Laboratory Measurement and Boundary Conditions for the Water Vapour Resistivity Properties of Typical Australian Impermeable and Smart Pliable Membranes

The duo of better insulated and more air-tight envelopes without appropriate consideration of water vapour diffusion and envelope moisture management has often demonstrated an increased potential of moisture accumulation, interstitial condensation, and mould growth within the building envelope. To inform a resilient, energy efficient, and healthy building design, long-term transient hygrothermal modelling are required. Since 2008, concern has been raised to the Australian building regulators regarding the need to establish the vapour diffusion properties of construction materials, in order to develop a hygrothermal regulatory framework. This paper discusses the results from laboratory testing of the vapour diffusion properties of two common reflective pliable membranes, and one smart pliable membrane. The two reflective pliable membranes are often used within the exterior walls of Australian buildings. The smart pliable membrane is a relatively new, internationally available product. The three membranes were tested as per ISO 12,572 at 23 °C and 50% RH. To establish if the vapour resistivity properties were constant, under different relative humidity conditions, the membranes were further tested at 23 °C and relative humidity values of 35%, 65%, and 80%. The results of the three pliable membranes show that the vapour resistivity properties varied in a non-linear (dynamic) manner subject to relative humidity. In conclusion, this research demonstrates that regardless of the class, each of the tested membrane types behaved differently under varying relative humidity and pressure gradients within the testing laboratory.

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Untersuchungen zum Diffusionswiderstand von Holzwerkstoffen | Diffusion resistance of timber materials

Schweizerische Zeitschrift fur Forstwesen ◽

10.3188/szf.2005.0100 ◽

2005 ◽

Vol 156 (3-4) ◽

pp. 100-103

Author(s):

Rudolf Popper ◽

Peter Niemz ◽

Gerhild Eberle

Keyword(s):

Relative Humidity ◽

Water Vapour ◽

Middle Lamella ◽

Solid Wood ◽

Diffusion Resistance ◽

Water Vapour Diffusion ◽

Wood Panels ◽

Vapour Diffusion ◽

Wet Climate ◽

Panel Thickness

The water vapour diffusion resistance of timber materials were tested in a wet climate (relative humidity ranging from 100%to 65% at 20 °C) and in a dry climate (relative humidity ranging from 0% to 65% and from 0% to 35% at 20 °c) with variation by relative humidity and vapour pressure gradient. The diffusion resistance of multilayer solid wood panels lies under or within the range of the solid wood (spruce), tending even to a lower range. This can be attributed to the loosely inserted middle lamella of the used solid wood panels, which were not correctly glued by the manufacturer. The diffusion resistance of the solid wood panels increases with decreasing moisture content and decreasing panel thickness, as well as with increasing water vapour gradient from 818 to 1520 Pa. There were clear differences between the tested timber materials. The diffusion resistance of particle composites is strongly dependent on the specific gravity. Due to laminar particles OSBs(Oriented Strand Boards) have a larger diffusion resistance than chipboards. The water vapour diffusion resistance of OSBs lies within the range of plywood.

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Empirical Investigation of the Hygrothermal Diffusion Properties of Permeable Building Membranes Subjected to Variable Relative Humidity Condition

Energies ◽

10.3390/en14134053 ◽

2021 ◽

Vol 14 (13) ◽

pp. 4053

Author(s):

Toba Samuel Olaoye ◽

Mark Dewsbury ◽

Hartwig Künzel

Keyword(s):

Relative Humidity ◽

Empirical Investigation ◽

Construction Material ◽

Building Envelope ◽

Test Method ◽

Relative Humidity Condition ◽

Current Test ◽

Vapour Diffusion ◽

Standard Tests ◽

Diffusion Properties

Hygrothermal modelling is increasingly used to inform building envelope design. A key input for these calculations is the material’s vapour diffusion properties. Respecting a growing international concern, this research has questioned the appropriateness of the current test method to establish construction material for vapour diffusion properties. This article reports on the empirical measurement of the vapour diffusion properties of two vapour-permeable building membranes commonly used in Australia residential systems when subjected to variable relative humidity conditions. The method involved completing dry cup and wet cup standard tests as specified in ISO 12572, (23 °C and 50% relative humidity RH). Further tests were then conducted as temperature remained at 23 °C but the relative humidity changed to 35%, 65% and 80%, respectively, in order to know if the diffusion properties are the same or change with varying relative humidity. The results from the wet cup and dry cup tests under different relative humidity conditions were non-linear and different. These results indicate vapour-permeable membranes behave differently when exposed to different relative humidity conditions. In conclusion, this research demonstrates that the current vapour resistivity test method is inadequate, hence the need to establish more detailed diffusion resistivity properties in different humidity ranges that represent conditions experienced within a building’s external envelope.

