ALUMINIUM WINDOWS: ADVANTAGES AND DISADVANTAGES
Some time ago, in my article “Standards for choosing the right window” – click here to read it, I examined the criteria for choosing the windows best suited to your needs. Now I would like to deepen the characteristics of the various windows with which they can be made. In particular, in this focus I will talk about aluminum frames, their advantages and disadvantages.
But first let’s see what aluminum is and what its characteristics are.
It is one of the most common elements in nature. Bauxite is the mineral from which it is obtained, and is the third most abundant element on the Earth’s surface, after oxygen and silicon.
Aluminium can be 100% recycled with limited energy consumption and without ever losing its original features. It is not harmful to the environment and, even in the event of fire, it does not release any harmful substances.
It is a light material (it weighs about 1/3 of copper and steel), but at the same time robust and resistant to atmospheric agents: it oxidizes immediately in contact with air, creating a surface protection that makes it resistant to water and certain chemicals.
It is malleable with both low and high temperature processes. Most of the aluminium profiles for window frames are extruded and, in the cross-section, it can take on very varied and precise dimensional shapes. The extrusion allows the realization of sections also very complex and including ribs that make the profiles more resistant to bending and torsion, allowing the realization of large-scale doors and windows without compromising their safety and functionality.
It can be extruded into various geometries and lends itself well to any aesthetic need: it can be anodized, oxidized and painted with both powder and sublimation. In addition to a wide range of colours, it is possible to realize various finishes such as wood effect, which recreates an aesthetic rendering very similar to that of wood.
Aluminium also has high electrical, thermal and sound conductivity. This is obviously a peculiarity against the realization of windows, while it makes it the ideal material for the construction of radiators, heating equipment, food containers and some musical instruments.
That said, considering their characteristics of eco-sustainability, lightness, robustness, durability, ductility and economy, aluminum doors and windows are an advantageous choice in contemporary construction.
It is appropriate, however, to properly correct the high conductivity property described above that could make the fixtures less performing from the point of view of thermal and acoustic insulation.
Therefore, to overcome this inconvenience and ensure good insulation performance aluminum windows are produced with the technique of “thermal cut” which consists in the insertion of plastic materials laths with low thermal conductivity, inside the air chambers of the profiles, interrupting the continuity of the metal and limiting the thermal dispersions of the window.
Exploiting, therefore, the principle of thermal break aluminum windows thermal break ensure good insulation, both thermal and acoustic, and allow considerable energy savings, even more if you use glass with the right characteristics.
The most suitable ones are the chamber glasses, simple or, even better, double, with low emissivity glasses (that do not disperse the heat), with “warm edge” (that allows to minimize the risk of condensation on the perimeter of the glass), with Argon or Kripton gas (the air between the glass plates is replaced with a noble gas which results in a lower heat exchange coefficient).
In addition, in the joints between mobile and fixed frames, to increase the water tightness, it is important to use the gasket extruded neoprene or EPDM, a material with extraordinary mechanical properties. It is characterized for the instant return to the original form and for the excellent permanent elasticity, even in the face of prolonged periods of pressure (for example in the case of windows that remain closed for a long time). The EPDM gaskets ensure, then, greater resistance to aging, atmospheric agents and temperature variations.
As already mentioned, thanks to the behavior of oxidized aluminum, aluminum windows are generally very durable. It should be noted, however, that they are not free from the risk of corrosion in an acidic environment, for example in marine environments or in urban areas which are highly polluted, there may be corrosions which, in the long term, would reduce the useful life which would otherwise exceed 40-50 years. In these cases, it is better to prefer painting with special treatments or anodized finishes.