The UK is building data centres at a scale it has never attempted before, and a growing share of that construction is heading for the North East of England and Scotland. At Cambois in Northumberland, QTS has started work on a £10bn, 720MW campus of up to ten buildings. In North Lanarkshire, DataVita has secured £300m to expand its Chapelhall campus and has applied for a further £850m building. Across Scotland, 24 hyperscale proposals total around 6,000MW, in a country whose largest existing data centre is 12MW.

The fire safety conversation has not kept pace. Most of what is written about fire in data centres concerns detection and suppression, whilst compartmentation and fire stopping – the fire-resisting walls, floors and seals that hold a fire where it starts – are barely discussed. Yet much of the rest depends on them. We have published a research briefing on the subject, and its main findings are summarised here.

A modern data centre is a different building from a server room

UK regulation still largely treats data centres as rooms full of electronic equipment. The modern AI data centre is something else. Lithium-ion batteries in the uninterruptible power supply (UPS), on-site power generation, very dense cabling and liquid cooling all add fire load, ignition sources or both. Most of the major data centre fires reported since 2022 began in battery or electrical rooms rather than in the data halls.

Lithium-ion fires behave differently from ordinary fires. A damaged cell can enter ‘thermal runaway’, a chain reaction that heats the cell, releases flammable gas and spreads to the cells next to it. FM, the insurer, states plainly that “once thermal runaway starts, it can’t be stopped”. The Korean government’s investigation into the 2022 Pangyo fire, which took the KakaoTalk messaging service offline for more than 11 hours, found that the batteries had not been physically separated from the UPS and were “resistant to gas fire extinguishers”. Laboratory testing of Novec 1230, one of the gases used in data halls, found it failed to stop runaway spreading between cells at the concentration tested. Fire and Rescue NSW in Australia now requires lithium-ion battery rooms in data centres to achieve 240 minutes of fire resistance. No UK fire service has an equivalent position.

Once a battery fire has started, the realistic aim is to keep it in the room until it burns out or can be cooled with large volumes of water. The only thing doing that job is the construction around it, and the quality of every seal where a cable, pipe or duct passes through.

Compartmentation is what the other fire protection depends on

In most buildings, compartmentation exists to protect people while they escape. Data centres have few occupants, so its job there is different, and more closely tied to the systems around it.

First, it keeps a fire in a battery or electrical room out of the data halls. Second, it makes gas suppression work. Gas systems only put out a fire if the room holds the gas for long enough, which is why rooms must pass an integrity test. Aviva’s data centre standard says that test should be repeated “after every change to the room and at least annually”. An unsealed penetration is not only a route for fire; it is a reason the suppression system may fail. Third, it holds the fire in place until firefighters can safely act. At the 2021 OVHcloud fire in Strasbourg, electrical isolation was confirmed almost two hours after the emergency call. The building’s design allowed smoke to spread through every floor within 15 minutes, and the building was destroyed.

None of this means detection and suppression are overrated. Very early detection is the best way to stop a fault becoming a fire, and it rightly gets attention. The point is that active and passive protection work together, and the passive half is the one that is least visible, least certified and least recorded.

What is at risk

Fires in data centres are rare, but they are costly when they happen. In one 15-year study, fire accounted for 10.9% of data centre loss events but 42.3% of loss costs. Allianz found fire to be the leading driver of loss severity in data centre construction claims, at well over half of claim value.

The consequences also reach well beyond the building. In September 2025, a lithium-ion battery fire at a South Korean government data centre in Daejeon disrupted 647 public services, including emergency and postal services, with recovery expected to take up to a month. The fire started during works to relocate ageing batteries in a live building – a maintenance fire, not a construction one.

Where compartmentation goes wrong

The commercial model behind the boom puts pressure on exactly the stages where compartmentation is installed and checked. Buildings are let before they are finished, lenders set the programme, and late handover is penalised. In one industry survey, 45% of operators said faster timelines were reducing time for testing, commissioning or quality assurance. Every UK respondent to a Turner & Townsend survey reported shortages of qualified mechanical and electrical workers. Fire stopping follows those trades, because it seals the openings they make, so when they run late it is squeezed at the end.

