1、BS EN ISO14683:2007ICS 91.120.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDThermal bridges inbuilding construction Linear thermaltransmittance Simplified methodsand default values (ISO14683:2007)Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 30/03/2
2、009 08:35, Uncontrolled Copy, (c) BSIThis British Standardwas published underthe authority of theStandards Policy andStrategy Committee on 3ember 2008 BSI 2008ISBN 978 0 580 64347 7Amendments/corrigenda issued since publicationDate CommentsBS EN ISO 14683:2007National forewordThis British Standard i
3、s the UK implementation of EN ISO 14683:2007.It supersedes BS EN ISO 14683:1999 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee B/540, Energy performance of materials components andbuildings.A list of organizations represented on this committee can be o
4、btained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.1DecLicensed Copy: Wang Bin, ISO/EXCHANGE CHINA
5、 STANDARDS, 30/03/2009 08:35, Uncontrolled Copy, (c) BSIEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 14683December 2007ICS 91.120.10 Supersedes EN ISO 14683:1999 English VersionThermal bridges in building construction - Linear thermaltransmittance - Simplified methods and default values (IS
6、O14683:2007)Ponts thermiques dans les btiments - Coefficient liniquede transmission thermique - Mthodes simplifies etvaleurs par dfaut (ISO 14683:2007)Wrmebrcken im Hochbau - LngenbezogenerWrmedurchgangskoeffizient - Vereinfachte Verfahren undAnhaltswerte (ISO 14683:2007)This European Standard was a
7、pproved by CEN on 7 November 2007.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nation
8、alstandards 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 translationunder the responsibility of a CEN member into its own language and notif
9、ied to the CEN Management Centre has the same status as theofficial 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,
10、 Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2007 CEN All rights of exploitati
11、on in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 14683:2007: ELicensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 30/03/2009 08:35, Uncontrolled Copy, (c) BSIBS EN ISO 14683:2007EN ISO 14683:2007 (E) 3 Foreword This document (EN ISO 14683:2007) has been p
12、repared 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 s
13、tatus of a national standard, either by publication of an identical text or by endorsement, at the latest by June 2008, and conflicting national standards shall be withdrawn at the latest by June 2008. Attention is drawn to the possibility that some of the elements of this document may be the subjec
14、t 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 14683:1999. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement th
15、is 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
16、 United Kingdom. Endorsement notice The text of ISO 14683:2007 has been approved by CEN as a EN ISO 14683:2007 without any modification. Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 30/03/2009 08:35, Uncontrolled Copy, (c) BSIBS EN ISO 14683:2007ISO 14683:2007(E) ISO 2007 All rights reserv
17、ed iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Normative references 1 3 Terms, definitions, symbols and units 1 3.1 Terms and definitions .1 3.2 Symbols and units.2 3.3 Subscripts 2 4 Influence of thermal bridges on overall heat transfer3 4.1 Transmission heat transfer coefficient .3 4.2
18、 Linear thermal transmittance .3 4.3 Internal and external dimensions.4 5 Determination of linear thermal transmittance.4 5.1 Available methods and expected accuracy 4 5.2 Numerical calculations4 5.3 Thermal bridge catalogues.4 5.4 Manual calculation methods.5 5.5 Default values of linear thermal tr
19、ansmittance.5 Annex A (informative) Default values of linear thermal transmittance6 Annex B (informative) Example of the use of default values of linear thermal transmittance in calculating the heat transfer coefficient19 Bibliography 23 Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 30/03/2
20、009 08:35, Uncontrolled Copy, (c) BSIBS EN ISO 14683:2007ISO 14683:2007(E) iv ISO 2007 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is nor
21、mally 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
22、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 prepar
23、e 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 som
24、e 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 14683 was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use in the built environment, Subcommittee SC 2, Calculati
25、on methods. This second edition cancels and replaces the first edition (ISO 14683:1999), which has been technically revised. The following principal changes have been made to the first edition: the Scope has been amended to remove the restriction on window and door frames and curtain walling, and sp
26、ecifies that the default values of linear thermal transmittance are provided for information; 5.2 is a new subclause replacing some elements previously contained in 4.2; 5.5 is a summary into a short text of the former 5.4, the remainder of which has been transferred into informative Annex A; Annex
27、A contains values of linear thermal transmittance which have all been reviewed, many of them amended upwards as a result of changing the basis in Table A.1 (intermediate floor slabs thickness of 200 mm instead of 150 mm; frames in openings of thickness 60 mm instead of 100 mm). Licensed Copy: Wang B
28、in, ISO/EXCHANGE CHINA STANDARDS, 30/03/2009 08:35, Uncontrolled Copy, (c) BSIBS EN ISO 14683:2007ISO 14683:2007(E) ISO 2007 All rights reserved vIntroduction This International Standard provides the means (in part) to assess the contribution that building products and services make to energy conser
29、vation and to the overall energy performance of buildings. Thermal bridges in building constructions give rise to changes in heat flow rates and surface temperatures compared with those of the unbridged structure. These heat flow rates and temperatures can be precisely determined by numerical calcul
