Always on: three unique fire-related challenges in mission-critical data centres

So, how can data centre operators ensure their assets are protected from the unique fire prevention challenges these vast structures face, and keep on-site and emergency services personnel safe?

The value of the hardware inside a data centre can run to millions of pounds, and downtime caused by a data centre going offline can be just as costly. Of the 55% of operators who told the 2023 Uptime Institute Data Center Survey they had experienced an outage in the previous three years, 16% said the incident cost them at least $1 million (£762,000) ⁽¹⁾.

Data centres are also mission-critical. In September 2024, the UK government declared that data centres will sit alongside services such as healthcare, energy and water systems as Critical National Infrastructure - meaning they will receive government support in the event of critical incidents such as extreme weather or cyberattacks.

The government described data centres as the "engines of modern life", ⁽²⁾ so creating a holistic fire engineering strategy at the start of a development - one that evolves to account for the challenges thrown up by what is a fast-growing market - is key.

The tens of thousands of servers that can make up a data centre means these buildings are far from compact. In the UK, data centres can be tens of thousands of square metres in size ⁽³⁾ - dwarfing the average large UK supermarket. From a fire safety perspective, means of escape, firefighter access and water supplies must be taken into consideration at the building design stage - both for staff exiting the building in case of a fire, and the emergency services entering to tackle the incident.

Occupancy of data centres is comparatively low - Microsoft for example employs around 50 people ⁽⁴⁾ at its sites - so getting staff to safety is easier than at more densely-populated buildings of a similar size. However, keeping fire and rescue teams safe once they are inside is a different challenge.

The large footprint of data centres means firefighters have limited hose coverage (approximately 45 metres, rising to 60 metres if a sprinkler system is also in operation). As a result, similar to tackling fires in high-rise buildings, good practice is to establish a firefighting bridgehead, i.e. a protected space to operate from and retreat to. However, the size of data centres means that the distance from the bridgehead to the fire itself has the potential to be greater than usual, elevating the risk and emphasising the importance of considering suitable bridgehead locations early on.

This greater distance is exacerbated by the nature of the space fire response teams need to travel through. A typical residential building or office block is compartmentalised by internal walls and fire doors, which help to contain fires and slow their spread. Data centres, however, are not typical commercial buildings. The server equipment they house is power-hungry and gives off a lot of heat, and superfluous internal walls are not conducive to effective cooling. This means that should a fire start, containing it becomes a much greater challenge.

With compartmentalisation not easy to implement, a suitable fire suppression system is paramount. Given the size of most data centres, an automatic suppression setup that can contain a fire until emergency services arrive is an obvious choice, but there is a delicate balancing act to achieve here; the system must be suitable to function as required, while at the same time minimising any unnecessary damage to valuable equipment and downtime.

Water mist suppression systems are growing in popularity because their low-pressure solutions mitigate the risk of damage and are more water-efficient, but again, there is a need to achieve equilibrium between a system that operates alongside HVAC systems in what are large, open spaces, with high-air velocities to maintain cooling and one that does not cause excessive collateral damage while the fire is being suppressed. There is no one-size-fits-all answer to data centre fire prevention, so giving it serious consideration at the design concept stage is the only way to integrate a bespoke solution that meets the needs of facilities and their operators.

A fire prevention protection system is only as good as its water supply, and for data centres in more remote locations, this typically means the installation of multiple tanks big enough to deliver enough water should the worst happen - typically a tank for the suppression system, one for emergency services to use to extinguish the fire, and additional tanks as a redundancy. There are also likely to be attenuation tanks, especially if the data centre is located on or close to greenfield or brownfield land.

Another environmental concern is that a byproduct of fire suppression systems is polluted wastewater. Having a suitable fire safety strategy that prevents runoff from entering the local ecosystem is crucial, as the data centre operator could be held - at least partially - liable for pollution caused by firefighting run-off ⁽⁵⁾ and face legal repercussions; the Water Resources Act 1991 makes polluting a watercourse a criminal offence, while under certain circumstances, discharging firefighting runoff into a sewer is an offence under the Water Industry Act 1991.

Site constraints often mean that no two data centres are exactly alike, especially as edge data centres and retrofitted buildings become more prevalent, so addressing fire prevention at the concept stage of each project remains critical. Involving fire safety to ensure considerations are met during planning will assist in de-risking the holistic solution that first and foremost keeps the structures and its occupants safe, but also delivers on the sustainability and efficiency needs of buildings that are increasingly essential to our day-to-day lives.

The definition of what constitutes a 'traditional' data centre is changing. Space for warehouse-style single-storey units is at a premium, and as the way we use technology evolves, so too is the way data centres are designed. Edge data centres - smaller, more agile sites located closer to the 'edge' of a network that offer faster response times - are appearing with increasing frequency.

In London, we are advising on the upwards expansion of a 13-storey data centre to deliver increased capacity, which signifies what is likely to be a growing trend of improving the capabilities of existing sites. Developers will need to consider a number of fire safety implications, including how the extended height will impact escape routes and access for fire response teams, and whether there is a need to reassess the fire resistance of the existing structure with the addition of extra floors.

Data centres situated across multiple levels need a very different fire safety approach to vast single-storey warehouses. Limited hose coverage becomes less of a concern, but this is replaced by a need for firefighting shafts and lifts to ensure that teams can respond to blazes on upper floors quickly, effectively and safely.

- David Thompson, Director of Fire Safety – South at Hydrock, now Stantec.

We are providing our fire engineering expertise at planning level and beyond for this project, along with support to overcome the acoustic design challenges presented by the building's expansion.

1. Uptime Institute's Global Data Center Survey Results 2023

2. Data centres to be given massive boost and protections from cyber criminals and IT blackouts - GOV.UK (www.gov.uk)

3. Property - tescoplc.com

4. Frequently asked questions about our datacenters - Microsoft Local

5. Environmental principles policy statement - Gov.uk, Preventing Pollution from Fire Fighting Run-Off - Aviva.io