SIST EN ISO 11092:2026

Textiles - Physiological effects - Measurement of thermal and water-vapour resistance under steady-state conditions (sweating guarded-hotplate test) (ISO 11092:2026)

This document specifies methods for the measurement of the thermal resistance and water-vapour resistance , under steady-state conditions, of e.g. fabrics, films, coatings, foams and leather, including multilayer assemblies, for use in clothing, quilts, sleeping bags, upholstery and similar textile or textile-like products.
The application of this measurement technique is restricted to a maximum thermal resistance and water-vapour resistance which depend on the dimensions and construction of the apparatus used (e.g. 2 m2·K/W and 700 m2·Pa/W respectively, for the minimum specifications of the equipment referred to in this document).
The test conditions used in this document are not intended to represent specific comfort situations, and performance specifications in relation to physiological comfort are not stated.

Textilien - Physiologische Wirkungen - Messung des Wärme- und Wasserdampfdurchgangswiderstands unter stationären Bedingungen (sweating guarded-hotplate test) (ISO 11092:2026)

Dieses Dokument legt Verfahren zur Messung des Wärmedurchgangswiderstandes und Wasserdampfdurchgangswiderstandes unter stationären Bedingungen fest, z. B. von textilen Flächengebilden, Folien, Beschichtungen, Schaumstoffen und Leder, einschließlich mehrschichtiger Materialaufbauten für den Einsatz in Kleidung, Steppbetten, Schlafsäcken, Polsterungen und ähnlichen Textilen oder textilartigen Erzeugnissen.
Die Anwendung dieses Messverfahrens ist auf einen bestimmten Höchstwert des Wärme- und Wasserdampfdurchgangswiderstandes beschränkt, der von den Maßen und der Ausführung des verwendeten Messgerätes abhängt (z. B. 2 m2·K/W bzw. 700 m2·Pa/W für die Mindestanforderungen, die in diesem Dokument an das Messgerät gestellt werden).
Die in diesem Dokument angewendeten Prüfbedingungen sind nicht dafür vorgesehen, bestimmte Komfortsituationen nachzustellen; es werden keine Festlegungen bezüglich der Leistung im Hinblick auf einen guten thermophysiologischen Komfort angegeben.

Textiles - Effets physiologiques - Mesurage de la résistance thermique et de la résistance à la vapeur d'eau en régime stationnaire (essai de la plaque chaude gardée transpirante) (ISO 11092:2026)

Le présent document prescrit des méthodes pour la détermination de la résistance thermique et de la résistance à la vapeur d’eau, en régime stationnaire, de produits tels que matières textiles, films, enductions, mousses et cuir, y compris les assemblages multicouches, qui sont utilisés pour l’habillement, les couettes, les sacs de couchage, les garnitures de siège et produits similaires textiles ou apparentés aux textiles.
L’application de cette technique de mesurage est limitée à des valeurs maximales de résistance thermique et de résistance à la vapeur d’eau qui dépendent des dimensions et de la construction de l’appareil utilisé (par exemple, respectivement 2 m2·K/W et 700 m2·Pa/W pour les spécifications minimales de l’équipement auquel il est fait référence dans le présent document).
Les conditions d’essai du présent document n’ont pas pour objet de représenter des situations de confort spécifiques et aucune spécification de performance relative au confort physiologique n’est énoncée.

Tekstilije - Fiziološki učinki - Merjenje toplotne in vodne paroprepustnosti v stacionarnih pogojih (test z varovano vročo ploščo za potenje) (ISO 11092:2026)

Ta dokument določa metode za merjenje toplotne upornosti in odpornosti proti vodni pari v stacionarnih pogojih, npr. tkanin, folij, premazov, pen in usnja, vključno z večplastnimi sestavi, za uporabo v oblačilih, odejah, spalnih vrečah, oblazinjenju in podobnih tekstilnih ali tekstilu podobnih izdelkih.
Uporaba te merilne tehnike je omejena na največjo toplotno upornost in odpornost proti vodni pari, ki sta odvisni od dimenzij in konstrukcije uporabljenega aparata (npr. 2 m2·K/W in 700 m2·Pa/W za minimalne specifikacije opreme, navedene v tem dokumentu).
Preskusni pogoji, uporabljeni v tem dokumentu, niso namenjeni predstavljanju specifičnih udobnih situacij, in specifikacije zmogljivosti v zvezi s fiziološkim udobjem niso navedene.

