We hear things because of the amazing properties of sound. But when that sound becomes a disturbance to the ear, it turns into unwanted noise. So how do we counter the noise that comes from external factors?
One solution lies in double or triple glazing the glass panes of the house.
So which is the best option? Is triple glazing more soundproof?
Triple glazing does not necessarily make the house more soundproof.
Not much difference is noted between double glazing and triple glazing the window when it comes to the reduction of noise. This is because sound travels in a wave pattern.
In the scientific world, it is called wave propagation. This simply means that the sound wave expands outward as it travels. Much like a ripple of water in a lake when you throw a big rock in the water.
The gapping or space in between the glass panes that make a considerable difference in the reduction of noise. Some double pane windows have specialized tape and window film that produces a better soundproofing quality than other triple pane varieties.
It really all depends on each individual item used to construct the window.
The level of outside noise also matters in determining the soundproof-ness of the double or triple glazing.
A high pitch noise from a tower transmitter will respond differently than a low pitch noise like a deep car muffler sound.
Therefore, it all depends on a person’s hearing ability and differs in what you consider annoyance.
So, what is glazing?
Glazing is basically the laminating of two or more glass panes with an adhesive material. In the process of making a room or house soundproof, the step of glazing the windows is quite a necessary procedure.
Think of it as laying clothes on your body during the winter. Increasing
layers means more heat is retained in the body and cold air from the outside environment is kept out. The same thing applies here.
Layers of window panes keep silence insulated inside the
house and noise from the environment stays outside. The laminating of the glass is done with a thin layer of plastic covering over the glass panes. The
glass panes are then bonded together using clear adhesive resin such as polyvinyl butyral or PVB.
The bonded glass thus gives the appearance of a single pane glass, which is also known as acoustic glass.
Benefits of glazing the glass panes
- Stronger Glass – The glazing if the glass helps in making it stronger due to the addition of the PVB resin. Therefore, it definitely offers better security.
- Noise minimization – The glazing of the glass aids in the reduction of noise pollution. If one resides in the cities with many elements that create noise, having the glass double or triple glazed will work wonders in the minimization of the outside noise.
- Insulation – As the glass is either double or triple-paned, it helps in the trapping of sunlight which in turn helps in the better insulation of the house/room. For homes in the colder regions having the glass double or triple glazed will help in keeping the warmth longer.
- Less fuel consumption – Owing to the excellent insulation provided due to the double or triple glazing, the prospect of consuming less fuel comes in. That is because it aids in the better insulation of the home. It also helps in the cutting down of the electricity bill, which is definitely a bonus.
- Ecologically friendly – As more sunlight and warmth is trapped inside the home, less is the fuel consumption. It results in the judicious use of the fuel, which makes it eco-friendly and aids in leaving behind less carbon footprint.
The concept of sound
Sound, what is it and how does it travel? Sound is, in essence, just a vibration that travels in the form of waves.
Sound is what we hear when the waves pass through a medium (air) and are received by our ears. In the view of physics, the sound is the vibration that reproduces as a wave of pressure.
Have you ever noticed that you can feel a deep bass thumping? That is the physical characteristic of the pressure waves.
Sound essentially travels from one medium to another in the form of waves. The medium the sound is propagating or traveling through may be of any form, i.e., solid, liquid or gas.
Examples of this are the sounds you hear when underwater. Sound can propagate through almost any medium but it becomes less audible when the medium is made of dense or thick material.
For instance, you can clearly hear the person sitting next to you in your car when they are talking to you.
But if they get out of the car and walk around to your side but your window is rolled up, you can still hear them but not as clearly.
The human ear can hear sound between the range of 20-2000 Hertz (Hz.) So, the sound becomes noise or painful to the ear when the frequency reaches 2000-5000 Hz. At this higher range, you will find motorcycles and large construction equipment machines.
How glazing works in noise reduction
So now that we have a gist of what glazing and sound are let’s discuss how glazing works in the minimization of sound, i.e., noise.
The soundproof glazing works due to two main reasons.
- The deflection of the soundwaves
- The dissipation of the soundwaves.
Glass is a hard, non-porous, and reflective material. The molecules in the glass are tightly packed as it is solid.
The lamination of the glass for glazing makes the soundwaves harder to penetratethrough the glass. Thus, about 90-95% of the soundwaves gets deflected when glass and laminate are combined.
