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	<id>https://fire-safety.academy/w/index.php?action=history&amp;feed=atom&amp;title=Ventilation-controlled_fire</id>
	<title>Ventilation-controlled fire - Revision history</title>
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	<updated>2026-11-04T14:54:02Z</updated>
	<subtitle>Revision history for this page on the wiki</subtitle>
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	<entry>
		<id>https://fire-safety.academy/w/index.php?title=Ventilation-controlled_fire&amp;diff=2577&amp;oldid=prev</id>
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		<updated>2026-11-02T17:12:46Z</updated>

		<summary type="html">&lt;p&gt;Add Intermediate SVG figures with Fire Safety Academy watermark at planned locations; preserve article text&lt;/p&gt;
&lt;table style=&quot;background-color: #fff; color: #202122;&quot; data-mw=&quot;interface&quot;&gt;
				&lt;col class=&quot;diff-marker&quot; /&gt;
				&lt;col class=&quot;diff-content&quot; /&gt;
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				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;← Older revision&lt;/td&gt;
				&lt;td colspan=&quot;2&quot; style=&quot;background-color: #fff; color: #202122; text-align: center;&quot;&gt;Revision as of 18:12, 2 November 2026&lt;/td&gt;
				&lt;/tr&gt;&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l14&quot;&gt;Line 14:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 14:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;== How the openings limit the fire ==&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;== How the openings limit the fire ==&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Once a hot layer fills most of a room, the inflow of air through a window or door depends mainly on the size of the opening. Above a gas temperature of about 150 °C, the flow hardly depends on temperature. It is then proportional to the area of the opening multiplied by the square root of its height.&amp;lt;ref name=&amp;quot;WT-174&amp;quot;&amp;gt;Walton and Thomas (2002), p. 3-174.&amp;lt;/ref&amp;gt; This product is known as the [[ventilation factor]]. Its first use to analyse post-flashover test data is attributed to Kawagoe.&amp;lt;ref name=&amp;quot;WT-174&amp;quot; /&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Once a hot layer fills most of a room, the inflow of air through a window or door depends mainly on the size of the opening. Above a gas temperature of about 150 °C, the flow hardly depends on temperature. It is then proportional to the area of the opening multiplied by the square root of its height.&amp;lt;ref name=&amp;quot;WT-174&amp;quot;&amp;gt;Walton and Thomas (2002), p. 3-174.&amp;lt;/ref&amp;gt; This product is known as the [[ventilation factor]]. Its first use to analyse post-flashover test data is attributed to Kawagoe.&amp;lt;ref name=&amp;quot;WT-174&amp;quot; /&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;[[File:fse-ventilation-controlled-fire-v1.svg|thumb|upright=1.5|alt=Cross-section of a burning room: air flows in at the bottom of the doorway, fuel-rich hot gases flow out at the top and burn outside.|In a ventilation-controlled fire, the air flowing in through the opening limits the burning inside the room; surplus fuel gases leave through the top of the opening and burn outside. Based on Walton and Thomas (2002), pp. 3-172 and 3-174.]]&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The commonly used constant gives an air inflow of 0.5 kg/s for each unit of ventilation factor, while calculated values range from 0.40 to 0.61 depending on the discharge coefficient.&amp;lt;ref name=&amp;quot;WT-174&amp;quot; /&amp;gt; For most fuels, burning with 1 kg of air releases about 3000 kJ of heat. The heat release rate that the inflowing air can support with complete combustion is called the stoichiometric heat release rate:&amp;lt;ref name=&amp;quot;WT-184&amp;quot;&amp;gt;Walton and Thomas (2002), p. 3-184.&amp;lt;/ref&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The commonly used constant gives an air inflow of 0.5 kg/s for each unit of ventilation factor, while calculated values range from 0.40 to 0.61 depending on the discharge coefficient.&amp;lt;ref name=&amp;quot;WT-174&amp;quot; /&amp;gt; For most fuels, burning with 1 kg of air releases about 3000 kJ of heat. The heat release rate that the inflowing air can support with complete combustion is called the stoichiometric heat release rate:&amp;lt;ref name=&amp;quot;WT-184&amp;quot;&amp;gt;Walton and Thomas (2002), p. 3-184.&amp;lt;/ref&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l38&quot;&gt;Line 38:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 40:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The air inflow is 0.5 times 2.23, or 1.12 kg/s.