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)This British Standardwas published underthe authority of theSt
2、andards 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forewordThis British Standard is the UK implementation of EN ISO 14683:2007.It supersedes BS EN ISO 14683:1999 which is withdrawn.
3、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 obtained onrequest to its secretary.This publication does not purport to include all the necessary p
4、rovisionsof a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.1DecEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 14683December 2007ICS 91.120.10 Supersedes EN ISO 14683:1999 English VersionThermal brid
5、ges in building construction - Linear thermaltransmittance - Simplified methods and default values (ISO14683:2007)Ponts thermiques dans les btiments - Coefficient liniquede transmission thermique - Mthodes simplifies etvaleurs par dfaut (ISO 14683:2007)Wrmebrcken im Hochbau - LngenbezogenerWrmedurch
6、gangskoeffizient - Vereinfachte Verfahren undAnhaltswerte (ISO 14683:2007)This European Standard was approved 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 s
7、tandard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards 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 othe
8、r language made by translationunder the responsibility of a CEN member into its own language and notified 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, Fi
9、nland,France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMI
10、TEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2007 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 14683:2007: EBS EN ISO 14683:2007EN ISO 14683:2007 (E) 3 Foreword This document (EN ISO 14683:2007) has bee
11、n 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 th
12、e status 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 sub
13、ject 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
14、 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
15、the United Kingdom. Endorsement notice The text of ISO 14683:2007 has been approved by CEN as a EN ISO 14683:2007 without any modification. BS EN ISO 14683:2007ISO 14683:2007(E) ISO 2007 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Normative references 1 3 Terms, defin
16、itions, 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 Linear thermal transmittance .3 4.3 Internal and external dimensions.4 5 Determination of linea
17、r 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 transmittance.5 Annex A (informative) Default values of linear thermal transmittance6 Annex B (inf
18、ormative) Example of the use of default values of linear thermal transmittance in calculating the heat transfer coefficient19 Bibliography 23 BS EN ISO 14683:2007ISO 14683:2007(E) iv ISO 2007 All rights reservedForeword ISO (the International Organization for Standardization) is a worldwide federati
19、on 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
20、. 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 w
21、ith 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 appr
22、oval 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 14683 was prepared by Technical Commit
23、tee 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 14683:1999), which has been technically revised. The following principal changes have been made to the first edition: t
24、he Scope has been amended to remove the restriction on window and door frames and curtain walling, and specifies 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 s
25、hort text of the former 5.4, the remainder of which has been transferred into informative Annex A; Annex 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
26、200 mm instead of 150 mm; frames in openings of thickness 60 mm instead of 100 mm). BS 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
27、conservation 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
28、calculation 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 ele
29、ment, 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 wo
30、rth noting that thermal bridges can also give rise to low internal surface temperatures, with an associated risk of surface condensation or mould growth. BS EN ISO 14683:2007BS EN ISO 14683:2007INTERNATIONAL STANDARD ISO 14683:2007(E) ISO 2007 All rights reserved 1Thermal bridges in building constru
31、ction Linear thermal transmittance Simplified methods and default values 1 Scope This International Standard deals with simplified methods for determining heat flows through linear thermal bridges which occur at junctions of building elements. This International Standard specifies requirements relat
32、ing to thermal bridge catalogues and manual calculation methods. Default values of linear thermal transmittance 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 editi
33、on cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 7345, Thermal insulation Physical quantities and definitions ISO 10211, Thermal bridges in building construction Heat flows and surface temperatures Detailed calculations 3
34、 Terms, definitions, symbols and units 3.1 Terms and definitions For the purposes of this document, the terms 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
35、bridge localized thermal bridge whose influence can be represented by a point thermal transmittance 3.1.3 linear 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 th
36、ermal transmittance is a quantity describing the influence of a linear thermal bridge on the total heat flow. BS 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 env
37、ironments 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
38、 by the difference 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 coeffici
39、ent through 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 ther
40、mal transmittance W/K 3.3 Subscripts Subscript Definition e external i internal oi overall internal BS EN ISO 14683:2007ISO 14683:2007(E) ISO 2007 All rights reserved 34 Influence of thermal bridges on overall heat transfer 4.1 Transmission heat transfer coefficient Between internal and external env
41、ironments 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, is calculated using Equation (2): TDgUH HHH=+(2) where HDis the direct heat transfer coeffi
42、cient 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 calculated in accordance with ISO 13789. 4.2 Linear thermal transmittance The calculation o
43、f 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; Uiis the thermal transmittance of element i of the building envelope, in W/(m2K); lkis th
44、e 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 influence of point thermal bridges (insofar as they result from the intersection of linea
45、r 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 transmittances should be calculated in accordance with ISO 10211. Linear thermal bridges a
46、re 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; BS EN ISO 146
47、83:2007ISO 14683:2007(E) 4 ISO 2007 All rights reserved at columns in external walls; around windows and doors. 4.3 Internal and external dimensions There are three dimension systems commonly in use: internal dimensions, measured between the finished internal faces of each room in a building (thus e
48、xcluding the thickness of internal partitions); overall internal dimensions, measured between the finished internal faces of the external elements of the building (thus including the thickness of internal partitions); external dimensions, measured between the finished external faces of the external
49、elements of the building. These are described further in ISO 13789. Any of these dimension systems may be used, provided that the system chosen is used consistently for all parts of the building construction. Linear thermal transmittance values depend on the system used, i.e. on the areas used for one-dimensional heat flow in iiiAUin Equation (3), but the total transmission coefficient HTis the same provided that all thermal bridges are taken into account. 5 Determination of
