1、BS EN ISO6946:2007ICS 91.060.01; 91.120.10NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDBuilding componentsand buildingelements Thermalresistance and thermaltransmittance Calculation method(ISO 6946:2007)This British Standardwas published under theauthority of
2、 the StandardsPolicy and StrategyCommittee on 32008 BSI 2008ISBN 978 0 580 54937 3Amendments/corrigenda issued since publicationDate CommentsBS EN ISO 6946:2007National forewordThis British Standard is the UK implementation of EN ISO 6946:2007. Itsupersedes BS EN ISO 6946:1997 which is withdrawn.The
3、 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 prov
4、isionsof a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.0 SeptemberEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 6946December 2007ICS 91.060.01; 91.120.10 Supersedes EN ISO 6946:1996 English Versio
5、nBuilding components and building elements - Thermalresistance and thermal transmittance - Calculation method (ISO6946:2007)Composants et parois de btiments - Rsistance thermiqueet coefficient de transmission thermique - Mthode decalcul (ISO 6946:2007)Bauteile - Wrmedurchlasswiderstand undWrmedurchg
6、angskoeffizient - Berechnungsverfahren (ISO6946:2007)This European Standard was approved by CEN on 7 December 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 a
7、lteration. 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 other language made by tr
8、anslationunder 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, Finland,France, Germany
9、, 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 KOMITEE FR NORMUNGManagem
10、ent 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 6946:2007: EBS EN ISO 6946:2007EN ISO 6946:2007 (E) 3 Foreword This document (EN ISO 6946:2007) has been prepared by Technical C
11、ommittee 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
12、andard, 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 subject of patent rights. CE
13、N and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 6946:1996. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: A
14、ustria, 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. Endors
15、ement notice The text of ISO 6946:2007 has been approved by CEN as a EN ISO 6946:2007 without any modification. BS EN ISO 6946:2007ISO 6946:2007(E) ISO 2007 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references . 1 3 Terms, definitions, symbols and units
16、. 1 3.1 Terms and definitions. 1 3.2 Symbols and units 2 4 Principles. 2 5 Thermal resistances . 3 5.1 Thermal resistance of homogeneous layers . 3 5.2 Surface resistances 3 5.3 Thermal resistance of air layers 4 5.4 Thermal resistance of unheated spaces 6 6 Total thermal resistance 7 6.1 Total ther
17、mal resistance of a building component consisting of homogeneous layers. 7 6.2 Total thermal resistance of a building component consisting of homogeneous and inhomogeneous layers. 7 7 Thermal transmittance . 11 Annex A (normative) Surface resistance. 12 Annex B (normative) Thermal resistance of airs
18、paces 15 Annex C (normative) Calculation of the thermal transmittance of components with tapered layers . 18 Annex D (normative) Corrections to thermal transmittance 22 Bibliography . 28 BS EN ISO 6946:2007ISO 6946:2007(E) iv ISO 2007 All rights reservedForeword ISO (the International Organization f
19、or 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 th
20、e 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. Internat
21、ional 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
22、 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.
23、 ISO 6946 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 6946:1996), which has been technically revised. It also incorporates the Amen
24、dment ISO 6946:1996/Amd.1:2003. The following changes have been made to the first edition: information on the calculation of heat flow rates has been transferred from the Introduction to the note in Clause 4; 5.3.3 provides an amended basis for slightly ventilated air layers; 5.4.2 provides clarific
25、ation of the applicability of Table 3; 5.4.3 has been completely revised; 6.2.1 provides a new text to allow calculation of a component that is part of a complete element; it also clarifies exceptions and the limit of applicability; Annex B provides additional data for other temperature differences
26、across cavities; it also provides a correction to the formula for radiation transfer in divided airspaces; Annex C contains an additional shape; D.2 has been completely rewritten to clarify the intentions, the former Annex E having been deleted (national annexes can be attached to this International
27、 Standard giving examples in accordance with local building traditions); D.3 provides a revised procedure for mechanical fasteners, including recessed fasteners; D.4 does not apply in cooling situations. BS EN ISO 6946:2007ISO 6946:2007(E) ISO 2007 All rights reserved vIntroduction This Internationa
28、l Standard provides the means (in part) to assess the contribution that building products and services make to energy conservation and to the overall energy performance of buildings. BS EN ISO 6946:2007BS EN ISO 6946:2007INTERNATIONAL STANDARD ISO 6946:2007(E) ISO 2007 All rights reserved 1Building
29、components and building elements Thermal resistance and thermal transmittance Calculation method 1 Scope This International Standard provides the method of calculation of the thermal resistance and thermal transmittance of building components and building elements, excluding doors, windows and other
30、 glazed units, curtain walling, components which involve heat transfer to the ground, and components through which air is designed to permeate. The calculation method is based on the appropriate design thermal conductivities or design thermal resistances of the materials and products for the applica
