<p>Structure hardening is a key strategy to help mitigate building destruction during wildland-urban interface fires. Windows represent an important vulnerability for structure failure by allowing heat transfer to interior combustibles, and in cases of mechanical failure, an entry point for flames and/or embers. The purpose of this study is to characterize heat transfer through windows with various common construction variables (plain (annealed) versus tempered glass, single- versus double-pane, low-emissivity coating versus no coating, and air-filled versus argon-filled pane gap). Small-scale experiments were performed with 23 cm by 23 cm windows exposed to a radiant panel producing centerpoint incident heat fluxes of 10 <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10694_2024_1685_Article_IEq1.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="53" /> </InlineMediaObject> <EquationSource Format="TEX">$\hbox {kW/m}^{2}$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mtext>kW/m</mtext> <mn>2</mn> </msup> </math></EquationSource> </InlineEquation>, 20 <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10694_2024_1685_Article_IEq1.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="53" /> </InlineMediaObject> <EquationSource Format="TEX">$\hbox {kW/m}^{2}$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mtext>kW/m</mtext> <mn>2</mn> </msup> </math></EquationSource> </InlineEquation>, 30 <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10694_2024_1685_Article_IEq1.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="53" /> </InlineMediaObject> <EquationSource Format="TEX">$\hbox {kW/m}^{2}$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mtext>kW/m</mtext> <mn>2</mn> </msup> </math></EquationSource> </InlineEquation>, 40 <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10694_2024_1685_Article_IEq1.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="53" /> </InlineMediaObject> <EquationSource Format="TEX">$\hbox {kW/m}^{2}$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mtext>kW/m</mtext> <mn>2</mn> </msup> </math></EquationSource> </InlineEquation>, and 50 <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10694_2024_1685_Article_IEq1.gif" Format="GIF" Height="22" Rendition="HTML" Resolution="72" Type="Linedraw" Width="53" /> </InlineMediaObject> <EquationSource Format="TEX">$\hbox {kW/m}^{2}$</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mtext>kW/m</mtext> <mn>2</mn> </msup> </math></EquationSource> </InlineEquation>. Total heat flux was measured 5.1 cm behind the window glass. Times of pane cracking and other failure events were recorded. Double-pane designs reduced heat transfer through a window more than the single-pane design (measured 13% to 43% and 39% to 60% of the incident heat flux, respectively). Heat transfer was further reduced when a low-emissivity coating was present (measured 5 to 14% of the incident heat flux). The differences in measured heat flux behind plain glass versus tempered glass windows and air-filled versus argon-filled windows were not statistically significant. Tempered glass performed better than plain glass, and double-pane argon-filled windows consistently survived longer than double-pane air-filled windows. In some cases, heat fluxes measured behind the windows surpassed the critical heat flux required for ignition of some common household combustibles.</p>

Experimental Study of Heat Transfer Through Windows Exposed to a Radiant Panel Heater

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2025年1月8日

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Rebekah L. Schrader,
Shuna Ni,
Nicholas W. Dow,
Joseph M. Willi,
Matthew J. DiDomizio,
Gavin P. Horn

摘要

Structure hardening is a key strategy to help mitigate building destruction during wildland-urban interface fires. Windows represent an important vulnerability for structure failure by allowing heat transfer to interior combustibles, and in cases of mechanical failure, an entry point for flames and/or embers. The purpose of this study is to characterize heat transfer through windows with various common construction variables (plain (annealed) versus tempered glass, single- versus double-pane, low-emissivity coating versus no coating, and air-filled versus argon-filled pane gap). Small-scale experiments were performed with 23 cm by 23 cm windows exposed to a radiant panel producing centerpoint incident heat fluxes of 10 $\hbox {kW/m}^{2}$ ${kW/m}^{2}$ , 20 $\hbox {kW/m}^{2}$ ${kW/m}^{2}$ , 30 $\hbox {kW/m}^{2}$ ${kW/m}^{2}$ , 40 $\hbox {kW/m}^{2}$ ${kW/m}^{2}$ , and 50 $\hbox {kW/m}^{2}$ ${kW/m}^{2}$ . Total heat flux was measured 5.1 cm behind the window glass. Times of pane cracking and other failure events were recorded. Double-pane designs reduced heat transfer through a window more than the single-pane design (measured 13% to 43% and 39% to 60% of the incident heat flux, respectively). Heat transfer was further reduced when a low-emissivity coating was present (measured 5 to 14% of the incident heat flux). The differences in measured heat flux behind plain glass versus tempered glass windows and air-filled versus argon-filled windows were not statistically significant. Tempered glass performed better than plain glass, and double-pane argon-filled windows consistently survived longer than double-pane air-filled windows. In some cases, heat fluxes measured behind the windows surpassed the critical heat flux required for ignition of some common household combustibles.