Non-Storage Occupancies in ESFR/CMSA Buildings

A logistics building is never just racking. There are offices, packing lines, shipping docks, break rooms and workshops — and each needs its own sprinkler design. Transition zones, zone separation and hydraulic balance are the most critical part of designing fire protection for a mixed-occupancy building.

One e-commerce warehouse was initially designed as a single zone: 8000 m² of ESFR and 1500 m² of offices on the same control valve set and the same flow switch. The pump pressure needed for ESFR was 8 bar; running office sprinklers above 8 bar produces a spray so aggressive that it damages furnishings. The insurer required separate zones and every control valve set had to be replaced. A mixed-occupancy building should always be zoned from the start — a single zone is not a saving, it is deferred expense.

Typical areas in a mixed building

• Main storage: HHS3–HHS12 depending on storage height
• Shipping dock: HHP3 or HHS1
• Packing: OH3
• Forklift charging: OH3 plus specific lithium-ion measures
• Open-plan office: OH1
• Meeting rooms, lobby, corridors: OH1
• Kitchen and canteen: OH3
• Server room: clean agent or OH3
• Workshop and maintenance: HHP1–2
• Changing rooms and showers: OH1

Zoning principles

1. Each main function gets its own zone
2. Each zone gets its own control valve set
3. Each zone gets its own flow switch and alarm
4. Hydraulic balance: the zone with the highest pressure demand sets the pump pressure
5. A fire wall (REI 90–120 min) between zones is preferred

Designing the transition zone

Where there is no fire wall, use a 3–6 m buffer at the change of occupancy:

• The last ESFR row provides full protection
• Both systems overlap across the 3–6 m transition
• The OH system starts 6 m beyond
• Fire damper (FD-90) in the ceiling
• The zone transition is supervised by a line of smoke detectors

Pump pressure conditions

Zone	Sprinkler pressure	Pump duty
ESFR HHS6	4 bar	8 bar (friction plus static)
CMSA ceiling	3 bar	6 bar
OH3	1.5 bar	3–4 bar
OH1	0.7 bar	2–3 bar

The zone with the highest pressure demand — usually ESFR — sets the pump duty, and pressure-reducing valves are fitted to the ordinary hazard zones.

Field error — the forklift charging area was overlooked

In one logistics warehouse the forklift charging area, with twelve lithium-ion trucks, had been rolled into the OH1 office classification. A thermal runaway event overwhelmed OH1 and flame and smoke spread rapidly. After the incident the charging area was rebuilt as a separate zone with OH3 density, early lithium-ion detection (CO and H₂ sensors) and a clean-agent backup system. A lithium-ion charging area always warrants its own design.

Shipping dock area

• Temporary pallet staging: HHS1 is sufficient (≤ 4 m)
• Heavy forklift traffic: OH3
• Cardboard waste accumulation: specific housekeeping rules apply
• External dock doors: dry-type sprinklers with freeze protection
• With the doors open, air movement disrupts ESFR operation

Office area

• Open plan: OH1 concealed pendent
• Server room: clean agent (HFC-227ea or inert gas) or pre-action
• Meeting rooms: OH1, deflector under a 3 m ceiling
• Break and rest areas: OH1
• Kitchen: OH3 plus a UL 300 listed cooking-hood suppression system

Turkish regulation and local practice

BYKHY classifies buildings by occupancy (storage, office, commercial and so on). In mixed-occupancy projects each area is referred to EN 12845 or NFPA 13 according to its own classification. Newer Turkish distribution centres model every zone in BIM at design stage; in older buildings, zoning is retrofitted after the fact and is far harder to achieve.

Quick check list

• Occupancy classification documented for every area.
• Each main function has its own zone and valve set.
• Fire wall or transition zone designed.
• Pump pressure set by the most demanding zone.
• Pressure-reducing valves on the ordinary hazard zones.
• Lithium-ion forklift charging is a separate zone with dedicated detection.
• Server room on clean agent or pre-action.
• Kitchen protected by a UL 300 system.

Frequently Asked Questions

Why must storage and office areas be on separate zones?

Because their pressure demands are incompatible. ESFR may need 8 bar at the pump while office sprinklers operate at under 1 bar; running office heads at ESFR pressure produces a spray aggressive enough to damage the space it is protecting.

How wide should a transition zone be where there is no fire wall?

Typically 3–6 m, with both systems overlapping across the buffer, a fire damper in the ceiling, and a line of smoke detectors supervising the change of occupancy.

How should a forklift charging area be protected?

As its own zone at OH3 density, with early lithium-ion detection (CO and hydrogen sensors) and, where the risk justifies it, a clean-agent backup. Rolling it into an office classification is a well-documented failure mode.

What protects a server room inside a logistics building?

Either a clean agent system (HFC-227ea or inert gas) or a pre-action sprinkler system — usually double interlock, so that a single false signal cannot fill the pipework.

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