31、tion concerned. The method applies to components and elements consisting of thermally homogeneous layers (which can include air layers). This International Standard also provides an approximate method that can be used for elements containing inhomogeneous layers, including the effect of metal fasten
32、ers, by means of a correction term given in Annex D. Other cases where insulation is bridged by metal are outside the scope of this International Standard. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the
33、 edition 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 10456, Building materials and products Hygrothermal properties Tabulated design values and procedures
34、 for determining declared and design thermal values ISO 13789, Thermal performance of buildings Transmission and ventilation heat transfer coefficients Calculation method 3 Terms, definitions, symbols and units 3.1 Terms and definitions For the purposes of this document, the terms and definitions gi
35、ven in ISO 7345 and ISO 10456 and the following apply. 3.1.1 building element major part of a building such as a wall, floor or roof BS EN ISO 6946:2007ISO 6946:2007(E) 2 ISO 2007 All rights reserved3.1.2 building component building element or a part of it NOTE In this International Standard, the wo
36、rd “component” is used to indicate both element and component. 3.1.3 thermally homogeneous layer layer of constant thickness having thermal properties which may be regarded as being uniform 3.2 Symbols and units Symbol Quantity Unit A area m2d thickness m h surface heat transfer coefficient W/(m2K)
37、R design thermal resistance (surface to surface) m2K/W Rgthermal resistance of airspace m2K/W Rseexternal surface resistance m2K/W Rsiinternal surface resistance m2K/W RTtotal thermal resistance (environment to environment) m2K/W TR upper limit of total thermal resistance m2K/W TR lower limit of tot
38、al thermal resistance m2K/W Ruthermal resistance of unheated space m2K/W U thermal transmittance W/(m2K) design thermal conductivity W/(mK) 4 Principles The principle of the calculation method is as follows: to obtain the thermal resistance of each thermally homogeneous part of the component; to com
39、bine these individual resistances so as to obtain the total thermal resistance of the component, including (where appropriate) the effect of surface resistances. Thermal resistances of individual parts are obtained in accordance with 5.1. The values of surface resistance given in 5.2 are appropriate
40、 in most cases. Annex A gives detailed procedures for low emissivity surfaces, specific external wind speeds and non-planar surfaces. Air layers may be regarded as thermally homogeneous for the purposes of this International Standard. Values of the thermal resistance of large air layers with high em
41、issivity surfaces are given in 5.3. Annex B provides procedures for other cases. The resistances of the layers are combined as follows: a) for components consisting of thermally homogeneous layers, obtain the total thermal resistance in accordance with 6.1 and the thermal transmittance in accordance
42、 with Clause 7; BS EN ISO 6946:2007ISO 6946:2007(E) ISO 2007 All rights reserved 3b) for components having one or more thermally inhomogeneous layers, obtain the total thermal resistance in accordance with 6.2 and the thermal transmittance in accordance with Clause 7; c) for components containing a
43、tapered layer, obtain the thermal transmittance and/or the total thermal resistance in accordance with Annex C. Finally, corrections are applied to the thermal transmittance, if appropriate, in accordance with Annex D, in order to allow for the effects of air voids in insulation, mechanical fastener
44、s penetrating an insulation layer and precipitation on inverted roofs. The thermal transmittance calculated in this way applies between the environments on either side of the component concerned, e.g. internal and external environments, two internal environments in the case of an internal partition,
45、 an internal environment and an unheated space. Simplified procedures are given in 5.4 for treating an unheated space as a thermal resistance. NOTE Calculation of heat flow rates are commonly undertaken using operative temperature (usually approximated to the arithmetic mean of air temperature and m
46、ean radiant temperature) to represent the environment inside buildings, and air temperature to represent the external environment. Other definitions of the temperature of an environment are also used when appropriate to the purpose of the calculation. See also Annex A. 5 Thermal resistances 5.1 Ther
47、mal resistance of homogeneous layers Design thermal values can be given as either design thermal conductivity or design thermal resistance. If thermal conductivity is given, obtain the thermal resistance of the layer from dR= (1) where d is the thickness of the material layer in the component; is th
48、e design thermal conductivity of the material, either calculated in accordance with ISO 10456 or obtained from tabulated values. NOTE The thickness, d, can be different from the nominal thickness (e.g. when a compressible product is installed in a compressed state, d is less than the nominal thickne
49、ss). If relevant, it is advisable that d also make appropriate allowance for thickness tolerances (e.g. when they are negative). Thermal resistance values used in intermediate calculations shall be calculated to at least three decimal places. 5.2 Surface resistances Use the values in Table 1 for plane surfaces in the absence of specific information on the boundary conditions. The values under “horizontal” apply to heat flow directions 30 from the horizontal plane. For non-planar surfaces or
