ASTM F1291-22

Standard Test Method for Measuring the Thermal Insulation of Clothing Using a Heated Manikin

SIGNIFICANCE AND USE
4.1 This test method can be used to quantify and compare the insulation provided by different clothing systems. For example, variations in the design and fabric used in component garments can be evaluated. The effects of garment layering, closure, and fit can be measured for clothing ensembles. The insulation values for ensembles can be used in models that predict the physiological responses of people in different environmental conditions. Garment insulation values can be compared as well (see Annex A1).  
4.2 The measurement of the insulation provided by clothing is complex and dependent on the apparatus and techniques used. It is not practical in a test method of this scope to establish details sufficient to cover all contingencies. Departures from the instructions in this test method have the potential to lead to significantly different test results. Technical knowledge concerning the theory of heat transfer, temperature and air motion measurement, and testing practices is needed to evaluate which departures from the instructions given in this test method are significant. Standardization of the method reduces, but does not eliminate, the need for such technical knowledge. Report any departures with the results.  
4.3 Report the insulation values in SI units or clo units as standard procedure. Conversion factors to other units are given in Test Method D1518.
SCOPE
1.1 This test method covers the determination of the insulation value of clothing ensembles. It describes the measurement of the resistance to dry heat transfer from a heated manikin to a relatively calm, cool environment. Information on measuring the local thermal resistance values for individual garments and ensembles is provided in Annex A1.  
1.1.1 This is a static test that provides a baseline clothing measurement on a standing manikin.  
1.1.2 The effects of body position and movement are not addressed in this test method.  
1.2 The insulation values obtained apply only to the particular ensembles evaluated and for the specified environmental conditions of each test, particularly with respect to air movement.  
1.3 The values stated in either clo or SI units are to be regarded separately as standard. Each system shall be used independently of the other. The thermal resistance units, clo or SI, shall be identified clearly and consistency of units shall be maintained throughout reporting process.  
1.4 The evaporative resistance of a clothing ensemble can be measured in accordance with Test Method F2370.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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.

General Information

• Status: Published
• Publication Date: 30-Jun-2022
• ICS: 61.020 - Clothes
• Technical Committee: F23 - Personal Protective Clothing and Equipment
• Drafting Committee: F23.60 - Human Factors

Relations

• Refers: ASTM F2370-15 - Standard Test Method for Measuring the Evaporative Resistance of Clothing Using a Sweating Manikin
• Effective Date: 01-Nov-2015
• Refers: ASTM E691-13 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-May-2013
• Refers: ASTM E691-11 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2011
• Refers: ASTM D1518-11a - Standard Test Method for Thermal Resistance of Batting Systems Using a Hot Plate
• Effective Date: 01-Jul-2011
• Refers: ASTM F2732-11 - Standard Practice for Determining the Temperature Ratings for Cold Weather Protective Clothing
• Effective Date: 01-Jun-2011
• Refers: ASTM D1518-11 - Standard Test Method for Thermal Resistance of Batting Systems Using a Hot Plate
• Effective Date: 01-Jan-2011
• Refers: ASTM F2370-10 - Standard Test Method for Measuring the Evaporative Resistance of Clothing Using a Sweating Manikin
• Effective Date: 01-Jan-2010
• Refers: ASTM F2732-09 - Standard Practice for Determining the Temperature Ratings for Cold Weather Protective Clothing
• Effective Date: 15-May-2009
• Refers: ASTM E691-08 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Oct-2008
• Refers: ASTM E691-05 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 01-Nov-2005
• Refers: ASTM F2370-05 - Standard Test Method for Measuring the Evaporative Resistance of Clothing Using a Sweating Manikin
• Effective Date: 15-Sep-2005
• Refers: ASTM E691-99 - Standard Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
• Effective Date: 10-May-1999
• Refers: ASTM D1518-85(1998)e1 - Standard Test Method for Thermal Transmittance of Textile Materials
• Effective Date: 10-Jun-1998
• Refers: ASTM D1518-85(2003) - Standard Test Method for Thermal Transmittance of Textile Materials
• Effective Date: 26-Jul-1985

Overview

ASTM F1291-22 is a critical standard test method developed by ASTM International for measuring the thermal insulation of clothing using a heated manikin. This standard provides a reliable laboratory procedure to evaluate and compare the thermal resistance of complete clothing ensembles under controlled conditions. By quantifying how effectively garments insulate a standing manikin in a calm, cool environment, ASTM F1291-22 helps organizations select suitable clothing systems, optimize garment design, and ensure wearer comfort for various environmental settings.

