{"id":56816,"date":"2015-11-30T18:10:23","date_gmt":"2015-11-30T16:10:23","guid":{"rendered":"http:\/\/wpcalc.com\/?p=56816"},"modified":"2026-09-30T18:43:11","modified_gmt":"2026-09-30T15:43:11","slug":"ventilation-2","status":"publish","type":"post","link":"https:\/\/wpcalc.com\/en\/engineering\/ventilation-2\/","title":{"rendered":"Ventilation Power Calculator"},"content":{"rendered":"<section class=\"not-prose calculator-box\" aria-labelledby=\"calculator-title\"><div class=\"flex items-baseline sm:items-center justify-between gap-2 sm:gap-3\"><div class=\"flex flex-col sm:flex-row sm:items-center gap-2\"><span class=\"icon icon-calculator text-primary-700! text-base! dark:text-primary-300!\" aria-hidden=\"true\"><\/span><h2 id=\"calculator-title\" class=\"text-lg font-display font-bold\">Air Flow Rate Estimator for Ventilation<\/h2><\/div><div class=\"calcdash-favorite group\">\n  <button type=\"button\" class=\"favorite\" id=\"favorite\" data-favorite-id=\"56816\" data-favorite-title=\"Ventilation Power\" data-favorite-url=\"https:\/\/wpcalc.com\/en\/engineering\/ventilation-2\/\" data-favorite-excerpt=\"Calculate the required ventilation air flow rate (m\u00b3\/h) from room area, ceiling height, and desired air changes per hour. Enter three values to size fans, diffusers, and ductwork correctly.\" aria-label=\"Add to Favorites\" data-favorite-icon=\"icon icon-ventilation\">\n    <span class=\"icon icon-shape-star-empty\" aria-hidden=\"true\"><\/span>\n  <\/button>\n  <div class=\"calcdash-favorite__tip\" aria-hidden=\"true\">\n   <span class=\"favorite-tooltip\" id=\"favorite-tooltip\"><\/span>\n  <\/div>\n  <span class=\"sr-only\" role=\"status\" id=\"favorite-status\"><\/span>\n<\/div><\/div><form action=\"https:\/\/wpcalc.com\/en\/engineering\/ventilation-2\/\" method=\"POST\" class=\"calculator\" id=\"calculator-56816\" data-post=\"56816\"><fieldset class=\"fieldset-input is-3\"><legend class=\"sr-only\">Input Fields<\/legend><div class=\"field has-term\" id=\"input-1\"><label for=\"field-1\">Size of room<\/label><div class=\"term\">area<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"number\" name=\"size_of_room\" id=\"field-1\" aria-describedby=\"calc-unit-1\" placeholder=\"Area in m\u00b2\" step=\"any\" value=\"20\"\/><div class=\"unit\" id=\"calc-unit-1\">m\u00b2<\/div><\/div><div class=\"field has-term\" id=\"input-2\"><label for=\"field-2\">Room height<\/label><div class=\"term\">height<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"number\" name=\"room_height\" id=\"field-2\" aria-describedby=\"calc-unit-2\" placeholder=\"Height in meters\" step=\"any\" value=\"2.5\"\/><div class=\"unit\" id=\"calc-unit-2\">m<\/div><\/div><div class=\"field has-term\" id=\"input-3\"><label for=\"field-3\">Number of air<\/label><div class=\"term\">air<\/div>  <div class=\"absolute bottom-0 left-16 top-8 w-2 h-0.5 bg-blue-500\"><\/div><input type=\"number\" name=\"number_of_air\" id=\"field-3\" placeholder=\"Air changes per hour\" step=\"any\" value=\"2\"\/><\/div><\/fieldset><div class=\"buttons\"><button type=\"submit\" data-text=\"Re-Calculate\" id=\"calculate-button\" data-post=\"56816\">Calculate<\/button><button type=\"reset\">Reset<\/button><\/div><div class=\"field is-checkbox hidden!\" id=\"field-auto-calc\"><input type=\"checkbox\" id=\"auto-calc\"><label for=\"auto-calc\">Calculate automatically<\/label><small>If enabled, the result will update automatically when you change any value.