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2011
Conference Paper
Titel
Reducing the risk of microbial growth on insulated walls by PCM enhanced renders and IR reflecting paints
Abstract
Staining of façades due to microbial growth has been on the rise in recent years. Especially walls with external insulation systems are affected because low thermal mass of the exterior render combined with high thermal resistance of the insulation layer leads to frequent overcooling of the render's surface by long-wave radiation exchange with the sky. Condensation forming on the overcooled façade is of major importance for microbial growth. Therefore, the best way to prevent growth is to reduce the frequency of condensation by limiting the periods of overcooling. This could be achieved by increasing the thermal inertia of the exterior render through the addition of phase change materials (PCM) or by applying low IR emissivity (Low-E) paint coats. The performance of novel rendering systems including PCM additives and/or Low-E coating has been investigated by field tests as well hygrothermal simulations. The results show that Low-E coats may be more effective than PCM additives because the latent heat of phase change is only beneficial when the surface temperature coincides with PCM's melting temperature range.