Key Topics

• Thermal Resistance Measurement: Establishes a static method for determining the resistance to dry heat transfer from a heated manikin to the surrounding environment.
• Clothing Systems Evaluation: Allows assessment of clothing ensembles, considering garment layering, closure systems, fit, and design variations.
• Reporting Units: Insulation values are reported in both SI units (such as °C·m²/W) and clo units, supporting global consistency.
• Standardized Conditions: Specifies the requirements for manikin construction, calibration, environmental chamber conditions, and specimen preparation to ensure repeatability and comparability.
• Test Limitations: This method is specific to standing (static) conditions and does not account for dynamic effects such as body movement or changes in posture.
• Data Interpretation: Allows analysis at both ensemble and localized body zone levels, improving understanding of insulation distribution.

Applications

ASTM F1291-22 is widely used across various industries, including:

• Protective Clothing Design: Guides the development and comparative evaluation of workwear, firefighter suits, military uniforms, and chemical protective gear to ensure adequate thermal protection.
• Occupational Health & Safety: Helps employers select appropriate personal protective equipment (PPE) for workers in cold or thermally challenging environments based on insulation performance.
• Comfort and Performance Predictions: Supports the modeling of human physiological responses to environmental exposure, aiding in the prediction of thermal comfort or stress for users.
• Quality Assurance: Offers manufacturers and testing laboratories a uniform method for validating claims about clothing insulation and for research and development of new textile solutions.
• Regulatory Compliance: Assists organizations in meeting thermal insulation requirements specified by government or industry regulations for occupational safety.

Related Standards

For broader or complementary measurements, ASTM F1291-22 references and aligns with several other influential standards and guidelines, including:

• ASTM D1518: Standard Test Method for Thermal Resistance of Batting Systems Using a Hot Plate, important for material-level insulation evaluation.
• ASTM F2370: Standard Test Method for Measuring the Evaporative Resistance of Clothing Using a Sweating Manikin, addressing moisture management.
• ASTM F2732: Practice for Determining the Temperature Ratings for Cold Weather Protective Clothing, useful for predicting the protective range of garments.
• ASHRAE 55-2013: Thermal Environmental Conditions for Human Occupancy, an industry recognized standard for thermal comfort conditions.
• ISO 7730:2005: Moderate Thermal Environments - Determination of the PMV and PPD Indices, supporting global practices for evaluating comfort.
• ISO 9920:2007: Ergonomics of the Thermal Environment - Estimation of the Thermal Insulation and Evaporation Resistance of a Clothing Ensemble.

Keywords: ASTM F1291-22, clothing insulation, thermal resistance, heated manikin, protective clothing, garment thermal testing, standard test method, thermal comfort, personal protective equipment, SI units, clo units.

Standards Content (Sample)

