{"id":100129,"date":"2026-02-15T20:19:19","date_gmt":"2026-02-15T20:19:19","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100129"},"modified":"2026-04-05T15:42:49","modified_gmt":"2026-04-05T15:42:49","slug":"heat-loss-wall","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/bn\/calculators\/heat-loss-wall\/","title":{"rendered":"Heat Loss Through Wall Calculator | Free U-Value Tool"},"content":{"rendered":"\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Heat Loss Through Wall Calculator\",\"description\":\"Calculate heat loss through composite walls. U-value, R-value, heat flow.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/heat-loss-wall\/\",\"applicationCategory\":\"Engineering Calculator\",\"operatingSystem\":\"Any\",\"offers\":{\"@type\":\"Offer\",\"price\":\"0\",\"priceCurrency\":\"EUR\"},\"creator\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\"datePublished\":\"2024-01-01\",\"dateModified\":\"2025-02-14\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true}<\/script>\n\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[\n{\"@type\":\"Question\",\"name\":\"What is U-value?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"U-value (thermal transmittance) is the rate of heat transfer through a structure per unit area per degree of temperature difference. Lower U = better insulation. Units: W\/(m\u00b2\u00b7K). U = 1\/R_total.\"}},\n{\"@type\":\"Question\",\"name\":\"How is wall heat loss calculated?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Q = U \u00d7 A \u00d7 \u0394T, where Q is heat flow (W), U is thermal transmittance (W\/m\u00b2K), A is wall area (m\u00b2), and \u0394T is temperature difference between inside and outside.\"}},\n{\"@type\":\"Question\",\"name\":\"What is R-value?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"R-value is thermal resistance: R = thickness\/conductivity for each layer. Total R = R_si + \u03a3R_layers + R_se (including surface film resistances). U = 1\/R_total. Higher R = better insulation.\"}},\n{\"@type\":\"Question\",\"name\":\"What are typical wall U-values?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Uninsulated brick wall: U \u2248 2.0 W\/m\u00b2K. Insulated cavity wall: U \u2248 0.3-0.5 W\/m\u00b2K. Well-insulated wall (modern code): U \u2248 0.15-0.25 W\/m\u00b2K. Passive house: U < 0.15 W\/m\u00b2K.\"}},\n{\"@type\":\"Question\",\"name\":\"What are surface film resistances?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"R_si (internal surface) \u2248 0.13 m\u00b2K\/W and R_se (external surface) \u2248 0.04 m\u00b2K\/W account for the thin boundary layer of still air at each surface. They are included in the total thermal resistance calculation.\"}}\n]}<\/script>\n\n<script type=\"application\/ld+json\">{\"@context\":\"https:\/\/schema.org\",\"@type\":\"BreadcrumbList\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/vibromera.eu\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Calculators\",\"item\":\"https:\/\/vibromera.eu\/calculators\/\"},{\"@type\":\"ListItem\",\"position\":3,\"name\":\"Heat Loss Wall\",\"item\":\"https:\/\/vibromera.eu\/calculators\/heat-loss-wall\/\"}]}<\/script>\n\n<link rel=\"preconnect\" href=\"https:\/\/fonts.googleapis.com\">\n\n<link rel=\"preconnect\" href=\"https:\/\/fonts.gstatic.com\" crossorigin>\n\n<link href=\"https:\/\/fonts.googleapis.com\/css2?family=DM+Sans:ital,opsz,wght@0,9..40,300;0,9..40,400;0,9..40,500;0,9..40,600;0,9..40,700;1,9..40,400&#038;family=JetBrains+Mono:wght@400;500;600&#038;family=Fraunces:opsz,wght@9..144,700;9..144,800&#038;display=swap\" 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class=\"vc-calculator\">\n<header class=\"vc-header\"><p class=\"vc-header-eyebrow\">Free Engineering Tool<\/p><h1 class=\"vc-header-title\">Heat Loss Through Wall Calculator<\/h1><p class=\"vc-header-subtitle\">Calculate heat loss Q = U \u00d7 A \u00d7 \u0394T through composite walls. Add material layers, set temperatures, and get U-value and heat flow.