A data centre fire can take down critical services for millions. With the UK's data centre capacity expanding rapidly, fire protection of these facilities requires specialist expertise.. The Stakes Could Not Be Higher Data centres are the backbone of the modern digital economy. A single data centre outage can affect millions of users, cost millions in lost revenue, and potentially compromise critical national infrastructure. Fire is one of the most significant risks — and protecting against it requires a fundamentally different approach to most building types. The UK data centre market is expanding rapidly, driven by cloud computing, AI workloads, and data sovereignty requirements. Every new facility must integrate world class fire protection from day one. Unique Fire Risks in Data Centres Electrical Fire Risk Dense concentrations of electrical equipment and cabling High power densities (20kW+ per rack in modern facilities) UPS batteries (increasingly lithium ion) with thermal runaway risk Transformer and switchgear fire risk Cable fires can propagate rapidly through cable trays Environmental Factors Continuous operation (24/7/365) means constant heat generation Cooling system failure can rapidly escalate temperatures Sub floor cable management creates concealed fire spread paths Raised access floors act as plenums — fire and smoke can spread beneath the floor Operational Factors Live electrical work during maintenance Hot aisle/cold aisle configurations affect smoke detection performance High air change rates can dilute smoke, delaying detection Equipment density makes access for firefighting difficult Detection Systems VESDA (Very Early Smoke Detection Apparatus) The gold standard for data centre detection: Aspirating smoke detection that samples air continuously through a pipe network Detection sensitivity: 0.025% obscuration/metre (far more sensitive than point detectors) Can detect smouldering cable insulation before visible smoke develops Multiple alert thresholds: Alert → Action → Fire Sampling points in both supply and return air paths Sub floor and above ceiling coverage essential Complementary Detection Linear heat detection along cable trays and in risers Point type smoke detectors in ancillary spaces Gas detection in battery rooms (hydrogen from lead acid, HF from lithium ion) Thermal imaging — emerging technology for continuous monitoring of equipment temperatures Suppression Systems Clean Agent Gas Suppression The primary suppression technology for data centre server halls: Novec 1230 — most commonly specified clean agent, zero ODP, low GWP FM 200 (HFC 227ea) — widely used but higher GWP Inert gas systems (IG 541, IG 55) — nitrogen/argon blends, zero GWP Gas systems suppress fire without water damage to equipment Room integrity testing (door fan test) is critical — the room must hold agent concentration for the specified hold time Pre Action Sprinkler Systems For areas where gas suppression is not appropriate: Pre action systems require two triggers (detection + sprinkler head activation) Minimises risk of accidental water discharge Used in support spaces, loading docks, offices Water mist variants available for reduced water application Design Considerations Compartmentation Server halls separated by 120 minute fire rated construction UPS/battery rooms as separate fire compartments Switchgear rooms separated from server halls Cable routes fire stopped at every compartment boundary Business Continuity N+1 or 2N redundancy in fire protection systems Fire in one compartment must not affect operations in others Suppression system discharge must not cause thermal shock to equipment Emergency power for fire detection and suppression systems Automatic transfer to alternative cooling if primary system fails Operational Procedures Hot work permit systems for all maintenance involving heat or flame Cable management standards to prevent cable overloading Regular thermal imaging surveys of electrical connections Housekeeping programmes to manage combustible materials Detailed emergency response plans coordinated with the fire service For data centre fire protection design and consultancy, contact Magnus Opifex.