Hygrothermal performance of highly insulated external walls subjected to indoor air exfiltration

dc.contributorAalto-yliopistofi
dc.contributorAalto Universityen
dc.contributor.authorViljanen, Klaus
dc.contributor.authorPuttonen, Jari
dc.contributor.authorLu, Xiaoshu
dc.contributor.departmentStructures – Structural Engineering, Mechanics and Computation
dc.contributor.departmentDepartment of Civil Engineering
dc.date.accessioned2022-09-28T06:28:24Z
dc.date.available2022-09-28T06:28:24Z
dc.date.issued2022-09
dc.description.abstractThe study comprises three laboratory tests in which typical Finnish highly insulated (HI) walls were exposed to concentrated leakages of indoor air under steady outdoor temperatures of 1–5°C. Airflows with a relative humidity of 50% and at rates of 1–3 L/min were directed close to the wooden frames inside the walls. The thermal resistance ratios between the exterior sheathing(s) and the whole wall (Γ) were 20%–22% and 1%–10% for the HI and baseline (BL) walls. The HI walls that presented Γ values of at least 20% were observed to be resistant to air exfiltration, and their durability was not affected by the addition of a gypsum sheathing outside the wooden frame or a more permeable vapor retarder. This is related to the negative linear correlation that exists between the moisture accumulation rate in wood-based material and the dew point depression (DPD) value. The developed approach, called the DPD method, shows that a significant degree of moisture accumulation does not occur even for DPD values of as low as−2°C if the exterior sheathing is vapor permeable. The airflow does not penetrate into the rigid mineral wool sheathing, which helps to avoid interstitial condensation. Regardless of thermal transmittance, the HI and BL walls with maximum Γ values of 1% were exposed to a high relative humidity and even interstitial condensation because the DPD values were often below −2°C. For these walls, the mold index analysis and visual observations confirmed the local risk for mold growth on the opposite side of the leakage point. In practice, long-term mold growth may be limited if the seasonal periods during which the outdoor temperature is 1–5°C last for a maximum of about 1 month every year.en
dc.description.versionPeer revieweden
dc.format.extent55
dc.format.extent967-1021
dc.format.mimetypeapplication/pdf
dc.identifier.citationViljanen , K , Puttonen , J & Lu , X 2022 , ' Hygrothermal performance of highly insulated external walls subjected to indoor air exfiltration ' , Journal of Building Physics , vol. 46 , no. 2 , pp. 967-1021 . https://doi.org/10.1177/17442591221109956en
dc.identifier.doi10.1177/17442591221109956
dc.identifier.issn1744-2591
dc.identifier.issn1744-2583
dc.identifier.otherPURE UUID: 52556c82-36e9-40eb-979c-4a0473bf020d
dc.identifier.otherPURE ITEMURL: https://research.aalto.fi/en/publications/52556c82-36e9-40eb-979c-4a0473bf020d
dc.identifier.otherPURE LINK: http://www.scopus.com/inward/record.url?scp=85135847353&partnerID=8YFLogxK
dc.identifier.otherPURE FILEURL: https://research.aalto.fi/files/88476062/Hygrothermal_performance_of_highly_insulated_external_walls_subjected_to_indoor_air_exfiltration.pdf
dc.identifier.urihttps://aaltodoc.aalto.fi/handle/123456789/116975
dc.identifier.urnURN:NBN:fi:aalto-202209285771
dc.language.isoenen
dc.publisherSAGE PUBLICATIONS
dc.relation.ispartofseriesJournal of Building Physicsen
dc.relation.ispartofseriesVolume 46, issue 2en
dc.rightsopenAccessen
dc.subject.keywordExfiltration
dc.subject.keywordair leakage
dc.subject.keywordmoisture convection
dc.subject.keywordhighly insulated
dc.subject.keyworddew point
dc.subject.keywordmold growth risk
dc.subject.keywordMOISTURE CONDITIONS
dc.subject.keywordMOLD GROWTH
dc.subject.keywordWOOD
dc.subject.keywordPERMEABILITY
dc.subject.keywordASSEMBLIES
dc.subject.keywordPRODUCTS
dc.subject.keywordLEAKAGE
dc.subject.keywordMODEL
dc.titleHygrothermal performance of highly insulated external walls subjected to indoor air exfiltrationen
dc.typeA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessäfi
dc.type.versionpublishedVersion
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