&amp;lt;ref name=&amp;quot;GL-80&amp;quot; /&amp;gt; The door can therefore support a fire of only about 3.3 MW inside the room. The estimated fire of 4.5 MW is larger than this, so the fire is ventilation-controlled. The handbook expresses the same result as an [[equivalence ratio]] of 1.3, meaning that 1.3 times as much fuel is burning as the incoming air can consume.&amp;lt;ref name=&amp;quot;GL-80&amp;quot; /&amp;gt; The difference of about 1.2 MW represents fuel gases that cannot burn inside the room and leave it unburnt.&amp;lt;ref name=&amp;quot;WT-172&amp;quot; /&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The air inflow is 0.5 times 2.23, or 1.12 kg/s.&amp;lt;ref name=&amp;quot;GL-80&amp;quot; /&amp;gt; The door can therefore support a fire of only about 3.3 MW inside the room. The estimated fire of 4.5 MW is larger than this, so the fire is ventilation-controlled. The handbook expresses the same result as an [[equivalence ratio]] of 1.3, meaning that 1.3 times as much fuel is burning as the incoming air can consume.&amp;lt;ref name=&amp;quot;GL-80&amp;quot; /&amp;gt; The difference of about 1.2 MW represents fuel gases that cannot burn inside the room and leave it unburnt.&amp;lt;ref name=&amp;quot;WT-172&amp;quot; /&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;[[File:fse-ventilation-controlled-fire-v2.svg|thumb|upright=1.5|alt=Line chart: heat release inside the room rises with the fuel&#039;s potential heat release up to 3.3 MW and then stays flat; the excess is shaded as burning outside.|Heat release rate inside a room with one door (0.76 m by 2.05 m) against the heat release rate the burning fuel could produce; above about 3.3 MW the fire is ventilation-controlled. Based on Walton and Thomas (2002), p. 3-184, and Gottuk and Lattimer (2002), p. 2-80.]]&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The same ventilation factor also sets a lower bound for flashover. A method by Babrauskas gives a minimum heat release rate for flashover of 600 times the ventilation factor.&amp;lt;ref name=&amp;quot;WT-184&amp;quot; /&amp;gt; For the door in the example this is about 1.3 MW, well below the stoichiometric 3.3 MW. Early experiments with wood fires in rooms with small windows found that the fires burned at roughly stoichiometric rates.&amp;lt;ref name=&amp;quot;WT-174&amp;quot; /&amp;gt; Empirical observations on such wood fires gave a burning rate of 0.09 kg/s per unit of ventilation factor.&amp;lt;ref name=&amp;quot;WT-174&amp;quot; /&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;The same ventilation factor also sets a lower bound for flashover. A method by Babrauskas gives a minimum heat release rate for flashover of 600 times the ventilation factor.&amp;lt;ref name=&amp;quot;WT-184&amp;quot; /&amp;gt; For the door in the example this is about 1.3 MW, well below the stoichiometric 3.3 MW. Early experiments with wood fires in rooms with small windows found that the fires burned at roughly stoichiometric rates.&amp;lt;ref name=&amp;quot;WT-174&amp;quot; /&amp;gt; Empirical observations on such wood fires gave a burning rate of 0.09 kg/s per unit of ventilation factor.&amp;lt;ref name=&amp;quot;WT-174&amp;quot; /&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;[[File:fse-ventilation-controlled-fire-v3.svg|thumb|upright=1.5|alt=Line chart of heat release rate against ventilation factor with three straight lines for flashover, stoichiometric and IFEG cellulosic limits.|Minimum heat release rate for flashover and ventilation-limited heat release rates as functions of the ventilation factor. Based on Walton and Thomas (2002), p. 3-184, and National Research Council of Canada et al. (2005), p. 2.4-15.]]&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;== Effect on the products of combustion ==&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;== Effect on the products of combustion ==&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot; id=&quot;mw-diff-left-l45&quot;&gt;Line 45:&lt;/td&gt;
&lt;td colspan=&quot;2&quot; class=&quot;diff-lineno&quot;&gt;Line 51:&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Ventilation control changes the chemistry of the fire. Well-ventilated fires are generally of little concern for toxic gases, whereas underventilated burning produces high levels of products of [[incomplete combustion]], in particular carbon monoxide.&amp;lt;ref name=&amp;quot;GL-54&amp;quot; /&amp;gt; In hood experiments, carbon monoxide production was minimal below an equivalence ratio of 0.6. It increased above this value and levelled out above about 1.2 for most fuels.&amp;lt;ref name=&amp;quot;GL-60&amp;quot;&amp;gt;Gottuk and Lattimer (2002), p. 2-60.&amp;lt;/ref&amp;gt; Hydrogen and unburned hydrocarbons also appeared as the ratio approached 1.&amp;lt;ref name=&amp;quot;GL-60&amp;quot; /&amp;gt; In the worked example above, the carbon monoxide yield inside the room is 0.14 kg per kilogram of fuel burned.