Designing efficient data centers: Codes and standards
Doug Bristol, PE, Electrical Engineer, Spencer Bristol, Peachtree Corners, Ga.,
Terry Cleis, PE, LEED AP, Principal, Peter Basso Associates Inc., Troy, Mich.
Scott Gatewood, PE, Project Manager/Electrical Engineer/Senior Associate, DLR Group, Omaha, Neb.
Darren Keyser, Principal, kW Mission Critical Engineering, Troy, N.Y.
Bill Kosik, PE, CEM, LEED AP, BEMP, Senior Engineer – Mission Critical, exp, Chicago
Keith Lane, PE, RCDD, NTS, LC, LEED AP BD&C, President, Lane Coburn & Associates LLC, Seattle
John Peterson, PE, PMP, CEM, LEED AP BD+C, Program Manager, AECOM, Washington, D.C.
Brandon Sedgwick, PE, Vice President, Commissioning Engineer, Hood Patterson & Dewar Inc., Atlanta
Daniel S. Voss, Mission Critical Technical Specialist, M.A. Mortenson Co., Chicago
CSE: Please explain some of the codes, standards, and guidelines you commonly use during a data center’s design process. Which codes/standards should engineers be most aware of?
Lane: NFPA 70: National Electrical Code (NEC) is used extensively during the design of a data center. Load calculations, equipment clearances, grounding requirements, fault current, selective-coordination studies, arc flash studies, Neher-McGrath studies, conduit and wire sizing, and numerous other requirements are dictated by NFPA 70.
Keyser: While the NFPA is a widely accepted association for design standards, it is still necessary to know the code requirements of the local authority having jurisdiction (AHJ). The client’s underwriter’s requirements are also important.
Bristol: In addition to specifying equipment that meets UL requirements and system designs to comply with the NFPA, the International Building Code (IBC), International Energy Conservation Code (IECC), and ASHRAE requirements, data centers are frequently designed to some level of Telecommunications Industry Association (TIA) criteria and the Uptime Institute’s Tier rating system.
Voss: The actual codes used for a given project depends on the country and geographic location of the data center. A meeting with the AHJ prior to starting the design of a project is always beneficial. Many of the standards are determined by the owner, and we are more than happy to vet them or suggest additional standards. A guideline that I follow is to train myself on the electrical/mechanical design and associated major equipment functionality to understand the major electrical and mechanical sequence of operations.
CSE: What are some best practices to ensure that such buildings meet and exceed codes and standards?
Voss: A complete and thorough review of all major equipment submittals to ensure all equipment meets local and any national codes. Keeping a watchful eye on the equipment installation and associated electrical and mechanical supporting infrastructure.
Keyser: Our approach is to know the locally adopted codes for a particular site. By understanding any unique features for that jurisdiction, we can incorporate those and adapt the needs of our clients to those codes. Then, in the very early stages of design, meet face to face with the building code enforcement officer and the fire marshal. Another key component is understanding the client’s underwriter’s requirements. These may often exceed code, and it’s important for the entire team to be on the same page from the start. This will save design rework and potential delays in the project.
CSE: How are codes, standards, or guidelines for energy efficiency impacting the design of such buildings?
Bristol: For areas that enforce strict energy codes, some systems traditionally employed for data centers aren’t even available for use due to their inability to meet those codes, so the menu of systems available to the building owner is limited.
Lane: Designing data centers that are continually more efficient is the goal. The data centers’ efficiency is driven by financial reasons. Power-usage effectiveness is a metric used to determine the energy efficiency of data centers. A decade or so ago, data centers would typically have a PUE of 2 or greater. Now we see PUEs in the range of 1.2 or less.
Voss: Almost all lighting fixtures are now a type of LED, and the mechanical equipment is being furnished with premium energy-saving motors and variable frequency drives. The electrical transformers are available in models that are highly energy efficient. The implementation of these and other items increase the building’s energy efficiency.
CSE: What new code or standard do you feel will benefit data centers? This may be a code that your authority having jurisdiction has not yet adopted but will directly impact your work in the future.
Voss: For data centers in Chicago, when the AHJ amends the local code to include premanufactured branch cable sets and liquid-tight flexible metal conduit that is longer than 6 ft under raised-access floors.
Bristol: UL is developing a new standard, UL 3223, which will serve as the basis for a new data center certification program. The motivation is apparently the burgeoning proliferation of cloud computing and the perceived need to create a standard that can be implemented across multiple sites to assure minimum requirements are met. Some data center operators are already looking at certifying their facilities to this new standard.
Peterson: There is a renewed push for ASHRAE 90.4: Energy Standard for Data Centers to be adopted, and we are currently making sure that we are aware of what it is asking to be calculated. Additionally, The Green Grid has presented more comprehensive ways of showing data center sustainability along with the tools to accurately measure and improve. These knowledge leaders, among others, contribute to educating those in the industry to improve how data center operators view their facilities.
CSE: How will updated codes and standards (e.g., ASHRAE 90.4) impact decision-making for new and existing data centers?
Kosik: ASHRAE 90.4 gives the engineer a completely new method for determining compliance with the energy standard. New terminology is introduced for demonstrating compliance: design and annual mechanical-load component (MLC) and electrical-loss component (ELC). ASHRAE is careful to note that these values are not comparable to PUE and are to be used only in the context of ASHRAE 90.4. The standard includes compliance tables consisting of the maximum load components for each of the 19 ASHRAE climate zones. Assigning an energy efficiency target, either in the form of design or an annualized MLC to a specific climate zone, will certainly raise awareness to the inextricable link between climate and data center energy performance. Since strategies like using elevated temperatures in the data center and employing different forms of economization are heavily dependent on the climate, an important goal is to increase the appreciation and understanding of these connections throughout the data center design community.
Voss: Updated codes and standards help drive manufacturers to design and fabricate more energy-efficient equipment and systems.
Peterson: As the standards are adopted, they will drive data center providers to make improvements in not just the equipment selections but also in how the mechanical systems are operating across wider ranges. Scenarios for low-load conditions to high-load, and specialized zones will need to be planned ahead to match the need for flexibility while still being able to comply. Also, as ASHRAE updates and releases their “Datacom” book series, we adjust our recommendations for clients.
CSE: Give an example of a project that conflicted with what the building owner wanted and certain codes and standards. How was this situation resolved?
Bristol: Although emergency power-off (EPO) systems to turn off power to data center areas in an emergency have always been mandated, now codes allow that if a facility meets certain conditions, the EPOs may be eliminated. Many data center operators see the EPOs as an unacceptable risk of inadvertent power shutdown and push to have these eliminated from the facility. It’s the design team’s duty to inform the owner that this can never just be done unilaterally and describe what the conditions are under which the facility can go without EPOs.