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: F1291 − 22
Standard Test Method for
Measuring the Thermal Insulation of Clothing Using a
Heated Manikin
This standard is issued under the fixed designation F1291; 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.
INTRODUCTION
Thetypeofclothingwornbypeopledirectlyaffectstheheatexchangebetweenthehumanbodyand
the environment. The heat transfer is both sensible (conduction, convection, and radiation) and latent
(evaporation). The insulation provided by a clothing ensemble is dependent upon the designs and
materials used in the component garments, the amount of body surface area covered by the clothing,
the distribution of the layers over the body, looseness or tightness of fit, and the increased surface area
for heat loss. Insulation measurements made on fabrics alone do not take these factors into account.
Measurements of the resistance to dry heat loss provided by clothing can be used to determine the
thermal comfort or stress of people in a variety of environments (see Practice F2732, ASHRAE 55-
2013, and ISO 7730:2005). However, the moisture permeability of clothing is more important in
environmental conditions where heat balance can only be achieved by the evaporation of sweat.
1. Scope 1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This test method covers the determination of the insu-
responsibility of the user of this standard to establish appro-
lation value of clothing ensembles. It describes the measure-
priate safety, health, and environmental practices and deter-
ment of the resistance to dry heat transfer from a heated
mine the applicability of regulatory limitations prior to use.
manikin to a relatively calm, cool environment. Information on
1.6 This international standard was developed in accor-
measuring the local thermal resistance values for individual
dance with internationally recognized principles on standard-
garments and ensembles is provided in Annex A1.
ization established in the Decision on Principles for the
1.1.1 This is a static test that provides a baseline clothing
Development of International Standards, Guides and Recom-
measurement on a standing manikin.
mendations issued by the World Trade Organization Technical
1.1.2 The effects of body position and movement are not
Barriers to Trade (TBT) Committee.
addressed in this test method.
1.2 The insulation values obtained apply only to the par-
2. Referenced Documents
ticular ensembles evaluated and for the specified environmen-
2.1 ASTM Standards:
tal conditions of each test, particularly with respect to air
D1518 Test Method for Thermal Resistance of Batting
movement.
Systems Using a Hot Plate
1.3 The values stated in either clo or SI units are to be
E691 Practice for Conducting an Interlaboratory Study to
regarded separately as standard. Each system shall be used
Determine the Precision of a Test Method
independently of the other. The thermal resistance units, clo or
F2370 Test Method for Measuring the Evaporative Resis-
SI, shall be identified clearly and consistency of units shall be
tance of Clothing Using a Sweating Manikin
maintained throughout reporting process.
F2732 Practice for Determining the Temperature Ratings for
Cold Weather Protective Clothing
1.4 The evaporative resistance of a clothing ensemble can
be measured in accordance with Test Method F2370.
This test method is under the jurisdiction ofASTM Committee F23 on Personal
Protective Clothing and Equipment and is the direct responsibility of Subcommittee
F23.60 on Human Factors. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved July 1, 2022. Published August 2022. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1990. Last previous edition approved in 2016 as F1291 – 16. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/F1291-22. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1291 − 22
2.2 ASHRAE Standards: closure, and fit can be measured for clothing ensembles. The
ASHRAE 55-2013 Thermal Environmental Conditions for insulation values for ensembles can be used in models that
Human Occupancy predict the physiological responses of people in different
2.3 ISO Standards: environmental conditions. Garment insulation values can be
compared as well (see Annex A1).
ISO 7730:2005 Moderate Thermal Environments—
Determination of the PMV and PPD Indices and Specifi-
4.2 The measurement of the insulation provided by clothing
cation of the Conditions for Thermal Comfort
is complex and dependent on the apparatus and techniques
ISO 9920:2007 Ergonomics of the Thermal Environment—
used. It is not practical in a test method of this scope to
Estimation of the Thermal Insulation and Evaporation
establish details sufficient to cover all contingencies. Depar-
Resistance of a Clothing Ensemble
turesfromtheinstructionsinthistestmethodhavethepotential
to lead to significantly different test results. Technical knowl-
3. Terminology
edgeconcerningthetheoryofheattransfer,temperatureandair
3.1 Definitions:
