1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN ISO 13788:2012Hygrothermal performanceof building components andbuilding elements Internalsurface temperature to avoidcritical surface humidity andinterstitial condensation
2、 Calculation methods (ISO13788:2012)BS EN ISO 13788:2012 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN ISO13788:2012. It supersedes BS EN ISO 13788:2002 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee B/540, Energ
3、y performance of materials components andbuildings.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British St
4、andards Institution 2013. Published by BSI StandardsLimited 2013ISBN 978 0 580 72096 3ICS 91.060.01; 91.120.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 Ja
5、nuary 2013.Amendments issued since publicationDate Text affectedEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 13788 December 2012 ICS 91.060.01; 91.120.10 Supersedes EN ISO 13788:2001English Version Hygrothermal performance of building components and building elements - Internal surface t
6、emperature to avoid critical surface humidity and interstitial condensation - Calculation methods (ISO 13788:2012) Performance hygrothermique des composants et parois de btiments - Temprature superficielle intrieure permettant dviter lhumidit superficielle critique et la condensation dans la masse -
7、 Mthodes de calcul (ISO 13788:2012) Wrme- und feuchtetechnisches Verhalten von Bauteilen und Bauelementen - Raumseitige Oberflchentemperatur zur Vermeidung kritischer Oberflchenfeuchte und Tauwasserbildung im Bauteilinneren - Berechnungsverfahren (ISO 13788:2012) This European Standard was approved
8、by CEN on 28 December 2012. 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 st
9、andards 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
10、 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungar
11、y, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management
12、 Centre: Avenue Marnix 17, B-1000 Brussels 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 13788:2012: EBS EN ISO 13788:2012EN ISO 13788:2012 (E) 3 Foreword This document (EN ISO 13788:2012) has been prepared by Technical
13、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 st
14、andard, either by publication of an identical text or by endorsement, at the latest by June 2013, and conflicting national standards shall be withdrawn at the latest by June 2013. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CE
15、N and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 13788:2001. According to the CEN/CENELEC Internal Regulations, the national standards organisations of the following countries are bound to implement this European Standard:
16、Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, S
17、weden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 13788:2012 has been approved by CEN as a EN ISO 13788:2012 without any modification. BS EN ISO 13788:2012ISO 13788:2012(E) ISO 2012 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope . 12 Normativ
18、e references 13 Terms and definitions, symbols and units . 13.1 Terms and definitions . 13.2 Symbols and units 33.3 Subscripts 44 Input data for the calculations . 44.1 Material and product properties . 44.2 External boundary conditions . 44.3 Internal boundary conditions 64.4 Surface resistances 65
19、 Calculation of surface temperature to avoid critical surface humidity . 75.1 General . 75.2 Determining parameters 75.3 Design for avoidance of mould growth, corrosion or other moisture damage 75.4 Design for the limitation of surface condensation on low thermal inertia elements 86 Calculation of i
20、nterstitial condensation . 96.1 General . 96.2 Principle 96.3 Limitation of sources of error . 106.4 Calculation . 106.5 Criteria used to assess building components 167 Calculation of drying of building components .167.1 General 167.2 Principle . 177.3 Specification of the method 177.4 Criteria used
21、 to assess drying potential of building components 17Annex A (informative) Internal boundary conditions .18Annex B (informative) Examples of calculation of the temperature factor at the internal surface to avoid critical surface humidity .20Annex C (informative) Examples of calculation of interstiti
22、al condensation 24Annex D (informative) Example of the calculation of the drying of a wetted layer .34Annex E (informative) Relationships governing moisture transfer and water vapour pressure .37Bibliography .40BS EN ISO 13788:2012ISO 13788:2012(E)ForewordISO (the International Organization for Stan
23、dardization) 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
24、 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 St
25、andards 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 In
26、ternational 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 13788
27、was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use in the built environment, Subcommittee SC 2, Calculation methods in cooperation with CEN/TC 89, Thermal performance of buildings and building components.This second edition cancels and replaces the first edition (ISO
28、13788:2001), which has been technically revised.iv ISO 2012 All rights reservedBS EN ISO 13788:2012ISO 13788:2012(E)IntroductionMoisture transfer is a very complex process and the knowledge of moisture transfer mechanisms, material properties, initial conditions and boundary conditions is often limi
29、ted. Therefore this International Standard lays down simplified calculation methods, which assume that moisture transport is by vapour diffusion alone and use monthly climate data. The standardization of these calculation methods does not exclude use of more advanced methods. If other sources of moi
30、sture, such as rain penetration or convection, are negligible, the calculations will normally lead to designs well on the safe side and if a construction fails a specified design criterion according to this procedure, more accurate methods may be used to show that the design will pass.This Internati
