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Hot-box measurements to investigate the internal convection of highly insulated loose-fill insulation roof structures

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Hot-box measurements to investigate the internal convection of highly insulated loose-fill insulation roof structures. / Kivioja, Henna; Vinha, Juha.

In: Energy and Buildings, Vol. 216, 109934, 01.06.2020.

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@article{8dcfc338987b462ba588f6beaca2c5b2,
title = "Hot-box measurements to investigate the internal convection of highly insulated loose-fill insulation roof structures",
abstract = "The purpose of this study was to investigate how internal convection in loose-fill insulations affects the insulation properties of highly insulated roof structures. This study consists of laboratory measurements of roof structures insulated by two different blown-in insulations. The measurements are repeated with two temperature differences and air velocities for 300 mm and 600 mm thick insulation layers both with and without trusses, making a total of 24 case studies. The measurements were conducted with equipment using the calibrated hot-box method. The results of the tests show that internal convection can reduce insulation capacity significantly, especially with low-density loose-fill insulations, such as blown-in glass wool. A critical evaluation should be performed as to whether international standards and national building regulations take internal convection into account adequately. According to this study, 5 should be used as a critical modified Rayleigh number for horizontal roof structures with an open upper surface when used insulation material is loose-fill glass wool or wood fibre insulation as in this study.",
keywords = "Calibrated hot-box, Heat transfer, Internal convection, Laboratory measurements, Roof structures, Thermal insulation, Thermal transmittance",
author = "Henna Kivioja and Juha Vinha",
year = "2020",
month = "6",
day = "1",
doi = "10.1016/j.enbuild.2020.109934",
language = "English",
volume = "216",
journal = "Energy and Buildings",
issn = "0378-7788",
publisher = "Elsevier Science",

}

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TY - JOUR

T1 - Hot-box measurements to investigate the internal convection of highly insulated loose-fill insulation roof structures

AU - Kivioja, Henna

AU - Vinha, Juha

PY - 2020/6/1

Y1 - 2020/6/1

N2 - The purpose of this study was to investigate how internal convection in loose-fill insulations affects the insulation properties of highly insulated roof structures. This study consists of laboratory measurements of roof structures insulated by two different blown-in insulations. The measurements are repeated with two temperature differences and air velocities for 300 mm and 600 mm thick insulation layers both with and without trusses, making a total of 24 case studies. The measurements were conducted with equipment using the calibrated hot-box method. The results of the tests show that internal convection can reduce insulation capacity significantly, especially with low-density loose-fill insulations, such as blown-in glass wool. A critical evaluation should be performed as to whether international standards and national building regulations take internal convection into account adequately. According to this study, 5 should be used as a critical modified Rayleigh number for horizontal roof structures with an open upper surface when used insulation material is loose-fill glass wool or wood fibre insulation as in this study.

AB - The purpose of this study was to investigate how internal convection in loose-fill insulations affects the insulation properties of highly insulated roof structures. This study consists of laboratory measurements of roof structures insulated by two different blown-in insulations. The measurements are repeated with two temperature differences and air velocities for 300 mm and 600 mm thick insulation layers both with and without trusses, making a total of 24 case studies. The measurements were conducted with equipment using the calibrated hot-box method. The results of the tests show that internal convection can reduce insulation capacity significantly, especially with low-density loose-fill insulations, such as blown-in glass wool. A critical evaluation should be performed as to whether international standards and national building regulations take internal convection into account adequately. According to this study, 5 should be used as a critical modified Rayleigh number for horizontal roof structures with an open upper surface when used insulation material is loose-fill glass wool or wood fibre insulation as in this study.

KW - Calibrated hot-box

KW - Heat transfer

KW - Internal convection

KW - Laboratory measurements

KW - Roof structures

KW - Thermal insulation

KW - Thermal transmittance

U2 - 10.1016/j.enbuild.2020.109934

DO - 10.1016/j.enbuild.2020.109934

M3 - Article

VL - 216

JO - Energy and Buildings

JF - Energy and Buildings

SN - 0378-7788

M1 - 109934

ER -