{"id":10839,"date":"2026-02-19T12:06:18","date_gmt":"2026-02-19T11:06:18","guid":{"rendered":"https:\/\/aluplast.buges.sk\/slovnik-oknara\/psi-%cf%88g-linear-heat-transfer-coefficient-at-the-frame-glass-junction-spacer-frame\/"},"modified":"2026-09-02T13:47:35","modified_gmt":"2026-09-02T11:47:35","slug":"psi-%cf%88g-linear-heat-transfer-coefficient-at-the-frame-glass-junction-spacer-frame","status":"publish","type":"glossary","link":"https:\/\/www.aluplast.sk\/en\/slovnik-oknara\/psi-%cf%88g-linear-heat-transfer-coefficient-at-the-frame-glass-junction-spacer-frame\/","title":{"rendered":"Psi (\u03a8g) &#8211; Linear Heat Transfer Coefficient at the Frame-Glass Junction (Spacer Frame)"},"content":{"rendered":"  <div id=\"page-header-551920111\" class=\"page-header-wrapper\">\n  <div class=\"page-title page-header-custom z-5 dark featured-title\">\n\n        <div class=\"page-title-bg\">\n      <div class=\"title-bg fill bg-fill\"\n        data-parallax-container=\".page-title\"\n        data-parallax-background\n        data-parallax=\"-\">\n      <\/div>\n      <div class=\"title-overlay fill\"><\/div>\n    <\/div>\n    \n    <div class=\"page-title-inner container align-center flex-row medium-flex-wrap\" >\n              <div class=\"title-wrapper flex-col text-left medium-text-center\">\n          <h1 class=\"entry-title mb-0\">\n            Psi (\u03a8g) &#8211; Linear Heat Transfer Coefficient at the Frame-Glass Junction (Spacer Frame)          <\/h1>\n        <\/div>\n                    <div class=\"title-content flex-col flex-right text-right medium-text-center\">\n        <div class=\"title-breadcrumbs pb-half pt-half\"><\/div>      <\/div>\n    <\/div>\n\n     \n<style>\n#page-header-551920111 .page-title-inner {\n  min-height: 23.6vh;\n}\n#page-header-551920111 .featured-title {\n  background-color: rgb(0,0,0);\n}\n#page-header-551920111 .title-bg {\n  background-position: 50% 50%;\n}\n<\/style>\n  <\/div>\n    <\/div>\n  \n\n\t<section class=\"section\" id=\"section_1026398196\">\n\t\t<div class=\"section-bg fill\" >\n\t\t\t\t\t\t\t\t\t\n\t\t\t\n\n\t\t<\/div>\n\n\t\t\n\n\t\t<div class=\"section-content relative\">\n\t\t\t\n<div class=\"row\"  id=\"row-635016509\">\n\n\t<div id=\"col-193752595\" class=\"col medium-6 small-12 large-6\"  >\n\t\t\t\t<div class=\"col-inner\"  >\n\t\t\t\n\t\t\t\n<h2>What Does This Value Indicate? How much heat escapes through the insulating glass spacer frame <\/h2>\n<h3>The lower the value, the better the insulation.<\/h3>\n<p>\u03a8g (Psi) is the linear heat transfer coefficient (thermal bridge) that expresses how much heat escapes through the perimeter boundary of the glass and frame (spacer frame) of insulating glass. A lower \u03a8g value means better thermal insulation and reduced heat loss at this critical point of the window, which improves the overall energy efficiency of the window. <\/p>\n\t<div class=\"img has-hover x md-x lg-x y md-y lg-y\" id=\"image_429570711\">\n\t\t\t\t\t\t\t\t<div class=\"img-inner dark\" >\n\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"1024\" src=\"https:\/\/www.aluplast.sk\/wp-content\/uploads\/TeplyRamik_hlinik-1024x1024-1.webp\" class=\"attachment-original size-original\" alt=\"\" \/>\t\t\t\t\t\t\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\n<style>\n#image_429570711 {\n  width: 100%;\n}\n<\/style>\n\t<\/div>\n\t\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\n\t\n\n\t<div id=\"col-404575940\" class=\"col medium-6 small-12 large-6\"  >\n\t\t\t\t<div class=\"col-inner\"  >\n\t\t\t\n\t\t\t\n<h4>Heat Transfer Coefficient (U-value)<\/h4>\n<p>Measures heat transfer across a surface (e.g., glass, frame).<\/p>\n<h4>Linear Heat Transfer Coefficient (\u03a8-value)<\/h4>\n<p>Measures heat transfer along a line (e.g., frame-glass junction) where heat loss occurs.<\/p>\n<h4>\u03a8g<\/h4>\n<p>Specifically refers to heat transfer at the point where the spacer meets the edge of the glass.<\/p>\n<h4>Unit<\/h4>\n<p>Watt per meter Kelvin W\/m\u00b7K<\/p>\n<h4>Significance<\/h4>\n<p>The spacer frame, which separates the glass panes, is often a thermal bridge. The \u03a8g value quantifies how effectively this frame interrupts heat flow. The lower the \u03a8g value, the better the thermal insulation of the joint, and the lower the overall Uw coefficient of the window.  <\/p>\n<h4>Comparison<\/h4>\n<p>While Ug is for glass and Uf is for the frame, \u03a8g is for the junction, allowing for a precise assessment of the glazing edge, which significantly impacts the window&#8217;s overall efficiency.<\/p>\n<h4>Related Values<\/h4>\n<p><strong>Uf:<\/strong> Heat transfer coefficient through the frame <a href=\"https:\/\/www.aluplast.sk\/en\/slovnik-oknara\/uf-value-frame-heat-transfer-coefficient\/\">(window glossary)<\/a><br \/><strong>Uw:<\/strong> Heat transfer coefficient through the entire window <a href=\"https:\/\/www.aluplast.sk\/en\/slovnik-oknara\/window-thermal-transmittance-uw\/\">(window glossary)<\/a><br \/><strong>Ug:<\/strong> Heat transfer coefficient through insulating glass <a href=\"https:\/\/www.aluplast.sk\/en\/slovnik-oknara\/glazing-heat-transfer-coefficient-ug\/\">(window glossary)<\/a><\/p>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\n\t\n<\/div>\n\t\t<\/div>\n\n\t\t\n<style>\n#section_1026398196 {\n  padding-top: 60px;\n  padding-bottom: 60px;\n}\n<\/style>\n\t<\/section>\n\t\n","protected":false},"featured_media":0,"template":"","meta":{"_acf_changed":false,"footnotes":""},"class_list":["post-10839","glossary","type-glossary","status-publish","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.aluplast.sk\/en\/wp-json\/wp\/v2\/glossary\/10839","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.aluplast.sk\/en\/wp-json\/wp\/v2\/glossary"}],"about":[{"href":"https:\/\/www.aluplast.sk\/en\/wp-json\/wp\/v2\/types\/glossary"}],"version-history":[{"count":0,"href":"https:\/\/www.aluplast.sk\/en\/wp-json\/wp\/v2\/glossary\/10839\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.aluplast.sk\/en\/wp-json\/wp\/v2\/media?parent=10839"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}