Generative reverse-modelling approach to hygrothermal material characterization

Klõšeiko, Paul; Freudenberg, Peggy

doi:10.1051/matecconf/201928202088

Cited by 3 publications

(8 citation statements)

References 4 publications

(3 reference statements)

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“…The liquid and vapour conductivity curves were created using the tool described in Klõšeiko and Freudenberg (2019). However, for this publication, new material characterizations were done compared to the ones in the aforementioned paper.…”

Section: Methodsmentioning

confidence: 99%

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Hygrothermal performance of a brick wall with interior insulation in cold climate: Vapour open versus vapour tight approach

Klõšeiko

Kalamees

2021

Journal of Building Physics

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Interior insulation of historic buildings is well-studied in Central Europe; however, their conclusions might not be directly applicable to colder climates. Heat, air and moisture (HAM) modelling can be a valuable tool for studying those solutions in different conditions. Recently, incorporating the capillary condensation redistribution (CCR) test into the material characterization process has shown to cause dramatic improvement in correlating hygrothermal modelling results to measurements in certain situations. It is also noteworthy, that the HAM modelling errors made using material data from conventional characterization process can be severely non-conservative. In this article a parametric study of a 51 cm thick mass masonry wall is undertaken to determine the effect of the improved material properties on the reliability of a vapour open ‘capillary active’ autoclaved aerated concrete (AAC) and calcium silicate (CaSi) interior insulation solutions and to compare them to a vapour tight insulation system. A 49-year real weather dataset from Estonia is used. The results show that compared to conventionally characterized material properties the CCR-optimized material data causes more critical conditions directly behind the interior insulation, while having a similar performance in the exterior part of the masonry. The differences occur close to the performance limits and highlight the importance of using the CCR test in material characterization process. The vapour tight and vapour open systems showed a very similar impact on the freeze-thaw cycles and on the maximum ice saturation of the exterior part of the masonry. The vapour open solutions perform better than the vapour tight PIR in terms of frost damage and possible mould growth behind the insulation – even though the advantage has been reduced when using the CCR-optimized material data. Regardless of the insulation solution, a case-specific approach is still required to avoid damaging the original wall and/or the added insulation system.

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Section: Methodsmentioning

confidence: 99%

“…Klõšeiko and Freudenberg (2019) suggest a method for generically optimizing the vapour and liquid conductivity curves by remodelling the material tests also involving the CCR test. Autoclaved aerated concrete (AAC) and calcium silicate (CaSi) were used as an example for this process.…”

Section: Introductionmentioning

confidence: 99%

Hygrothermal performance of a brick wall with interior insulation in cold climate: Vapour open versus vapour tight approach

Klõšeiko

Kalamees

2021

Journal of Building Physics

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“…Linear splines: We model Kv and Kl using linear splines with Nv and Nl points, respectively, which is similar as described in [4]. This approach dispenses a physical derivation of Kl, however it allows to freely determine both functions.…”

Section: Model and Parametersmentioning

confidence: 99%

“…However, these experiments are mostly isothermal with vapour and liquid fluxes occurring in the same direction, which hardly allows distinguishing between both. Hence, as it has been shown by Binder et al [8] [9] as well as by Klõšeiko et al [4], the determined parameter may not be valid for modelling a non-isothermal experiment and hence the hygrothermal simulation could not reconstruct real-world measurements.…”

Section: Introductionmentioning

confidence: 97%

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Capillary condensation experiment for inverse modelling of porous building materials

2020

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Hygrothermal simulations are of major importance for critical problems in building physics, such as the application of internal insulation in heritage buildings. These simulations require numerous material parameters that are challenging to determine. We present measurements of typical internal insulation materials, calcium-silicate and autoclaved aerated concrete, which we expose to a warm, humid climate on one side and a cold temperature on the other side. We measure the moisture gain over time and determine the moisture profile at experiment end. In an inverse modelling approach, the measurements are used to identify material parameters, in particular vapour conductivity and capillary conductivity as a function of moisture content. We found the measurements of crucial importance for the accurate determination of these parameters. When the parameters rely only on isothermal measurements such as the drying experiment, the model fails to predict the capillary condensation process. We demonstrate this on a dataset from another study with interior insulation subjected to changing boundary conditions. The model calibrated with capillary condensation data reliably reconstructs measurements while the drying-calibrated model drastically underestimates the moisture content.

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Capillary condensation redistribution (CCR) test: measurement results of 5 materials and comparison to modelling

Klõšeiko,

Valk,

Põldaru

et al. 2023

J. Phys.: Conf. Ser.

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To improve the accuracy of hygrothermal modelling, a capillary condensation redistribution (CCR) has been proposed to help distribute the share of vapour and liquid conductivity functions based on a wider experimental dataset. This paper aims to provide further data by presenting the CCR test measurement results of 2 calcium silicate (CaSi) boards, 2 aerated autoclaved concrete (AAC) boards and spruce (the latter both perpendicular and parallel to the grain). A variation of the CCR test setup is described. The measurement results agree with those from literature where some of the materials presented here were also tested. Modelling results using previously available material properties are compared to measurement results: none of the AAC and longitudinal spruce material properties can reproduce the moisture content levels achieved in the study, while CCR-optimized CaSi material data is close to the measured results. The best agreement between measurements and modelling of spruce perpendicular to grain are achieved with material properties which discard liquid conductivity and presume increased vapour permeability due to increase of moisture content instead.

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Generative reverse-modelling approach to hygrothermal material characterization

Cited by 3 publications

References 4 publications

Hygrothermal performance of a brick wall with interior insulation in cold climate: Vapour open versus vapour tight approach

Hygrothermal performance of a brick wall with interior insulation in cold climate: Vapour open versus vapour tight approach

Capillary condensation experiment for inverse modelling of porous building materials

Capillary condensation redistribution (CCR) test: measurement results of 5 materials and comparison to modelling

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