31、onal Standard deals with:a) the critical surface humidity likely to lead to problems such as mould growth on the internal surfaces of buildings,b) interstitial condensation within a building component, in: heating periods, where the internal temperature is usually higher than outside; cooling period
32、s, where the internal temperature is usually lower than the outside; cold stores, where the internal temperature is always lower than outside.c) an estimate of the time taken for a component, between high vapour resistance layers, to dry, after wetting from any source, and the risk of interstitial c
33、ondensation occurring elsewhere in the component during the drying process.This International Standard does not cover other aspects of moisture, e.g. ground water and ingress of precipitation.In some cases, airflow from the interior of the building into the structure is the major mechanism for moist
34、ure transport, which can increase the risk of condensation problems very significantly. This International Standard does not address this issue; where it is felt to be important, more advanced assessment methods should be considered.The limitations on the physical processes covered by this Internati
35、onal Standard mean that it can provide a more robust analysis of some structures than others. The results will be more reliable for lightweight, airtight structures that do not contain materials that store large amounts of water. They will be less reliable for structures with large thermal and moist
36、ure capacity and which are subject to significant air leakage. ISO 2012 All rights reserved vBS EN ISO 13788:2012BS EN ISO 13788:2012Hygrothermal performance of building components and building elements Internal surface temperature to avoid critical surface humidity and interstitial condensation Cal
37、culation methods1 ScopeThis International Standard gives simplified calculation methods for:a) The internal surface temperature of a building component or building element below which mould growth is likely, given the internal temperature and relative humidity. The method can also be used to assess
38、the risk of other internal surface condensation problems.b) The assessment of the risk of interstitial condensation due to water vapour diffusion. The method used does not take account of a number of important physical phenomena including: the variation of material properties with moisture content;
39、capillary suction and liquid moisture transfer within materials; air movement from within the building into the component through gaps or within air spaces; the hygroscopic moisture capacity of materials.Consequently, the method is applicable only where the effects of these phenomena can be consider
40、ed to be negligible.c) The time taken for water, from any source, in a layer between two high vapour resistance layers to dry out and the risk of interstitial condensation occurring elsewhere in the component during the drying process.2 Normative referencesThe following referenced documents are indi
41、spensable for the application 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 6946:2007, Building components and building elements Thermal resistance and thermal trans
42、mittance Calculation methodISO 9346, Hygrothermal performance of buildings and building materials Physical quantities for mass transfer VocabularyISO 15927-1, Hygrothermal performance of buildings Calculation and presentation of climatic data Part 1: Monthly means of single meteorological elements3
43、Terms and definitions, symbols and units3.1 Terms and definitionsFor the purposes of this document, the terms and definitions given in ISO 9346 and the following apply.INTERNATIONAL STANDARD ISO 13788:2012(E) ISO 2012 All rights reserved 1BS EN ISO 13788:2012ISO 13788:2012(E)3.1.1monthly mean temper
44、aturemean temperature calculated from hourly values or the daily maximum and minimum temperature over a month3.1.2temperature factor at the internal surfacedifference between the temperature of the internal surface and the external air temperature, divided by the difference between the internal oper
45、ative temperature and the external air temperature, calculated with a surface resistance at the internal surface Rsi:fRsisi eie=Note 1 to entry: The operative temperature is taken as the arithmetic mean value of the internal air temperature and the mean radiant temperature of all surfaces surroundin
46、g the internal environment.Note 2 to entry: Methods of calculating the temperature factor in complex constructions are given in ISO 10211.3.1.3design temperature factor at the internal surfaceminimum acceptable temperature factor at the internal surface:fRsi,minsi,min eie=3.1.4minimum acceptable tem
47、peraturelowest internal surface temperature before mould growth may start3.1.5mean annual minimum temperaturemean of the lowest temperature recorded in each year of a set of at least ten years data3.1.6internal moisture excessrate of moisture production in a space divided by the air change rate and
48、the volume of the space: = ie=G/(n)V3.1.7water vapour diffusion-equivalent air layer thicknessthickness of a motionless air layer which has the same water vapour resistance as the material layer in question:sd= d3.1.8relative humidityratio of the vapour pressure to the saturated vapour pressure at t
49、he same temperature: =ppsat3.1.9critical surface humidityrelative humidity at the surface that leads to deterioration of the surface, specifically mould growth3.1.10heating periodexternal climate that leads to risk of condensation when a building is being heated, so that the internal temperature and vapour pressure are higher than outside2 ISO 2012 All rights reservedBS EN ISO 13788:2012ISO 13788:2012(E)3.1.11cooling periodexternal climate that leads to risk of condensation when a building is being cooled
