By Pedro Novo
31 July 2017
Peabody's St. John's Hill residential development is located next to the train line passing through Clapham Junction - Europe's busiest station in terms of rail traffic.
The flats overlooking the railway are consequently exposed to significant levels of environmental noise.
Our aim was to develop a passive ventilation strategy for the flats to allow residents to control summertime overheating without being exposed to unacceptable levels of noise break-in.
The client was presented with various design options for the ventilator. To help evaluate the internal noise levels associated with each option an audio recording of a passing train was processed to simulate the acoustic performance of each ventilator. Considerations of space, architectural impact, as well as noise levels led to a final choice.
Image - Ambisonics auralization room - SoundSpace - where the demonstration took place in 2012
The audio file below demonstrates a simulation that was presented to the client - first with the windows open and then with the windows closed and the ventilator open. The open ventilator simulation corresponds to the ventilator that was actually installed. The levels you hear will depend on your volume settings but allow a relative comparison to be made. The sound is best listened to on headphones.
Design Phase Auralisation from Max Fordham LLP on Vimeo.
On completion of the first phase of the development, we made video and sound recordings in a flat to demonstrate the actual improvement achieved by the acoustic vent.
Post completion auralization and video from Max Fordham LLP on Vimeo.
The measured sound attenuation improvement was up to 15 dB which is consistent with the performance expected during the design phase.
The benefit of auralizing the noise levels was an immediate understanding by all involved of the relative advantages of each attenuated vent option. This led to a quick decision on which to adopt with everyone involved committed to achieve the agreed design target.
For further information on this project or on auralization at Max Fordham's 3D Ambisonics lab - SoundSpace - please contact firstname.lastname@example.org.
Can I please ask the following: Was the 15 dB attenuation improvement from the open ventilator over and above the attenuation (not the right word I know) provided by simply opening a window?
I understand that BS8223:2014 states that an open window will provide a 15 dB of attenuation.
Therefore, does this vent provide the same overall attenuation as an open window? (i appreciate that the frequency spectrum of the internal noise level will be different).
Thanks for your comments and I am glad that you have appreciated the videos.
Regarding your specific query.
The 15 dB attenuation is the improvement obtained when compared with the 'attenuation'
offered by opening a window (door) in that same room.
As can be observed in the video the area of the open window (door) represents a very
significant percentage of the facade area of the room in question, which results in an
'attenuation' significantly lower than the 15 dB quoted in BS8233 (which is deemed
representative of the 'attenuation' provided by a typical window on a typical facade).
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