In 1965, Intel co-founder Gordon E. Moore offered a bold prediction: Within a few generations of development, a silicon chip could be made to hold a billion transistors. He was right. And along with the exponential growth in computing power over the ensuing decades has come an exponential growth in the demand for data — by customers, shareholders and regulators. Behold the data center. With data centers becoming mission-critical facilities, facility executives need practical planning and design strategies to prevent, detect and suppress fire.
What fuels fires in data centers? An analysis of historical data maintained by the telecommunications industry suggests several common fuel sources:
Most facility executives are aware of these common risks and take pains to reduce or eliminate them. However, there are also risks associated with aging infrastructure and improperly executed rack expansions and building modifications: electrical cord failures and shorts and overloaded circuits and improper or poorly maintained terminations.
Of course, aging equipment can corrode over time, creating fire hazards. But these risks also reflect lack of planning for growth. Studies by microprocessor and server manufacturers have found that with an increase in computer equipment load density — from 50 watts per square foot to 100, 200, or even 300 watts per square foot — there is a parallel growth curve in the electrical and mechanical infrastructure required. Although such expansions do not necessarily overtax the fire protection system, which is designed based on an area or volume calculation, they do require a well-planned and well-executed expansion of the electrical and mechanical infrastructure to avoid the potential heat build-up that creates a fire risk.
The new generation of high-density data centers presents three special challenges or risks. In-rack cooling requires more cooling piping infrastructure, which may conflict with other equipment. Higher power calls for more wiring, resulting in a more constricted underfloor space. And the combination of higher power, more cooling equipment and more equipment per square foot means more opportunities for failure. Under certain conditions, overheating may result, increasing the fire risk. This is one reason why it is important to use an integrated design approach to the mechanical, electrical, plumbing and fire-protection systems for mission-critical facilities.
Computer engineers may debate the future of the microprocessor: Already at a billion-plus, can the number of transistors on a silicon chip continue to double roughly every two years? To facility executives of mission-critical facilities, the debate has as much value as the medieval theological question concerning the number of angels who can stand on the head of a pin. What is needed today is a practical, cost-effective strategy for managing fire risks through a conservative, integrated approach to design, construction and third-party commissioning.
It is important for facility executives to take a hard look at risks during the planning, design and installation of fire protection systems. Failing to do that may lead facility executives to spend too little — or too much.
Lack of compliance with current minimum building and life safety codes for construction and operation of data centers is rare. However, minor code oversights easily can be overlooked during design or construction. This is one reason why experts strongly recommend spending the money for a third-party commissioning agent.
Problems can also result from lack of coordination among trades for installation of components and systems. For example, an improperly programmed software point for the detection system might indicate smoke in a space other than where the event actually occurred. Normally this type of error will be identified during commissioning.
An in-depth risk analysis can determine the best use of construction funds for the lowest life-cycle cost. For example, designers may recommend a buildingwide clean-agent system, failing to consider the risk-benefit at the facility or more cost-effective designs, such as limiting the clean-agent system to the data center itself.
In fact, there is a tendency to over-design fire protection systems for critical facilities. While facility executives should design a fire protection system in a conservative manner, this goal must be balanced with effective value engineering to reduce the cost while providing an appropriate level of risk control and building protection. In some facilities, for example, an expensive pre-action system in redundant support spaces, such as UPS and battery rooms, might be a case of over-design. In these spaces, a wet-pipe sprinkler system may provide acceptable protection at a much lower cost.
Facility executives also need to be alert for designs that are incompatible with the geographic location and local conditions. For example, when designing a wet-pipe sprinkler system, it is important to provide for more than one source of water connection to assure redundancy. However, in some locations the tap fee imposed by the municipal water utility is so high that it is more cost-effective to design a system with a single tap plus on-site water storage.
— John Eagar
John Eagar, P.E., is a senior associate in the critical facilities group of Syska Hennessy Group, Inc., in its Atlanta, Ga., office.