motion measurement, and testing practices is needed to evalu-
3.1.1 clo, n—unit of thermal resistance (insulation) equal to
ate which departures from the instructions given in this test
0.155 K m /W.
method are significant. Standardization of the method reduces,
but does not eliminate, the need for such technical knowledge.
3.1.1.1 Discussion—The value of the clo was selected as
Report any departures with the results.
roughly the insulation value of typical indoor clothing, which
should keep a resting person (producing heat at the rate of 4.3 Report the insulation values in SI units or clo units as
58 W⁄m ) comfortable in an environment at 21 °C, air move- standard procedure. Conversion factors to other units are given
ment 0.1 m/s.When clo was developed, typical indoor clothing in Test Method D1518.
consisted of a three-piece suit and light underclothes.
5. Apparatus
3.1.2 clothing area factor (f ), n—the ratio of the surface
cl
area of the clothed body to the surface area of the nude body.
5.1 Manikin—A standing manikin shall be used that is
3.1.3 clothing ensemble, n—a group of garments worn formed in the shape and size of an adult male or female and
together on the body at the same time. heated to a constant average skin temperature.
5.1.1 Size and Shape—The manikin shall be constructed to
3.1.4 thermal insulation, n—the resistance to dry heat trans-
simulate the body of a human being; that is, it shall consist of
fer via conduction, convection, and radiation.
a head, chest/back, abdomen/buttocks, arms, hands (preferably
3.1.4.1 Discussion—The following insulation values are
with fingers extended to allow gloves to be worn), legs, and
determined in this method:
feet. Total surface area shall be 1.8 6 0.3 m , and height shall
be170 610cm.Themanikin’sdimensionsshallcorrespondto
R = thermal resistance (insulation) of the air layer on the
those required for standard sizes of garments because devia-
a
surface of the nude manikin, tions in fit will affect the results.
R = total thermal resistance (insulation) of the clothing
5.1.2 Surface Temperature—The manikin shall be con-
t
ensembleandsurfaceairlayeraroundthemanikin,and
structed so as to maintain a uniform temperature distribution
R = intrinsic thermal resistance (insulation) of the clothing
cl overthenudebodysurface,withnolocalhotorcoldspots.The
ensemble.
mean surface (skin) temperature of the manikin shall be 35 °C.
Local deviations from the mean skin temperature shall not
R , R, and R are typically used for SI units, while I , I,
a t cl a t
exceed 60.5 °C. Temperature uniformity of the nude manikin
and I are typically used with clo units.
cl
shall be evaluated at least once annually using an infrared
Total insulation values are measured directly with a
thermal imaging system or equivalent method. This procedure
manikin. Intrinsic clothing insulation values are determined
shall also be repeated after repairs or alterations are completed
by subtracting the air layer resistance around the clothed
that could affect temperature uniformity, for example, replace-
manikin from the total insulation value for the ensemble.
ment of a heating element.
Intrinsic clothing insulation values are used in several
thermal comfort and clothing standards (see 2.1, 2.2, and
5.2 Power-Measuring Instruments—Power to the manikin
2.3).
shall be measured so as to give an average over the period of
a test. If time proportioning or phase proportioning is used for
4. Significance and Use
power control, then devices that are capable of averaging over
4.1 This test method can be used to quantify and compare
the control cycle are required. Integrating devices (watt-hour
the insulation provided by different clothing systems. For
meters) are preferred over instantaneous devices (watt meters).
example, variations in the design and fabric used in component
Overall accuracy of the power monitoring equipment must be
garments can be evaluated. The effects of garment layering,
within 62 % of the reading for the average power for the test
period.Sincethereareavarietyofdevicesandtechniquesused
Available from American Society of Heating, Refrigerating, and Air-
Conditioning Engineers, Inc. (ASHRAE), 1791 Tullie Circle, NE, Atlanta, GA
30329, http://www.ashrae.org. Information on laboratories with thermal manikins can be obtained from the
Available from American National Standards Institute (ANSI), 25 W. 43rd St., Institute for Environmental Research, Kansas State University, Manhattan, KS
4th Floor, New York, NY 10036, http://www.ansi.org. 66506.
F1291 − 22
for power measurement, no specified calibration procedures 60.15 °C is acceptable (for example, RTD, thermocouple,
shall be given. However, an appropriate power calibration thermistor). The sensor shall have a time constant not exceed-
procedure is to be developed and documented. ing 1 min.The sensor(s) shall be 0.5 m in front of the manikin.
If a single sensor is used it shall be 1.0 m above the floor. If
5.3 Equipment for Measuring the Manikin’s Surface (Skin)
