ISO INTERNATIONAL STANDARD 6946 Third edition 2017-06 Building components and building elements Thermal resistance and thermal transmittance Calculation methods Composants et parois de batiments - Résistance thermique et coefficient de transmission thermique - Méthodes de calcul Reference number IS0 6946:2017(E) International Organization for Standardization @ IS0 2017 ee=ZHEJIANG INST OF STANDARDIZATION C15956617 mitted without license from IHS IS0 6946:2017(E) COPYRIGHT PROTECTED DOCUMENT IS0 2017, Published in Switzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form written permission. Permission can be requested from either Iso at the address below or Iso's member body in the country of the requester. ISO copyright office Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 copyright@iso.org www.iso.org Internatinir DrganizationforStandardization Licensee-ZHEJIANG INST OF STANDARDIZoISQ37 -All rights reserved Not for Resale, 2017/9/12 02:47:43 No reproduction or networking permited without license from IHS IS0 6946:2017(E) Contents Page Foreword ..iv Introduction. .. 1 Scope. ..1 2 Normative references 3 Terms and definitions ..2 4 Symbols and subscripts. .3 4.1 Symbols .3 4.2 Subscripts. .3 5 Description of the method .3 5.1 Output. .3 5.2 General description.. ..4 5.3 Detailed calculation method .4 5.4 Simplified calculation method .4 6 Calculation of thermal transmittance and thermal resistance ..4 6.1 Output data .4 6.2 Calculation time intervals .4 6.3 Input data 4 6.4 Principles of the simplified calculation procedure .5 6.5 Thermal transmittance. .6 6.5.1 By detailed calculation method. .6 6.5.2 By simplified calculation method .6 6.6 Thermal resistance.. .7 6.7 Total thermal resistance ..7 6.7.1 Thermal resistance of homogeneous components .7 6.7.2 Total thermal resistance of a building component consisting of homogeneous and inhomogeneous layers. ..8 6.8 Surface resistances ..12 6.9 Thermal resistance of air layers ..12 6.9.1 Applicability ..12 6.9.2 Unventilated air layer .13 6.9.3 Slightly ventilated air layer .13 6.9.4 Well-ventilated air layer .14 6.10 Thermal resistance of unheated spaces .14 6.10.1 General ..14 6.10.2 Roof spaces ..14 6.10.3 Other spaces .. 15 Annex A (normative) Input and method selection data sheet - Template ..16 Annex B (informative) Input and method selection data sheet - Default choices ..19. Annex C (normative) Surface resistances. ..22 Annex D (normative) Thermal resistance of airspaces. ..25 Annex E (normative) Calculation of the thermal transmittance of components with tapered layers. .29 Annex F (normative) Correction to thermal transmittance ..34 Bibliography. ..40 ii icensee=ZHEJIANG INST OF STANDARDIZATION C1 5956617 d without license from IHS