Increasing Energy Efficiency With Aisle Containment in Data Centers: A Comprehensive Guide

Aisle containment has emerged as a pivotal strategy for boosting energy efficiency in both newly constructed and existing data centers. By isolating hot and cold air streams, containment systems significantly improve energy efficiency and enhance Power Usage Effectiveness (PUE) scores. However, improper implementation of these systems can introduce significant fire protection hazards.

Updated Fire Protection Standards

To address these concerns, the National Fire Protection Association (NFPA) revised its standards for aisle containment fire protection in data centers. The 2012 edition of NFPA Standard 76 and the 2013 edition of NFPA Standard 75 include critical requirements aimed at mitigating fire risks associated with aisle containment. Despite their importance, these updates are not widely understood within the industry, affecting both retrofits and new constructions.

The Traditional Data Center Setup

Traditionally, data centers operated without aisle containment, leading to the mixing of hot and cold air. This mixing lowered return air temperatures, which negatively impacted the efficiency of HVAC systems. The introduction of hot aisle containment systems (HACS), cold aisle containment systems (CACS), and “chimneys” (also known as “hot collars”) aimed to eliminate this mixing. These systems allowed higher supply air temperatures to reach IT equipment, thereby optimizing HVAC efficiency.

Fire Protection Challenges in Data Centers

Fire protection in data centers is complex, involving detection, suppression, and response measures tailored to specific fuel loads and potential hazards. Aisle containment presents unique challenges in several areas:

• Prevention: This includes concerns about material combustibility and issues related to plenums.
• Detection: Challenges include appropriate detector locations and ensuring rapid response times.
• Suppression: Issues include potential obstructions to sprinklers and ensuring proper gas concentrations.
• Response: Challenges include the impact on detection and suppression efficacy, as well as accessibility for first responders.

Key Updates in NFPA Standards

The updated NFPA standards comprehensively address these challenges. Here are some of the key updates:

• Obstructions: Aisle containment introduces barriers that can affect the effectiveness of suppression and detection systems. The updated NFPA standards provide clear guidelines on how to manage these obstructions effectively.
• Automatic Obstruction Removal: Previous solutions, such as fusible links, proved to be inadequate. The new standards require automatic means of smoke detection to initiate obstruction removal before the suppression system is activated.
• Multiple Volumes: Aisle containment creates multiple enclosed spaces within a room, affecting gas concentration and smoke detection. The updated standards ensure uniform gas concentrations and effective cross-zoning of detectors to address these challenges.
• Higher Temperatures: Containment systems can result in temperatures that exceed the limits of standard detection equipment. The new standards mandate higher-rated sprinkler heads and detection devices suitable for these elevated temperatures.
• High Airflow Velocities: Containment can increase airflow rates, which can impact smoke detection and gas dispersion. Ongoing research seeks to comprehensively address these issues.

Implications for Fire Protection and Energy Efficiency

While aisle containment significantly improves energy efficiency by preventing the mixing of hot and cold air, it also introduces complex fire safety challenges. The 2012 and 2013 NFPA standards provide detailed requirements to mitigate these risks. By adhering to these standards, data center operators can ensure that their aisle containment projects meet both energy efficiency and fire protection goals.

Conclusion

Aisle containment has become a standard practice in data centers due to its substantial energy savings potential. However, this practice also brings about complex fire protection challenges. The updated NFPA standards provide clarity on acceptable practices and eliminate outdated methods, such as fusible link curtains, while redefining aisle containment as non-plenum.

By understanding and implementing these new requirements, MEP consultants, data center owners, and manufacturers can ensure that their projects achieve optimal energy efficiency without compromising fire safety. Following these guidelines will help navigate the complexities of aisle containment, ensuring both operational efficiency and compliance with the highest safety standards.

Contact Cool Shield

For more information or to receive a quick quote on hot aisle or cold aisle containment, contact Cool Shield today.

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Attribution:
This article is based on the original work “Complying With NFPA’s Aisle Containment Requirements” by Donald L. Beaty and David Quirk, published in the September 2015 issue of ASHRAE Journal (Vol. 57, Issue 9).