Dynamic coupling between vapour and heat transfer in wall assemblies: Analysis of measurements achieved under real climate

Labat, Matthieu; Woloszyn, Monika; Garnier, Géraldine; Roux, Jean-Jacques

doi:10.1016/j.buildenv.2015.01.022

Cited by 47 publications

(15 citation statements)

References 33 publications

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“…All of these elements have different hygrothermal properties, so that the behaviour of the whole assembly cannot be simply assessed. Some examples can be found in [40] for classical assemblies in a wooden frame-house. Numerical simulations at wall and building scales combined with an experimental campaign at wall scale could help to explore these aspects for straw-clay.…”

Section: Resultsmentioning

confidence: 99%

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From the experimental characterization of the hygrothermal properties of straw-clay mixtures to the numerical assessment of their buffering potential

Labat

Magniont

Oudhof³

et al. 2016

Building and Environment

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111

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. From the experimental characterization of the hygrothermal properties of straw-clay mixtures to the numerical assessment of their buffering potential. Building and Environment, Elsevier, 2016, 97, pp.69 -81. 10.1016/j.buildenv.2015 1 From the experimental characterization of the hygrothermal properties of straw-clay mixtures to the numerical assessment of their buffering potential ABSTRACTThe development of innovative materials has to respond to both environmental and energy concerns. Bio-based materials are relevant because they are made from renewable raw materials and are carbon neutral. Similarly, unprocessed earth has a very low embodied energy. In this paper, the basic hygrothermal properties of straw-clay samples provided by two French companies were determined. Mixes with densities lower than 450 kg.m -3 would be suitable for use as self-insulating material in current construction. In addition, the material showed a high sorption capacity and very high water vapour permeability. The measurements were then implemented in a numerical model in order to simulate the hygric response of a small room. The straw-clay mixture was found to have a moisture buffering effect of the same magnitude as walls made of hemp concrete and largely higher than conventional walls. The influence of various indoor finishing materials was investigated through additional simulations.

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Section: Resultsmentioning

confidence: 99%

“…For multi-layered walls, it has also been observed [40] that moisture transfers are influenced by the wall assembly. For example, vapour barriers are often used in lightweight buildings, which strongly impact the moisture balance at room scale.…”

Section: Buffering Potential Of Hygroscopic Materialsmentioning

confidence: 96%

From the experimental characterization of the hygrothermal properties of straw-clay mixtures to the numerical assessment of their buffering potential

Labat

Magniont

Oudhof³

et al. 2016

Building and Environment

Self Cite

111

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“…Labat et al [13] compared 6 different wall assemblies with mineral wool, wood fibre and cellulose insulations in a full scale timber frame building to validate a numerical model. They observed that the U-values of the wood fibre and cellulose insulations decreased by 53% and 46% from their dry value as a result of exposure to high internal relative humidity.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

Hygrothermal performance of wood-hemp insulation in timber frame wall panels with and without a vapour barrier

Latif

Ciupala

Tucker

et al. 2015

Building and Environment

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An in situ experiment on a full-scale timber frame test building was carried out to study the hygrothermal performance of wood-hemp composite insulation in timber frame wall panels with and without a vapour barrier. The heat transfer properties and the likelihood of mould growth and condensation in the panels were compared. Step changes in the internal relative humidity were performed to explore the effects of high, normal and low internal moisture loads on the wall panels. No significant difference in the average equivalent thermal transmittance (U-values) between the panels with and without a vapour barrier was observed. The average equivalent Uvalues of the panels were close to the U-values calculated from the manufacturers' declared thermal conductivity values of the insulation. The likelihood of condensation was higher at the interface of the wood-hemp insulation and the oriented strand board (OSB) in the panel without a vapour barrier. In terms of the parametric assessment of the mould germination potential, the relative humidity, the temperature and the exposure conditions in the insulation-OSB interfaces of the panel without a vapour barrier were found to be more favourable to the germination of mould spores. Nonetheless, when the insulations were dismantled, no mould was visually detected.

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“…These requirements gave rise to several experimental and theoretical works intended to deeply describe the effects of coupled heat and mass transfer in hygroscopic materials. These works are performed at the scales of wall assembly or building envelope (Labat et al, 2015;Rafidiarison et al, 2015;Zhang et al, 2017;Rouchier et al, 2017) These new requirement of building simulation are likely to benefit from the mature domain of drying and processing of hygroscopic materials (Perré, 2010;Perré et al, 2013). With the increasing performances of the building envelops, accurate characterization of building materials in terms of heat and mass transfer is crucial.…”

Section: Introductionmentioning

confidence: 99%

Heat and moisture diffusion in spruce and wood panels computed from 3-D morphologies using the Lattice Boltzmann method

Louërat

Ayouz

Perré

2018

International Journal of Thermal Sciences

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In this paper, the Lattice Boltzmann method is used to simulate heat and mass diffusion in bio-based building materials. The numerical method is presented and the methodology developed to reduce the calculation time is described. The 3-D morphologies of spruce and wood fibers are obtained using synchrotron X-ray micro-tomography. Equivalent macroscopic properties (heat conductivity and mass diffusivity) are therefore determined from the real micro-structure of the materials. The results reveal the anisotropy of the studied materials. The computed equivalent heat conductivity varies from 0.036 W m −1 K −1 to 0.52 W m −1 K −1 and the computed dimensionless mass diffusivity varies from 0.0088 to 0.78 depending on the materials and on the diffusion directions. Using these results, morphology families are identified and simple expressions are proposed to predict the equivalent properties as a function of phase properties and solid fraction.

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Dynamic coupling between vapour and heat transfer in wall assemblies: Analysis of measurements achieved under real climate

Cited by 47 publications

References 33 publications

From the experimental characterization of the hygrothermal properties of straw-clay mixtures to the numerical assessment of their buffering potential

From the experimental characterization of the hygrothermal properties of straw-clay mixtures to the numerical assessment of their buffering potential

Hygrothermal performance of wood-hemp insulation in timber frame wall panels with and without a vapour barrier

Heat and moisture diffusion in spruce and wood panels computed from 3-D morphologies using the Lattice Boltzmann method

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