[PDF] Water Vapor Transmission Through Building Materials And Systems eBook

Author : Phalguni Mukhopadhyaya
Publisher :
Page : 8 pages
File Size : 13,88 MB
Release : 2011
Category : Air permeability
ISBN :

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Two fundamental properties of building materials that influence the hygrothermal performance of building envelope systems are water vapor permeability and air permeability. The driving forces for water vapor and air transmission through building materials are, respectively, partial water vapor pressure and total air pressure differentials. The theoretical similarity of the driving forces would suggest the possibility of a relationship between water vapor and air permeability. During past two decades, researchers at the National Research Council of Canada--Institute for Research in Construction have compiled a database of measured air permeability and water vapor permeability properties of building materials commonly used in North America. This material properties database was examined to identify the degree to which air permeability and water vapor permeability of the building materials might be functionally related. The database was segregated into categories for different material types. An approximately linear relationship could, within some categories, be observed between water vapor permeability and air permeability. There were however approximately as many categories within which no relationship between the parameters was apparent as there were categories within which functional relationships between the parameters were apparent. Within categories where functional relationships were apparent, the form of the relationships generally depended on the mean relative humidity at which water vapor permeability was measured. In most cases, a definitive functional form of the relationship between water vapor permeability and air permeability could not be established.

Author : Hugo S. L. Hens
Publisher : John Wiley & Sons
Page : 323 pages
File Size : 27,73 MB
Release : 2012-01-09
Category : Technology & Engineering
ISBN : 3433601275

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Die Energiekrise der 1970er Jahre, häufig auftretende Feuchteprobleme, Klagen über das Sick-Building-Syndrom und mangelnden Komfort hinsichtlich Raumklima und Behaglichkeit und nicht zuletzt das Bemühen um Nachhaltigkeit haben die Bauphysik zu einem Innovationsmotor auf dem Gebäudesektor gemacht. Dabei war die gesellschaftliche Forderung nach Energieeinsparung in Gebäuden ohne Gebrauchseinschränkungen der Auslöser für die ganzheitliche Planung. Wie alle Ingenieurwissenschaften ist auch die Bauphysik anwendungsorientiert, weshalb sich nach einem ersten Buch über die Grundlagen das vorliegende zweite Buch mit den Hintergründen der Gebrauchstauglichkeit und den Anforderungen an Energieeffizienz in Gebäuden befasst. Außenklimabedingungen und Raumklimaberechnungen werden diskutiert, Energieverluste und -gewinne werden für Gebäude und separat für die Gebäudehülle untersucht. Die wichtigen physikalischen Eigenschaften für den gekoppelten Wärme- und Feuchtetransport durch Baukonstruktionen werden für zahlreiche Materialien aufgeführt. Für das Buch stützt sich der Autor auf seine Erfahrungen aus 35 Jahren Lehre der Bauphysik für Architekten und Bauingenieure und 40 Jahre Tätigkeit in der Forschung und als Beratender Ingenieur.

Author : João M. P. Q. Delgado
Publisher : Springer Nature
Page : 62 pages
File Size : 48,62 MB
Release : 2019-09-10
Category : Technology & Engineering
ISBN : 3030308030

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The knowledge of moisture migration inside building materials and construction building components is decisive for the way they behave when in use. The durability, waterproofing, degrading aspect and thermal behaviour of these materials are strongly influenced by the existence of moisture within their interior, which provoke changes in their normal performance, something that is normally hard to predict. Due to the awareness of this problem, the scientific community have per-formed various studies about the existence of moisture inside porous materials. The complex aspects of moisture migration phenomenon tended to encompass monolithic building elements, since the existence of joints or layers contributes to the change of moisture transfer along the respective building element that contribute to the change of mass transfer law. The presentation of an experimental analyses concerning moisture transfer in the interface of material that makes up masonry is described in such a way as to evaluate the durability and/or avoid building damages. In this work it was analysed, during the wetting process, the influence of different types of interface, commonly observed in masonry, such as: perfect con-tact, joints of cement mortar, lime mortar, and the air space interface. The results allow the calculation of the hygric resistance. With these results, it is possible to use any advanced hygrothermal simulation program to study the water transport in building elements, considering different interfaces and their hygric resistance.

Author : William B. Rose
Publisher : John Wiley & Sons
Page : 290 pages
File Size : 27,62 MB
Release : 2005-04-07
Category : Architecture
ISBN : 0471468509

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The definitive guide to understanding and managing the effects of water on buildings Water in Buildings: An Architect's Guide to Moisture and Mold is a detailed and highly useful reference to help architects and other design professionals create dry, healthy environments, without jeopardizing a project with poor liability management. Much more than a book of "quick fixes," this practical guide illuminates an essential understanding of the "whys" of moisture problems, including valuable information on how water behaves and how its performance can be anticipated and managed in building design. With a special emphasis on water's role in creating mold, an issue of growing concern and liability, Water in Buildings offers the most up-to-date information on rainwater management, below-grade water management, foundations, wall and roof construction, mechanical systems, moisture, and much more! Providing authoritative guidance to designers and builders, this definitive guide features: * Clear explanations of how water interacts with building materials and equipment * An in-depth exploration of the paths of leaks * Numerous case studies on such well-known structures as Mount Vernon, Independence Hall, and Wingspan (Frank Lloyd Wright) * Numerous descriptive drawings and photographs