ISO INTERNATIONAL STANDARD 13788 Second edition 2012-12-15 Hygrothermal performance of building components and building elements Internal surface temperature to avoid critical surface humidity and interstitial condensation Calculation methods Performance hygrothermique des composants et parois de batiments-Température superficielleintérieurepermettant d'eéviter I'humidité superficielle critique et la condensation dans la masse Méthodes de calcul Reference number ISO 13788:2012(E) LSO @ ISO 2012 I without license from IHS Not for Resale IS0 13788:2012(E) COPYRIGHTPROTECTEDDOCUMENT IS02012 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either IsO at the address below or Iso's member body in the country of the requester. ISO copyright office Case postale 56:CH-1211 Geneva 20 Tel.+41227490111 Fax +41 22 749 09 47 E-mail [email protected] Web www.iso.org Published in Switzerland @ IS0 2012 - All rights reserved No reproductic etworking permitted without license from IHS Not for Resale IS0 13788:2012(E) Contents Page Foreword ..iv Introduction. ..V 1 Scope. .1 2 Normative references ..1 3 Terms and definitions, symbols and units ..1 3.1 Terms and definitions .1 3.2 Symbols and units.... 3.3 Subscripts 4 4 Input data for the calculations. .4 4.1 Material and product properties .4 4.2 External boundary conditions. 4 4.3 Internal boundary conditions .6 4.4 Surfaceresistances ..6 5 Calculation of surface temperature to avoid critical surface humidity .7 5.1 General .7 5.2 Determining parameters .7 5.3 Design for avoidance of mould growth, corrosion or other moisture damage .7 5.4 Design for the limitation of surface condensation on low thermal inertia elements .8 6 Calculation of interstitial condensation 9 6.1 General .9 6.2 Principle. .9 6.3 Limitation of sources of error. ..10 6.4 Calculation .10 6.5 Criteria used to assess building components ..16 7 Calculation of drying of building components ..16 7.1 General .16 7.2 Principle .17 7.3 Specification of the method .17 7.4 Criteria used to assess drying potential of building components ..17 AnnexA(informative)Internalboundaryconditions .18 Annex B (informative) Examples of calculation of the temperature factor at the internal surface to avoid critical surface humidity. 20 Annex C (informative) Examples of calculation of interstitial condensation ..24 Annex D (informative) Example ofthe calculation of the drying of a wetted layer ..34 Annex E (informative) Relationships governing moisture transfer and water vapour pressure....37 Bibliography .40 ZAn rights reserved iii se with IS thout license from IHS Not for Resale