Aluminum windows thermal insulation properties improvement - what else is possible?
Aluminum windows have gone through a huge progress in their development in recent decades - from the thermal bridge, they have evolved into a highly efficient component that is even suitable for passive houses. Of course, there is still much room for the improvement of the properties.
To begin with, there are still a lot of ways of improving aluminum composite windows. A new approach can always be found with a strong will and desire. As the writer Franz Kafka said:
Paths are made by walking them.
Tip 1: Improving U-values with wide polyamide insulating strips
Windows made of metals led to high energy losses due to the high thermal conductivity of the material in the past. In order to minimize the heat transmission through the frame of a modern aluminum window, the profiles are thermally separated today. This task was accomplished by insulating strips made of polyamide, since the material has a very low thermal conductivity. Also, the ABS insulating bars, which consist of the acrylonitrile-butadiene-styrene copolymer are being used. In order to achieve a further improvement of the U-values of the window frame, a larger insulating zone could be utilized, for example, by wider distances between the aluminum frame shells of the window profile. With appropriately fitted polyamide insulating bars with reduced lambda value, energy efficiency can also be increased. However, as the stability and usability of the window must be guaranteed, it is important to limit the broadening of the profiles and the increase in the distance between the aluminum shells.
Tip 2: Optimizing the insulation values by foaming the hollow chambers of the profile
Due to their design, aluminum window frames have some empty space inside. These can be used to optimize the U-value of the frame and thus the insulating effect of the window. For this purpose, some insulating foams are introduced into the interstices of hollow chambers insulating profile. For example, polyurethane foam insulation is commonly used for his cause. These measures allow to achieve efficient thermal separation.
Tip 3: Increasing the efficiency with the insulating glazing
Depending on the type of building, the glass surfaces of windows can make up a large proportion of the exterior wall and therefore they should have corresponding insulation values. Because of that, Insulating glazing, consisting of two or more panes is frequently used. The cavities between the panes get hermetically sealed and filled with gases as argon or krypton to minimize heat flow through the glass. Triple-glazed aluminum windows and polyamide insulating bars achieved sufficient enough U-values so that now they can be even used in the passive house area.
Tip 4: Lowering the heat loss with reflective foil or low-E foil
With highly reflective low-E foils, also known as reflection foils, the thermal properties of the frame and thus of the entire aluminum window can be significantly improved. The low-E foil is applied to the bar or the glazing across the direction of the heat transmission, reducing the energy losses caused by the heat radiation emerging outside. This allows the further optimization of their insulating effect and efficiency of a window without changing its structure. And of course, the highly reflective foils for glass surfaces are transparent, allowing the light into the room without major losses.
Tip 5: Energy consumption optimization through software
Improved insulation zones with insulating bars made of polyamide and foam-filled hollow chambers turns an aluminum composite window into highly energy-saving one and therefore environmentally friendly. Therefore, the profiles of such aluminum window frames are considered as "High Sustainability Profiles", i.e. as frame profiles that are most suited to ecological sustainability in all respects. Taking into account complex design and a large number of materials used in production, the level of U-value of an aluminum window can no longer be precisely calculated without the aid of software. The mechanical load capacity must be also included in the development of windows in addition to thermal protection issues. Software that visually displays heat flow helps identify profile vulnerabilities and optimize energy efficiency.
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