The thermal insulation of the windows is one of the fundamental elements to obtain high standards of comfort and to contribute to the energy efficiency of the buildings.
Thermal transmission of windows (Uw) = Frame (Uf) thermal profiles transmission + Glass thermal transmission (Ug) + Insulating double glass spacer
In order to obtain energy-efficient windows, it is essential that they have the lowest thermal transfer value (Uw value), which results from the combination of low thermal value (Uf) frames with a low heat transfer value of the glass (Ug ).
As regards PVC frame systems, these are the ones with the lowest thermal transmission values, well above the "thermal bridge rupture" aluminum systems. PVC profiles for framework do not require "thermal bridge break" because as the thermal conductivity of PVC is quite low (0'16 W / m • K), it corresponds to a value that is a thousand times smaller than that of aluminium.