Bromley South Central

Our Role in the Project

Initial measurements included noise and vibration from the adjacent freight and local railway, road traffic outside, and an assessment of potential vibration effects on the cinema. Due to the cinema’s placement in the building there was a possibility of cinema noise transmitting through the building to the residential apartments above, exacerbated by the fact that they were all part of the same structure. Restaurant and leisure spaces on the ground floor also had the potential to generate noise that disturbed either the cinema or the apartments.

Specific Considerations

Included within the basement of the building is a 9 screen multiplex cinema capable of holding 450 people. To ensure noise from the cinema didn’t pollute the apartments, hotel, restaurants and leisure space above, we advised on and oversaw the construction and installation of floating boxes that sit on rubber springs to contain each screen. Furthermore, raised seats were placed on rubber screen, the walls fixed back to concrete with rubber fixings, and the screen hung on rubber hangers.

Aside from the cinema, the following noise sources had to be considered during the build process; mechanical plant equipment, adjacent railway and road, and ground floor restaurants and leisure spaces.

The build had to comply with local planning requirements, Vue cinema operators acoustic specification, and the Premier Inn hotel acoustic specification (one of the most rigorous within the hotel market).

Acoustic Features of this Project

On completion of the project we carried out a full set of building regulations sound insulation measurements within the apartments and hotel. In regards to the cinema, we were required to demonstrate railway noise was below the required levels within the screens as well as proving the cinema noise was practically inaudible in the apartments above.

To meet the requirement of ‘inaudible’, we required an objective definition be created - to find this objective definition, we made reference to guidance from other local authorities including Manchester and Westminster. After finding an objective standard for inaudibility, we demonstrated this by placing a high power PA system in the cinema playing white and pink noise, while measuring sound in the spaces above. We used the same system to measure sound insulation between the cinema screens, as the cinema operator’s specification demanded a high standard of noise control.  

Resolution of noise pollution from the road and railway was achieved with high performance acoustic glazing and ventilation, as well as the external façade.

To stop the rooftop mechanical plant equipment noise from affecting the neighbouring homes, a horizontal acoustic louvre was installed across the roof. In addition to this, we identified local enclosures for roof-mounted pumps.

Through our willingness to be thorough in understanding, identifying and quantifying the sources of noise, we were able to develop an ovel acoustic design. Combined with our approach of working with the contractor, suppliers and subcontractors to assist with the buildability of a complex system, we provided an inclusive resolution to the myriad of acoustic challenges involved in this project.