smart vapor retarder

Smart vapor barrier is based on the variability of its permeability according to relative humidity level.

Smart vapor barriers are introduced to building envelope for improved moisture performance in Europe. It can be transferred and/or developed for Canadian market. Need to evaluate: the actual performance improvement in real envelopes; the design difference to conventional barriers; and, the relationship and interaction of barrier to other materials and designs (such as the what air barrier is required for the improve moisture performance of this barrier)

Many types: Fraunhofer Institute for Building Physics, Germany (ref: R-7): a nylon-based membrane that has property of humidity-dependent variation of vapor permeability, due to its capacity to absorb water, which creates its own selective pores in the materials. By adapting its vapor permeability according to the ambient conditions in a range between 0.7 perm and 36 perm, the smart retarder opens up its pores when good drying conditions for the assembly prevail. Principle: humidity-dependent variation of vapor permeability is due to its capacity to absorb water, which creates its own selective pores in the materials. Material: Consists of a nylon-based membrane. Nylon has three (3) times the tensile strength of the polyethylene film.

Laboratory of Building Physics, University Leuven, Belgium:a cellulose-based felt, reinforced with a glass fiber fabric and coated with a thin layer of polyethylene and latex. Ammonium salts are added to upgrade the fire-retarding properties; self-drying vapor retarder used on roof,

a product to be sprayed or wrapped on wood studs,

the barrier allows moisture flow out and not in, a kind of one way vapor barrier

to be explored Principle: the interaction between water and polymer molecules causes the diffusion resistance to be moisture-dependent.

cellulose-based felt

Application of a new type of air and vapor retarder in a self-drying sloped roof with a cathedral ceiling, by Hens, H. and Janssens, A., 1998

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Flexible vapor control solves moisture problems of building assemblies - smart retarder to replace the conventional PE-film, by K¨ąnzel, H. M., 1999

humidity controlled vapor retarder

Hygric properties of a new humidity controlled vapor retarder, by Hens, H., 1997

nylon-based membrane, warm climate

More moisture load tolerance of construction assemblies through the application of a smart vapor retarder, by Kunzel, H. M., 1998

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Smart vapor retarder: an innovation inspired by computer simulations, by Kunzel, H. M., 1998

film material with permeance depedent, computer simulation

The smart vapor retarder: an innovation inspired by computer simulations, by Kunzel, H. M., 1998

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Vapor-barrier film permits home insulation to `breathe', by Modern Plastics Editorial Staff, 1997