&amp;lt;ref name=&amp;quot;GL-81&amp;quot;&amp;gt;Gottuk and Lattimer (2002), p. 2-81.&amp;lt;/ref&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Ventilation control changes the chemistry of the fire. Well-ventilated fires are generally of little concern for toxic gases, whereas underventilated burning produces high levels of products of [[incomplete combustion]], in particular carbon monoxide.&amp;lt;ref name=&amp;quot;GL-54&amp;quot; /&amp;gt; In hood experiments, carbon monoxide production was minimal below an equivalence ratio of 0.6. It increased above this value and levelled out above about 1.2 for most fuels.&amp;lt;ref name=&amp;quot;GL-60&amp;quot;&amp;gt;Gottuk and Lattimer (2002), p. 2-60.&amp;lt;/ref&amp;gt; Hydrogen and unburned hydrocarbons also appeared as the ratio approached 1.&amp;lt;ref name=&amp;quot;GL-60&amp;quot; /&amp;gt; In the worked example above, the carbon monoxide yield inside the room is 0.14 kg per kilogram of fuel burned.&amp;lt;ref name=&amp;quot;GL-81&amp;quot;&amp;gt;Gottuk and Lattimer (2002), p. 2-81.&amp;lt;/ref&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td colspan=&quot;2&quot; class=&quot;diff-side-deleted&quot;&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot; data-marker=&quot;+&quot;&gt;&lt;/td&gt;&lt;td style=&quot;color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #a3d3ff; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;&lt;ins style=&quot;font-weight: bold; text-decoration: none;&quot;&gt;[[File:fse-ventilation-controlled-fire-v4.svg|thumb|upright=1.5|alt=Line chart: carbon monoxide yield stays near zero at low equivalence ratios and rises to about 0.2 kg/kg above a ratio of about 1.5.|Correlations for the minimum carbon monoxide yield of compartment fires against the equivalence ratio, for cool and hot upper layers. Based on Gottuk and Lattimer (2002), p. 2-78.]]&lt;/ins&gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;br&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;tr&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Once the oxygen in the room is used up, incomplete combustion becomes more likely, and the yields of carbon monoxide and soot of hydrocarbon fuels rise strongly.&amp;lt;ref name=&amp;quot;Q-164&amp;quot;&amp;gt;Quintiere (2002a), p. 3-164.&amp;lt;/ref&amp;gt; Material data measured in well-ventilated conditions then no longer apply.&amp;lt;ref name=&amp;quot;Q-164&amp;quot; /&amp;gt; Soot yields in common tables are pre-flashover values, measured with an excess of oxygen.&amp;lt;ref name=&amp;quot;VR-6.2&amp;quot; /&amp;gt; In New Zealand, the Verification Method C/VM2 (second edition, 2025) therefore prescribes higher yields once a design fire becomes ventilation limited or reaches flashover. From that moment the soot yield is 0.14 kg/kg and the carbon monoxide yield 0.40 kg/kg.&amp;lt;ref name=&amp;quot;NZ-21&amp;quot;&amp;gt;Ministry of Business, Innovation and Employment (2025b), p. 21.&amp;lt;/ref&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;td class=&quot;diff-marker&quot;&gt;&lt;/td&gt;&lt;td style=&quot;background-color: #f8f9fa; color: #202122; font-size: 88%; border-style: solid; border-width: 1px 1px 1px 4px; border-radius: 0.33em; border-color: #eaecf0; vertical-align: top; white-space: pre-wrap;&quot;&gt;&lt;div&gt;Once the oxygen in the room is used up, incomplete combustion becomes more likely, and the yields of carbon monoxide and soot of hydrocarbon fuels rise strongly.&amp;lt;ref name=&amp;quot;Q-164&amp;quot;&amp;gt;Quintiere (2002a), p. 3-164.&amp;lt;/ref&amp;gt; Material data measured in well-ventilated conditions then no longer apply.&amp;lt;ref name=&amp;quot;Q-164&amp;quot; /&amp;gt; Soot yields in common tables are pre-flashover values, measured with an excess of oxygen.&amp;lt;ref name=&amp;quot;VR-6.2&amp;quot; /&amp;gt; In New Zealand, the Verification Method C/VM2 (second edition, 2025) therefore prescribes higher yields once a design fire becomes ventilation limited or reaches flashover. From that moment the soot yield is 0.14 kg/kg and the carbon monoxide yield 0.40 kg/kg.&amp;lt;ref name=&amp;quot;NZ-21&amp;quot;&amp;gt;Ministry of Business, Innovation and Employment (2025b), p. 21.&amp;lt;/ref&amp;gt;&lt;/div&gt;&lt;/td&gt;&lt;/tr&gt;
&lt;/table&gt;</summary>
		<author><name>Lisa</name></author>
	</entry>
	<entry>
		<id>https://fire-safety.academy/w/index.php?title=Ventilation-controlled_fire&amp;diff=436&amp;oldid=prev</id>
		<title>Daan: New FSE wiki article: Ventilation-controlled fire (written by Claude Opus 5.5)</title>
		<link rel="alternate" type="text/html" href="https://fire-safety.academy/w/index.php?title=Ventilation-controlled_fire&amp;diff=436&amp;oldid=prev"/>
		<updated>2026-11-01T22:45:27Z</updated>

		<summary type="html">&lt;p&gt;New FSE wiki article: Ventilation-controlled fire (written by Claude Opus 5.5)&lt;/p&gt;
