4.1 Sound reduction
For noise reduction there is a need for a different approach to the construction of triple glazing.
The thickness of the glass used is one of the key elements of the sound insulation. Each thickness of glass will block a different frequency, so a combination of panes of different thickness is very effective at keeping noise out. This is known as asymmetrical glazing. It should be mentioned that even the weight of the glass plays a part since the compact mass reduces sounds.
The second key element is the size of the gap between the panes. The larger the gap, the better the overall sound insulation effect. So by having a second gap, triple glazing has a clear advantage over double glazing.
The third element is the use of an acoustical resistant gas, such as sulphur hexafluoride to augment or replace the inert gas fill. This effectively reflects noise away.
If triple glazing is being considered solely for sound insulation then it would be worth considering secondary double glazing instead. This is because it will have a much greater air gap than can be achieved in triple glazing, and can achieve great noise reduction at considerably less cost.
4.2 How to improve the sound reduction
There are lots of ways to improve the existing sound reduction and noise canceling that windows provide. One simple and rather normal way is to apply draught excluder to the windows, this should be placed between the window frame and casement. It is also important to make sure that the gap between the window and the wall has been sealed properly. To reach the best possible sound reduction two layers of draught excluders can be applied.
A problem can arise with a window which is in good condition but still has bad sound reduction. It could be a good idea to add another layer of glass to the window, this would improve the sound reduction immensely. This is of course depending on the type of window that has already been fitted. If this alternative is possible then make sure to install a sheet of glass that varies in thickness from the other layers of glass. This will not only reduce noise but improve the windows U-Value as well. (See paragraph 3.2.4)
When purchasing new windows to reduce noise its advisable to make sure that the windows fit into the facade so the aesthetic beauty will be preserved. Be certain to observe local and countrywide rules and regulations regarding changes to buildings as some areas will not allow changes that effects the character of the building.
To sum up, there are a few simple criteria a sound proof window should meet.
- The window should be air tight
- The window should be fitted and sealed properly against the surrounding wall
- Avoid installing air ventilators in the frame
- Maximize the gap between the layers of glass (at least 30 mm in total)
- Alternate the thickness on the different layers of glass
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