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Advances in Materials Science and Engineering
Volume 2014, Article ID 650752, 16 pages
http://dx.doi.org/10.1155/2014/650752
Research Article

External Thermal Insulation Composite Systems: Critical Parameters for Surface Hygrothermal Behaviour

Laboratory of Building Physics (LFC), Civil Engineering Department (DEC), Faculty of Engineering-University of Porto (FE/UP), Rua Dr. Roberto Frias, 4200-465 Porto, Portugal

Received 13 May 2013; Accepted 4 November 2013; Published 5 February 2014

Academic Editor: Markku Leskela

Copyright © 2014 Eva Barreira and Vasco P. de Freitas. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

External Thermal Insulation Composite Systems (ETICS) are often used in Europe. Despite its thermal advantages, low cost, and ease of application, this system has serious problems of biological growth causing the cladding defacement. Recent studies pointed that biological growth is due to high values of surface moisture content, which mostly results from the combined effect of exterior surface condensation, wind-driven rain, and drying process. Based on numerical simulation, this paper points the most critical parameters involved in hygrothermal behaviour of ETICS, considering the influence of thermal and hygric properties of the external rendering, the effect of the characteristics of the façade, and the consequences of the exterior and interior climate on exterior surface condensation, wind-driven rain, and drying process. The model used was previously validated by comparison with the results of an “in situ” campaign. The results of the sensitivity analyses show that relative humidity and temperature of the exterior air, atmospheric radiation, and emissivity of the exterior rendering are the parameters that most influence exterior surface condensation. Wind-driven rain depends mostly on horizontal rain, building’s height, wind velocity, and orientation. The drying capacity is influenced by short-wave absorbance, incident solar radiation, and orientation.