&lt;p&gt;&lt;b&gt;New page&lt;/b&gt;&lt;/p&gt;&lt;div&gt;A &amp;#039;&amp;#039;&amp;#039;ventilation-controlled fire&amp;#039;&amp;#039;&amp;#039; is a fire in an enclosed space whose rate of burning is limited by the supply of air rather than by the amount of fuel that is burning. In such a fire the combustion process is governed by the available oxygen, or by the lack of it.&amp;lt;ref name=&amp;quot;VR-4.8&amp;quot;&amp;gt;Van Rossum (2027), §4.8.&amp;lt;/ref&amp;gt; It is the counterpart of a [[fuel-controlled fire]], in which there is enough oxygen and the fire size depends on the rate at which the fuel releases flammable gases.&amp;lt;ref name=&amp;quot;VR-4.8&amp;quot; /&amp;gt; A ventilation-controlled fire develops when the fire is large and the room has only limited openings for the inflow of air and the outflow of smoke.&amp;lt;ref name=&amp;quot;VR-4.8&amp;quot; /&amp;gt;&lt;br /&gt;
&lt;br /&gt;
In a ventilation-controlled fire, more fuel is pyrolysed than can be burned with the oxygen available in the room.&amp;lt;ref name=&amp;quot;WT-172&amp;quot;&amp;gt;Walton and Thomas (2002), p. 3-172.&amp;lt;/ref&amp;gt; The hot fire gases then contain almost no oxygen.&amp;lt;ref name=&amp;quot;IS-2-4&amp;quot;&amp;gt;Iqbal and Salley (2004), p. 2-4.&amp;lt;/ref&amp;gt; The surplus fuel leaves the room with the gas flow and may burn outside, which produces the flames seen coming out of windows and doors.&amp;lt;ref name=&amp;quot;WT-172&amp;quot; /&amp;gt; A fully developed fire after flashover is usually ventilation-controlled. Its heat release rate is then set mainly by the supply of fresh air through openings such as windows and doors.&amp;lt;ref name=&amp;quot;VR-4.11&amp;quot;&amp;gt;Van Rossum (2027), §4.11.&amp;lt;/ref&amp;gt; The book &amp;#039;&amp;#039;Introduction to Fire Safety Engineering&amp;#039;&amp;#039; notes that most compartment fires are ventilation-controlled.&amp;lt;ref name=&amp;quot;VR-6.2&amp;quot;&amp;gt;Van Rossum (2027), §6.2.&amp;lt;/ref&amp;gt;&lt;br /&gt;
&lt;br /&gt;
== Fuel control and ventilation control ==&lt;br /&gt;
Every fire in a room starts as a fuel-controlled fire. In the early stage the fire is small compared with the room, and there is plenty of oxygen.&amp;lt;ref name=&amp;quot;VR-4.8&amp;quot; /&amp;gt; A fire in the open air is always fuel-controlled, because it always has enough oxygen.&amp;lt;ref name=&amp;quot;VR-4.8&amp;quot; /&amp;gt; In the growth stage the fire is described by its own rate of energy release, with little influence from the compartment.&amp;lt;ref name=&amp;quot;WT-171&amp;quot;&amp;gt;Walton and Thomas (2002), p. 3-171.&amp;lt;/ref&amp;gt;&lt;br /&gt;
&lt;br /&gt;
As the fire grows, the openings of the room begin to restrict the airflow. The fire then moves from overventilated to underventilated, or fuel-rich, burning.&amp;lt;ref name=&amp;quot;GL-54&amp;quot;&amp;gt;Gottuk and Lattimer (2002), p. 2-54.&amp;lt;/ref&amp;gt; In a [[post-flashover fire]], the rate of air flow into the room and therefore the peak rate of burning become limited. The limit is set by the size, shape and position of the openings, or by the rate of mechanical ventilation.&amp;lt;ref name=&amp;quot;IS-2-3&amp;quot;&amp;gt;Iqbal and Salley (2004), p. 2-3.&amp;lt;/ref&amp;gt; Flashover usually brings the fire to its fully developed state, in which all fuel in the room is involved. Not all the fuel gases can then burn inside the room, because the air supply is limited.&amp;lt;ref name=&amp;quot;IS-2-4&amp;quot; /&amp;gt;&lt;br /&gt;
&lt;br /&gt;
The type of control can change during a fire. Immediately after flashover, small items and easily pyrolysed materials burn very quickly, which gives a strongly ventilation-controlled regime with long flames from the openings.&amp;lt;ref name=&amp;quot;ABCB-B1-14&amp;quot;&amp;gt;Australian Building Codes Board (2020a), Data Sheet B1, p. 14.&amp;lt;/ref&amp;gt; Later the pyrolysis rate falls until conditions in the room are close to stoichiometric, and the flames from the openings become much shorter. At some stage the fire becomes fuel-controlled again.&amp;lt;ref name=&amp;quot;ABCB-B1-14&amp;quot; /&amp;gt; In the decay stage, the fire may also change from ventilation control to fuel control as the fuel is consumed.&amp;lt;ref name=&amp;quot;WT-172&amp;quot; /&amp;gt;&lt;br /&gt;
&lt;br /&gt;
Openings themselves change as well. Doors and windows may be opened, and a closed window may fail partly or completely during the growth phase.&amp;lt;ref name=&amp;quot;ABCB-B1-21&amp;quot;&amp;gt;Australian Building Codes Board (2020a), Data Sheet B1, pp. 21–22.&amp;lt;/ref&amp;gt; In the World Trade Center towers in 2001, the fires were generally ventilation limited: they burned and spread only as fast as windows broke.&amp;lt;ref name=&amp;quot;NIST-183&amp;quot;&amp;gt;National Institute of Standards and Technology (2005), p. 183.&amp;lt;/ref&amp;gt; Experiments for the same investigation showed the effect of ventilation control directly. When three office workstations burned together in a compartment, the total mass loss was three times that of the earlier tests with a single workstation. The peak heat release rate, however, was only about 50 per cent higher, which reflected the ventilation-limited nature of the tests.&amp;lt;ref name=&amp;quot;NIST15-xlii&amp;quot;&amp;gt;Gann, Hamins, et al. (2005), p. xlii.&amp;lt;/ref&amp;gt;&lt;br /&gt;
