The Brief
The Atrium space was being under used due to the uncomfortably high reverberance within.
A good deal of absorption would be required to tackle the problem but the many fixing points required were extremely limited. Aesthetics was a key factor along with introducing an element of diffraction and installing for maximum absorption. Treating the booths within the Atrium also assisted with the performance.
CAD modelling helped to identify problem areas and prove our design and calculations
Design
The design was two-fold; firstly deciding the best acoustic materials to use in order to achieve the required results and secondly the most efficient way to install them. We created CAD drawings of each wall and panel to enable the framework and panels to be designed with the highest accuracy.
We would require 560 metres of aluminium extrusion to build a secure frame on which we could mount the absorption panels.
Fixing the frame to the upright aluminium extrusions was a precise exercise with every fixing point requiring a tolerance of less than 0.25mm. Any tiny error would lead to failure and so precise jigs were made to ensure we were on the mark every time.
The absorption panels were arranged in a number of ways to both absorb and diffract unwanted sound and therefore a number of frame/panel arrangements were created around the atrium.
Provided by CMS Danskin at very short notice, the absorption panels arrived in good time and perfectly cut to our specification.
“We engaged with BL acoustics to come up with the solution to our sound issues. From the start they impressed us with their technical understanding of the issue, and the solution proposed made sense. Now that the installation has been completed we can honestly say that has made a huge difference to the staff experience. We are now able to host large company events without concerns over the audio quality, and we are sure that our savings on external venue hire will pay back our investment in a very short space of time.”
Earl Peacock
on behalf of Amadeus
Installation
The brilliant white panels needed to be installed up to a height of 9 metres and above some very large bleacher steps.
Specialist access equipment was going to be required. Access to the Atrium was restricted via a series of four doorways, the narrowest being 850mm wide. This meant that access for both the 9m Scissor Lift and the 20m Spider required for the installation was going to be extremely tricky. Some excellent driving skills and much patience we eventually arrived in situ. All floors protected by boarding throughout to avoid any damage.
Refectory
In addition to the Atrium the adjacent Refectory was a high noise area which was uncomfortable for all those taking lunch.
The area was too active, destroying communication and resulting in raised noise levels.
Two levels of treatment were offered; Foam in the soffit areas and strategically positioned suspended absorption panels at ceiling height
Installation was developed in two ways. Firstly, the use of the area at soffit level and the ‘I’ beams by filling the cavity with acoustically absorbent foam. Secondly, we installed a series of vertical and horizontally mounted panels that were distributed to give a general coverage of absorption. The objective was to provide a comfortable environment with easy communication for people sitting and talking across the dinner tables.
Performance
The Atrium reverberation time was measured at 3.4 seconds and our target was to reduce this to 2.1 seconds. On completion we measured 1.1 Seconds (at worst point at 250Hz). This resulted in a significant improvement in comfort and intelligibility.
Our target was to reduce RT from 1.9 seconds to 1.25 seconds. On completion we measured 0.45 Seconds (at worst point) again resulting in a significant improvement in comfort, communication and a reduction in background noise when occupied.
“I would say this was a very successful project. From a detailed and innovative design through to the installation and final test results, it was managed very professionally. The initial scope objective to reduce reverberation of noise and improve the audio quality and experience in the Atrium and Refectory was bettered and has exceeded expectations. A job well done by all”
James Newman
on behalf of CBRE