Dissipation means the process of transforming the initial form of energy (sound) to another that is irrecoverable.
In the contact of the soundwaves with the glazed glass, the soundwaves are
dissipating (think dissolved) into a form of energy which gets trapped within the glass molecules and diminishes further.
With this property of glazed glass in mind, three factors need to be taken into account to make the soundproofing of the windows into superior quality.
The thickness or density of the glass
The process of glazing soundproof windows includes the thickness or density of the glass as a high determinant factor.
The variation in thickness of the glass layers helps in reducing the amount of sound penetration.
The thicker or more dense the glass, the lesser is the amount of sound penetrated. However, on the opposite side, glass also has a property of amplifying the sound at a certain pitch. This is known as the coincidence frequency of the glass.
In order to address this issue, double or triple glazing is often recommended.
The glass of varying densities or thickness is installed to counterbalance or neutralize the coincidence frequency of the glasses. The thickness of the glass can vary from 4mm – 6mm.
The spacing between the glass
Spacing or the gapping between the glass layers also works successfully in managing the penetration of sound in the double or triple glazing. A minimum of about 10mm- 30mm gapping between each glass panes will help in blocking the sound.
As we mentioned earlier, one form of medium sound passes through is gas. Air is a gas and therefore has an effect on the sound as it attempts to propagate through it. Multiple air layers will dampen the resulting sound.
In the spacings of the glass panes, gases are added to act as a buffer and to absorb the vibrations. Gases such as argon and krypton are added to block the noise. Of the two, argon is preferable as it is easily available.
The interlayer material
The process of glazing involves the laminating of the glass panes with thin material. This is done so as to make the glass stronger and work in the blocking and reduction of soundwaves.
The thin layer that is interlayer is usually polyvinyl butyral or PVB. It is a resin that works as an adhesive to join the glass panes as well as make the glass tougher and offer better security.
The addition of the PVB also does not interfere with the amount of light that passes through unlike the other resins. The thickness of the PVB interlayer is as thin as about 0.38mm.
The three factors mentioned are important in making the home soundproof.
A comparison between double and triple glazing
The name itself suggests what double glazing is. It is basically the use of two panes of glass instead of just the single one.
In double glazing, the two glass panes of the same or different
thickness are placed together with a gap of air space.
In triple glazing, three glass panes are used with air space in between the three panes. In between the panes, gases such as argon are filled to enhance their various properties.
Between the two types of glazing, there are just some few variations:
The number of glass panes – The double glazing has two glass panes, and the triple glazing has three, pretty straight forward.
- Insulation level – Though both the types offer good insulation, the triple glazing with the additional glass pane obviously adheres to trapping more sound than the other. Thus, the triple glazing is better in retaining sound and offers better insulation.
- Noise penetration – The amount of noise that penetrates through the glazed windows definitely varies. This variation depends on the placing and the spacing of the glass panes in the frame. So, the idea that triple glazing offers better noise pollution control than double does not hold true. The validation of this lies with the combination of the other factors as well, such as the thickness and the spacing.
- Costs – It is evident that the triple glazing will definitely cost more than the double glazing for sure. Also, the spacing is more in the triple glazing. Therefore, more amount of the inert gas must be added, which adds to the cost of making the glass triple glazed. The question that remains is, how much are you ready to shell out or invest in making the home double or triple glazed and if it is going to be cost-effective .
- Thickness – The triple glazing is wider in thickness as compared to the double glazing because of the additional glass pane. Inclusive of the thickness is also the overall weight of the glass. If you are renovating an old home and are planning to build in triple glazing, then the issue of supporting the weight of the glass along with the frame arises.
After having a thorough idea of what double and triple glazing is and the various aspects of it, it should be clear that both types have their own positives and negatives.
So, the question of whether triple glazing is more soundproof or not is quite elusive. This is because it varies from one person to another on how well they hear sounds and how the glass panes are constructed and placed.
Maybe it’s just an assumption that triple glazing is better in soundproofing because more layers are used in the construction?
Various research has shown that in window soundproofing, there is not much difference between the double and the triple glazing.
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Xin, F. X., & Lu, T. J. (2011). Analytical modeling of sound transmission through clamped triple-panel partition separated by enclosed air cavities. European Journal of Mechanics-A/Solids, 30(6), 770-782.