EN ISO 12241:2008
(Main)Thermal insulation for building equipment and industrial installations - Calculation rules (ISO 12241:2008)
Thermal insulation for building equipment and industrial installations - Calculation rules (ISO 12241:2008)
ISO 12241:2008 gives rules for the calculation of heat-transfer-related properties of building equipment and industrial installations, predominantly under steady-state conditions. ISO 12241:2008 also gives a simplified approach for the treatment of thermal bridges.
Wärmedämmung an haus- und betriebstechnischen Anlagen - Berechnungsregeln (ISO 12241:2008)
Diese Internationale Norm enthält Regeln zur Berechnung der mit dem Wärmetransport im Zusammenhang stehenden Eigenschaften von haus und betriebstechnischen Anlagen, überwiegend unter stationären Bedingungen. Diese Internationale Norm liefert auch eine vereinfachte Herangehensweise für die Behandlung von Wärmebrücken.
Isolation thermique des équipements de bâtiments et des installations industrielles - Méthodes de calcul (ISO 12241:2008)
L'ISO 12241:2008 donne des méthodes pour calculer les propriétés relatives au transfert de chaleur des équipements de bâtiments et des installations industrielles, principalement en régime stationnaire. Elle fournit également une approche simplifiée de traitement des ponts thermiques.
Toplotna izolacija za opremo stavb in industrijske inštalacije - Pravila za računanje (ISO 12241:2008)
General Information
Relations
Standards Content (Sample)
SLOVENSKI STANDARD
01-september-2008
1DGRPHãþD
SIST EN ISO 12241:1999
7RSORWQDL]RODFLMD]DRSUHPRVWDYELQLQGXVWULMVNHLQãWDODFLMH3UDYLOD]DUDþXQDQMH
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Thermal insulation for building equipment and industrial installations - Calculation rules
(ISO 12241:2008)
Wärmedämmung an haus- und betriebstechnischen Anlagen - Berechnungsregeln (ISO
12241:2008)
Isolation thermique des équipements du bâtiment et des installations industrielles -
Méthodes de calcul (ISO 12241:2008)
Ta slovenski standard je istoveten z: EN ISO 12241:2008
ICS:
91.120.10 Toplotna izolacija stavb Thermal insulation of
buildings
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
EUROPEAN STANDARD
EN ISO 12241
NORME EUROPÉENNE
EUROPÄISCHE NORM
June 2008
ICS 91.140.01; 91.120.10 Supersedes EN ISO 12241:1998
English Version
Thermal insulation for building equipment and industrial
installations - Calculation rules (ISO 12241:2008)
Isolation thermique des équipements de bâtiments et des Wärmedämmung an haus- und betriebstechnischen
installations industrielles - Méthodes de calcul (ISO Anlagen - Berechnungsregeln (ISO 12241:2008)
12241:2008)
This European Standard was approved by CEN on 1 May 2008.
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 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 Management Centre has the same status as the
official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
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EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: rue de Stassart, 36 B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 12241:2008: E
worldwide for CEN national Members.
Contents Page
Foreword.3
Foreword
This document (EN ISO 12241:2008) has been prepared by Technical Committee ISO/TC 163 "Thermal
performance and energy use in the built environment" in collaboration with Technical Committee CEN/TC 89
“Thermal performance of buildings and building components” the secretariat of which is held by SIS.
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 2008, and conflicting national standards shall be withdrawn
at the latest by December 2008.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 12241:1998.
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, Cyprus, Czech
Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,
Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 12241:2008 has been approved by CEN as a EN ISO 12241:2008 without any modification.
INTERNATIONAL ISO
STANDARD 12241
Second edition
2008-06-15
Thermal insulation for building
equipment and industrial installations —
Calculation rules
Isolation thermique des équipements de bâtiments et des installations
industrielles — Méthodes de calcul
Reference number
ISO 12241:2008(E)
©
ISO 2008
ISO 12241:2008(E)
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ii © ISO 2008 – All rights reserved
ISO 12241:2008(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols. 1
3.1 Terms and definitions. 1
3.2 Definition of symbols . 2
3.3 Subscripts . 3
4 Calculation methods for heat transfer. 3
4.1 Fundamental equations for heat transfer. 3
4.2 Surface temperature. 14
4.3 Prevention of surface condensation. 17
4.4 Determination of total heat flow rate for plane walls, pipes and spheres . 20
5 Calculation of the temperature change in pipes, vessels and containers. 21
5.1 Longitudinal temperature change in a pipe . 21
5.2 Temperature change and cooling times in pipes, vessels and containers . 22
6 Calculation of cooling and freezing times of stationary liquids . 22
6.1 Calculation of the cooling time for a given thickness of insulation to prevent the freezing
of water in a pipe. 22
6.2 Calculation of the freezing time of water in a pipe. 24
7 Determination of the influence of thermal bridges . 25
7.1 General. 25
7.2 Calculation of correction terms for plane surfaces . 26
7.3 Calculation of correction terms for pipes . 26
8 Underground pipelines. 27
8.1 General. 27
8.2 Calculation of heat loss (single line) without channels. 27
8.3 Other cases . 29
Annex A (normative) Thermal bridges in pipe insulation . 30
Annex B (informative) Projecting thermal bridges of roughly constant cross-section . 33
Annex C (informative) Examples . 38
Bibliography . 45
ISO 12241:2008(E)
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 12241 was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use in the
built environment, Subcommittee SC 2, Calculation methods.
This second edition cancels and replaces the first edition (ISO 12241:1998), which has been technically
revised, including methods to determine the correction terms for thermal transmittance and linear thermal
transmittance for pipes that are added to the calculated thermal transmittance to obtain the total thermal
transmittance to calculate the total heat losses for an industrial installation.
iv © ISO 2008 – All rights reserved
ISO 12241:2008(E)
Introduction
Methods relating to conduction are direct mathematical derivations from Fourier’s law of heat conduction, so
international consensus is purely a matter of mathematical verification. No significant difference in the
equations used in the member countries exists. For convection and radiation, however, there are no methods
in practical use that are mathematically traceable to Newton’s law of cooling or the Stefan-Boltzman law of
thermal radiation, without some empirical element. For convection in particular, many different equations have
been developed, based on laboratory data. Different equations have become popular in different countries,
and no exact means are available to select between these equations.
Within the limitations given, these methods can be applied to most types of industrial, thermal-insulation, heat-
transfer problems.
These methods do not take into account the permeation of air or the transmittance of thermal radiation
through transparent media.
The equations in these methods require for their solution that some system variables be known, given,
assumed or measured. In all cases, the accuracy of the results depends on the accuracy of the input variables.
This International Standard contains no guidelines for accurate measurement of any of the variables. However,
it does contain guides that have proven satisfactory for estimating some of the variables for many industrial
thermal systems.
lt should be noted that the steady-state calculations are dependent on boundary conditions. Often a solution at
one set of boundary co
...
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