Context
A pharmaceutical logistics operator was developing a 34,000 m² distribution warehouse in the east of England to hold high-value specialised medication, including chilled medication. The scale of the building and a large multi-tiered mezzanine put parts of the design beyond what prescriptive guidance could answer directly — the travel distances involved exceeded the standard tables, and the passive fire protection the tables would otherwise call for was not compatible with how the mezzanine needed to work operationally.
The brief
Apex was appointed to produce the design fire strategy and to provide building control support through to approval. The operator needed the strategy to accommodate the building as designed — the footprint, the mezzanine, the travel distances the layout produced — without defaulting to a conservative redesign, and needed that position agreed with building control rather than contested.
Our approach
Apex used BS 9999 as the design framework, in conjunction with fire engineering analysis, to assess the building against its actual risk profile rather than a generic worst case.
CFD (computational fluid dynamics) modelling was used to support extended travel distances beyond the guidance tables and to justify reduced passive fire protection to the large multi-tiered mezzanine, testing how fire and smoke would actually develop in a volume of this scale rather than relying on prescriptive assumptions.
The modelling was carried through to demonstrate available safe egress time against required safe egress time (ASET/RSET), and to test the contribution sprinklers would make in a fire — evidence used to agree the design position with building control.
Outcome
The fire strategy evidenced adequate ASET/RSET margins through the CFD analysis, and demonstrated that sprinkler installation would prevent fire spread throughout the building — including assisting in preventing structural collapse of the mezzanine areas, through cooling and by potentially suppressing the fire before it could spread. That evidence base supported the extended travel distances and the reduced passive fire protection to the mezzanine that the operational design needed.
What a duty holder can take from this
Large-format warehousing with multi-tiered mezzanines routinely runs into the limits of prescriptive guidance on travel distance and passive protection. BS 9999 combined with CFD modelling gives a route through that isn't guesswork: it tests what a fire and its smoke would actually do in the space, and what sprinklers would actually achieve against it, before anyone commits to the departure. For a facility holding specialised and chilled medication, that evidence is what let the design proceed as operationally intended rather than as a conservative fallback.