<\/small><\/div><div class=\"fieldset-result is-hidden\" aria-labelledby=\"result-title\" aria-live=\"polite\" role=\"region\"> <h3 class=\"result-title bg-gradient-to-r from-primary-50 to-gray-50 dark:from-primary-900 dark:to-gray-800\" id=\"result-title\"><span class=\"icon icon-s-pulse\" aria-hidden=\"true\"><\/span> Your Results<\/h3><div class=\"result-box\"><div class=\"field-result\" id=\"output-1\"><span class=\"field-title\"><span>Required performance<\/span><\/span><span class=\"field-value\" id=\"result-1\"><\/span><button type=\"button\" class=\"copy-result\" data-tooltip=\"Copy Result\" aria-label=\"Copy Result\"><span class=\"copy-icon icon icon-document-copy\" aria-hidden=\"true\"><\/span><\/button><\/div><\/div><div class=\"result-actions\"><button type=\"button\" class=\"copy-link\"><svg viewBox=\"0 0 20 20\" fill=\"currentColor\" aria-hidden=\"true\"><path d=\"M12.232 4.232a2.5 2.5 0 0 1 3.536 3.536l-1.225 1.224a.75.75 0 0 0 1.061 1.06l1.224-1.224a4 4 0 0 0-5.656-5.656l-3 3a4 4 0 0 0 .225 5.865.75.75 0 0 0 .977-1.138 2.5 2.5 0 0 1-.142-3.667l3-3Z\"\/><path d=\"M11.603 7.963a.75.75 0 0 0-.977 1.138 2.5 2.5 0 0 1 .142 3.667l-3 3a2.5 2.5 0 0 1-3.536-3.536l1.225-1.224a.75.75 0 0 0-1.061-1.06l-1.224 1.224a4 4 0 1 0 5.656 5.656l3-3a4 4 0 0 0-.225-5.865Z\"\/><\/svg><span class=\"copy-link__text\">Copy link to this calculation<\/span><\/button><span class=\"sr-only\" role=\"status\" id=\"copy-link-status\"><\/span><\/div><\/div><a href=\"#respond\" class=\"hidden transition-opacity duration-300 opacity-0 w-50 text-sm justify-center items-center gap-2 px-4 py-2 rounded bg-gray-200 text-gray-700 hover:bg-gray-300\" id=\"leave-comment\"><span class=\"icon icon-comments\" aria-hidden=\"true\"><\/span>Leave a Comment<\/a><\/form><\/section><section id=\"calc-reactions\" class=\"not-prose hidden my-12 bg-gradient-to-r from-primary-50 to-gray-50 border border-indigo-100 rounded-xl px-6 py-4 shadow-sm\" data-post=\"56816\" aria-live=\"polite\" aria-labelledby=\"calc-reactions-title\"><p id=\"calc-reactions-title\" class=\"text-sm text-gray-500 text-center mb-2\">How did this result make you feel?<\/p><div role=\"group\" aria-labelledby=\"calc-reactions-title\" class=\"grid grid-cols-3 sm:flex sm:flex-row sm:justify-around gap-4 sm:items-center sm:flex-wrap\"><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"like\"><span class=\"reaction-count\" data-reaction-count=\"like\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude00 <\/span><span class=\"reaction-description font-medium\">Like <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"helpful\"><span class=\"reaction-count\" data-reaction-count=\"helpful\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\udca1 <\/span><span class=\"reaction-description font-medium\">Helpful <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"confused\"><span class=\"reaction-count\" data-reaction-count=\"confused\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude15 <\/span><span class=\"reaction-description font-medium\">Confused <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"disappointed\"><span class=\"reaction-count\" data-reaction-count=\"disappointed\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\ud83d\ude1e <\/span><span class=\"reaction-description font-medium\">Disappointed <\/span><\/button><button type=\"button\" aria-pressed=\"false\" class=\"reaction-btn flex flex-col items-center gap-1 text-sm text-gray-700 hover:text-primary-600 cursor-pointer transition-transform hover:scale-105\" data-reaction=\"inaccurate\"><span class=\"reaction-count\" data-reaction-count=\"inaccurate\">0<\/span><span class=\"reaction text-3xl\" aria-hidden=\"true\">\u274c <\/span><span class=\"reaction-description font-medium\">Inaccurate <\/span><\/button><\/div><div id=\"reaction-message\" class=\"hidden mt-8 rounded-md border border-primary-100 bg-white\/50 backdrop-blur-sm px-4 py-2 text-sm text-center shadow-sm\"><\/div><\/section><div class=\"calcdash-ad not-prose calcdash-ad--calc_result calcdash-ad--in-article\"><ins class=\"adsbygoogle\" style=\"display:block\" data-ad-client=\"ca-pub-1721569815777345\" data-ad-slot=\"6317458308\" data-ad-layout=\"in-article\" data-ad-format=\"fluid\"><\/ins><script>(adsbygoogle = window.adsbygoogle || []).push({});<\/script><\/div>\n<style id=\"wpcoderpro-inline-1\">.formula-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section class=\"formula-box\" aria-labelledby=\"formula-title\">\r\n\t<div id=\"formula-title\" class=\"not-prose font-display mb-4\"><span class=\"icon icon-formula\" aria-hidden=\"true\"><\/span><h2>Ventilation Power Formula<\/h2><\/div>\r\n\t<figure class=\"not-prose formula\">\r\n\t\t<figcaption class=\"formula-title\">Formula<\/figcaption>\r\n\t\t<div class=\"text-base text-gray-800\" id=\"formula\">\n\\[ Q = A \\cdot H \\cdot N \\]\n<\/div>\r\n\t<\/figure>\r\n\t<\/p>\n<p><strong>Where:<\/strong><\/p>\n<ul>\n<li>\\(Q\\) \u2014 required air flow rate, or ventilation power (m\u00b3\/h)<\/li>\n<li>\\(A\\) \u2014 floor area of the room (m\u00b2)<\/li>\n<li>\\(H\\) \u2014 height of the room (m)<\/li>\n<li>\\(N\\) \u2014 number of air changes per hour (1\/h)<\/li>\n<\/ul>\n<p>The formula multiplies the room volume by the air exchange rate: the entire volume of air in the space must be replaced \\(N\\) times every hour, so the fan or ventilation unit must deliver at least that much flow.<\/p>\n<p>\r\n<\/section>\n<style id=\"wpcoderpro-inline-459\">.calculation-box {\r\n\tborder-bottom: none !important;\r\n}<\/style><section id=\"calculation\" class=\"calculation-box\" aria-labelledby=\"calculation-title\">\r\n\t<div id=\"calculation-title\" class=\"not-prose font-display\"><span class=\"icon icon-unordered-list\" aria-hidden=\"true\"><\/span><h2>Ventilation Power \u2013 Calculation Example<\/h2><\/div>\r\n\r\n<\/p>\n<p><strong>Example:<\/strong> a living room with a floor area of 20 m\u00b2 and a ceiling height of 2.5 m needs 2 air changes per hour.<\/p>\n<p>\\[ Q = A \\cdot H \\cdot N = 20 \\cdot 2.5 \\cdot 2 = 100 \\, \\text{m}^3\/\\text{h} \\]<\/p>\n<p><strong>Result:<\/strong> the required performance is <strong>100 m\u00b3\/h<\/strong>. Any ventilation unit serving this room should provide at least this air flow rate at the designed duct resistance.<\/p>\n<p>\n\r\n<\/section>\n<h2>How to use the calculator<\/h2>\n<ol>\n<li>Enter the <strong>Size of room<\/strong> \u2014 the floor area in square meters (for a rectangular room, multiply length by width).<\/li>\n<li>Enter the <strong>Room height<\/strong> \u2014 the floor-to-ceiling height in meters. If the ceiling is sloped, use the average height.<\/li>\n<li>Enter the <strong>Number of air<\/strong> \u2014 the desired air changes per hour (ACH). Typical residential values are 1\u20133; kitchens, bathrooms, and workshops need more (see the table below).<\/li>\n<li>Read the <strong>Required performance<\/strong> \u2014 the result is the air flow rate in m\u00b3\/h that your fan or ventilation system must deliver.<\/li>\n<\/ol>\n<h2>What is ventilation power?<\/h2>\n<p>\"Ventilation power\" in this context means the required air flow rate \u2014 the volume of air, in cubic meters per hour, that a ventilation system must move through a room to keep the air fresh. It is not electrical power; it is the capacity you use to select fans, air handling units, diffusers, and duct sizes. The result is often denoted \\(Q\\) or \\(V\\) and expressed in m\u00b3\/h (to convert to liters per second, divide by 3.6).<\/p>\n<p>The calculation is based on the <em>air change method<\/em>: instead of sizing ventilation per person or per pollutant source, you specify how many times per hour the full volume of the room's air should be replaced. A room with \\(N = 1\\) has its air fully exchanged once an hour; \\(N = 5\\) means the air is replaced every 12 minutes. The product of room volume \\(A \\cdot H\\) and the exchange rate \\(N\\) directly gives the required flow.