General Information

• Status: Published
• Public Enquiry End Date: 29-Sep-2025
• Publication Date: 18-Jun-2026
• ICS: 59.080.01 - Textiles in general
• Technical Committee: ITEK - Textile and textile products
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 11-Jun-2026
• Due Date: 16-Aug-2026
• Completion Date: 19-Jun-2026
• Ref Project: EN ISO 11092:2026 - Textiles - Physiological effects - Measurement of thermal and water-vapour resistance under steady-state conditions (sweating guarded-hotplate test) (ISO 11092:2026)

Relations

• Referred By: SIST EN 4863:2023 - Aerospace series - Rotorcraft immersion suits - Requirements, testing and marking
• Effective Date: 10-Jun-2026
• Referred By: SIST EN 16779-1:2018 - Textile child care articles - Safety requirements and test methods for children's cot duvets - Part 1: Duvet (excluding duvet covers)
• Effective Date: 10-Jun-2026
• Referred By: SIST EN 343:2003+A1:2007 - Protective clothing - Protection against rain
• Effective Date: 10-Jun-2026
• Referred By: SIST-TP CEN/TR 16422:2013 - Classification of thermoregulatory properties
• Effective Date: 10-Jun-2026
• Referred By: SIST EN 469:2006 - Protective clothing for firefighters - Performance requirements for protective clothing for firefighting
• Effective Date: 10-Jun-2026
• Referred By: SIST EN 16781:2018 - Textile child care articles - Safety requirements and test methods for children's sleep bags for use in a cot
• Effective Date: 10-Jun-2026
• Referred By: SIST EN 17534:2023 - Textiles - Physiological effects - Measurement of liquid sweat transport and buffering
• Effective Date: 10-Jun-2026
• Referred By: SIST EN 15614:2007 - Protective clothing for firefighters - Laboratory test methods and performance requirements for wildland clothing
• Effective Date: 10-Jun-2026
• Referred By: SIST EN 14605:2005+A1:2009 - Protective clothing against liquid chemicals - performance requirements for clothing with liquid-tight (Type 3) or spray-tight (Type 4) connections, including items providing protection to parts of the body only (Types PB [3] and PB [4])
• Effective Date: 10-Jun-2026
• Referred By: SIST EN 471:2003+A1:2008 - High-visibility warning clothing for professional use - Test methods and requirements
• Effective Date: 10-Jun-2026
• Referred By: SIST EN 14058:2004 - Protective clothing - Garments for protection against cool environments
• Effective Date: 10-Jun-2026
• Referred By: SIST EN 342:2004 - Protective clothing - Ensembles and garments for protection against cold
• Effective Date: 10-Jun-2026
• Referred By: SIST EN 17528:2022 - Clothing - Physiological effects - Measurement of water vapour resistance by means of a sweating manikin
• Effective Date: 10-Jun-2026
• Referred By: SIST EN 16689:2017 - Protective clothing for firefighters - Performance requirements for protective clothing for technical rescue
• Effective Date: 10-Jun-2026
• Revised: SIST EN ISO 11092:2014 - Textiles - Physiological effects - Measurement of thermal and water-vapour resistance under steady-state conditions (sweating guarded-hotplate test) (ISO 11092:2014)
• Effective Date: 19-Jan-2023

Overview

SIST EN ISO 11092:2026 specifies laboratory methods for the measurement of thermal resistance and water-vapour resistance of textiles and related materials under steady-state conditions using the sweating guarded-hotplate test. This standard is highly relevant to the assessment of fabrics, films, coatings, foams, leathers, and multilayer assemblies used in clothing, bedding, upholstery, and other textile products. It provides a consistent approach for evaluating the heat and moisture transfer properties of textile materials, which are essential indicators of physiological comfort and performance in end-use applications.

Key Topics

• Thermal Resistance (Rct): Defines the material’s ability to resist heat transfer. This is critical for understanding insulation performance in textiles.
• Water-Vapour Resistance (Ret): Measures the resistance to water-vapour transfer, which affects breathability and comfort.
• Sweating Guarded-Hotplate Test: Sometimes referred to as the "skin model," this test simulates heat and moisture transfer between materials and the skin under controlled laboratory conditions.
• Test Scope: Applies to a wide range of textiles and similar products, covering both single- and multilayered structures.
• Standardized Test Conditions: Although the method provides precise control of temperature, humidity, and air flow, these test conditions are not meant to simulate specific in-use comfort situations.
• Equipment Limitations: The methodology specifies the maximum values for thermal and water-vapour resistance measurements, which are dependent on apparatus design and capabilities.

