What to look out for? What is the right product for you? Answers in the topic below.
Aluminium, a fully recyclable product, belongs to the light metals and is suitable for the construction of small or large frames with a long service life and without the need for special maintenance.
Aluminium doors, windows, glazing and shading systems incorporate state-of-the-art technology, offering high thermal insulation, excellent safety levels, high aesthetics, sound insulation, functionality and minimal maintenance requirements.
The advantages of thermally insulated – thermally broken frames
Modern thermally broken aluminium frames have high standards and several advantages. They cover a multitude of design requirements for small or large building openings in various shapes, giving flexibility to engineers and architects, due to the robustness of the aluminium profiles from which they are made and the possibility of many reliable colour options, even two-tone (exterior-interior).
Aluminium is an environmentally friendly material, an ecological product, which, as already mentioned, even in case of fire, does not emit dangerous gases. This makes it non-combustible for fire resistance regulations and is another important reason why aluminium frames are first in consumer preference.
In recent years, the development of aluminium architectural profiles has been significant in terms of improving their thermal insulation properties.
By the term thermal break in frames, we mean the interruption of the thermal bridge (heat transfer), which is achieved by separating the profile into two parts and joining them through the use of insulating materials that isolate the inner and outer surfaces.
This allows a significant reduction in the transfer of heat (or cooling) from the inside to the outside environment (or vice versa).
How the thermal break works
The role of the thermal break is played by polyamide 6.6, which is a thermoplastic material, extremely “noble” and relatively high cost, which for this specific use is also reinforced with glass fibres, at a rate of about 25%.
The glass fibres are essentially the armour of the blade (barrette). In this way the mechanical properties of the polyamide, which has low thermal conductivity, are enhanced. With polyamide, cross-sections of reduced thickness can be made without this being at the expense of the stability of the final structure.
Increasing the width of the profile by simultaneously increasing the width of the polyamide used as a thermal barrier material significantly reduces the heat transfer from the mass of the material.
The thermal transmittance coefficients of profiles now range from approximately 1.6 to 3.0 W/m2K. This is further enhanced by the addition of a foam insulating material in the space between the polyamides.
In this way, thermal transmittance coefficients of the profiles of about 1-1,8 W/m2K are achieved, and thermal transmittance coefficients of less than unity have also been reported.
One of the most important advantages of the thermal break is the reduction of condensation of water vapour on the surface of the frame and other adjacent smooth, (non-porous), surfaces inside the room. Increasing the width of the profile enables the use of thicker glass panes (double or triple), contributing positively to the thermal and sound insulation offered by the frame.
In addition, the use of rubber gaskets with as large a contact surface as possible with the aluminium improves not only thermal insulation, but also airtightness and waterproofing.
Modern frames in practice
If we take as an example a house which has 4 balcony doors measuring 1.20×2.20 with a construction year of 1980. Replacing these with new aluminium ones with thermal break can bring about the following results:
Energy savings of about 30%/year (~1900kWh)
Savings of approximately €600/year from cooling and heating costs.
Reduction in CO2 emissions of about 1570 Kg/year
The overall energy saving performance of a frame does not depend solely on the Uw factor, but also on other properties such as air permeability.
An example in order to understand this better. If a frame has a very good coefficient of thermal conductivity, (a low value of 1.8), but does not have a good value of air permeability (a value of 1), then we lose a lot of energy due to convection from the air, (the frame gets stuck), even though the energy loss due to heat flow in the frame is low.
The overall result, however, is not good.
This is why simply replacing crystals in old frames is most of the time not effective in terms of the overall effect.
Source : Article by Mr. Theophilos Pagiatis, President of the Panhellenic Federation of Aluminosilicon Craftsmen.