&lt;br /&gt;
== How the openings limit the fire ==&lt;br /&gt;
Once a hot layer fills most of a room, the inflow of air through a window or door depends mainly on the size of the opening. Above a gas temperature of about 150 °C, the flow hardly depends on temperature. It is then proportional to the area of the opening multiplied by the square root of its height.&amp;lt;ref name=&amp;quot;WT-174&amp;quot;&amp;gt;Walton and Thomas (2002), p. 3-174.&amp;lt;/ref&amp;gt; This product is known as the [[ventilation factor]]. Its first use to analyse post-flashover test data is attributed to Kawagoe.&amp;lt;ref name=&amp;quot;WT-174&amp;quot; /&amp;gt;&lt;br /&gt;
&lt;br /&gt;
The commonly used constant gives an air inflow of 0.5 kg/s for each unit of ventilation factor, while calculated values range from 0.40 to 0.61 depending on the discharge coefficient.&amp;lt;ref name=&amp;quot;WT-174&amp;quot; /&amp;gt; For most fuels, burning with 1 kg of air releases about 3000 kJ of heat. The heat release rate that the inflowing air can support with complete combustion is called the stoichiometric heat release rate:&amp;lt;ref name=&amp;quot;WT-184&amp;quot;&amp;gt;Walton and Thomas (2002), p. 3-184.&amp;lt;/ref&amp;gt;&lt;br /&gt;
&lt;br /&gt;
&amp;lt;math display=&amp;quot;block&amp;quot;&amp;gt;\dot{Q}_\mathrm{stoich} = 3000 \cdot 0.5\, A_0 \sqrt{H_0} = 1500\, A_0 \sqrt{H_0}&amp;lt;/math&amp;gt;&lt;br /&gt;
&lt;br /&gt;
{| class=&amp;quot;wikitable&amp;quot;&lt;br /&gt;
! Symbol !! Description !! Unit&lt;br /&gt;
|-&lt;br /&gt;
| &amp;lt;math&amp;gt;\dot{Q}_\mathrm{stoich}&amp;lt;/math&amp;gt; || maximum heat release rate inside the room that the inflowing air can support || kW&lt;br /&gt;
|-&lt;br /&gt;
| &amp;lt;math&amp;gt;A_0&amp;lt;/math&amp;gt; || area of the opening || m²&lt;br /&gt;
|-&lt;br /&gt;
| &amp;lt;math&amp;gt;H_0&amp;lt;/math&amp;gt; || height of the opening || m&lt;br /&gt;
|-&lt;br /&gt;
| &amp;lt;math&amp;gt;A_0 \sqrt{H_0}&amp;lt;/math&amp;gt; || ventilation factor || m&amp;lt;sup&amp;gt;5/2&amp;lt;/sup&amp;gt;&lt;br /&gt;
|}&lt;br /&gt;
&lt;br /&gt;
The relation applies to fires close to or after flashover in rooms with a door or window, when the smoke layer reaches down to near the floor.&amp;lt;ref name=&amp;quot;WT-174&amp;quot; /&amp;gt; The International Fire Engineering Guidelines (2005) apply such relations with the total area of the vents and their effective height.&amp;lt;ref name=&amp;quot;IFEG-14&amp;quot;&amp;gt;National Research Council of Canada et al. (2005), p. 2.4-14.&amp;lt;/ref&amp;gt; In mechanically ventilated rooms, the air supply is set by the ventilation rate of the system instead.&amp;lt;ref name=&amp;quot;IS-2-3&amp;quot; /&amp;gt;&lt;br /&gt;
&lt;br /&gt;
As a worked example, the SFPE Handbook considers a room 7 m wide, 4 m deep and 2.43 m high with one open door of 0.76 m by 2.05 m and no other ventilation. The door area is 1.56 m², and the peak heat release rate of the fire is estimated at 4.5 MW.&amp;lt;ref name=&amp;quot;GL-80&amp;quot;&amp;gt;Gottuk and Lattimer (2002), p. 2-80.&amp;lt;/ref&amp;gt; The task is to decide whether the fire is ventilation-controlled and how much carbon monoxide can reach other rooms.&amp;lt;ref name=&amp;quot;GL-80&amp;quot; /&amp;gt;&lt;br /&gt;
&lt;br /&gt;
&amp;lt;math display=&amp;quot;block&amp;quot;&amp;gt;\dot{Q}_\mathrm{stoich} = 1500 \times 1.56 \times \sqrt{2.05} = 1500 \times 2.23 = 3350\ \mathrm{kW}&amp;lt;/math&amp;gt;&lt;br /&gt;
&lt;br /&gt;
The air inflow is 0.5 times 2.23, or 1.12 kg/s.&amp;lt;ref name=&amp;quot;GL-80&amp;quot; /&amp;gt; The door can therefore support a fire of only about 3.3 MW inside the room. The estimated fire of 4.5 MW is larger than this, so the fire is ventilation-controlled. The handbook expresses the same result as an [[equivalence ratio]] of 1.3, meaning that 1.3 times as much fuel is burning as the incoming air can consume.&amp;lt;ref name=&amp;quot;GL-80&amp;quot; /&amp;gt; The difference of about 1.2 MW represents fuel gases that cannot burn inside the room and leave it unburnt.&amp;lt;ref name=&amp;quot;WT-172&amp;quot; /&amp;gt;&lt;br /&gt;
&lt;br /&gt;
