![Night view of a high-rise building with an open parallel window in the glass façade.](/sites/default/files/public/styles/page_header_large/public/2022-03/Reynaers-Aluminium-U-value-3.png?h=16a6ccf5&itok=8R6oQIZ-) 07 March 2022 # U-value: what does thermal insulation mean for your building project? Sustainable homes and buildings are the only way forward. Every aspect counts. A less known, yet extremely significant factor to measure energy efficiency is the U-value. The lower it is, the better the thermal efficiency or insulation. Rising energy costs and growing sustainability awareness have considerably increased the focus on a building’s energy performance. Efficiency standards – imposed and often made stricter by regulation – are a major indirect driving force behind enhancing the comfort level of a project. Thanks to an optimal U-value, you not only save energy, you also increase your quality of life. ![Detail view of the Reynaers Experience Centre’s glass façade.](/sites/default/files/public/styles/landscape_small/public/2022-03/Reynaers-Aluminium-U-value-1.jpg?h=7721ddbf&itok=Jzvmvbti) ## Sustainable living and working Reynaers Aluminium not only cares about energy efficiency. Your [comfort](/inspiration/stories/how-improve-your-comfort-aluminium "How to improve your comfort with aluminium") counts too. An excellent duo, as the latter is often generated by technological innovations that focus on efficient energy use. In thermal insulation, some of our Reynaers Aluminium systems have reached a limit for U-values at Passive House level, well under 1.0 W/m²k. Ventilation, solar control and airtight building connections are essential as well. The mix of all these elements makes it possible to achieve a comfortable climate, even directly behind a large glass façade, regardless of the weather. That is what we call “quality of life”. ![Woman indoors, standing in front of large sliding window.](/sites/default/files/public/styles/image_max_width/public/2022-03/Reynaers-Aluminium-U-value-2.jpg?itok=rKUMZdPa) Copyright [**Reynaers Campus: Experience Centre**](/inspiration/aluminium-project-references/sliding-folding-solar-shading-windows-facades-reynaers-campus-experience-centre-duffel "Reynaers Campus: Experience Centre") – Jaspers-Eyers Architects (architect); Phillippe Van Gelooven, Georges De Kinder (photographers) Share this story - [f](https://www.facebook.com/sharer/sharer.php?u=https%3A//www.reynaers.se/markdownify/node/6279%3Futm_source%3Dfacebook%26utm_medium%3Dsocial%26utm_campaign%3Dwebsite) - [t](https://twitter.com/intent/tweet?text=https%3A//www.reynaers.se/markdownify/node/6279%3Futm_source%3Dtwitter%26utm_medium%3Dsocial%26utm_campaign%3Dwebsite) - [l](https://www.linkedin.com/shareArticle?mini=1&url=https%3A//www.reynaers.se/markdownify/node/6279%3Futm_source%3Dlinkedin%26utm_medium%3Dsocial%26utm_campaign%3Dwebsite) - [p](https://pinterest.com/pin/create/button/) - [m]() ## You might also like [ See all stories ](/stories) - ![Close up of glazed façade](/sites/default/files/public/styles/teaser_medium/public/2026-03/150478F0005-BOSL.jpg?h=17fd743d&itok=sJUFKDUv) ### Low-carbon simulation and optimisation at Reynaers Aluminium [](/inspiration/stories/sustainability/low-carbon-simulation-and-optimisation) Read this - ![ReTurn logo in front of pile of aluminium scrap in blue bin.](/sites/default/files/public/styles/teaser_medium/public/2026-03/reynaers-aluminium-return-banner.png?h=61f1cca7&itok=l0XPyQ3N) ### ReTurn: Reynaers Aluminium turns waste into resources with new closed-loop systems [](/inspiration/stories/sustainability/closed-loop-systems) Read this [ See all stories ](/stories)