multiple sensors are used, they shall be spaced at equal height
Temperature—The mean surface temperature shall be mea-
intervals and their readings averaged.
sured with point sensors or distributed temperature sensors.
5.4.5 Air Velocity Indicator—An omnidirectional anemom-
5.3.1 Point Sensors—Point sensors shall be thermocouples,
eter with 60.05 m/s accuracy shall be used. Measurements
resistance temperature devices (RTDs), thermistors, or equiva-
shall be averaged for at least 1 min at each location. If it is
lent sensors. They shall be no more than 2 mm thick and shall
demonstrated that velocity does not vary temporally by more
be well bonded, both mechanically and thermally, to the
than 60.05 m/s, then it is not necessary to monitor air velocity
manikin’s surface. Lead wires shall be bonded to the surface or
during a test. The value of the mean air velocity must be
pass through the interior of the manikin, or both. Each sensor
reported, however. If air velocity is monitored, then measure-
temperature shall be area-weighted when calculating the mean
ment location requirements are the same as for temperature.
skin temperature for the body. If point sensors are used, a
minimum of 17 point sensors are required.At least one sensor
6. Sampling and Test Specimens
shall be placed on the head, chest, back, abdomen, buttocks,
and both the right and left upper arm, lower arm, hand, thigh, 6.1 Sampling—It is desirable to test three identical en-
calf, and foot. These sensors must be placed in the same sembles to reflect sample variability. However, if only one
position for each test, and the placement of the sensors shall be ensemble is available (that is often the case with prototype
given in the report. garments), replicate measurements shall be made on one
5.3.2 Distributed Sensors—If distributed sensors are used ensemble.
(for example, resistance wire), then the sensors must be
6.2 Specimen Size and Fit—Select the size of garments that
distributed over the surface so that all areas are equally
will fit the manikin appropriately (that is, the way the manu-
weighted. If several such sensors are used to measure the
facturer designed them to be worn on the human body during
temperature of different parts of the body, then their respective
their intended end use). For example, some knitted garments
temperaturesshallbearea-weightedwhencalculatingthemean
are designed to fit the body relatively tightly. Others are
surface (skin) temperature. Distributed sensors must be less
designed to fit loosely to accommodate a wider range of body
than 1 mm in diameter and firmly attached to the manikin
dimensions or to allow other garments to be worn underneath.
surface at all points.
In a stationary manikin test, large air layers in the clothing
5.4 Controlled Environmental Chamber—The manikin shall system will contribute to a higher insulation value than small
be placed in a chamber at least 1.5 by 1.5 by 2.5 m in air layers.Therefore, garments that do not have the appropriate
dimension that can provide uniform conditions, both spatially fit on the manikin (that is, are too tight or too loose) will cause
and temporally. errors in measurement.
6.2.1 When manikin measurements are used to compare
5.4.1 Spatial Variations—Spatial variations shall not exceed
the following: air temperature 61.0 °C, relative humidity materials used in certain garments, those garments must be
made from the same pattern so that design and fit variables are
65 %, and air velocity 650 % of the mean value. In addition,
the mean radiant temperature shall not be more than 1.0 °C held constant. In addition, they must be tested with the same
companion garments in the ensemble (for example, underwear,
different from the mean air temperature.The spatial uniformity
shall be verified at least annually or after any significant footwear, and so forth).
6.2.2 When manikin measurements are used to compare a
modificationsaremadetothechamber.Spatialuniformityshall
be verified by recording values for the conditions stated above variety of garments, the same size garments of a given type
shallbetestedasindicatedbythesizelabelinthegarments(for
at heights of 0.1, 0.6, 1.1, 1.4, and 1.7 m above the floor at the
location occupied by the manikin. Sensing devices specified example, large). However, if it is determined that the fit of a
garment is inappropriate, it is acceptable to use another size
below shall be used when measuring the environmental con-
ditions. and state it in the report.
5.4.2 Temporal Variations—Temporal variations shall not
6.3 Specimen Preparation—Garments shall be tested in the
exceed the following: air temperature 60.5 °C, mean radiant
as-received condition or after dry cleaning or laundering in
temperature 60.5 °C, relative humidity 65 %, air velocity
accordance with the manufacturer’s instructions. The cleaning
620 % of the mean value for data averaged over 5 min (see
procedures and number of processings shall be stated in the
5.4
...