Applications

SIST EN ISO 11092:2026 is crucial for:

• Product Development: Textile and apparel manufacturers use the standard to evaluate new fabrics for thermal and moisture management, supporting innovation in performance wear, outdoor gear, and protective clothing.
• Quality Assurance: Consistent measurement protocols allow comparison across products and suppliers, improving material selection and procurement processes.
• Research and Testing: Laboratories and research institutions use the guarded-hotplate method to conduct comparative studies on heat and moisture transfer characteristics of textiles.
• Certification and Compliance: Meeting the requirements of this standard can be a prerequisite for certain market entries or customer specifications, particularly in high-performance and technical textile sectors.
• Consumer Safety and Comfort: By providing reproducible values for key physiological parameters, the standard helps ensure end products deliver anticipated comfort and functional performance.

Related Standards

• ISO 3696: Specifies requirements for water used in laboratory testing, referenced for the water quality needed in the sweating guarded-hotplate method.
• ISO/TC 38: The technical committee responsible for textiles standards, developing methods related to fiber, yarn, fabric, and finished product performance.
• Other Comfort Testing Standards: There are various ISO and EN methodologies relating to comfort, breathability, and thermal insulation of textiles, complementing ISO 11092’s focus on steady-state properties.

Practical Value

By adhering to SIST EN ISO 11092:2026, stakeholders in the textile supply chain gain:

• Reliable Data: Standardized measurements for accurate benchmarking and product specification.
• Enhanced Product Differentiation: Clear, quantifiable performance metrics aid in marketing and product positioning.
• Increased Market Confidence: Demonstrates compliance with international best practices, facilitating global trade and acceptance.

This standard is an essential tool for advancing textile engineering, optimizing comfort, and supporting innovation in clothing and technical textile applications.

Standards Content (Sample)

SLOVENSKI STANDARD
01-julij-2026
Tekstilije - Ugotavljanje fizioloških lastnosti - Merjenje toplotne in parne upornosti
pri ustaljenih pogojih (preskus z vročo ploščo, zaščiteno pred izgubo) (ISO
11092:2026)
Textiles - Physiological effects - Measurement of thermal and water-vapour resistance
under steady-state conditions (sweating guarded-hotplate test) (ISO 11092:2026)
Textilien - Physiologische Wirkungen - Messung des Wärme- und
Wasserdampfdurchgangswiderstands unter stationären Bedingungen (sweating
guarded-hotplate test) (ISO 11092:2026)
Textiles - Effets physiologiques - Mesurage de la résistance thermique et de la
résistance à la vapeur d'eau en régime stationnaire (essai de la plaque chaude gardée
transpirante) (ISO 11092:2026)
Ta slovenski standard je istoveten z: EN ISO 11092:2026
ICS:
59.080.01 Tekstilije na splošno Textiles in general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 11092
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2026
EUROPÄISCHE NORM
ICS 59.080.01 Supersedes EN ISO 11092:2014
English Version
Textiles - Physiological effects - Measurement of thermal
and water-vapour resistance under steady-state
conditions (sweating guarded-hotplate test) (ISO
11092:2026)
Textiles - Effets physiologiques - Mesurage de la Textilien - Physiologische Wirkungen - Messung des
résistance thermique et de la résistance à la vapeur Wärme- und Wasserdampfdurchgangswiderstands
d'eau en régime stationnaire (essai de la plaque chaude unter stationären Bedingungen (Sweating Guarded-
gardée transpirante) (ISO 11092:2026) Hotplate Prüfung) (ISO 11092:2026)
This European Standard was approved by CEN on 29 May 2026.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2026 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11092:2026 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 11092:2026) has been prepared by Technical Committee ISO/TC 38 "Textiles"
in collaboration with Technical Committee CEN/TC 248 “Textiles and textile products” the secretariat of
which is held by BSI.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by December 2026, and conflicting national standards
shall be withdrawn at the latest by December 2026.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 11092:2014.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 11092:2026 has been approved by CEN as EN ISO 11092:2026 without any modification.

