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.

Wednesday, 6 March 2019

How to sound proof windows in India ?

By soundproof windows, i mean unwanted sound proof or, better word to use is NOISE-PROOF. Now check following info to understand NOISE ??




To make a room noise- proof , we need to bring outside unwanted sound level ( i.e. noise) under 50 dB. To start with, We need to understand few basics…





Most of the time the problem is traffic noise which is low & medium frequencies.

Sound is measured on logarithmic scale, not on arithmetic scale.

In Sound 60 * 2 is not equal to 120 as sound is measured on logarithmic scale not arithmetic scale. Few more examples for clarification


For our ear, difference of
  • 1 dB is virtually inaudible.
  • 3 dB is barely audible.
  • 5 dB is clearly audible.
  • 10 dB is equivalent to a 50% reduction in the perception of the sound intensity.
  • 20 dB is equivalent to a 75% reduction in the perception of the the sound intensity.
This difference of 20 dB or, 75% reduction is generally possible. I can say that it is better results of using noise proof windows.

I presume that i have covered WHAT part of the problem, now try to cover HOW it is possible part of the question.

There are two ways by which we experience noise, one is air-borne noise, other is structure-borne noise.




By Door/window, we can control air-borne noise, not the structure- borne noise. There are two aspects of noise reduction via Door/window.

Frame/sash material specification - All Door/window should be air tight. Let us define air tightness as following
  • If you are choosing aluminium as an material in sash/frame then go with thermal break aluminium with multi point locking. In India, all thermal break aluminium door & window systems are imported from europe & you can find their acoustic performance or, noise insulation in their performance table as mentioned following -

You can see acoustic performance 35~39 dB in above performance table.
Pl note that non-thermal break system in aluminium are not as good as thermal break system. Even most of the products from renowned brand like alumil, schüco, reynaers, technal & other european make are not tested for acoustic performance or, noise insulation in non thermal version. Main reason for low product quality is due to price pressure of Project market. Also locking in most of the opneable & sliding windows are single point lock which again ensures poor noise insulation.
  • If you are choosing uPVC Door/window as a material, go with Class A according to EN 12608/ or, GB/T 8814 ( wall thickness min. 2.8 mm) uPVC profile which gives approx. 42 dB noise reduction; These figures are for frame/sash irrelevant of glass      ( Few European names to choose Aluplast, VEKA, Koemmerling, Rehau, Deceuninck, Salamander) . To know more about material specification read following link How to buy uPVC Door/Window in India ?



Don’t forget multi point locking in all uPVC Door/window which will ensure sash/frame alignment & avoid any kind of air leakage.
  • If you are choosing Wooden Door/window as a material, go with brand which share performance table mentioned acoustic performance or, noise insulation.
Also worth to mention never go with sliding for noise insulation as conventional sliding door/window can NEVER be noise proof. ( It has less air tightness than as compare to casement system)



Gaskets make Casement or, openable superior product than Sliding for noise insulation.
Glass performance specification- There are few insights which i would like to share with you
  • 12 mm glass has a better noise insulation rather than 24 mm ( 6 mm clear glass + 12 mm argon filled /or, air gap + 6 mm clear glass).
  • Dissymmetrical Double glazed unit e.g. 23 mm ( 6mm clear glass+ 12mm argon filled/ or, air gap + 5 mm clear glass) has better noise insulation then symmetrical 24mm Double Glazed Unit.
  • Acoustic PVB has better noise insulation rather than Normal PVB laminated glass only for high pitch sound. For traffic noises or, low pitch sound, both behave equally same.


Glass specifications are based noise insulation or, Acoustic comfort required as well as on selected uPVC/or, Aluminium/ or, wooden system's allowable glass thickness, weight capacity of available hardware.



Bottomline -The factors that affect the level of unwanted sound insulation provided by noise proof windows
  • Air tightness of Door/window
  • Aluminium/uPVC/Wood windows material specification
  • In-situ sound performance also varies due to acoustic condition of environment ( type of sound source, location in relation to said source, etc. )
If you want to know more about noise insulation, Pl check following articles written by me   ( I have written these articles almost 4 years back just to share my knowledge & on-site experiences without promoting any brand on this blog -Doorwindow Basics. This blog is created to help people understand Door/window system & choose according to performance & functionality required, not on the basis of attractive advertisements claiming no.1 company in India )
Given the complex nature of sound proof windows, assistance from industry experts or, speciality consultancy or indeed test on site to be used may prove useful.

P.S. To reduce structure borne noise, noise barriers must be installed. Pl check following link to read more Barriers to filter out train noise near Jamia University - Times of India



Do you want any help for unwanted sound proofing. You can write to me on shivendrasinghk@gmail.comI can share my knowledge, experience for noise insulation.