The same ventilation factor also sets a lower bound for flashover. A method by Babrauskas gives a minimum heat release rate for flashover of 600 times the ventilation factor.&amp;lt;ref name=&amp;quot;WT-184&amp;quot; /&amp;gt; For the door in the example this is about 1.3 MW, well below the stoichiometric 3.3 MW. Early experiments with wood fires in rooms with small windows found that the fires burned at roughly stoichiometric rates.&amp;lt;ref name=&amp;quot;WT-174&amp;quot; /&amp;gt; Empirical observations on such wood fires gave a burning rate of 0.09 kg/s per unit of ventilation factor.&amp;lt;ref name=&amp;quot;WT-174&amp;quot; /&amp;gt;&lt;br /&gt;
&lt;br /&gt;
== Effect on the products of combustion ==&lt;br /&gt;
The degree of ventilation control is expressed by the equivalence ratio. It compares the fuel burning rate with the air supply, relative to the ratio needed for complete combustion.&amp;lt;ref name=&amp;quot;GL-58&amp;quot;&amp;gt;Gottuk and Lattimer (2002), p. 2-58.&amp;lt;/ref&amp;gt; A fire is overventilated when the ratio is below 1 and underventilated when it is above 1.&amp;lt;ref name=&amp;quot;Stroup-3-31&amp;quot;&amp;gt;Stroup et al. (2016), p. 3-31.&amp;lt;/ref&amp;gt;&lt;br /&gt;
&lt;br /&gt;
Ventilation control changes the chemistry of the fire. Well-ventilated fires are generally of little concern for toxic gases, whereas underventilated burning produces high levels of products of [[incomplete combustion]], in particular carbon monoxide.&amp;lt;ref name=&amp;quot;GL-54&amp;quot; /&amp;gt; In hood experiments, carbon monoxide production was minimal below an equivalence ratio of 0.6. It increased above this value and levelled out above about 1.2 for most fuels.&amp;lt;ref name=&amp;quot;GL-60&amp;quot;&amp;gt;Gottuk and Lattimer (2002), p. 2-60.&amp;lt;/ref&amp;gt; Hydrogen and unburned hydrocarbons also appeared as the ratio approached 1.&amp;lt;ref name=&amp;quot;GL-60&amp;quot; /&amp;gt; In the worked example above, the carbon monoxide yield inside the room is 0.14 kg per kilogram of fuel burned.&amp;lt;ref name=&amp;quot;GL-81&amp;quot;&amp;gt;Gottuk and Lattimer (2002), p. 2-81.&amp;lt;/ref&amp;gt;&lt;br /&gt;
&lt;br /&gt;
Once the oxygen in the room is used up, incomplete combustion becomes more likely, and the yields of carbon monoxide and soot of hydrocarbon fuels rise strongly.&amp;lt;ref name=&amp;quot;Q-164&amp;quot;&amp;gt;Quintiere (2002a), p. 3-164.&amp;lt;/ref&amp;gt; Material data measured in well-ventilated conditions then no longer apply.&amp;lt;ref name=&amp;quot;Q-164&amp;quot; /&amp;gt; Soot yields in common tables are pre-flashover values, measured with an excess of oxygen.&amp;lt;ref name=&amp;quot;VR-6.2&amp;quot; /&amp;gt; In New Zealand, the Verification Method C/VM2 (second edition, 2025) therefore prescribes higher yields once a design fire becomes ventilation limited or reaches flashover. From that moment the soot yield is 0.14 kg/kg and the carbon monoxide yield 0.40 kg/kg.&amp;lt;ref name=&amp;quot;NZ-21&amp;quot;&amp;gt;Ministry of Business, Innovation and Employment (2025b), p. 21.&amp;lt;/ref&amp;gt;&lt;br /&gt;
&lt;br /&gt;
The unburnt gases also create other hazards. Mixed with oxygen, they form a combustible mixture that needs only ignition energy to burn.&amp;lt;ref name=&amp;quot;VR-4.8&amp;quot; /&amp;gt; If fresh air suddenly enters a closed room in which such gases have built up, for example when a door is opened, the gases can burn explosively in a [[backdraft]].&amp;lt;ref name=&amp;quot;VR-4.9&amp;quot;&amp;gt;Van Rossum (2027), §4.9.&amp;lt;/ref&amp;gt;&lt;br /&gt;
&lt;br /&gt;
== Burning outside the room ==&lt;br /&gt;
In a ventilation-controlled fire, the excess fuel does not disappear. When the pyrolysis rate exceeds what the air supply can burn, unburnt volatiles are ejected from the room, and in some cases the inward airflow is reduced.&amp;lt;ref name=&amp;quot;ABCB-B1-14&amp;quot; /&amp;gt; A significant part of the heat is then released outside the room, and the heat release rate inside it falls.&amp;lt;ref name=&amp;quot;ABCB-B1-14&amp;quot; /&amp;gt; The maximum heat release rate inside the room occurs when the pyrolysis rate and the air supply are close to stoichiometric.&amp;lt;ref name=&amp;quot;ABCB-B1-14&amp;quot; /&amp;gt;&lt;br /&gt;
&lt;br /&gt;
Flames outside the openings are a characteristic feature of a developed fire, because part of the pyrolysis gases burns outside the room.&amp;lt;ref name=&amp;quot;VR-4.11&amp;quot; /&amp;gt; These hot, fuel-rich gases can also flow into adjacent rooms, mix with air and form a separate burning zone, known as external burning.&amp;lt;ref name=&amp;quot;GL-55&amp;quot;&amp;gt;Gottuk and Lattimer (2002), p. 2-55.&amp;lt;/ref&amp;gt; Burning outside the room generally reduces the carbon monoxide and smoke carried to other parts of a building.&amp;lt;ref name=&amp;quot;GL-71&amp;quot;&amp;gt;Gottuk and Lattimer (2002), p. 2-71.&amp;lt;/ref&amp;gt; In the worked example, the equivalence ratio of 1.3 is below the value of 1.6 at which external burning was first observed in tests. The carbon monoxide formed in the room is therefore assumed to flow on to other rooms.&amp;lt;ref name=&amp;quot;GL-80&amp;quot; /&amp;gt;&amp;lt;ref name=&amp;quot;GL-81&amp;quot; /&amp;gt;&lt;br /&gt;
