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Title:Difference between using tabulated and exact values of thermal properties of materials in numerical simulations of heat transfer through a high-performance window
Authors:ID Jukić, Miha (Author)
ID Jordan, Sabina (Author)
Files:URL URL - Source URL, visit https://www.witpress.com/elibrary/wit-transactions-on-engineering-sciences/124/37194
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MD5: 323BE5B974D8C5E4679B0572B607F88D
 
Language:English
Typology:1.08 - Published Scientific Conference Contribution
Organization:Logo ZAG - Slovenian National Building and Civil Engineering Institute
Abstract:The thermal properties of materials, primarily the thermal conductivity, are an essential input for numerical modelling of heat transfer in buildings and building components. When determining them according to relevant European standards, it is not uncommon to encounter materials for which the exact values are not appropriately specified and the tabulated values in standards are overly conservative. In such situations, the thermal conductivity of the material can be determined by measurement. However, this approach may prove inconvenient and too expensive, especially if the material in question turns out to have little influence on the overall thermal performance of the product. It is, therefore, of great interest to know how the thermal performance is affected by choosing either the accurate (measured) or the conservative (tabulated) value of the thermal conductivity. In this work, the two approaches are compared in a practical example – a high-performance window, Jelovica Jelofuture – using numerical simulations. Our study shows that modifying the thermal properties of individual materials generally leaves the thermal transmittances of the frame (Uf) and the window (UW) almost unaffected. If all of the materials considered are modified simultaneously, Uf changes by 1–2% while the change in UW remains below 1%. However, due to their small values, the calculated changes of Uf and UW may be significantly affected (further increased or reduced) by the rounding of the results according to the relevant standards. In contrast, using the tabulated value of linear thermal transmittance (Ψg) of the junction with the glazing leads to an overestimation of UW by up to 15%.
Keywords:thermal transmittance, numerical simulation, conductivity, tabulated and exact values, practical example
Publication status:Published
Publication version:Version of Record
Publication date:31.07.2019
Publisher:WIT
Year of publishing:2019
Number of pages:Str. 119-130
PID:20.500.12556/DiRROS-18335 New window
UDC:620.1/.2
DOI:10.2495/MC190121 New window
COBISS.SI-ID:2499943 New window
Copyright:© 2019 WIT Press
Note:Nasl. z nasl. zaslona; Opis vira z dne 28. 11. 2019;
Publication date in DiRROS:08.03.2024
Views:739
Downloads:505
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JUKIĆ, Miha and JORDAN, Sabina, 2019, Difference between using tabulated and exact values of thermal properties of materials in numerical simulations of heat transfer through a high-performance window. In : Materials and contact characterisation IX [online]. Published Scientific Conference Contribution. Wessex : WIT. 2019. p. 119–130. [Accessed 22 April 2025]. Retrieved from: https://dirros.openscience.si/IzpisGradiva.php?lang=eng&id=18335
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Record is a part of a monograph

Title:Materials and contact characterisation IX
Place of publishing:Wessex
Publisher:WIT
Year of publishing:2019
ISBN:978-1-78466-332-2
COBISS.SI-ID:2499687 New window
Collection title:WIT transactions on engineering sciences
Collection numbering:ǂvol. ǂ124
Collection ISSN:1743-3533

Licences

License:Other
Description:This paper will be freely available, without charge, for users to read, download, copy, distribute, print, search, link to the full text, or use for any other lawful purpose, without asking prior permission from the publisher or the author as long as the author/copyright holder is attributed.

Secondary language

Language:Slovenian
Keywords:toplotna prehodnost, numerične simulacije, prevodnost, tabeliranje in točne vrednosti, praktični primer


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