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: F1291 − 16 F1291 − 22
Standard Test Method for
Measuring the Thermal Insulation of Clothing Using a
Heated Manikin
This standard is issued under the fixed designation F1291; 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.
INTRODUCTION
The type of clothing worn by people directly affects the heat exchange between the human body and
the environment. The heat transfer is both sensible (conduction, convection, and radiation) and latent
(evaporation). The insulation provided by a clothing ensemble is dependent upon the designs and
materials used in the component garments, the amount of body surface area covered by the clothing,
the distribution of the layers over the body, looseness or tightness of fit, and the increased surface area
for heat loss. Insulation measurements made on fabrics alone do not take these factors into account.
Measurements of the resistance to dry heat loss provided by clothing can be used to determine the
thermal comfort or stress of people in cold to comfortablea variety of environments (see Practice
F2732, ASHRAE 55-2013, and ISO 7730:2005). However, the moisture permeability of clothing is
more important in environmental conditions where heat balance can only be achieved by the
evaporation of sweat.
1. Scope
1.1 This test method covers the determination of the insulation value of clothing ensembles. It describes the measurement of the
resistance to dry heat transfer from a heated manikin to a relatively calm, cool environment. Information on measuring the local
thermal resistance values for individual garments and ensembles is provided in Annex A1.
1.1.1 This is a static test that provides a baseline clothing measurement on a standing manikin.
1.1.2 The effects of body position and movement are not addressed in this test method.
1.2 The insulation values obtained apply only to the particular ensembles evaluated and for the specified environmental conditions
of each test, particularly with respect to air movement.
1.3 The values stated in either clo or SI units are to be regarded separately as standard. Within the text, the SI units are shown
in parentheses. The values stated in each system are not exact equivalents; therefore, each system Each system shall be used
independently of the other. The thermal resistance units, clo or SI, shall be identified clearly and consistency of units shall be
maintained throughout reporting process.
1.4 The evaporative resistance of a clothing ensemble can be measured in accordance with Test Method F2370.
This test method is under the jurisdiction of ASTM Committee F23 on Personal Protective Clothing and Equipment and is the direct responsibility of Subcommittee
F23.60 on Human Factors.
Current edition approved Oct. 1, 2016July 1, 2022. Published October 2016August 2022. Originally approved in 1990. Last previous edition approved in 20152016 as
F1291 - 15.F1291 – 16. DOI: 10.1520/F1291-16.10.1520/F1291-22.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1291 − 22
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 consult and establish appropriate safety safety, health, and healthenvironmental practices and
determine the applicability of regulatory limitations prior to use.
1.6 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.
2. Referenced Documents
2.1 ASTM Standards:
D1518 Test Method for Thermal Resistance of Batting Systems Using a Hot Plate
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
F2370 Test Method for Measuring the Evaporative Resistance of Clothing Using a Sweating Manikin
F2732 Practice for Determining the Temperature Ratings for Cold Weather Protective Clothing
2.2 ASHRAE Standards:
ASHRAE 55-2013 Thermal Environmental Conditions for Human Occupancy
2.3 ISO Standards:
ISO 7730:2005 Moderate Thermal Environments—Determination of the PMV and PPD Indices and Specification of the
Conditions for Thermal Comfort
ISO 9920:2007 Ergonomics of the Thermal Environment—Estimation of the Thermal Insulation and Evaporation Resistance of
a Clothing Ensemble
3. Terminology
3.1 Definitions:
3.1.1 clo, n—unit of thermal resistance (insulation) equal to 0.155 K m /W.
3.1.1.1 Discussion—
The value of the clo was selected as roughly the insulation value of typical indoor clothing, which should keep a resting manperson
(producing heat at the rate of 58 58 W W/m⁄m ) comfortable in an environment at 21°C,21 °C, air movement 0.1 m/s. When clo
was developed, typical indoor clothing consisted of a three-piece suit and light underclothes.
3.1.2 clothing area factor (f ), n—the ratio of the surface area of the clothed body to the surface area of the nude body.
cl
3.1.3 clothing ensemble, n—a group of garments worn together on the body at the same time.
3.1.4 thermal insulation, n—the resistance to dry heat transfer via conduction, convection, and radiation.
3.1.4.1 Discussion—
The following insulation values can be are determined in this method using SI units:method:
R = thermal resistance (insulation) of the air layer on the surface of the nude manikin.
a
R = total thermal resistance (insulation) of the clothing and surface air layer around the manikin.
t
R = intrinsic thermal resistance (insulation) of the clothing.
cl
R = thermal resistance (insulation) of the air layer on the surface of the nude manikin,
a
R = total thermal resistance (insulation) of the clothing ensemble and surface air layer around the manikin, and