30、ation in accordance with ISO 10211. However, for linear thermal bridges, it is often convenient to use simplified methods or tabulated values to obtain an estimate of their linear thermal transmittance. The effect of repeating thermal bridges which are part of an otherwise uniform building element,
31、such as wall ties penetrating a thermal insulation layer or mortar joints in lightweight blockwork, needs to be included in the calculation of the thermal transmittance of the building element concerned, in accordance with ISO 6946. Although not covered by this International Standard, it is worth no
32、ting that thermal bridges can also give rise to low internal surface temperatures, with an associated risk of surface condensation or mould growth. Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 30/03/2009 08:35, Uncontrolled Copy, (c) BSIBS EN ISO 14683:2007Licensed Copy: Wang Bin, ISO/EXCH
33、ANGE CHINA STANDARDS, 30/03/2009 08:35, Uncontrolled Copy, (c) BSIBS EN ISO 14683:2007INTERNATIONAL STANDARD ISO 14683:2007(E) ISO 2007 All rights reserved 1Thermal bridges in building construction Linear thermal transmittance Simplified methods and default values 1 Scope This International Standard
34、 deals with simplified methods for determining heat flows through linear thermal bridges which occur at junctions of building elements. This International Standard specifies requirements relating to thermal bridge catalogues and manual calculation methods. Default values of linear thermal transmitta
35、nce are given in Annex A for information. 2 Normative references The following referenced documents are indispensable 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 amend
36、ments) applies. ISO 7345, Thermal insulation Physical quantities and definitions ISO 10211, Thermal bridges in building construction Heat flows and surface temperatures Detailed calculations 3 Terms, definitions, symbols and units 3.1 Terms and definitions For the purposes of this document, the term
37、s and definitions given in ISO 7345 and the following apply. 3.1.1 linear thermal bridge thermal bridge with a uniform cross section along one of the three orthogonal axes 3.1.2 point thermal bridge localized thermal bridge whose influence can be represented by a point thermal transmittance 3.1.3 li
38、near thermal transmittance heat flow rate in the steady state divided by length and by the temperature difference between the environments on either side of a thermal bridge NOTE The linear thermal transmittance is a quantity describing the influence of a linear thermal bridge on the total heat flow
39、. Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 30/03/2009 08:35, Uncontrolled Copy, (c) BSIBS EN ISO 14683:2007ISO 14683:2007(E) 2 ISO 2007 All rights reserved3.1.4 point thermal transmittance heat flow rate in the steady state divided by the temperature difference between the environments
40、 on either side of a thermal bridge NOTE The point thermal transmittance is a quantity describing the influence of a point thermal bridge on the total heat flow. 3.1.5 transmission heat transfer coefficient heat flow rate due to thermal transmission through the fabric of a building, divided by the d
41、ifference between the environment temperatures on either side of the construction 3.2 Symbols and units Symbol Quantity Unit A area m2b width md thickness m HTtransmission heat transfer coefficient W/K HDdirect transmission heat transfer coefficient W/K HUtransmission heat transfer coefficient throu
42、gh unconditioned spaces W/K l length mR thermal resistance m2K/W Rseexternal surface resistance m2K/W Rsiinternal surface resistance m2K/W U thermal transmittance W/(m2K) Celsius temperature C design thermal conductivity W/(mK) heat flow rate W linear thermal transmittance W/(mK) point thermal trans
43、mittance W/K 3.3 Subscripts Subscript Definition e external i internal oi overall internal Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 30/03/2009 08:35, Uncontrolled Copy, (c) BSIBS EN ISO 14683:2007ISO 14683:2007(E) ISO 2007 All rights reserved 34 Influence of thermal bridges on overall
44、heat transfer 4.1 Transmission heat transfer coefficient Between internal and external environments with temperatures iand e respectively, the transmission heat flow rate through the building envelope, , is calculated using Equation (1): ()Ti eH= (1) The transmission heat transfer coefficient, HT, i
45、s calculated using Equation (2): TDgUH HHH=+(2) where HDis the direct heat transfer coefficient through the building envelope defined by Equation (3); Hg is the ground heat transfer coefficient calculated in accordance with ISO 13370; HUis the heat transfer coefficient through unconditioned spaces c
46、alculated in accordance with ISO 13789. 4.2 Linear thermal transmittance The calculation of the transmission heat transfer coefficient includes the contribution due to thermal bridges, according to Equation (3): D ii k k jikHAUl =+(3) where Aiis the area of element i of the building envelope, in m2;
47、 Uiis the thermal transmittance of element i of the building envelope, in W/(m2K); lkis the length of linear thermal bridge k, in m; kis the linear thermal transmittance of linear thermal bridge k, in W/(mK); j is the point thermal transmittance of the point thermal bridge j, in W/K. In general, the
48、 influence of point thermal bridges (insofar as they result from the intersection of linear thermal bridges) can be neglected and so the correction term involving point thermal bridges can be omitted from Equation (3). If, however, there are significant point thermal bridges, then the point thermal
49、transmittances should be calculated in accordance with ISO 10211. Linear thermal bridges are generally liable to occur at the following locations in a building envelope: at junctions between external elements (corners of walls, wall to roof, wall to floor); at junctions of internal walls with external walls and roofs; at junctions of intermediate floors with external walls; Licensed Copy: Wang Bin, ISO/EXCHANGE CHINA STANDARDS, 30/03/2009 08:35, Uncontrolled Copy, (c) BSIBS EN ISO 14683:20
