Fire Safety in Data Centres: Protecting Your Critical Data

This concentration creates a paradox. On paper, a data centre is an ultra-controlled environment: air conditioning regulated to the precise degree, restricted access and redundant power supplies. Yet it is precisely this technical density that increases the number of potential sources of ignition: electrical supplies permanently under load, batteries undergoing continuous charging and components that generate heat during normal operation. The risk is not an anomaly; it is an integral part of how the room operates.

The consequences of a fire, however, are anything but ordinary. A fire in a computer room can result in irreversible data loss, an immediate halt to production, financial losses that can quickly reach hundreds of thousands of pounds, and lasting damage to the company's reputation among customers and partners. This is why fire safety in a data centre cannot be treated in the same way as fire safety in a warehouse: it requires a specific approach that reflects what is at stake.

Before discussing solutions, it is important to understand what we are trying to prevent. In a data centre, fires most commonly originate from the same groups of causes.

Fire safety in a data centre falls within a specific regulatory and standards framework. Compliance is not simply a legal matter: it can also be a condition of insurance cover and a demonstration of professionalism towards customers and partners.

In the UK, fire safety in data centres is governed by a combination of legislation, building regulations and technical standards. In England and Wales, the Regulatory Reform (Fire Safety) Order 2005 (RRO) provides the main legal framework for fire safety in non-domestic premises. It places responsibility on the person with overall responsibility for the premises to carry out and regularly review a suitable fire risk assessment and implement appropriate fire safety measures.

The Building Regulations and associated guidance, including Approved Document B, also provide requirements and guidance relating to fire safety, compartmentation, fire resistance and means of escape.

For fire detection and alarm systems, BS 5839-1 is a key reference standard. It provides recommendations for the planning, design, installation, commissioning and maintenance of fire detection and fire alarm systems in non-domestic premises.

At international level, NFPA 75 covers the protection of information technology equipment and its premises: it defines construction, compartmentation and fire protection requirements applicable to computer rooms. NFPA 76, which is more specific, applies to telecommunications facilities. These two US standards are now considered references for good practice well beyond the United States.

ISO 27001, meanwhile, is not strictly a fire safety standard: it is a standard for information security management. However, as part of the risk assessment it requires, serious consideration must be given to physical risks affecting data, of which fire is naturally one. An organisation certified to ISO 27001 must therefore be able to demonstrate that its data centre is protected in proportion to the risks identified.

When it comes to fire safety, one principle takes precedence over all others: detect as early as possible to act as quickly as possible. In a data centre, the aim is not to detect the flame, but to identify the warning signs of a fire long before it appears.

Aspirating smoke detection (HSSD) systems, of which VESDA is the best-known technology, operate according to a different principle from conventional detectors: a network of pipes continuously draws small quantities of air from the room and analyses them for particles that are invisible to the naked eye.

Their sensitivity can reach up to 1,000 times that of a standard smoke detector. In practical terms, this means detection at the pre-fire stage, even before visible smoke appears. An additional advantage is the ability to minimise false alarms caused by ambient dust, a significant consideration in IT environments. Today, it is one of the leading technologies for protecting critical server rooms.

Other technologies usefully complement this system: optical smoke detectors, heat detectors and linear heat detection systems, the latter being particularly suitable for monitoring cable trays. These systems do not offer the same level of detection sensitivity as HSSD, but they provide valuable additional protection in peripheral or less critical areas of the site: plant rooms, storage areas and circulation spaces.

One principle is clear from the outset: traditional water sprinklers should be avoided above server racks. Water is conductive, it can irreversibly damage electronic equipment, and the damage caused by an accidental discharge can exceed that caused by the fire itself. Data centre protection therefore relies on suppression technologies specifically designed to operate alongside electronic equipment.

The principle behind inert gases is to reduce the ambient oxygen concentration to a level at which combustion can no longer continue, while remaining compatible with short-term human occupancy. This approach has the advantage of being clean, leaving no residue to remove after discharge, and being safe for electronic equipment. However, it requires a room to be perfectly sealed in order to maintain the effective gas concentration, as well as a rigorous evacuation procedure for personnel.

Inhibitory gases work differently: they chemically interrupt the combustion reaction without affecting the oxygen concentration. Their main advantage is the small storage volume required compared with inert gases, combined with very rapid dispersion and equally safe operation for electronic equipment. Novec 1230 is particularly distinguished by a more favourable environmental profile than previous generations of inhibitory gases, a criterion that is increasingly considered by sustainability and ESG departments.

These three technologies meet different needs. The table below summarises the main considerations.

Table

The best detection and suppression technology is not sufficient on its own. Fire safety in a data centre relies on a holistic approach, in which technology is just one link in the chain.

These three points form a genuine checklist that should not be overlooked: they determine the actual effectiveness of the entire fire safety system, well beyond the performance of the equipment installed.

Fire safety in a data centre is never about a single system. It is a chain: prevention, early detection, appropriate suppression and rigorous maintenance. Every link matters, and it is the strength of the whole chain that truly protects your data and your business.

There is no single answer: the choice depends on the size of the room, the budget and the criticality of the equipment being protected. Inert gas and Novec 1230 remain standard solutions for protecting server racks, while water mist is particularly relevant for large volumes or areas with specific risks, such as batteries. The right solution is always the one that results from a tailored risk assessment.

Traditional sprinklers should be avoided above servers because of the damage they can cause. High-pressure water mist is, however, an exception: it uses around 90% less water than a conventional sprinkler, such a small quantity that it evaporates quickly, causing little or no damage.

BS 5839-1 is a British Standard, not legislation in itself. Its application should be considered alongside the legal requirements that apply to the premises, including the Regulatory Reform (Fire Safety) Order 2005 in England and Wales. It is nevertheless a key technical reference for the design, installation, commissioning and maintenance of fire detection and alarm systems.

This varies considerably: from a few days for a small room to several weeks for a large data centre. The determining factors are the technology selected (pipework for a gas suppression system), the need to carry out work outside production hours and the overall complexity of the site.

These systems are designed to remain safe: an alarm followed by a time delay allows evacuation before discharge. Inert gases reduce the oxygen concentration, but to a level that remains breathable for a short period. Inhibitory gases are also safe at the concentrations used.

It identifies the early signs of a fire and particles associated with overheating long before visible smoke or flames appear. This provides valuable time for human intervention, such as disconnecting a faulty power supply, before automatic suppression becomes necessary. This is often what prevents a service interruption.

Equipment, including detectors and nozzles, has an average lifespan of 10 to 15 years. Gas cylinders and containers, meanwhile, must undergo periodic inspection and testing, generally every 10 years. Rigorous maintenance remains the key to the longevity and reliability of the entire system.

The cost can range from a few thousand pounds for a small room to several hundred thousand pounds for a large site. It should always be considered in relation to the value of the protected assets, both equipment and data, as well as the actual cost of business downtime. Viewed from this perspective, it is an investment in business resilience rather than simply an expense.