t
R = intrinsic thermal resistance (insulation) of the clothing ensemble.
cl
WhenR ,R , theand measurementsR are expressed in clo units, the symbol typically used for SI units, while I ,I , isand usedI
a t cl a t cl
instead ofare typically R.used with clo units.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from American Society of Heating, Refrigerating, and Air-Conditioning Engineers, Inc. (ASHRAE), 1791 Tullie Circle, NE, Atlanta, GA 30329,
http://www.ashrae.org.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
F1291 − 22
I = thermal resistance (insulation) of the air layer on the surface of the nude manikin.
a
I = total thermal resistance (insulation) of the clothing and surface air layer around the manikin.
t
I = intrinsic thermal resistance (insulation) of the clothing.
cl
Total insulation values are measured directly with a manikin. Intrinsic clothing insulation values are determined by subtracting
the air layer resistance around the clothed manikin from the total insulation value for the ensemble. Intrinsic clothing insulation
values are used in several thermal comfort and clothing standards (see 2.1, 2.2, and 2.3).
4. Significance and Use
4.1 This test method can be used to quantify and compare the insulation provided by different clothing systems. For example,
variations in the design and fabric used in component garments can be evaluated. The effects of garment layering, closure, and fit
can be measured for clothing ensembles. The insulation values for ensembles can be used in models that predict the physiological
responses of people in different environmental conditions. Garment insulation values can be compared as well (see Annex A1).
4.2 The measurement of the insulation provided by clothing is complex and dependent on the apparatus and techniques used. It
is not practical in a test method of this scope to establish details sufficient to cover all contingencies. Departures from the
instructions in this test method have the potential to lead to significantly different test results. Technical knowledge concerning the
theory of heat transfer, temperature,temperature and air motion measurement, and testing practices is needed to evaluate which
departures from the instructions given in this test method are significant. Standardization of the method reduces, but does not
eliminate, the need for such technical knowledge. Report any departures with the results.
4.3 Report the insulation values in SI units or clo units as standard procedure. Conversion factors to other units are given in Test
Method D1518.
5. Apparatus
5.1 Manikin—A standing manikin shall be used that is formed in the shape and size of an adult male or female and heated to a
constant,constant average skin temperature.
5.1.1 Size and Shape—The manikin shall be constructed to simulate the body of a human being; that is, it shall consist of a head,
chest/back, abdomen/buttocks, arms, hands (preferably with fingers extended to allow gloves to be worn), legs, and feet. Total
surface area shall be 1.8 6 0.3 m , and height shall be 170 6 10 cm. The manikin’s dimensions shall correspond to those required
for standard sizes of garments because deviations in fit will affect the results.
5.1.2 Surface Temperature—The manikin shall be constructed so as to maintain a uniform temperature distribution over the nude
body surface, with no local hot or cold spots. The mean surface (skin) temperature of the manikin shall be 35°C.35 °C. Local
deviations from the mean skin temperature shall not exceed 60.5°C.60.5 °C. Temperature uniformity of the nude manikin shall
be evaluated at least once annually using an infrared thermal imaging system or equivalent method. This procedure shall also be
repeated after repairs or alterations are completed that could affect temperature uniformity, for example, replacement of a heating
element.
5.2 Power-Measuring Instruments—Power to the manikin shall be measured so as to give an average over the period of a test. If
time proportioning or phase proportioning is used for power control, then devices that are capable of averaging over the control
cycle are required. Integrating devices (watt-hour meters) are preferred over instantaneous devices (watt meters). Overall accuracy
of the power monitoring equipment must be within 62 % of the reading for the average power for the test period. Since there are
a variety of devices and techniques used for power measurement, no specified calibration procedures shall be given. However, an
appropriate power calibration procedure is to be developed and documented.
5.3 Equipment for Measuring the Manikin’s Surface (Skin) Temperature—The mean surface temperature shall be measured with
point sensors or distributed temperature sensors.
Information on laboratories with thermal manikins can be obtained from the Institute for Environmental Research, Kansas State University, Manhattan, KS 66506.
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5.3.1 Point Sensors—Point sensors shall be thermocouples, resistance temperature devices (RTD’s),(RTDs), thermistors, or
equivalent sensors. They shall be no more than 2 mm thick and shall be well bonded, both mechanically and thermally, to the
manikin’s surface. Lead wires shall be bonded to the surface or pass through the interior of the manikin, or both. Each sensor
