Doors & windows are available in all kinds of material e.g. wood, aluminium, uPVC, GRP & Steel. The choice of material has repercussions on the structure and the design of door/window. Locally extruded aluminium sections are in use since more than three decades.
|Local extruded non thermal openable aluminium window
|Non thermal sliding aluminium window
Thermally break aluminium consists of inner and outer shell that are crimped by heat-insulating plastic profiles ( i.e. polyamide strip).
|Thermal Break Aluminium Sliding Door
Thermal insulation of a thermally broken aluminium Door/window is far better than non thermal aluminium Door/window. U-value of of non thermal aluminium Door/window frame is approx. 6.1 W/m2K. But in thermal break aluminium Door/window frame it is approximate 2 W/m2 K.
Does it matter ?
If we are using Double Glazed Glass , the performance of Door/window will be approx. 30 ~45% less in non thermal aluminium Door/window.
Let us check an example of a openable Door of size in width 3 ft ( 915 mm) & height 8 ft ( 2440 mm). Let us compare it with 3 kind of material- Non thermal aluminium Door, Thermal break aluminium Door & uPVC Door made up using Class "A" uPVC profile ( as per EN 12608).
Glass specification are as following 24 mm Double glazed glass - 6 mm toughened clear glass + 12 mm air ( or, argon filled gap) + 6 mm toughened clear glass- U value of glass is 2.8 W/m2 K.
U value of window (Uw) is combination of U value of glass (Ug) & U value of frame (Uf)
|Uw Value with local extruded non thermal aluminium openable Door
|Uw value with Thermal break Openable Door
|Uw value with uPVC Openable Door
The U-value of non thermal locally extruded aluminium openable Door is approx. 55% more than Thermal break aluminium Door as well as uPVC openable Door. That means energy efficiency during winter as well as in summer ( Thermal break creates heat break) will be extremely POOR in non thermal aluminium system.