In this roundtable, engineers discuss the most important trends for fire protection design in modern AI data centers.
Fire and life safety insights
- Fire protection design in data centers requires balancing strict code compliance with the need to minimize water damage and downtime.
- The growing use of lithium-ion batteries in uninterruptible power supplies and battery energy storage systems is increasing fire risk complexity and requiring enhanced detection, suppression and explosion control strategies.
Respondents:
- Brook Gummere, PE, FPE, ATD, Colorado BES Market Sector Leader, HDR, Denver
- Brian Schlosser, PE, Principal Fire Protection Engineer, Jensen Hughes, Columbia, Maryland
- Ken Urbanek, PE, LEED AP, ASHRAE HBDP, ATD, Client Executive and Senior Principal, IMEG, Denver
What are some of the unique challenges regarding fire/life safety system design that youโve encountered for data center projects?
Brook Gummere: Designing fire and life safety systems for data centers presents unique challenges, particularly balancing effective fire suppression with the need to protect critical infrastructure from water damage. While there are many alternative suppression systems that do not require the use of water, such as FM-200 and other clean agents, the International Building Code (IBC) does not allow buildings to use alternative suppression systems in certain areas and the building still be classified as fully sprinklered. This means the building cannot take advantage of code exceptions related to building size, travel distances and fire separation reductions. As a result, small server rooms in nondedicated facilities often use clean agents as the primary suppression method in the event of a fire, while still backed up by dry, double-interlock sprinkler systems to limit the risk of accidental discharge.
For large data centers with high air exchange rates, clean agent systems are generally not practical, making double-interlock dry sprinkler systems the standard approach.โฏHowever, there continues to be scrutiny of this approach by insurance companies due to concerns about system failure and delayed water release in the event of a fire. The challenge becomes selecting a detection system that is both highly sensitive and low maintenance. Very early smoke detection apparatus (VESDA) early-warning detection remains the industry standard, but as data halls grow, some owners have turned to linear heat detection. This is a lower maintenance option that will reduce the potential for false alarms, though it responds more slowly than VESDA.
Brian Schlosser: Lithium-ion batteries associated with uninterruptible power supplies (UPS) are often found in data centers and present unique fire protection challenges. Hazards include overheating, off-gassing and thermal runaway, which can lead to fires and/or explosions. Fire protection challenges associated with lithium-ion battery energy storage systems (BESS) include the design of appropriate fire and smoke detection systems, suppression systems, explosion control systems and passive fire-resistance-rated compartmentation of battery rooms. These challenges can be exacerbated when trying to retrofit such systems into existing buildings.
Ken Urbanek: Changes in fire codes around UPS batteries have been significant for lithium-ion battery systems. On one project, all UPS systems needed to be located outside while a different project required significant limitations on UPS systems within the building. Understanding these code requirements early and adjusting the basis of design during the concept or schematic design period is important to avoid highly impactful changes later.
How do you balance fire protection and life safety requirements with the need to minimize downtime and avoid accidental system discharge in data center environments?
Brian Schlosser: Fire protection systems typically consist of normally dry, double-interlock preaction fire sprinkler systems activated by air-sampling smoke detection. The double-interlock configuration helps prevent accidental water discharge, while the multilevel alarm thresholds associated with air-sampling detection help avoid inadvertently filling the sprinkler piping with water during nuisance alarm events.
Ken Urbanek: Compartmentalization and redundancy is one way to balance this. We continue to use preaction dry fire suppression systems to minimize risk of accidental water discharge. We see fewer deployments of chemical suppression systems than we did a decade ago.
Brook Gummere: Balancing fire protection and life safety requirements with the need to minimize downtime and avoid accidental discharge relies heavily on selecting the right detection technologies and placing them strategically. VESDA provides the quick response needed to activate double-interlock dry sprinkler systems prior to significant fire growth occurring.
However, VESDAโs high sensitivity can lead to false alarms and increased maintenance. For VESDA that are located above ceilings or at the deck of open data halls, this maintenance is challenging, time consuming and costly. To reduce this risk, linear heat detection can be used in hard-to-access areas, at the deck or above ceiling, as an alternative with reduced susceptibility to false alarms.โฏ VESDA is then still used in accessible, high-risk spaces โ such as within hot air containment areas โ where early detection is most critical.
What clean agent, aerosol, oxygen reduction or other fire suppression systems are typically specified? Describe a project and the chosen system.
Ken Urbanek: Most of our projects are settling on preaction dry pipe sprinkler systems only. We are seeing a shift away from clean agent chemical suppression systems both in high-density artificial intelligence (AI) data centers and in higher criticality mission-critical communication facilities.
Brook Gummere: Clean-agent systems such as FM-200 remain widely used in data centers along with other NFPA 2001: Standard on Clean Agent Fire Extinguishing Systems-compliant agents. However, systems are typically paired with a water-based suppression system to meet the IBC requirements for a fully sprinklered building.
Brian Schlosser: Fire suppression systems are typically limited to double-interlock preaction fire sprinkler systems. The use of clean agent fire suppression systems as a supplemental system is determined via a risk assessment and/or desire by the building owner or tenant. Partially due to ongoing environmental impact concerns, as well as the increased cost of providing such systems, clean agent fire suppression systems are not often specified.
How has the cost and complexity of fire protection systems involved with data center projects changed over the years?
Brook Gummere: Over the years, the cost and complexity of fire protection systems in data centers have evolved alongside the facilities themselves. Interestingly, as data centers have become more sophisticated, the design of fire and life safety systems has, in many ways, become more streamlined. The use of the double-interlock dry sprinkler systems has simplified protection strategies by limiting the risk of water discharge on sensitive equipment. While these systems require higher operating pressures โ often necessitating a fire pump โ the incremental cost of upsizing and maintaining a larger pump is relatively small compared to the overall investment in suppression infrastructure.
Ken Urbanek: Cost and complexity changes have been mostly insignificant compared to mechanical and electrical systems. We have seen much consistency in the design of fire protection systems over the last decade, unlike other systems for AI deployments.
Brian Schlosser: The use of lithium-ion BESS often increases the cost and complexity of fire protection for a data center project. Provisions for enhanced fire alarm/detection systems, fire sprinkler systems and explosion control systems can greatly impact a project. In some cases, development of a hazard mitigation analysis specific to the batteries being used can be critical in meeting exceptions to requirements for various design elements, including the need for explosion control systems. The potential cost savings associated with development of such an analysis can be significant for both initial construction costs as well as ongoing system inspections, testing and maintenance.
How have changes to codes, building information modeling and wireless devices/systems impacted fire and life safety system design for these buildings?
Brian Schlosser: The code development process takes time and often lags the need for developing fire protection schemes for new mechanical and electrical technologies associated with data centers. Historical examples include development of hot/cold aisle containment systems and the use of lithium-ion batteries. Building information modeling has proven to be extremely effective in coordinating and collaborating among the various design disciplines to reduce clashes between building systems. This helps ensure that the construction of a data center proceeds as smoothly and as efficiently as possible, potentially saving both time and money.
Brook Gummere: There has not been a significant change here over the years. However, the most significant shift in fire and life-safety design stems from updates to the 2021 to 2024 IBC. These revisions reclassified data centers from Business (Group B) to Storage (Group S) occupancy, which triggers new requirements, most notably the addition of smoke exhaust systems in larger facilities. This is creating more design challenges as more authorities having jurisdiction adopt the latest code standard.