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Hygrothermal performance of building equipment and industrial installations. Calculation of water vapour diffusion. Cold pipe insulation systems

10.3403/30242980 ◽

2014 ◽

Keyword(s):

Water Vapour ◽

Water Vapour Diffusion ◽

Vapour Diffusion ◽

Hygrothermal Performance ◽

Insulation Systems ◽

Pipe Insulation

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Effects of exposure on water relations and photosynthesis of western hemlock in habitat forms

Canadian Journal of Forest Research ◽

10.1139/x76-006 ◽

1976 ◽

Vol 6 (1) ◽

pp. 40-48 ◽

Cited By ~ 4

Author(s):

R. A. Keller ◽

E. B. Tregunna

Keyword(s):

Light Intensity ◽

Water Content ◽

Water Vapour ◽

Western Hemlock ◽

Diffusion Resistance ◽

The Sun ◽

Evaporative Demand ◽

Photosynthetic Rates ◽

Water Vapour Diffusion ◽

Vapour Diffusion

Measurements of relative turgidity, transpiration rates, and photosynthetic rates on sun-grown and shade-grown western hemlock (Tsugaheterophylla (Raf.) Sarg.) were used to indicate effects of varying degrees of exposure.The sun-adapted form had low photosynthetic rates but maintained its water content under conditions of high evaporative demand. The shade-adapted form desiccated under exposed conditions, and in contrast with the sun-adapted form, its water vapour diffusion resistance decreased with increasing light intensity.

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Hygric Properties of HPC with Natural Pozzolana

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.677.93 ◽

2016 ◽

Vol 677 ◽

pp. 93-97 ◽

Cited By ~ 1

Author(s):

Jaroslava Koťátková ◽

Monika Čáchová ◽

Dana Koňáková ◽

Eva Vejmelková

Keyword(s):

Water Vapour ◽

High Performance ◽

High Performance Concrete ◽

Diffusion Resistance ◽

Supplementary Cementitious Material ◽

Water Vapour Transport ◽

Water Vapour Diffusion ◽

Natural Pozzolana ◽

Vapour Diffusion ◽

Liquid Water Transport

The water vapour transport and the liquid water transport of high performance concrete (HPC) with the content of natural pozzolana are the described in this paper. Studied properties are presented by means of water vapour diffusion coefficient, water vapour diffusion resistance factor and absorption coefficient respectively. The natural pozzolana (NP), namely natural zeolite, is used as supplementary cementitious material which affects the durability properties of the end product. The obtained results revealed the effectiveness of NP in the terms of both studied properties when used in small amounts, i.e. at about 20% of cement weight. On the other hand substitutions higher than 40% result in worsening of the resistance of the concrete to water and water vapour ingress and its movement trough the material.

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Combined bound water and water vapour diffusion of Norway spruce and European beech in and between the principal anatomical directions

Holzforschung ◽

10.1515/hf.2011.091 ◽

2011 ◽

Vol 65 (6) ◽

pp. 819-828 ◽

Cited By ~ 12

Author(s):

Walter Sonderegger ◽

Manuele Vecellio ◽

Pascal Zwicker ◽

Peter Niemz

Keyword(s):

Diffusion Coefficient ◽

Steady State ◽

Water Vapour ◽

Diffusion Coefficients ◽

Bound Water ◽

European Beech ◽

Unsteady State ◽

Water Vapour Diffusion ◽

Vapour Diffusion ◽

Water Vapour Resistance

Abstract The combined bound water and water vapour diffusion of wood is of great interest in the field of building physics. Due to swelling stresses, the steady-state-determined diffusion coefficient clearly differs from the unsteady-state-determined diffusion coefficient. In this study, both diffusion coefficients and the water vapour resistance factor of Norway spruce (Picea abies [L.] Karst.) and European beech (Fagus sylvatica L.) were investigated for the principal anatomical directions (radial, tangential and longitudinal) and in 15° steps between these directions. The values were determined with the cup method as the basic principle. The unsteady-state-determined diffusion coefficient is, independent of the direction, about half that of the steady-state-determined diffusion coefficient. Both diffusion coefficients are about two to three times higher for spruce than for beech. They are up to 12 times higher in the longitudinal direction than perpendicular to the grain for spruce, and up to 15 times higher for beech. With increasing moisture content, the diffusion coefficients exponentially increase. The water vapour resistance factor shows converse values to the diffusion coefficients.

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Condensation of Water Vapour in the Functional Gap of Window - Experimental Measurement of Exfiltration at 15 Pa

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.820.285 ◽

2016 ◽

Vol 820 ◽

pp. 285-292

Author(s):

Adela Palková ◽

Ľuboš Kamenický ◽

Milan Palko

Keyword(s):

Heat Transfer ◽

Water Vapour ◽

Experimental Measurement ◽

Experimental Analysis ◽

Experimental Measurements ◽

Air Filtration ◽

Climatic Chamber ◽

University Of Technology ◽

Water Vapour Diffusion ◽

Vapour Diffusion

The article is focused on the experimental analysis of water vapour in functional gap of wooden window. The experimental measurements were held in a laboratory of heat engineering of the Slovak university of Technology in Bratislava – in a big climatic chamber for synergic phenomena of heat transfer, water vapour diffusion and air filtration.

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