties
conditions. This method is also used to measure the thermal
of the instrumentation used in making the measurements.
performance of a building material at standardized test condi-
1.3.1 In an ideal hotbox test of a homogenous material there
tions such as those required in material Specifications C739,
is no temperature difference on either the warm or cold
C764, C1224 and Practice C1373.
specimen faces to drive a flanking heat flow. In addition, there
1.2 This test method is used for large homogeneous or
would be no temperature differences that would drive heat
non-homogeneous specimens. This test method applies to
across the boundary of the metering chamber walls. However,
building structures or composite assemblies of building mate-
experience has demonstrated that maintaining a perfect guard/
rials for which it is possible to build a representative specimen
metering chamber balance is not possible and small corrections
that fits the test apparatus. The dimensions of specimen
are needed to accurately characterize all the heat flow paths
projections or recesses are controlled by the design of the hot
from the metering chamber. To gain this final confidence in the
box apparatus. Some hot boxes are limited to planar or nearly
test result, it is necessary to benchmark the overall result of the
planar specimens. However, larger hot boxes have been used to
hot box apparatus by performing measurements on specimens
characterize projecting skylights and attic sections. See 3.2 for
having known heat transfer values and comparing those results
a definition of the test specimen and other terms specific to this
to the expected values.
method.
1.3.2 The benchmarking specimens are homogeneous pan-
NOTE 1—This test method replaces Test Methods C236, the Guarded
els whose thermal properties are uniform and predictable.
Hot Box, and C976, the Calibrated Hot Box which have been withdrawn.
These panels, or representative sections of the panels, have had
Test apparatus designed and operated previously under Test Methods
their thermal performance measured on other devices that are
C236 and C976 will require slight modifications to the calibration and
2
operational procedures to meet the requirements of Test Method C1363. directly traceable or have been favorably compared to a
national standards laboratory. For example, a Test Method
1.3 A properly designed and operated hot box apparatus is
C177 Hot Plate, a Test Method C518 Heat Meter or another
directly analogous to the Test Method C177 guarded hot plate
Test Method C1363 Hot Box will provide adequate specimens.
for testing large specimens exposed to air induced temperature
Note that the use of Test Method C518 or similar apparatus
differences. The operation of a hot box apparatus requires a
creates additional uncertainty since those devices are calibrated
significant number of fundamental measurements of
using transfer standards or standard reference materials. By
temperatures, areas and power. The equipment performing
performing this benchmarking process, the hot box operator is
these measurements requires calibration to ensure that the data
able to develop the additional equations that predict the
are accurate. During initial setup and periodic verification
magnitude of the corrections to the net heat flow through the
testing, each measurement system and sensor is calibrated
specimen that account for any hot box wall loss and flanking
loss. This benchmarking provides substantial confidence that
1
This test method is under the jurisdiction of ASTM Committee C16 on
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C1363 − 19 C1363 − 24
Standard Test Method for
Thermal Performance of Building Materials and Envelope
1
Assemblies by Means of a Hot Box Apparatus
This standard is issued under the fixed designation C1363; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method establishes the principles for the design of a hot box apparatus and the minimum requirements for the
determination of the steady state thermal performance of building assemblies when exposed to controlled laboratory conditions.
This method is also used to measure the thermal performance of a building material at standardized test conditions such as those
required in material Specifications C739, C764, C1224 and Practice C1373.
1.2 This test method is used for large homogeneous or non-homogeneous specimens. This test method applies to building
structures or composite assemblies of building materials for which it is possible to build a representative specimen that fits the test
apparatus. The dimensions of specimen projections or recesses are controlled by the design of the hot box apparatus. Some hot
boxes are limited to planar or nearly planar specimens. However, larger hot boxes have been used to characterize projecting
skylights and attic sections. See 3.2 for a definition of the test specimen and other terms specific to this method.
NOTE 1—This test method replaces Test Methods C236, the Guarded Hot Box, and C976, the Calibrated Hot Box which have been withdrawn. Test
apparatus designed and operated previously under Test Methods C236 and C976 will require slight modifications to the calibration and operational
2
procedures to meet the requirements of Test Method C1363.
1.3 A properly designed and operated hot box apparatus is directly analogous to the Test Method C177 guarded hot plate for
testing large specimens exposed to air induced temperature differences. The operation of a hot box apparatus requires a significant
number of fundamental measurements of temperatures, areas and power. The equipment performing these measurements requires
calibration to ensure that the data are accurate. During initial setup and periodic verification testing, each measurement system and
sensor is calibrated against a standard traceable to a national standards laboratory. If the hot box apparatus has been designed,
constructed and operated in the ideal manner, no further calibration or adjustment would be necessary. As such, the hot box is
considered a primary method and the uncertainty of the result is analyzed by direct evaluation of the component measurement
uncertainties of the instrumentation used in making the measurements.
1.3.1 In an ideal hotbox test of a homogenous material there is no temperature difference on either the warm or cold specimen
faces to drive a flanking heat flow. In addition, there would be no temperature differences that would drive heat across the boundary
of the metering chamber walls. However, experience has demonstrated that maintaining a perfect guard/metering chamber balance
is not possible and small corrections are needed to accurately characterize all the heat flow paths from the metering chamber. To
gain this final confidence in the test result, it is necessary to benchmark the overall result of the hot box apparatus by performing
measurements on specimens having known heat transfer values and comparing those results to the expected values.
1
This test method is under the jurisdiction of ASTM Committee C16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.30 on Thermal
Measurement.
Current edition approved Sept. 1, 2019March 1, 2024. Published September 2019March 2024. Originally approved in 1997. Last previous edition approved in 20112019
as C1363 – 11.C1363 – 19. DOI: 10.1520/C1363-19.10.1520/C1363-24.
2
Footnotes in the text are supplied to clarify the discussion only, and as such, are not mandatory.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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C1363 − 24
1.3.2 The benchmarking specimens are homogeneous panels whose thermal properties are uniform and predictable. These panels,
or representative sections of the panels, have had their thermal performance measured on ot
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