EN 12845-1 Annex P — The ESFR Informative Annex

Annex P is the ESFR informative annex to EN 12845-1 — the starting point for ESFR design in Europe. Since EN 12845-2:2024 was published the primary reference has changed, but Annex P remains useful for systems already in service.

An e-commerce warehouse installed an ESFR K200 system in 2020 to an Annex P reference, at 7 m storage height. In 2025 the racking was raised to 11 m. Annex P recommends K360 in that band, with a 12 m ceiling on storage height — but migrating to EN 12845-2 also required K360 plus a specific roof arrangement. On Annex P systems, growth in storage height automatically triggers migration to the EN 12845-2 requirements.

Annex P history

• 2003: Annex P published in the first edition of EN 12845
• 2009: K-factor range updated to K200–K280
• 2015+A1:2019: The current edition, with K360 added
• 2024: EN 12845-2 published; the primary ESFR reference changed
• Annex P retained as informative

What Annex P covers

1. Definition of ESFR (Early Suppression Fast Response)
2. The suppression philosophy — suppression rather than control
3. Recommended K-factors, K200–K360
4. Minimum pressure table
5. The twelve-sprinkler design rule
6. Placement (deflector 100–355 mm, spacing 2.4–3.7 m)
7. Roof slope ≤ 5 %
8. Skylights ≤ 5 m²
9. Hydraulic calculation basis
10. Listing requirements

Annex P K-factor table

Storage height	K-factor	Pressure	Note
≤ 7.6 m	K200	5.2 bar	Standard
≤ 9.1 m	K240	4.1 bar	Larger droplet
≤ 10.7 m	K280	3.5 bar	High-bay storage
≤ 12 m	K360	2.8 bar	The Annex P maximum

Note: K480 does not appear in Annex P; it was introduced with EN 12845-2 for storage up to 13.7 m.

Annex P versus EN 12845-2

Aspect	Annex P	EN 12845-2
Status	Informative	Normative
K-factor range	K200–K360	K200–K480
Maximum storage height	12 m	13.7 m
Dry-type ESFR	Limited	Detailed
Foam-water ESFR	Not covered	Covered
CE marking	Limited	Full
Storage commodity annex	Not covered	Extensive

The twelve-sprinkler rule

• Design area: 4 rows × 3 sprinklers = 12 heads
• Sprinkler spacing 2.4–3.7 m
• Design area works out at roughly 108 m²
• Calculate the twelve most remote and highest heads
• Every one must meet the minimum pressure
• EN 12845-2 keeps the same rule — no change here

Field error — Annex P design meets Group A plastics

A carton packaging warehouse installed a K360 system to Annex P at 11 m storage height for Class III commodity. A year later the commodity changed and Group A plastic packaging was introduced. Annex P is not adequate for Group A plastics; the fire test data supports K480 plus a specific roof arrangement. The annual audit recorded that Group A plastics were not accepted, and the choice was to change the commodity or upgrade the system. The resolution was K480 plus foam-water ESFR, referenced to EN 12845-2. On Annex P projects, a commodity change automatically triggers migration.

Migration scenarios

1. Existing system, same commodity: documentation reissued against EN 12845-2
2. Existing system, increased storage height: K-factor upgrade or roof modification
3. Existing system, changed commodity: re-listing, and sometimes a system upgrade
4. Extension: the new area designed to EN 12845-2
5. New project: EN 12845-2 mandatory

Listed products under Annex P

• K200 and K360 pendent ESFR heads are listed by all the major manufacturers
• Annex P-era listings generally stop at K360
• Newer K480 models are referenced to EN 12845-2 and sit outside the Annex P scope
• Always check the specific listing document, not the catalogue page
• Dry-type ESFR listings need separate confirmation

Insurer positions in 2026

• FM Global: EN 12845-2 required for new projects, Annex P accepted for existing systems
• VdS: a transition period running to 2027
• LPCB: EN 12845-2 as the main reference
• International insurers in Turkey: EN 12845-2 for new work, Annex P for existing
• Domestic insurers: BYKHY plus EN 12845 generally sufficient

Turkish regulation and local practice

BYKHY does not distinguish between Annex P and EN 12845-2; it refers simply to EN 12845. TS EN 12845-2:2024 is published and is the official reference. Existing Annex P installations typically receive a migration recommendation after their annual audit, and new projects from 2026 onwards should reference EN 12845-2. Newer Turkish distribution centres are being built to EN 12845-2 with ESFR K480.

Quick check list

• Which standard was the existing system installed to?
• Has storage height increased in the last five years?
• Has the stored commodity changed in the last five years?
• Listing match is current.
• New projects reference EN 12845-2.
• Extensions designed to EN 12845-2.
• Insurer preference documented.
• CE marking carried out under EN 12845-2.

Frequently Asked Questions

What is the twelve-sprinkler rule?

The ESFR design area is four rows of three sprinklers — twelve heads, roughly 108 m² — calculated at the most remote and highest position. EN 12845-2 retains the same rule.

What is the maximum storage height under Annex P?

12 m, with K360 as the largest listed K-factor. EN 12845-2 extends this to 13.7 m with K480.

Does raising the racking void an Annex P design?

In practice, yes. An increase in storage height changes the required K-factor and pressure, and the assessment has to be redone against EN 12845-2 as the current normative reference.

Does Annex P cover Group A plastics?

Not adequately. Group A plastics generally require the higher K-factors and the specific arrangements set out in EN 12845-2, often with foam-water ESFR.

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