Friday, 8 March 2019

What is Thermal Break Aluminium ?

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 Casement window 

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)

Casement Door

Uw Value with local extruded non thermal aluminium openable Door

Uw value with Thermal break Openable Door

Uw value with uPVC Openable Door

Uw 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.