One of double glazing’s many benefits is its ability to insulate the home from a variety of factors, including cold, heat, intruders and sound. The two panes of glass, plus the thermally insulating gas, provide exceptional thermal performance across the home, increasing the home’s energy efficiency and reducing carbon output and heating costs.
The acoustic performance of the home also drastically improves, keeping external noise out and ensuring that any noise generated by your own household does not travel outside. This will help you avoid conflict with neighbours over potential noise nuisance.
The question often comes up of just how effective double glazing actually is at dissipating sound waves and reducing noise. Double glazing installers will almost always focus on the U-values (the measure for thermal efficiency) to demonstrate the performance levels of their particular installations rather than providing a metric for comparison on noise reduction. Noise is measured in decibels (dB), and we rarely see these as strongly advertised as we do the U-value.
So, just how good are double glazed windows at reducing a variety of noise disturbances, including traffic noise, from the outside world? Here at Double Glazing on the Web, we’ll help you find out.
How do double glazed windows work?
Before we get into measurements and comparisons, it is probably a good idea to establish just how double glazed windows are able to perform the job of insulating a property against external factors.
Double glazed windows feature two panes of glass – the external pane and internal pane – either side of an air pocket. This air pocket is more accurately described as a vacuum that is filled with a thermally insulating gas, typically argon. The gas provides the window with its thermally insulating capabilities, as the gas does not conduct the heat well.
In terms of how the window performs with acoustic performance and noise reduction, the three key elements that make a difference are the glass, the size of the gap and the quality of the frame.
- The glass itself helps with stopping noise passing through because the dense material absorbs sound vibrations in the air. Use of specialised acoustic glass that is often thicker glass, and has been laminated to enhance acoustic insulation, will prevent unwanted sound entering the home.
- Similarly, the gap between the two panes forces the vibrations in the air to pass through a significant space. The larger the gap, the greater the noise reduction.
- Finally, the quality of the frame will bring the window’s performance together. You could have the largest gap possible with good quality glass, but if they’re not fitted properly in the right frame, you’re going to struggle to get the performance that the individual elements suggest.
How to measure noise reduction
Sound, as mentioned, is measured in decibels. The higher the dB value, the louder the noise and the more noticeable it is. The decibel level is actually measuring the force of the sound, in other words, how violently it is vibrating the air around the measuring instrument. The higher the force of the sound, the more vibrations there are and the louder it is.
- Humans can hear sounds between 0 and 140 decibels (dB), although it would be difficult to measure the difference between one or two-decibel measurements without keen training.
- Anything under 30 dB is considered to be extremely quiet. Breathing, for example, is considered to be around 10dB.
- We tend to speak (with our indoor voices) at around 60dB.
- Helicopters and police siren noise is around 100 dB to 110 dB.
- Fireworks and jet engines noise is well over 120-130 dB.
- Any noise level higher than 130dB is considered a risk to our ears.
In windows, we measure sound reduction with the RW rating, referring to the weighted sound reduction index. When purchasing new windows, you can ask to see the Rw rating, which measures the level of sound insulation in the product – the higher the rating, the better the sound insulation.
As sound travels through a double glazing installation, the glass and insulating gas dampen the vibrations and reduce the transmission of the sound. Double glazing reduces sound by around 20-65%, depending on the quality.
This translates to around 35 decibels reduction, which is quite significant and would mean a 65dB noise would be reduced to around 30dB. By way of an example, a conversation going on immediately outside the window would be reduced to barely a whisper, and if that outside noise was generated further away and had to travel some distance, it may end up being inaudible in the home.
Properly installed double glazing with good frames and a quality build can bring this value even higher, up to around 40 dB, but you would struggle to get much higher than that with double glazing.
What about triple glazing?
For those reading this article and thinking that’s just not enough for me, you may want to consider triple glazing as your soundproof windows option. Standard triple glazing works on the same basis as double glazing, except you have three glass panes and two air pockets instead of two and one, respectively.
With the extra layers of protection, you’re looking at even further noise reduction. Companies selling triple glazed windows are claiming levels as high as 54 dB, which would turn a conversation just outside the window quieter than someone breathing in the same room.
Some people argue that while triple glazing is great for insulation purposes, it isn’t necessarily the best option for noise reduction. This is because having two air gaps can create resonance and echo chambers, meaning that the original noise complaint is actually worse
Unfortunately, triple glazing does come with high costs, and it is yet to become the norm over double glazing. Still, it may be something worth considering for the future, even if it is out of your budget currently.
Is secondary glazing good for reducing noise?
In some circumstances, new double glazing may not be an option or it may not be your preferred option, in which case adding secondary glazing could be a viable solution. This involves the installation of a single glazed window panel behind the existing window – the wider space between the glazing panels meaning it can actually be more effective for noise reduction than double glazing itself
Secondary glazing offers good soundproofing benefits, and can reduce noise by up to 80%, especially when installed around 15mm-200m from the primary window. This type of window installation can be a good option for those that live in period properties where listed building regulations prevent the existing window frames being replaced or upgraded.
Double Glazing Noise Reduction Summary
Double glazing reduces noise pollution significantly in the home. A 35dB reduction in noise is significant and will greatly increase the tranquillity of your living spaces. Triple glazing or use of specialised acoustic glazing is sometimes the next step up for those looking for that little bit extra when it comes to eliminating unwanted noise. However, this comes with an increase in cost compared to standard double glazing.
Here at Double Glazing on the Web, we share our expertise with the public to help them feel confident when it comes to dealing with installers and have full understanding of what they are purchasing for their home and whether it is right for them
If you want to reliably reduce noise in your home, please use our quick and easy online pricing tool to get an accurate price from across the industry. We do all of the work for you and provide you with the absolute best prices and service so you can make an informed decision about your next glazing project. You can also contact us through our online contact form if you have any specific questions about noise reducing glazing.