International
Standard
ISO 11092
Third edition
Textiles — Physiological effects
2026-05
— Measurement of thermal and
water-vapour resistance under
steady-state conditions (sweating
guarded-hotplate test)
Textiles — Effets physiologiques — Mesurage de la résistance
thermique et de la résistance à la vapeur d'eau en régime
stationnaire (essai de la plaque chaude gardée transpirante)
Reference number
ISO 11092:2026(en) © ISO 2026
ISO 11092:2026(en)
© ISO 2026
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii
ISO 11092:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols, abbreviated terms and units . 2
5 Principle . 3
6 Apparatus . 4
7 Test specimens . 7
7.1 Materials ≤ 5 mm thick .7
7.2 Materials > 5 mm thick .7
8 Test procedure . 9
8.1 Determination of apparatus constants .9
8.1.1 General .9
8.1.2 Determination of R .9
ct0
8.1.3 Determination of R .9
et0
8.1.4 Reference material .10
8.1.5 Recalibration.10
8.2 Assembly of test specimens on the measuring unit .10
8.3 Measurement of thermal resistance, R .11
ct
8.4 Measurement of water-vapour resistance, R .11
et
9 Precision of results . .11
9.1 Repeatability .11
9.2 Reproducibility . 12
10 Test report .12
Annex A (normative) Mounting procedure for test specimens containing loose filling materials
or having uneven thickness .13
Annex B (normative) Determination of correction terms for heating power . 14
Annex C (normative) Test specimen assembly for materials prone to swelling .15
Bibliography . 17

iii
ISO 11092:2026(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee TC38, Textiles, in collaboration with the European
Committee for Standardization (CEN) Technical Committee CEN/TC 248, Textiles and textile products, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This third edition cancels and replaces the second edition (ISO 11092:2014), which has been technically
revised.
The main changes are as follows:
— the Normative references clause (Clause 2) has been added and subsequent clauses have been renumbered;
— in 8.1.3.1, the water supplied to the measuring plate has been changed to Grade 3 water in accordance
with ISO 3696;
— in 9.1 and 9.2, the thermal resistance values have been changed to standard notation;
— in 9.1, the precision is no longer only applicable to foams;
— in 9.2, the reproducibility of the water vapour resistance values has been updated based on the results
from the interlaboratory test in 2025;
— Annex C has been made normative;
— a Bibliography has been added.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
ISO 11092:2026(en)
Introduction
This document is the first of a number of standard test methods in the field of clothing comfort.
The physical properties of textile materials which contribute to physiological comfort involve a complex
combination of heat and mass transfer. Each can occur separately or simultaneously. They are time-
dependent, and can be considered in steady-state or transient conditions.
Thermal resistance is the net result of the combination of radiant, conductive and convective heat transfer,
and its value depends on the contribution of each to the total heat transfer. Although it is an intrinsic
property of the textile material, its measured value can change through the conditions of test due to the
interaction of parameters, such as radiant heat transfer with the surroundings.
Several methods exist which can be used to measure heat and moisture properties of textiles, each of which
is specific to one or the other and relies on certain assumptions for its interpretation.
The sweating guarded-hotplate (often referred to as the “skin model”) described in this document is
intended to simulate the heat and mass transfer processes which occur next to human skin. Measurements
involving one or both processes can be carried out either separately or simultaneously using a variety of
environmental conditions, involving combinations of temperature, relative humidity, air speed, and in the
liquid or gaseous phase. Hence transport properties measured with this apparatus can be made to simulate
different wear and environmental situations in both transient and steady-states. In this document only
steady-state conditions are selected.

v
International Standard ISO 11092:2026(en)
Textiles — Physiological effects — Measurement of thermal
and water-vapour resistance under steady-state conditions
(sweating guarded-hotplate test)
1 Scope
This document specifies methods for the measurement of the thermal resistance and water-vapour
resistance, under steady-state conditions, of e.g. fabrics, films, coatings, foams and leather, including
multilayer assemblies, for use in clothing, quilts, sleeping bags, upholstery and similar textile or textile-like
products.
The application of this measurement technique is restricted to a maximum thermal resistance and water-
vapour resistance which depend on the dimensions and construction of the apparatus used (e.g. 2 m ·K/W
and 700 m ·Pa/W respectively, for the minimum specifications of the equipment referred to in this
document).
The test conditions used in this document are not intended to represent specific comfort situations, and
performance specifications in relation to physiological comfort are not stated.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 3696, Water for analytical laboratory use — Specification and test methods
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at http:// www .electropedia .org/
3.1
thermal resistance
R
ct
temperature difference between the two faces of a material divided by the resultant heat flux per unit area
in the direction of the gradient
Note 1 to entry: It is a quantity specific to textile materials or composites which determines the dry heat flux across
a given area in response to a steady applied temperature gradient. The dry heat flux can consist of one or more
conductive, convective and radiant components.
Note 2 to entry: Thermal resistance is expressed in square metres kelvin per watt.