temperature shall be area-weighted when calculating the mean skin temperature for the body. If point sensors are used, a minimum
of 1517 point sensors are required. At least one sensor shall be placed on the head, chest, back, abdomen, buttocks, and both the
right and left upper arm, lower arm, hand, thigh, calf, and foot. These sensors must be placed in the same position for each test,
and the placement of the sensors shall be given in the report.
5.3.2 Distributed Sensors—If distributed sensors are used (for example, resistance wire), then the sensors must be distributed over
the surface so that all areas are equally weighted. If several such sensors are used to measure the temperature of different parts
of the body, then their respective temperatures shall be area-weighted when calculating the mean surface (skin) temperature.
Distributed sensors must be less than 1 mm in diameter and firmly attached to the manikin surface at all points.
5.4 Controlled Environmental Chamber—The manikin shall be placed in a chamber at least 1.5 by 1.5 by 2.5 m in dimension that
can provide uniform conditions, both spatially and temporally.
5.4.1 Spatial Variations—Spatial variations shall not exceed the following: air temperature 61.0°C,61.0 °C, relative humidity
65 %, and air velocity 650 % of the mean value. In addition, the mean radiant temperature shall not be more than 1.0°C1.0 °C
different from the mean air temperature. The spatial uniformity shall be verified at least annually or after any significant
modifications are made to the chamber. Spatial uniformity shall be verified by recording values for the conditions stated above at
heights of 0.1, 0.6, 1.1, 1.4, and 1.7 m above the floor at the location occupied by the manikin. Sensing devices specified below
shall be used when measuring the environmental conditions.
5.4.2 Temporal Variations—Temporal variations shall not exceed the following: air temperature 60.5°C,60.5 °C, mean radiant
temperature 60.5°C,60.5 °C, relative humidity 65 %, air velocity 620 % of the mean value for data averaged over 5 min.min
(see 5.4.5).
5.4.3 Relative Humidity Measuring Equipment—Any humidity sensing device with an accuracy of 65 % relative humidity and
a repeatability of 63 % is acceptable (for example, wet bulb/dry bulb, dew point hygrometer). Only one location needs to be
monitored during a test to ensure that the temporal uniformity requirements are met.
5.4.4 Air Temperature Sensors—Shielded air temperature sensors shall be used. Any sensor with an overall accuracy of
60.15°C60.15 °C is acceptable (for example, RTD, thermocouple, thermistor). The sensor shall have a time constant not
exceeding 1 min. The sensor(s) shall be 0.5 m in front of the manikin. If a single sensor is used it shall be 1.0 m above the floor.
If multiple sensors are used, they shall be spaced at equal height intervals and their readings averaged.
5.4.5 Air Velocity Indicator—An omni-directionalomnidirectional anemometer with 60.05 m/s accuracy shall be used.
Measurements shall be averaged for at least 1 min at each location. If it is demonstrated that velocity does not vary temporally
by more than 60.05 m/s, then it is not necessary to monitor air velocity during a test. The value of the mean air velocity must
be reported, however. If air velocity is monitored, then measurement location requirements are the same as for temperature.
6. Sampling and Test Specimens
6.1 Sampling—It is desirable to test three identical ensembles to reflect sample variability. However, if only one ensemble is
available (that is often the case with prototype garments), replicate measurements shall be made on one ensemble.
6.2 Specimen Size and Fit—Select the size of garments that will fit the manikin appropriately (that is, the way the manufacturer
designed them to be worn on the human body during their intended end use). For example, some knitted garments are designed
to fit the body relatively tightly. Others are designed to fit loosely to accommodate a wider range of body dimensions or to allow
other garments to be worn underneath. In a stationary manikin test, large air layers in the clothing system will contribute to a higher
insulation value than small air layers. Therefore, garments that do not have the appropriate fit on the manikin (that is, are too tight
or too loose),loose) will cause errors in measurement.
6.2.1 When manikin measurements are used to compare materials used in certain garments, those garments must be made from
the same pattern so that design and fit variables are held constant. In addition, they must be tested with the same companion
garments in the ensemble (for example, underwear, footwear, and so forth).
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6.2.2 When manikin measurements are used to compare a variety of garments, the same size garments of a given type shall be
tested as indicated by the size label in the garments (for example, large). However, if it is determined that the fit of a garment is
inappropriate, it is acceptable to use another size and state it in the report.
6.3 Specimen Preparation—Garments shall be tested in the as-received condition or after dry cleaning or laundering in accordance
with the manufacturer’s instructions. The cleaning procedures and number of processings shall be stated in the report.
6.4 Conditioning—Allow the clothing components to come to equilibrium wit
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