Current situation windows.

We have already mentioned the problem with frames and their heat loss, especially if they are made of glass parts. Over the years we had a great evolution in this areaand now we have many products on the market whit different types of material, profile and so on. Especially the introduction of dual-chamber (thus having triple glazing) made possible the improving of thermal performance. This has also been imposed by the Italian Law Decree 311/2006, which imposed limits on the value of U transmittance (parameter that determines the heat transfer of a body) depending on the italian climate zone.

Zona climatica	Valore di U [W/m2]
A	3.7
B	2.7
C	2.1
D	1.9
E	1.7
F	1.3

 Image www.linfissosas.it



Why do we have to introduce innovative technologies?

The answer lies in the behavior of the glass against the wavelengths of radiation. Solar energy can be transmitted into a room, and consequently absorbed by the objects and the walls. They emit a thermal radiation with a wavelength greater than 5 microns (then in the far infrared) where the glass is virtually opaque, and so the transmission is blocked. So the solar power provided tends to worsen the ambient quality (the greenhouse effect is accented in the summer) and requires the use of air conditioning to balance.


The perfect glass will be the on that allow light radiation transmittance and blocks infrared radiation, especially when the temperature rises. The problem isn't evident for traditional residential buildings in cold or mild climates, but manifest itself in recent buildings with large windows, or subjects in warmer climates.

Hence the idea of testing chromogenic glazing, including my favorite glasses: thermotropic and thermochromic ones.

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 www.saint-gobain-glass.com