<\/p><div class=\"vc-badges\"><span class=\"vc-badge\">Q = U\u00b7A\u00b7\u0394T<\/span><span class=\"vc-badge\">Multi-Layer<\/span><span class=\"vc-badge\">#176<\/span><\/div><\/header>\n\n<div class=\"vc-card\">\n    <form class=\"vc-form\" id=\"vc-form\" autocomplete=\"off\">\n        <div class=\"vc-form-grid\">\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-Ti\">Inside Temperature <span class=\"vc-label-hint\">(\u00b0C)<\/span><\/label><input class=\"vc-input\" type=\"number\" id=\"vc-Ti\" value=\"20\"><\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-To\">Outside Temperature <span class=\"vc-label-hint\">(\u00b0C)<\/span><\/label><input class=\"vc-input\" type=\"number\" id=\"vc-To\" value=\"-10\"><\/div>\n            <div class=\"vc-field\"><label class=\"vc-label\" for=\"vc-A\">Wall Area <span class=\"vc-label-hint\">(m\u00b2)<\/span><\/label><input class=\"vc-input\" type=\"number\" id=\"vc-A\" step=\"any\" min=\"0\" value=\"10\"><\/div>\n        <\/div>\n        <div style=\"margin-top:18px\">\n            <div class=\"vc-label\" style=\"margin-bottom:10px\">Wall Layers <span class=\"vc-label-hint\">(inside to outside)<\/span><\/div>\n            <div id=\"vc-layers\">\n                <div class=\"vc-layer-row\"><input class=\"vc-input vc-lname\" placeholder=\"Layer name\" value=\"Plaster\"><input class=\"vc-input vc-lk\" type=\"number\" step=\"any\" placeholder=\"k (W\/m\u00b7K)\" value=\"0.7\"><input class=\"vc-input vc-lt\" type=\"number\" step=\"any\" placeholder=\"t (mm)\" value=\"15\"><button type=\"button\" class=\"vc-rm-btn\" title=\"Remove\">\u00d7<\/button><\/div>\n                <div class=\"vc-layer-row\"><input class=\"vc-input vc-lname\" placeholder=\"Layer name\" value=\"Brick\"><input class=\"vc-input vc-lk\" type=\"number\" step=\"any\" placeholder=\"k (W\/m\u00b7K)\" value=\"0.8\"><input class=\"vc-input vc-lt\" type=\"number\" step=\"any\" placeholder=\"t (mm)\" value=\"240\"><button type=\"button\" class=\"vc-rm-btn\" title=\"Remove\">\u00d7<\/button><\/div>\n                <div class=\"vc-layer-row\"><input class=\"vc-input vc-lname\" placeholder=\"Layer name\" value=\"EPS Insulation\"><input class=\"vc-input vc-lk\" type=\"number\" step=\"any\" placeholder=\"k (W\/m\u00b7K)\" value=\"0.038\"><input class=\"vc-input vc-lt\" type=\"number\" step=\"any\" placeholder=\"t (mm)\" value=\"100\"><button type=\"button\" class=\"vc-rm-btn\" title=\"Remove\">\u00d7<\/button><\/div>\n            <\/div>\n            <button type=\"button\" class=\"vc-add-layer\" id=\"vc-add-layer\">+ Add Layer<\/button>\n        <\/div>\n        <div class=\"vc-presets\"><div class=\"vc-presets-label\">Quick presets<\/div>\n            <button type=\"button\" class=\"vc-preset-btn\" data-layers='[[\"Plaster\",0.7,15],[\"Brick\",0.8,240],[\"EPS\",0.038,100]]'>Insulated Brick Wall<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-layers='[[\"Plasterboard\",0.25,12.5],[\"Mineral Wool\",0.035,150],[\"OSB\",0.13,12],[\"Render\",0.8,15]]'>Timber Frame Wall<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-layers='[[\"Brick\",0.8,240]]'>Uninsulated Brick<\/button>\n        <\/div>\n    <\/form>\n    <div class=\"vc-results\" id=\"vc-results\">\n        <div class=\"vc-results-head\"><h2 class=\"vc-results-title\">Results<\/h2><button type=\"button\" class=\"vc-copy-btn\" id=\"vc-copy-btn\"><svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg> Copy<\/button><\/div>\n        <div class=\"vc-result-grid\">\n            <div class=\"vc-rcard vc-rcard-primary\"><div class=\"vc-rcard-label\">Heat Loss Q<\/div><div class=\"vc-rcard-value\" id=\"vc-r-Q\">\u2014<\/div><\/div>\n            <div class=\"vc-rcard\"><div class=\"vc-rcard-label\">U-Value<\/div><div class=\"vc-rcard-value\" id=\"vc-r-U\">\u2014<\/div><\/div>\n            <div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Total R-Value<\/div><div class=\"vc-rcard-value\" id=\"vc-r-R\">\u2014<\/div><\/div>\n            <div class=\"vc-rcard\"><div class=\"vc-rcard-label\">Heat Flux q<\/div><div