Technical Booklet E Fire Safety·Page 122·4.41(vii)
Cavity plenum recirculating air distribution systems
Where a cavity is used as a plenum for air distribution, the relevant recommendations of BS 9999 5588-9 regarding recirculating air distribution systems must be complied with.
where the cavity is used as a plenum – the relevant recommendations of BS 9999 5588-9 in relation to recirculating air distribution systems are complied with.
Source — /Users/richardhill/Documents/planning-arch-project/data/documents/regional/Technical Booklet E - Fire Safety.pdf