<\/p>\n<p>The air change method works best for rooms where contamination is distributed throughout the space \u2014 living rooms, bedrooms, offices, storage areas. For spaces where people are the main source of CO\u2082 and moisture, a per-person method may be more accurate; you can compare both approaches with our <a href=\"https:\/\/wpcalc.com\/en\/engineering\/ventilation-in-the-number-of-people\/\">ventilation per number of people calculator<\/a> and the <a href=\"https:\/\/wpcalc.com\/en\/engineering\/ventilation\/\">ventilation airflow requirement calculator<\/a>.<\/p>\n<h2>Typical air change rates<\/h2>\n<table>\n<thead>\n<tr>\n<th>Room type<\/th>\n<th>Air changes per hour (N)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>Living room, bedroom<\/td>\n<td>1\u20132<\/td>\n<\/tr>\n<tr>\n<td>Home kitchen<\/td>\n<td>3\u20138 (with extract hood)<\/td>\n<\/tr>\n<tr>\n<td>Bathroom, WC<\/td>\n<td>5\u201310<\/td>\n<\/tr>\n<tr>\n<td>Office, meeting room<\/td>\n<td>2\u20134<\/td>\n<\/tr>\n<tr>\n<td>Garage, workshop<\/td>\n<td>6\u201310<\/td>\n<\/tr>\n<tr>\n<td>Warehouse, storage<\/td>\n<td>1\u20133<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Local building codes and ASHRAE guidelines specify minimum values \u2014 always check the regulations that apply in your region before finalizing a design.<\/p>\n<h2>Assumptions and limitations<\/h2>\n<ul>\n<li>The formula assumes a simple rectangular room with uniform ceiling height. For L-shaped or sloped-ceiling rooms, split the space into parts, calculate each separately, and add the results.<\/li>\n<li>The result is the <em>required<\/em> flow, not the fan's advertised capacity. Real ducts, filters, and grilles create resistance, so choose a unit whose actual delivered flow at the design pressure matches or exceeds the calculated value.<\/li>\n<li>The air change method ignores heat and moisture loads. If the room gains a lot of heat or produces humidity (kitchens, gyms, industrial processes), additional calculations based on heat balance or pollutant removal may require a higher flow.<\/li>\n<li>Air changes per hour alone do not guarantee good air quality \u2014 the supply and extract must also be well distributed. To plan distribution, use the <a href=\"https:\/\/wpcalc.com\/en\/engineering\/number-of-diffusers\/\">ventilation diffuser count calculator<\/a> and the <a href=\"https:\/\/wpcalc.com\/en\/engineering\/number-of-grids\/\">ventilation grid count calculator<\/a>.<\/li>\n<li>All inputs must use metric units (m\u00b2, m). Mixing feet or cubic feet will give meaningless results.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Calculate the required ventilation air flow rate (m\u00b3\/h) from room area, ceiling height, and desired air changes per hour. Enter three values to size fans, diffusers, and ductwork correctly.<\/p>\n","protected":false},"author":70,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[4],"tags":[39],"class_list":["post-56816","post","type-post","status-publish","format-standard","hentry","category-engineering","tag-ventilation"],"acf":[],"_links":{"self":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/56816","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/users\/70"}],"replies":[{"embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/comments?post=56816"}],"version-history":[{"count":2,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/56816\/revisions"}],"predecessor-version":[{"id":66030,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/posts\/56816\/revisions\/66030"}],"wp:attachment":[{"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/media?parent=56816"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/categories?post=56816"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpcalc.com\/en\/wp-json\/wp\/v2\/tags?post=56816"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}