1、BSI Standards PublicationWB11885_BSI_StandardCovs_2013_AW.indd 1 15/05/2013 15:06Thermal performance of buildings and building components - Physical quantities and definitions (ISO 7345:2018)BS EN ISO 7345:2018National forewordThis British Standard is the UK implementation of EN ISO 7345:2018. It is
2、 identical to ISO 7345:2018. It supersedes BS EN ISO 7345:1996, which is withdrawn.The UK participation in its preparation was entrusted to Technical Committee B/540/8, Mirror committee for ISO/TC 163 - Thermal Performance and Energy use in the built Environment.A list of organizations represented o
3、n this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2018 Published by BSI Standards Limited 2018ISBN 978 0 580 85204
4、6ICS 27.220; 01.060Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 April 2018.Amendments/corrigenda issued since publicationDate Text affectedBRITISH STANDARD
5、BS EN ISO 7345:2018EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 7345April 2018ICS 01.060; 27.220 Supersedes EN ISO 7345:1995EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGCEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels 2018
6、 CEN Ref. No. EN ISO 7345:2018: EAll rights of exploitation in any form and by any means reserved worldwide for CEN national MembersThermal performance of buildings and building components - Physical quantities and definitions (ISO 7345:2018)Performance thermique des btiments et des matriaux pour le
7、 btiment - Grandeurs physiques et dfinitions (ISO 7345:2018)Wrmeverhalten von Gebuden und Baustoffen - Physikalische Gren und Definitionen (ISO 7345:2018)This European Standard was approved by CEN on 23 March 2018.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipul
8、ate 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-CENELEC Management Centre or to any CEN member.This European Sta
9、ndard 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-CENELEC Management Centre has the same status as the official versions.CEN members are the nat
10、ional standards bodies of 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, Se
11、rbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.English VersionEN ISO 7345:2018 (E)European forewordThis document (EN ISO 7345:2018) has been prepared by Technical Committee ISO/TC 163 “Thermal performance and energy use in the built environment“ in collaboration with
12、 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 October 2018, and
13、conflicting national standards shall be withdrawn at the latest by October 2018.Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN shall not be held responsible for identifying any or all such patent rights.This document supersed
14、es EN ISO 7345:1995.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, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Ma
15、cedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.Endorsement noticeThe text of ISO 7345:2018 has been approve
16、d by CEN as EN ISO 7345:2018 without any modification.2BS EN ISO 7345:2018ISO 7345:2018Foreword ivIntroduction v1 Scope .12 Normative references 13 Terms and definitions .1Annex A (informative) Concept of thermal conductivity .8Bibliography .12 ISO 2018 All rights reserved iiiContents PageBS EN ISO
17、7345:2018ISO 7345:2018ForewordISO (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
18、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
19、 (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should
20、be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see /www.iso.org/directives).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 ident
21、ifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenie
22、nce of users and does not constitute an endorsement.For an explanation on the voluntary nature of standards, the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the World Trade Organization (WTO) principles in the Technic
23、al Barriers to Trade (TBT) see the following URL: www.iso.org/iso/foreword.html.This document was prepared by Technical Committee ISO/TC 163, Thermal performance and energy use in the built environment.This third edition of ISO 7345 cancels and replaces the second edition (ISO 7345:1987), which has
24、been technically revised.This edition includes the following significant changes with respect to the previous edition: title of the standard updated from Thermal insulation Physical quantities and definitions to Thermal performance of buildings and building elements Physical quantities and definitio
25、ns ; title of ISO/TC 163 corrected (Foreword); ISO 31-4 replaced by ISO 80000-5 in the note in the Scope and added to the Bibliography; symbols, names and definitions (in 3.3 and 3.4) adapted to current state ( L, l L2D, Ul , coefficient of heat loss heat transfer coefficient); “areal” used instead
26、of “surface” in quantity names (Clause 3) where “surface” was meant to distinguish between a length-related quantity (“linear”) and an area-related quantity (now “areal”) with similar name; Formula in 3.1.4 corrected; subscript l added in 3.4; added a Note 1 to entry in 3.1.11 and a Note 3 to entry
27、in 3.1.13; H added in 3.2.2 as an alternative name for Fs; added “for homogeneous solids” to A.1 in Annex A.iv ISO 2018 All rights reservedBS EN ISO 7345:2018ISO 7345:2018IntroductionThis document is intended to be used in conjunction with other vocabularies related to thermal insulation. These incl
28、ude: ISO 7945, Thermal insulation Physical quantities and definitions ISO 9251, Thermal insulation Heat transfer conditions and properties of materials Vocabulary ISO 9346, Thermal insulation Mass transfer Physical quantities and definitions ISO 9229, Thermal insulation Thermal insulating materials
29、and products Vocabulary ISO 9288, Thermal insulation Heat transfer by radiation Physical quantities and definitionsNOTE Annex A provides an explanation of the concept of thermal conductivity. ISO 2018 All rights reserved vBS EN ISO 7345:2018This page deliberately left blankThermal performance of bui
