OVERVIEW

Westfield London Shopping Centre is the largest inner city shopping mall in Europe. In addition to over 265 shops Westfield Shopping Centre has a wide range of facilities including car parks, concourses, bars, restaurants and a multiplex cinema.

AMS REMIT

AMS were employed as Acoustic Consultants by Siemens to interpret and realise the Westfield specification. A crucial element of AMS’ remit was the prediction of STI (Speech Transmission Index). Many of the areas would be of high reverberation times and would have high noise levels due to the noisy emergency extractor fans.

DESIGN TARGETS

The design target SPL for evacuation messages was 93dBA. For general operation the SPL of the system is controlled by ambient noise sensors which fix the SPL to 10dBA above the background noise levels. The design target for the Speech Transmission Index (STI) was a minimum of 0.5 as defined in BS 5839 – part 8 : 2008.