&lt;br /&gt;
== Use in design and regulation ==&lt;br /&gt;
Fire engineering guidelines commonly calculate both limits and take the lower one. The International Fire Engineering Guidelines (2005) state that the heat release rate of a fully developed fire is the lesser of the value for ventilation control and the value for fuel control.&amp;lt;ref name=&amp;quot;IFEG-14&amp;quot; /&amp;gt; For cellulosic fuels, they estimate the air inflow as 0.52 kg/s per unit of ventilation factor. The stoichiometric fuel-to-air ratio of about 5.7 is increased by a factor of about 1.3 under ventilation-limited conditions.&amp;lt;ref name=&amp;quot;IFEG-14&amp;quot; /&amp;gt; With an effective heat of combustion of 18 MJ/kg, this gives a heat release rate of 2.16 MW per unit of ventilation factor.&amp;lt;ref name=&amp;quot;IFEG-15&amp;quot;&amp;gt;National Research Council of Canada et al. (2005), p. 2.4-15.&amp;lt;/ref&amp;gt; In Australia, the Fire Safety Verification Method data sheets (2020) use the same principle of the lesser of the two.&amp;lt;ref name=&amp;quot;ABCB-B1-13&amp;quot;&amp;gt;Australian Building Codes Board (2020a), Data Sheet B1, p. 13.&amp;lt;/ref&amp;gt;&lt;br /&gt;
&lt;br /&gt;
In New Zealand, C/VM2 (second edition, 2025) lets a design fire grow until flashover, until its peak heat release rate, until sprinkler activation or until it becomes ventilation limited.&amp;lt;ref name=&amp;quot;NZ-20&amp;quot;&amp;gt;Ministry of Business, Innovation and Employment (2025b), p. 20.&amp;lt;/ref&amp;gt; The ventilation limit is the heat release rate at which the predicted energy release first falls below the design fire because of a lack of oxygen. It is determined with a fire model.&amp;lt;ref name=&amp;quot;NZ-21&amp;quot; /&amp;gt; For ventilation-limited cases, the input is then ramped to 1.5 times this limit over 15 seconds. Growing the fire further to its tabulated peak would generate an excessive amount of unburned fuel in the model and could cause numerical problems.&amp;lt;ref name=&amp;quot;NZ-22&amp;quot;&amp;gt;Ministry of Business, Innovation and Employment (2025b), pp. 21–22.&amp;lt;/ref&amp;gt;&lt;br /&gt;
&lt;br /&gt;
Ventilation control also governs how long a fire lasts. The duration of a fully developed fire can be estimated as the fire load divided by the burning rate. A smaller ventilation factor gives a lower burning rate and a longer fire.&amp;lt;ref name=&amp;quot;WT-184&amp;quot; /&amp;gt; By comparison, domestic furniture burning freely has a fire duration of about 20 minutes.&amp;lt;ref name=&amp;quot;WT-184&amp;quot; /&amp;gt; Burning rate data published for single items reflect fuel-controlled burning. They may not apply where ventilation control limits the burning or radiation from the room increases it.&amp;lt;ref name=&amp;quot;IFEG-15&amp;quot; /&amp;gt;&lt;br /&gt;
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== Modelling and limitations ==&lt;br /&gt;
Fire models handle ventilation control in simplified ways. In the zone model CFAST, the pyrolysis rate is assumed to stay the same when oxygen limits the fire, but only part of the fuel burns.&amp;lt;ref name=&amp;quot;CF-13&amp;quot;&amp;gt;Peacock et al. (2026), p. 13.&amp;lt;/ref&amp;gt; The heat release rate is the lesser of the value set by the fuel supply and the value supported by the oxygen entrained into the fire. By default, burning stops when the oxygen mass fraction falls to 0.15.&amp;lt;ref name=&amp;quot;CF-13&amp;quot; /&amp;gt;&lt;br /&gt;
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The book &amp;#039;&amp;#039;Introduction to Fire Safety Engineering&amp;#039;&amp;#039; notes that the course of a ventilation-controlled fire is so complex that it can hardly be predicted in detail. Most models deal with it poorly.&amp;lt;ref name=&amp;quot;VR-8.4&amp;quot;&amp;gt;Van Rossum (2027), §8.4.&amp;lt;/ref&amp;gt; The user must therefore state what the model does when oxygen runs short. The options are to let all gases burn inside the room, to assume flames out of the openings so that the excess burns outside, or to stop combustion.&amp;lt;ref name=&amp;quot;VR-8.4&amp;quot; /&amp;gt; Many zone models, especially those for large spaces, ignore a fire that later becomes ventilation-controlled, and this should be stated as a limitation.&amp;lt;ref name=&amp;quot;VR-9.3Z&amp;quot;&amp;gt;Van Rossum (2027), §9.3 (How a zone model works).&amp;lt;/ref&amp;gt; In computational fluid dynamics, modelling of ventilation-controlled fires is limited and model-dependent, and it should be reported as an uncertainty.&amp;lt;ref name=&amp;quot;VR-11.4&amp;quot;&amp;gt;Van Rossum (2027), §11.4.&amp;lt;/ref&amp;gt;&lt;br /&gt;
&lt;br /&gt;