30、ldings and building components - Physical quantities and definitions 1 ScopeThis document defines physical quantities used in the thermal performance of buildings and building elements, and gives the corresponding symbols and units.NOTE Because the scope of this document is restricted to thermal per
31、formance and energy use in the built environment, some of the definitions it contains differ from those given ISO 80000-5.2 Normative referencesThere are no normative references in this document.3 Terms and definitionsISO and IEC maintain terminological databases for use in standardization at the fo
32、llowing addresses: IEC Electropedia: available at http:/www.electropedia.org/ ISO Online browsing platform: available at https:/www.iso.org/obp3.1 Physical quantities and definitions3.1.1heatquantity of heatQNote 1 to entry: Unit: J.3.1.2heat flow ratequantity of heat transferred to or from a system
33、 divided by time =dQdtNote 1 to entry: Unit: W.3.1.3density of heat flow rateqheat flow rate divided by area qddA=Note 1 to entry: The word “density” should be replaced by “areal density” when it may be confused with linear density (3.1.4).Note 2 to entry: Unit: W/m2.INTERNATIONAL STANDARD ISO 7345:
34、2018 ISO 2018 All rights reserved 1BS EN ISO 7345:2018ISO 7345:20183.1.4linear density of heat flow rateq1heat flow rate divided by length: qddll=Note 1 to entry: Unit: W/m.3.1.5thermal conductivityquantity defined by the following relation: qT= gradNote 1 to entry: A rigorous treatment of the conce
35、pt of thermal conductivity is given in the annex, which also deals with the application of the concept of thermal conductivity to porous isotropic or anisotropic materials and the influence of temperature and test conditions.Note 2 to entry: Unit: W/(mK).3.1.6thermal resistivityrquantity defined by
36、the following relation: gradTrq=Note 1 to entry: A rigorous treatment of the concept of thermal resistivity is given in Annex A.Note 2 to entry: Unit: (mK)/W.3.1.7thermal resistanceRtemperature difference divided by the density of heat flow rate in the steady state condition: RTTq=12Note 1 to entry:
37、 For a plane layer for which the concept of thermal conductivity applies, and when this property is constant or linear with temperature (see Annex A): Rd=Note 2 to entry: where d is the thickness of the layer.Note 3 to entry: These definitions assume the definition of two reference temperatures, T1a
38、nd T2,and the area through which the density of heat flow rate is uniform.Note 4 to entry: Thermal resistance can be related either to the material, structure or surface. If either T1or T2is not the temperature of a solid surface, but that of a fluid, a reference temperature must be defined in each
39、specific case (with reference to free or forced convection and radiation from surrounding surfaces, etc.).Note 5 to entry: When quoting values of thermal resistance, T1and T2must be stated.2 ISO 2018 All rights reservedBS EN ISO 7345:2018ISO 7345:2018Note 6 to entry: “Thermal resistance” should be r
40、eplaced by “areal thermal resistance” when it may be confused with linear thermal resistance (3.1.8).Note 7 to entry: Unit: (m2K)/W.3.1.8linear thermal resistanceRltemperature difference divided by the linear density of heat flow rate in the steady state condition: RTTqll=12Note 1 to entry: This ass
41、umes the definition of two reference temperatures, T1and T2, and the length along which the linear density of heat flow rate is uniform.Note 2 to entry: If within the system either T1or T2is not the temperature of a solid surface, but that of a fluid, a reference temperature must be defined in each
42、specific case (with reference to free or forced convection and radiation from surrounding surfaces, etc.).Note 3 to entry: When quoting values of linear thermal resistance, T1and T2must be stated.Note 4 to entry: Unit: (mK)/W.3.1.9surface coefficient of heat transferhdensity of heat flow rate at a s
43、urface in the steady state divided by the temperature difference between that surface and the surroundings: hqTT=+saNote 1 to entry: This assumes the definition of the surface through which the heat is transferred, the temperature of the surface, Ts, and the ambient temperature, Ta(with reference to
44、 free or forced convection and radiation from surrounding surfaces. etc.). The surface us usually denoted by an index e for external and i for internal surface.Note 2 to entry: Unit: W/(m2K).3.1.10thermal conductanceLreciprocal of thermal resistance from surface to surface under conditions of unifor
45、m density of heat flow rate: LR=1Note 1 to entry: “Thermal conductance” should be replaced by “areal thermal conductance” when it may be confused with linear thermal conductance (3.1.11)Note 2 to entry: Unit: W/(m2K).3.1.11linear thermal conductanceLlW/(mK) ISO 2018 All rights reserved 3BS EN ISO 73
46、45:2018ISO 7345:2018reciprocal of linear thermal resistance from surface to surface under conditions of uniform linear density of heat flow rate: LRll=1Note 1 to entry: Unit: W/(mK).3.1.12thermal transmittanceUheat flow rate in the steady state divided by area and by the temperature difference betwe
47、en the surroundings on both sides of a flat uniform system: UTTA=()12Note 1 to entry: This assumes the definition of the system, the two reference temperatures, T1and T2, and other boundary conditions.Note 2 to entry: “Thermal transmittance” should be replaced by “areal thermal transmittance” when i
48、t may be confused with linear thermal transmittance (3.1.13).Note 3 to entry: The reciprocal of the thermal transmittance is the total thermal resistance between the surroundings on both sides of the flat uniform system.Note 4 to entry: Unit: W/(m2K).3.1.13linear thermal transmittanceheat flow rate
49、in the steady state divided by length and by the temperature difference between the surroundings on each side of a system: =()TTl12Note 1 to entry: This assumes the definition of the system, the two reference temperatures, T1and T2, and other boundary conditions.Note 2 to entry: The reciprocal of the linear thermal transmittance is the total linear thermal resistance between the surroundings on each side of the system.Note 3 to entry: When is used to characterize linear