ISO 11092:2026(en)
3.2
water-vapour resistance
R
et
water-vapour partial pressure difference between the two faces of a material divided by the resultant
evaporative heat flux per unit area in the direction of the gradient
Note 1 to entry: It is a quantity specific to textile materials or composites which determines the “latent” evaporative
heat flux across a given area in response to a steady applied water-vapour partial pressure gradient. The evaporative
heat flux can consist of both diffusive and convective components.
Note 2 to entry: Water-vapour resistance is expressed in square metres pascal per watt.
3.3
water-vapour permeability index
i
mt
ratio of thermal and water-vapour resistances in accordance with Formula (1):
(1)
where
S equals 60 Pa/K
Note 1 to entry: The water-vapour permeability index is dimensionless, and has values between 0 and 1. A value of 0
implies that the material is water-vapour impermeable, that is, it has infinite water-vapour resistance, and a material
with a value of 1 has both the thermal resistance and water-vapour resistance of an air layer of the same thickness.
3.4
water-vapour permeability
W
d
characteristic of a textile material or composite depending on water-vapour resistance (3.2) and temperature
in accordance with Formula (2):
(2)
where
ϕT is the latent heat of vaporization of water at the temperature T of the measuring unit, equals,
m m
for example, 0,672 W·h/g at T = 35 °C
m
Note 1 to entry: Water-vapour permeability is expressed in grams per square metre hour pascal.
4 Symbols, abbreviated terms and units
Table 1 shows the symbols and abbreviations that are used in this document.
Table 1 — Symbols, abbreviated terms and units
Symbols and abbreviated terms Description Unit
A area of the measuring unit m²
b thickness of thermal guard m
d thickness of test specimen m
i water-vapour permeability index dimensionless
mt
H heating power supplied to the meas- W
uring unit
l length m
ISO 11092:2026(en)
TTabablele 1 1 ((ccoonnttiinnueuedd))
Symbols and abbreviated terms Description Unit
p water-vapour partial pressure of the Pa
a
air in the test enclosure at tempera-
ture, T
a
p the saturation water-vapour partial Pa
m
pressure at the surface of the measur-
ing unit at temperature, T
m
R thermal resistance m²·K/W
ct
R apparatus constant for the measure- m²·K/W
ct0
ment of thermal resistance, R
ct
R water-vapour resistance m²·Pa/W
et
R apparatus constant for the measure- m²·Pa/W
et0
ment of water vapour resistance, R
et
R.H. relative humidity %
S standard deviation of air speed v, m/s
v
T air temperature in the test enclosure °C
a
T temperature of the measuring unit °C
m
T temperature of the thermal guard °C
s
v speed of air above the surface of the m/s
a
test specimen
W water-vapour permeability g/(m²·h· Pa)
d
α slope of the correction line for the dimensionless
calculation of ΔH
c
β slope of the correction line for the dimensionless
calculation of ΔH
e
ΔH correction term for heating power for dimensionless
c
the measurement of thermal resist-
ance, R
ct
ΔH correction term for heating power dimensionless
e
for the measurement of water-vapour
resistance, R
et
ϕT latent heat of vaporization of water at Wh/g
m
the temperature, T
m
5 Principle
The test specimen is placed on an electrically heated plate with conditioned air ducted to flow across and
parallel to its upper surface as specified in this document.
For the determination of thermal resistance, the heat flux through the test specimen is measured after
steady-state conditions have been reached.
The technique described in this document enables the thermal resistance, R of a material to be determined
ct
by subtracting the thermal resistance of the boundary air layer above the surface of the test apparatus from
that of a test specimen plus boundary air layer, both measured under the same conditions.
For the determination of water-vapour resistance, an electrically heated porous plate is covered by a water-
vapour permeable but liquid-water impermeable membrane. Water fed to the heated plate evaporates and
passes through the membrane as vapour, so that no liquid water contacts the test specimen. With the test
spe
...