class=\"vc-rcard-value\" id=\"vc-r-q\">\u2014<\/div><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<div class=\"vc-section vc-open\" id=\"vc-sec-theory\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"true\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\ud83d\udcd8<\/span><span class=\"vc-section-title\">Theory &amp; Formulas<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner vc-theory\"><h3>Composite Wall Heat Transfer<\/h3><div class=\"vc-formula-box\" id=\"vc-katex-1\"><\/div><div class=\"vc-formula-box\" id=\"vc-katex-2\"><\/div><p>R_si = 0.13 m\u00b2K\/W (internal surface), R_se = 0.04 m\u00b2K\/W (external surface).<\/p><\/div><\/div><\/div>\n<div class=\"vc-section\" id=\"vc-sec-related\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\ud83d\udd17<\/span><span class=\"vc-section-title\">Related Calculators<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner\"><div class=\"vc-related\"><a class=\"vc-related-link\" href=\"\/calculators\/insulation-thickness-calculator\/\">Insulation Thickness<\/a><a class=\"vc-related-link\" href=\"\/calculators\/heater-power-calculator\/\">Heater Power<\/a><a class=\"vc-related-link\" href=\"\/calculators\/thermal-expansion-calculator\/\">Thermal Expansion<\/a><\/div><\/div><\/div><\/div>\n<div class=\"vc-section\" id=\"vc-sec-faq\"><button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\"><span class=\"vc-section-toggle-text\"><span class=\"vc-section-icon\">\u2753<\/span><span class=\"vc-section-title\">Frequently Asked Questions<\/span><\/span><svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-section-body\"><div class=\"vc-section-inner\"><div class=\"vc-faq-list\" id=\"vc-faq-list\"><\/div><\/div><\/div><\/div>\n<div class=\"vc-promo\"><div class=\"vc-promo-text\"><strong>Vibromera \u2014 Portable Balancing &amp; Vibration Analysis<\/strong><br>Professional instruments. 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Lower = better insulation. U = 1\/R_total. Units: W\/(m\u00b2\u00b7K).<\/p>'},{q:'How is wall heat loss calculated?',a:'<p>Q = U \u00d7 A \u00d7 \u0394T. U-value \u00d7 area \u00d7 temp difference gives total heat loss in watts.<\/p>'},{q:'What is R-value?',a:'<p>Thermal resistance: R = thickness \/ conductivity for each layer. Total R includes surface films (R_si=0.13, R_se=0.04).<\/p>'},{q:'What are typical U-values?',a:'<p>Uninsulated brick: ~2.0, Insulated cavity: ~0.3-0.5, Modern code: ~0.15-0.25, Passive house: <0.15 W\/m\u00b2K.<\/p>'},{q:'What are surface film resistances?',a:'<p>R_si \u2248 0.13 (internal) and R_se \u2248 0.04 m\u00b2K\/W (external) account for still air boundary layers at surfaces.<\/p>'}];\nvar fl=$('vc-faq-list');faqData.forEach(function(f){fl.innerHTML+='<div class=\"vc-faq-item\"><button type=\"button\" class=\"vc-faq-q\"><span>'+f.q+'<\/span><svg class=\"vc-faq-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-faq-a\"><div class=\"vc-faq-a-inner\">'+f.a+'<\/div><\/div><\/div>'});fl.addEventListener('click',function(e){var b=e.target.closest('.vc-faq-q');if(!b)return;b.closest('.vc-faq-item').classList.toggle('vc-open')});\nfunction saveHistory(e){var k='vc_history_'+SLUG;var a=[];try{a=JSON.parse(localStorage.getItem(k))||[]}catch(x){}e._ts=new Date().toISOString();a.unshift(e);if(a.length>10)a=a.slice(0,10);try{localStorage.setItem(k,JSON.stringify(a))}catch(x){}}\nfunction renderFormulas(){try{katex.render('R_{total}=R_{si}+\\\\sum\\\\frac{t_i}{k_i}+R_{se},\\\\quad U=\\\\frac{1}{R_{total}}',$('vc-katex-1'),{displayMode:true,throwOnError:false});katex.render('Q=U\\\\cdot A\\\\cdot\\\\Delta T\\\\quad[\\\\text{W}]',$('vc-katex-2'),{displayMode:true,throwOnError:false})}catch(e){}}\nfunction init(){renderFormulas();calculate()}if(document.readyState==='loading')document.addEventListener('DOMContentLoaded',init);else init();\n})();\n<\/script>\n","protected":false},"excerpt":{"rendered":"<p>Free heat loss calculator for walls. Q = U \u00d7 A \u00d7 \u0394T. Enter wall layers (conductivity, thickness), area, temperatures. 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