What RnD in aluminium window industry dream about

By Bogdan Grebenyuk, Product Manager at Thermevo
on May 28, 2018
Years back, I, probably just like you, dreamt of various things, including heaps of Lego blocks for construction, but would have never thought that years later, now, I would be constantly thinking about building materials, moreover – polyamide thermal break profiles and windows overall.
The sheer amount of information that was needed to understand at least a bit of what has been given to me always clouded my strife for knowledge so I decided to share some specifics for those of you, who are starting to embark on this journey just now, and to remind the autochthons of the core.

Three U Clarification

Visually all windows look similar and if we want to identify the quality of a window, we must look up their technical parameters.

The overall window system warmth conductivity coefficient is marked with Uw. A good warm window will have a ratio between 0,8 – 1,3 W/m2 K. For comparison – old wooden window warmth conductivity coefficient is 3 – 4,8 W/m2 K. The lower the Uw, the lower the conductivity, which means we'll lose less warmth from our household.

Noteworthy profile and window manufacturers are not afraid to show this and other U warmth conductivity rates, and technical window specifications in their declaration of product quality.

The profile warmth conductivity coefficient is marked with Uf. The same rules apply – lower ratio means warmer profile. Using polyamide thermal breaks helps lower the Uf significantly.

The third U ratio – glazing warmth conductivity coefficient Ug. Present warm glazing Ug equals from 0,7 to 1,8 W/m2 K.

The offers of Present

Present warm windows are far more advanced than their primitive ancestors were. It's as if I would compare a mobile phone with a landline phone. If you're buying one, you're not looking at a model made back in 1995 and while choosing a window, our head banging criteria is warmth. Windows were warm 20 years ago, but they were different from the present windows just as a landline phone is different from a smart mobile phone.

In my opinion, windows that have been changed 10-15 years ago should be swapped and changed, because the warmth control and functionality have improved tremendously. There were, as there are now, one day "garage" window manufacturers and resellers that would vanish without care and leave the customers without guarantees and/or service.

At first glance, windows look like very simple products, but in reality it is a very complex and important equipment, because thanks to their efforts, natural light enters buildings, they expand the space, create comfort and the feeling of safety. The investment in windows is long-term, so it makes sense to ensure that they are reliable. The glass surface must be treated with heat reflecting selective coating, but quite often the case is that the declared parameters defer from the truth: better selective coating properties, than in reality, are specified and it is very difficult to prove otherwise and is only possible in laboratory conditions after the dismantling of the glass envelope.

The window profile frame can be manufactured from inappropriate raw material, insufficient quantity of chambers and irregular metal structures inside the window profile (which is something that is impossible to check directly, without destroying the window). Improperly manufactured windows or doors can bend, change color, become leaky, hard to clean, dust adheres, emit a bad smell, poorly close or open. Window insulation can be impaired by improperly aggregated intermediate and window fittings. A disorderly sealed perimeter of the window frame during installation adds to the significant deterioration in sound and heat insulation.

Non visible parts in an already constructed and installed window are no less important. They perform window opening, stability, integrity and security functions. Аluminium in construction is one of the most perfect building materials, but it conducts energy.

In order to improve the Uf value of the aluminium, thermal breaks have to be used. That brings us energy efficient aluminium windows, doors, facades and etc.

Nowadays the primary material used for polyamide insulation bars is Polyamide 6.6, which improves Uf value significantly and can be painted, however polyamide is not perfect in terms of thermal efficiency.

What future can bring us

What can happen in the future – what could be the materials we will use in 10, 20, 30 years? There have been many innovative ideas in the window market, like the new type of smart glass that selectively blocks light and heat under the control of an electrical switch, created by scientists at the Lawrence Berkeley National Laboratory, back in 2013.

Recent developments in the plastic industry brought the manufacturers to the point when polyamide insulating strips (lambda value 0.3) might be replaced by the new composite plastics with lambda 0.2, but what if we imagine there are no limits, if nano-technology and the future brings us something with lambda less than 0.1 or even 0.05?

We can play around with FLIXO Cloud (the first online thermal conductivity analysis & optimization tool) to get a set of results.


This is something that comes up if we dream a bit.

The materials we will use:

  • Instead of a standard polyamide – we will use AeroPA 0,01 W/m2 K;
  • Instead of polyurethane, let's try Aerogel 0,017 W/m2 K;
  • And assume that all gaskets are made of EPDM foam;

While using the 72mm system, we obtain the value of Uf equal to 0.957 W/m2 K and that is a very good indicator considering the depth of the profile system.

Systems with 34mm thermal break are middle class – they pass heat engineering and we can insert a 32 - 46mm glazing, which is important for sound insulation and the heat engineering of the central Ug zone.
THERMEVO FLIXO Cloud can be your "to win" ally in R&D

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