New technologies – uninterruptible power supplies (UPS) in data centers

01 July 2024
An image of a data center

Today, we tackle a key issue in the world of data centers: the presence of uninterruptible power supplies (UPS) and how facility managers and asset owners can approach the installation of the equipment from the perspective of fire safety, mitigating the contingent threat of property loss and business interruption.


The continuous operation of data centers is essential to the smooth function of many aspects of modern life, and customers rightly expect uninterrupted service and the security of their data. Power cuts and fluctuations in grid supply pose a real and serious threat to computer systems and a power surge or failure could severely disrupt the service. Secondary power supplies are provided in data centers to mitigate against such risks and need to cater for outages of varying length in time. Uninterruptible power supplies, therefore, ensure data centers operate continuously until standby sources are active. Standby power is often provided by diesel generators which may take time to reach their peak power output and hence there is a clear need for UPS systems to safeguard continuous operation.


It’s time to take a closer look at these UPS systems. Although UPS systems provide a welcome solution to the issues of power variability and power cuts, they bring fresh challenges in ensuring fire safety. Data centers require large amounts of electricity and, so, battery UPS systems often need to be paired with large battery arrays. These batteries present an increased risk profile from the point of view of fire safety.


Lithium-ion battery UPS systems are increasingly preferred in data centers over other systems such as valve-regulated lead acid battery rooms. This is because li-ion offer greater energy density, lighter weight, longer design life, and lower maintenance costs (1). Lithium-ion battery UPS systems therefore help bring a lower total cost of ownership, improved sustainability credentials, and enhanced efficiency (2). While there is good reason to install Lithium-ion battery UPS systems in data centers, Lithium-ion batteries bring additional concerns in relation to fire safety due to their unique chemistries. Starting with EVs a few years ago, battery hazards have attracted a lot of attention across the world, and more recent incidents have often been associated with waste processing centers and logistic centers. These chemistries affect combustion, and mitigating these must be a key consideration for asset owners and facility managers when installing UPS systems.


It is of paramount importance to consider a full range of fire safety mitigation and prevention planning when installing UPS systems, including: space separation, fire resisting construction, a ventilation strategy; regular maintenance; thermal runaway avoidance concepts; early incident detection systems; and automatic suppression systems.


At Joule Group, our highly skilled engineers are privileged to find themselves daily working at the pinnacle of innovation in the protection of data centers, including AI and ML upgrade projects for existing sites, and through supporting the design and delivery of new facilities. We help our clients navigate the regulatory frameworks related to battery energy storage systems in the UK, Europe and the Middle East and we advise on best practices related to battery systems fire testing (such as UL 9540A) and mitigation strategies (such as those documented in NFPA 855).


De-risking data center projects at all levels brings, in turn, peace of mind to asset owners and managers alike.


To learn more about how Joule Group’s fire safety expertise could help you better protect your own data center-related assets and infrastructure, please get in touch with us at for an informal discussion. We’d be delighted to hear from you.



1 ‘Lead Acid vs. Lithium-ion’, Mitsubishi Electric, Link:

2 ‘Lithium-ion UPS is a smart choice’, Schneider Electric, Link:

3 ‘Data center fires raise concerns about lithium-ion batteries’, Network World, Link:

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