Data centers’ intricate design
Data centers are important structures that hold vital information for businesses, schools, public agencies, and private individuals. If these mission critical facilities aren’t properly designed and equipped, the gear inside and the data the servers handle is at risk.
Tim Chadwick, PE, LEED AP, President, AlfaTech Consulting Engineers, San Jose, Calif.
Robert C. Eichelman, PE, LEED AP, ATD, DCEP, Technical Director, EYP Architecture & Engineering, Albany, N.Y.
Barton Hogge, PE, ATD, LEED AP, Principal, Affiliated Engineers Inc., Chapel Hill, N.C.
Bill Kosik, PE, CEM, LEED AP, BEMP, Building Energy Technologist, Chicago
Keith Lane, PE, RCDD, NTS, RTPM, LC, LEED AP BD+C, President/Chief Engineer, Lane Coburn & Associates LLC, Seattle
Robert Sty, PE, SCPM, LEDC AP, Principal, Technologies Studio Leader, SmithGroupJJR, Phoenix
Debra Vieira, PE, ATD, LEEP AP, Senior Electrical Engineer, CH2M, Portland, Ore.
CSE: What's the No. 1 trend you see today in data center design?
Tim Chadwick: Scalability would be the top trend we have been seeing for the past 3 or more years, and it continues today. The challenge with designing for data centers is creating a facility designed to last for 15 to 20 years whose technologies will refresh or be changed out every 3 to 5 years. We are guessing at what the latest in server and storage design technologies will hold 4 to 5 years into the future. People are challenged when predicting the next generation, so looking that far out means you have to build a facility that can adjust on the fly and handle a wide variety of changes in technology or even in company growth/expansion.
Barton Hogge: That is removing as many infrastructure dependencies as possible—and seeing water as a critical utility to be treated as seriously as backup power; clients are requesting designs that have little or no dependency on water usage. Smaller-scaled and lower-density sites can achieve this with reasonable ease, while sites with high-density and HPC applications are continuing to rely on the efficiencies of water as a heat-rejection source, but are investing more often in local storage systems.
Bill Kosik: Cloud computing has really reshaped how data centers traditionally were realized. In most instances, cloud computing moves the computer power out of the customer's facilities and into cloud computing providers. However, sensitive business-critical applications will typically remain in the customer's facilities. In certain circumstances, the power and cooling demands in a customer's data center facility could be reduced or filled in by other types of computer requirements. Conversely, the cloud computing providers' data centers are growing in power and cooling demand. This requires strategic decisions on how computer, storage, and networking systems should behave under highly varying loads; there cannot be any negative impact on the business outcome, and they must operate in a highly energy- and cost-efficient manner.
Keith Lane: I see energy efficiency as the No. 1 trend. On the electrical side, we are seeing more efficient uninterruptible power supply (UPS) systems, 400/230 V system transformers, and topologies that allow for more efficient loading of the electrical components. On the mechanical side, we are seeing increased cold-aisle temperatures, increased delta T, outside-air economizers, and hot-aisle containment. On the information technology (IT) side, the 230 V electrical systems also increase the efficiency of the servers. UPS battery technology is also improving. We are seeing absorbed-glass-mat and pure-lead batteries as well as advances in battery-monitoring systems.
Robert Sty: I would say one of the latest design trends is the reduction in UPS battery storage. With standby generator technology allowing faster start-up and sync times (in many instances, less than 20 seconds), data center managers are far more comfortable moving from 15-minute battery storage to a few minutes, or even embracing flywheel technologies.
CSE: What trends should engineers be aware of for data centers or data closets in mixed-use buildings?
Robert C. Eichelman: In a mixed-use building, there are inherent risks to a data center that aren't present in a dedicated data center facility. Steps must be taken to minimize these risks and to ensure that tenants, and the systems that support them, have the least possible impact on critical operations. To this end, all electrical and mechanical infrastructure that is required to maintain power and cooling to critical IT equipment should be dedicated to the data center. Ideally, this would include dedicated electrical services, generators, chiller plants, fuel-oil systems, and all related downstream distribution and equipment. Equipment should be located in dedicated spaces that are accessible only to authorized data center personnel.
In cases where separate electrical services are not practical, steps should be taken to ensure that faults on the tenant system do not affect the data center. This should be considered in the overcurrent protective device coordination study for the facility. Utilities that serve other tenants or the building as a whole (such as distribution piping, sanitary and roof drains, fire protection piping, electrical feeders and branch circuits, and telecommunications cabling systems) should never pass through the computer room or data center support spaces. The floor slab above the data center should be completely sealed, without any penetrations, to ensure that water does not migrate into the data center if a flooding condition were to occur on an upper floor. Security measures, beyond those that are common for a data center, should be considered at the common entrance to the facility; this could include personnel and vehicle screening, access controls, intrusion detection, and video surveillance systems. A dedicated building for a data center is always preferred.
Sty: For many of our commercial-enterprise clients, their headquarters buildings contain a main distribution facility (MDF), an independent distribution facility, and other server rooms that have similar uptime requirements to their main enterprise data centers. These requirements can drive additional mechanical, electrical, and plumbing (MEP) infrastructure for the base buildings that would not have been in the original program of requirements for the space, or not part of the original core and shell infrastructure. Our mission critical team works very closely with our office/workplace/interiors teams to help provide space planning for additional mechanical and electrical equipment. They ensure that the supporting infrastructure meets the level of uptime required by the end user.
Lane: Increased power densities and modularity of the systems. Over the years, we have seen the average kilowatt per rack increase from 1 kW/rack to more than 10 kW/rack. We are seeing much more than 10 kW/rack in some higher-density areas within the data center. Coordinating the electrical and mechanical systems as well as both the UPS battery type and code-required battery electrolyte containment/ventilation within small data closets with space limitations is critical.
Chadwick: Current generations of server or IT storage equipment can handle higher inlet-air temperatures and humidity than typical occupied spaces. These higher inlet temperatures mean that a combined HVAC system serving offices and data centers cannot be optimized for both needs. To achieve the optimum efficiencies, separate HVAC systems are needed. This has always been true, but now the higher temperatures have opened up new cooling technologies and new economizer strategies to further enhance efficiencies. The typical direct-expansion cooled computer room air conditioning (CRAC) unit is no longer the best solution in most applications.