How is the acoustic performance of glass partitions tested on-site? Having previously considered laboratory testing in our blog posts, Essential tips when considering acoustic effectiveness for your glass partitions and What Affects the On-Site Performance of Glass Partitions? –Acoustic Performance of Glass Partitions – Questions to ask of your Acoustic Rating Test Certificate; our Technical Manager, Peter Long, takes a look at what this all means on-site. Understanding on-site testing On-site acoustic tests are in accordance with BS EN ISO 16283 and generate a value for the whole room front. This means the value of the door and screen become a single composite (aggregate) result. BREEAM also considers this in clause Hea 05 –Acoustic Performance. Here it makes reference to BS 8233: 2014, which sets out acceptable levels of sound insulation between rooms, measured in dB (Dw). To arrive at the desired Dw value the standard considers three key factors: The required Speech Privacy Level (SPL) The extent of background noise from mechanical services etc. (NR value) The occupancy type for the space on each side of the screen You can measure on-site performance in a number of ways: Dw dB (weighted level difference) This field method of measurement simply measures the difference in sound levels on either side of the partition and will include any losses from flanking. Depending on the individual circumstances, the measured value could be up to 8dB lower than the lab-tested value for the partition. DnT,w dB (weighted standardised level difference) A field measured value, derived in the same way as Dw and including the effects of flanking transmission, but corrected for the amount of absorption within the receiving room. You would expect the result to be at least 5dB (Rw) lower than the lab-tested value for the partition on its own. R’w dB (weighted apparent reduction) A field measured value, expressed in decibels, using the same method of measurement as Rw, again including the influence of flanking sound. You would not expect this method of measurement for typical office partition scenarios and is mainly for testing walls and partitions which have very large surface areas. Delivering Acoustic Performance On-Site There are a number of components in a finished fit-out that can cause the on-site performance of a partition to be poorer than the laboratory-tested value. This is Flanking Transmission and can occur through the ceiling or floor plenum, curtain wall mullions, abutments, around the partition via penetrations and around the door leaf. All elements of a room dividing construction need to perform in tandem. Any under-performing element will cause a failure against the specified performance. Hopefully this has been a useful summary of on-site acoustic testing. Keep an eye out for our next blog post when we will explore Flanking Transmission in more detail. Related posts: An Essential Tip When Comparing Acoustic Glass Partitions Acoustic Performance of Glass Partitions – Questions to ask of Your Test Certificate