The problem continues after handover. Data centres are designed to take new racks and cooling over 15-year leases, which means compartment walls and floors will be opened again and again once the building is live. Each re-cabling job is a chance to breach a seal and not reinstate it properly. The residential evidence is clear on how this plays out: CROSS reports describe around 70% of flats surveyed having compartmentation defects, “very often in unseen locations, for example above false ceilings”, with follow-on trades a common cause. Data centres have far more penetrations, most of them hidden in ceiling voids and raised floors.

What a competent approach looks like

Most of what is needed can be adopted now, through specification and contract, without waiting for regulation.

• Separate lithium-ion battery rooms from data halls and UPS equipment with fire-resisting construction rated against realistic battery fires, alongside early off-gas detection.
• Protect inspection, testing and commissioning time in the programme, with hold points where work cannot be covered up until the seals behind it have been inspected and signed off.
• Specify third-party certified installers for fire stopping, in the same way insurers already require approved contractors for sprinklers (LPS 1048) and gas suppression (LPS 1204).
• Keep a penetration register, with photographic evidence, for every seal.
• Control every penetration made after handover, requiring reinstatement to the tested system and a room integrity retest.

Experience and reputation are key

Ogilvie Fire Protection works across England and Scotland on compartmentation surveys, fire stopping and passive fire protection installation. Our installation work is third-party certified under FIRAS, and every job is documented through our QA system, so clients have an evidence trail of what was installed, where and by whom. That record matters most in buildings that will keep changing after handover.

If you are planning, building or insuring a data centre in the North East or Scotland and would like to talk about compartmentation or fire stopping, contact us at bruce@ogilviefp.com. Our full referenced research briefing, Hyperscale and fire safety, is available for download from our LinkedIn post: https://lnkd.in/p/ev6S33Dd

Sources
Allianz Commercial (2026) The data center construction boom. https://commercial.allianz.com/news-and-insights/reports/data-center-construction-risks.html

Aviva (2026) Data Centres – Detection and Fire Protection. https://static.aviva.io/content/dam/document-library/risk-solutions/data_centres_detection_and_fire_protection_lps.pdf

CROSS (2023) Inadequate fire stopping around cables and other services. https://www.cross-safety.org/us/safety-information/cross-safety-report/inadequate-fire-stopping-around-cables-and-other-1201

Data Centre Review (2026) AI data centre boom is straining the global construction workforce. https://datacentrereview.com/2026/08/ai-data-centre-boom-is-straining-the-global-construction-workforce/

DatacenterDynamics (2025) South Korea data center fire: government services could be offline for a month. https://www.datacenterdynamics.com/en/news/south-korea-data-center-fire-government-services-could-be-offline-for-a-month/

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FM (2025) Lithium-ion battery off-gas detection. https://www.fm.com/insights/what-businesses-should-know-about-lithium-ion-off-gas-detection

Korea Herald (2022) All stakeholders blamed for Kakao server shutdown. https://www.koreaherald.com/article/3015077

Place North East (2026) QTS doubles down as OpenAI pauses North East data centre ambitions. https://www.placenortheast.co.uk/qts-doubles-down-as-openai-pauses-north-east-data-centre-ambitions/

Project Scotland (2026) DataVita secures £300m for data centre innovation in North Lanarkshire AI Growth Zone. https://projectscot.com/2026/08/datavita-secures-300m-for-data-centre-innovation-in-north-lanarkshire-ai-growth-zone/

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Said and Stoliarov (2021) Analysis of effectiveness of suppression of lithium ion battery fires with a clean agent. Fire Safety Journal. https://www.sciencedirect.com/science/article/abs/pii/S0379711221000230

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The Register (2022) BEA-RI investigation report on the OVHcloud Strasbourg fire. https://regmedia.co.uk/2022/06/10/ovh_report.pdf