{"id":10792,"date":"2026-05-27T12:43:22","date_gmt":"2026-05-27T10:43:22","guid":{"rendered":"https:\/\/aluplast.buges.sk\/slovnik-oknara\/uf-value-frame-heat-transfer-coefficient\/"},"modified":"2026-09-02T13:44:39","modified_gmt":"2026-09-02T11:44:39","slug":"uf-value-frame-heat-transfer-coefficient","status":"publish","type":"glossary","link":"https:\/\/www.aluplast.sk\/en\/slovnik-oknara\/uf-value-frame-heat-transfer-coefficient\/","title":{"rendered":"Uf-value: Frame Heat Transfer Coefficient"},"content":{"rendered":"  <div id=\"page-header-1650255629\" 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            Uf-value: Frame Heat Transfer Coefficient          <\/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-1650255629 .page-title-inner {\n  min-height: 23.6vh;\n}\n#page-header-1650255629 .featured-title {\n  background-color: rgb(0,0,0);\n}\n#page-header-1650255629 .title-bg {\n  background-position: 50% 50%;\n}\n<\/style>\n  <\/div>\n    <\/div>\n  \n\n\t<section class=\"section\" id=\"section_1308062538\">\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-2053295218\">\n\n\t<div id=\"col-592522466\" class=\"col small-12 large-12\"  >\n\t\t\t\t<div class=\"col-inner\"  >\n\t\t\t\n\t\t\t\n<h2>What Does This Value Indicate? Heat Loss Through the Frame. <\/h2>\n<h3>Lower Value, Warmer Window.<\/h3>\n<p>The frame heat transfer coefficient, Uf (from English &#8216;frame&#8217;), indicates how well the window frame itself insulates. A lower number signifies better thermal insulation, which is crucial for the overall thermal efficiency of the window (Uw), also influenced by glazing (Ug) and other factors.<\/p>\n\t\t<\/div>\n\t\t\t\t\t<\/div>\n\n\t\n\n\t<div id=\"col-963115231\" class=\"col medium-5 small-12 large-5\"  >\n\t\t\t\t<div class=\"col-inner\"  >\n\t\t\t\n\t\t\t\n\t<div class=\"img has-hover x md-x lg-x y md-y lg-y\" id=\"image_1484653191\">\n\t\t\t\t\t\t\t\t<div class=\"img-inner dark\" >\n\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"540\" height=\"550\" src=\"https:\/\/www.aluplast.sk\/wp-content\/uploads\/povrchove_teploty_b_0f694dd72074c6cf.jpg\" 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_1484653191 {\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-1319638551\" class=\"col small-12 large-12\"  >\n\t\t\t\t<div class=\"col-inner\"  >\n\t\t\t\n\t\t\t\n<h3>What Does Uf Mean?<\/h3>\n<h4>Uf (f = frame) <\/h4>\n<p>The rate of heat loss through the window frame.<\/p>\n<h4>Unit<\/h4>\n<p>Expressed in watts per square meter Kelvin (W\/m\u00b2K).<\/p>\n<h4>Impact on Overall Window (Uw)<\/h4>\n<p>The Uf value, along with Ug (glass) and \u03a8g (spacer frame), determines the resulting Uw value for the entire window. Smaller windows have a poorer Uw value because, compared to the frame, they have a larger glass area, which insulates better.  <\/p>\n<h4>Why Is It Important?<\/h4>\n<p>A good (low) Uf prevents heat loss through the frame, which is critical, especially for aluminum and older window types.<\/p>\n<p><strong>For passive and low-energy buildings, windows with a very low Uw are ideal, and this also requires a high-quality Uf (e.g., below 0.8 W\/m\u00b2K). <\/strong><\/p>\n<h4> <\/h4>\n<h4>Related Values<\/h4>\n<p>Ug: Heat transfer coefficient through glazing <a href=\"https:\/\/www.aluplast.sk\/en\/slovnik-oknara\/glazing-heat-transfer-coefficient-ug\/\">(window glossary)<\/a><\/p>\n<p>Uw: Heat transfer coefficient for the entire window <a href=\"https:\/\/www.aluplast.sk\/en\/slovnik-oknara\/window-thermal-transmittance-uw\/\">(window glossary)<\/a><\/p>\n<p>\u03a8g (Psi): Linear heat transfer coefficient at the frame-glass junction (spacer) <a href=\"https:\/\/www.aluplast.sk\/en\/slovnik-oknara\/psi-%cf%88g-linear-heat-transfer-coefficient-at-the-frame-glass-junction-spacer-frame\/\">(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_1308062538 {\n  padding-top: 30px;\n  padding-bottom: 30px;\n}\n<\/style>\n\t<\/section>\n\t\n","protected":false},"featured_media":0,"template":"","meta":{"_acf_changed":false,"footnotes":""},"class_list":["post-10792","glossary","type-glossary","status-publish","hentry"],"acf":[],"_links":{"self":[{"href":"https:\/\/www.aluplast.sk\/en\/wp-json\/wp\/v2\/glossary\/10792","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\/10792\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.aluplast.sk\/en\/wp-json\/wp\/v2\/media?parent=10792"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}