The regulation is UNI EN 410.


The radioactive glass property has three values: solar factor, light transmission factor and light reflection.

Solar factor.
The raise of sunlight that hits a glass created heat exchange. The solar factor is the relationship between total energy and incident energy that is linked to glass’s thickness and characteristics.

The energy that is absorbed by glass, is immersed inside house partially, as a result of temperature increase that suffers glass and the other part is emitted in rooms, that is a total energy equal to the result energy that passes and energy immersed inside.

The parameter that measures this behavior, very important for estimating glass performance under thermal phenomena the SOLAR FACTOR that is a relation between total energy and incidental energy and it depends on glass thickness and characteristics.

Glasses with a high solar factor allow to have a high heat contribution.
In that areas characterized by high solar exposition, it is recommended to install glass with low solar factor, in order to maintain superheating in rooms. In this case it is recommended to install special glasses.

Light transmission.
The light transmission factor expresses the external light quantity that enters inside through glass.

If this percentage is high glasses are lighter and then rooms too.

light reflection
Light reflection is the light percentage reflected by glass.

Thermal transmittance is indicated by Ug expressed in W/m2K (Watt for m2 for Kelvin degree). The thermal transmittance expresses the thermal dispersion level. More low is the value Ug, more is the insulation glass power. A simple glass has a Ug coefficient equal to 5,8 compared to 2,8 of a traditional glass. An insulation glass, for example, can present a Ug coefficient of only 1,1.