To avoid heat transfer windows, it uses what is called a thermal break.
Is to prevent the inner and outer face to touch each other, sandwiching a poor conductor, so heat losses are reduced.
In the case of aluminum windows usually used a spacer profile polyamide (plastic) embedded in the aluminum itself forming the window.
The most widely used for aluminum windows rod system are polyamide 66 reinforced with 25 % glass fiber. This is one of the few thermoplastics authorized by European standards UNE -EN 14024.
Polyamide size will vary depending on the type of carpentry and the geographic area you have to install the window.
The larger polyamide thermal behavior will get better.
The advantages of using frames with thermal break are:
The energy savings. The legislation is becoming more stringent on energy efficiency in buildings .
This type of joinery promotes condensation prevention profiles both as crystals. In cold weather when the outdoor temperature is very low and inside there is high relative humidity, the phenomenon of condensation on the inside profiles is given. This is because the temperature of the inner profile is below the dew point. With thermal break is achieved by raising the surface temperature of the inner profile, thereby reducing the possibility of condensation on the window frame and the appearance of dew.
Compliance with the Technical Building Code (in Spain) mandates that are aluminum frames with thermal break 80 % of the Spanish geography.