The simple relations have limits of their own. The Swedish method for compartment temperatures assumes that the energy release is below stoichiometric and ignores excess fuel burning outside.&amp;lt;ref name=&amp;quot;WT-184&amp;quot; /&amp;gt; Most of its validation tests used wood cribs, which burn more slowly and produce less excess fuel than furnishings.&amp;lt;ref name=&amp;quot;WT-184&amp;quot; /&amp;gt; The test series used to validate fire models for US nuclear plants covered equivalence ratios of only 0 to 0.6, all in the overventilated range.&amp;lt;ref name=&amp;quot;Stroup-3-31&amp;quot; /&amp;gt; Underventilated fires therefore fall outside the range covered by that validation.&amp;lt;ref name=&amp;quot;Stroup-3-31&amp;quot; /&amp;gt;&lt;br /&gt;
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== See also ==&lt;br /&gt;
* [[Compartment fire]]&lt;br /&gt;
* [[Burning rate]]&lt;br /&gt;
* [[Smoke explosion]]&lt;br /&gt;
* [[Oxygen depletion]]&lt;br /&gt;
* [[Stoichiometry]]&lt;br /&gt;
* [[External flaming]]&lt;br /&gt;
&lt;br /&gt;
== Notes ==&lt;br /&gt;
&amp;lt;references /&amp;gt;&lt;br /&gt;
&lt;br /&gt;
== References ==&lt;br /&gt;
* Australian Building Codes Board. (2020a). &amp;#039;&amp;#039;Data sheets: Fire Safety Verification Method&amp;#039;&amp;#039; (Handbook annex, Print version 1.1).&lt;br /&gt;
* Gann, R. G., Hamins, A., McGrattan, K. B., Mulholland, G. W., Nelson, H. E., Ohlemiller, T. J., Pitts, W. M., &amp;amp; Prasad, K. R. (2005). &amp;#039;&amp;#039;Reconstruction of the fires in the World Trade Center towers&amp;#039;&amp;#039; (NIST NCSTAR 1-5). National Institute of Standards and Technology.&lt;br /&gt;
* Gottuk, D. T., &amp;amp; Lattimer, B. Y. (2002). Effect of combustion conditions on species production. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., &amp;amp; J. M. Watts Jr. (Eds.), &amp;#039;&amp;#039;SFPE handbook of fire protection engineering&amp;#039;&amp;#039; (3rd ed., pp. 2-54–2-82). National Fire Protection Association; Society of Fire Protection Engineers.&lt;br /&gt;
* Iqbal, N., &amp;amp; Salley, M. H. (2004). &amp;#039;&amp;#039;Fire Dynamics Tools (FDTs): Quantitative fire hazard analysis methods for the U.S. Nuclear Regulatory Commission Fire Protection Inspection Program&amp;#039;&amp;#039; (NUREG-1805). U.S. Nuclear Regulatory Commission, Office of Nuclear Reactor Regulation.&lt;br /&gt;
* Ministry of Business, Innovation and Employment. (2025b). &amp;#039;&amp;#039;Verification Method C/VM2: Framework for fire safety design&amp;#039;&amp;#039; (2nd ed.).&lt;br /&gt;
* National Institute of Standards and Technology. (2005). &amp;#039;&amp;#039;Final report on the collapse of the World Trade Center towers&amp;#039;&amp;#039; (NIST NCSTAR 1).&lt;br /&gt;
* National Research Council of Canada, International Code Council, Department of Building and Housing, &amp;amp; Australian Building Codes Board. (2005). &amp;#039;&amp;#039;International fire engineering guidelines&amp;#039;&amp;#039; (2005 ed.). Australian Building Codes Board.&lt;br /&gt;
* Peacock, R. D., McGrattan, K. B., Forney, G. P., &amp;amp; Reneke, P. A. (2026). &amp;#039;&amp;#039;CFAST – Consolidated Fire and Smoke Transport: Vol. 1. Technical reference guide&amp;#039;&amp;#039; (Version 7, NIST Technical Note 1889v1). National Institute of Standards and Technology. https://doi.org/10.6028/NIST.TN.1889v1&lt;br /&gt;
* Quintiere, J. G. (2002a). Compartment fire modeling. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., &amp;amp; J. M. Watts Jr. (Eds.), &amp;#039;&amp;#039;SFPE handbook of fire protection engineering&amp;#039;&amp;#039; (3rd ed., pp. 3-162–3-170). National Fire Protection Association; Society of Fire Protection Engineers.&lt;br /&gt;
* Stroup, D., Lindeman, A., McGrattan, K., Peacock, R., Overholt, K., Joglar, F., LeStrange, S., &amp;amp; Montanez, S. (2016). &amp;#039;&amp;#039;Verification and validation of selected fire models for nuclear power plant applications: Supplement 1&amp;#039;&amp;#039; (NUREG-1824, Supplement 1; EPRI 3002002182). U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research; Electric Power Research Institute.&lt;br /&gt;
* Van Rossum, E. (2027). &amp;#039;&amp;#039;Introduction to Fire Safety Engineering&amp;#039;&amp;#039;. Fire Safety Academy.&lt;br /&gt;
* Walton, W. D., &amp;amp; Thomas, P. H. (2002). Estimating temperatures in compartment fires. In P. J. DiNenno, D. Drysdale, C. L. Beyler, W. D. Walton, R. L. P. Custer, J. R. Hall Jr., &amp;amp; J. M. Watts Jr. (Eds.), &amp;#039;&amp;#039;SFPE handbook of fire protection engineering&amp;#039;&amp;#039; (3rd ed., pp. 3-171–3-188). National Fire Protection Association; Society of Fire Protection Engineers.&lt;br /&gt;
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[[Category:Enclosure Fires]]&lt;/div&gt;</summary>
		<author><name>Daan</name></author>
	</entry>
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