Surface heat transfer coefficients in building envelopes: Uncertainty levels in experimental methods

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dc.contributor.authorGaray-Martinez, Roberto
dc.contributor.authorArregi, Beñat
dc.contributor.authorLumbreras, Mikel
dc.contributor.institutionTecnalia Research & Innovation
dc.contributor.institutionEDIFICACIÓN DE ENERGÍA POSITIVA
dc.date.issued2023-07
dc.descriptionPublisher Copyright: © The Author(s) 2023.
dc.description.abstractThere are several research methods for the on-site assessment of U-values that aim to avoid the use of surface heat flux measurements and rely on tabulated or empirically developed correlations to define this parameter. This works performs a detailed process to estimate indoor surface heat transfer coefficients based on several experimental campaigns over building walls. Data is filtered out to remove periods with large temperature variations and/or unstable convective conditions due to HVAC. A statistical analysis is conducted, and the outcomes used to test the validity of U-value estimation approaches. The outcomes show that the actual surface heat transfer coefficients are in the range of reference works, but variations in the range of up to 2 W/m2 K are found. Uncertainty levels associated to the estimation of surface heat transfer coefficient are in the range 60% for instantaneous values while this is reduced down to 12%–20% for 8-h averages. Variations and uncertainty levels are higher for low temperature gradient situations, which are considered to be very likely for modern insulation levels. It is concluded that methods seeking to avoid the use of surface heat flux measurements need to develop much deeper knowledge in this field to gain accuracy and reliability.en
dc.description.statusPeer reviewed
dc.format.extent30
dc.identifier.citationGaray-Martinez , R , Arregi , B & Lumbreras , M 2023 , ' Surface heat transfer coefficients in building envelopes : Uncertainty levels in experimental methods ' , Journal of Building Physics , vol. 47 , no. 1 , pp. 62-91 . https://doi.org/10.1177/17442591221150250
dc.identifier.doi10.1177/17442591221150250
dc.identifier.issn1744-2591
dc.identifier.urlhttp://www.scopus.com/inward/record.url?scp=85147339836&partnerID=8YFLogxK
dc.language.isoeng
dc.relation.ispartofJournal of Building Physics
dc.rightsinfo:eu-repo/semantics/restrictedAccess
dc.subject.keywordsbuilding walls
dc.subject.keywordsHeat transfer
dc.subject.keywordson-site assessment
dc.subject.keywordsstatistical analysis
dc.subject.keywordssurface heat transfer
dc.subject.keywordsU-value
dc.subject.keywordsuncertainty
dc.subject.keywordsBuilding and Construction
dc.subject.keywordsGeneral Materials Science
dc.titleSurface heat transfer coefficients in building envelopes: Uncertainty levels in experimental methodsen
dc.typejournal article
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