Data center design: Automation and controls
In the information age, data centers are one of the most critical components of a facility. If the data center isn’t reliable, business can’t be done. Automation and controls play a key role.
- Kevin V. Dickens, PE, LEED BD+C, Mission critical design principal, Jacobs Engineering, St. Louis
- Terrence J. Gillick, President, Primary Integration Solutions Inc., Charlotte, N.C.
- Bill Kosik, PE, CEM, BEMP, LEED AP BD+C , Principal data center energy technologist, HP Technology Services, Chicago
- Keith Lane, PE, RCDD, NTS, RTPM, LC, LEED AP BD+C, President/CEO, Lane Coburn & Associates LLC, Bothell, Wash.
- David E. Wesemann, PE, LEED AP, ATD, President, Spectrum Engineers Inc., Salt Lake City
CSE: What factors do you need to take into account when designing automation and controls for a data center?
Wesemann: The ability to seamlessly integrate all mechanical and electrical controls, monitoring, and metering into a single platform, and one that has informative and user-friendly dashboards, charts, and graphics.
Dickens: The greatest factor in the modern data center is figuring out how to match infrastructure supply to IT demand in real time. This falls under the umbrella of what is euphemistically called data center infrastructure management (DCIM), but the definition of what exactly is needed under that umbrella is as varied as the number of vendors hawking it. The technology is there on both sides (IT and facilities), but bridging the gap and using the information intuitively is still in the defining stages. When designing today, one has to work to advance the science of DCIM without introducing undue risk.
CSE: According to a recent poll conducted by Consulting-Specifying Engineer, the automation and controls within a mission critical facility were the most complex issue. Do you agree? Why or why not?
Gillick: I agree. The automation systems can vary from simple to extremely complex depending on the Tier rating or the criticality of the structure, be it a hospital or a data center. When owners were using direct expansion cooling systems and other types of non-central plant cooling systems, the associated direct digital control (DDC) systems were relatively straightforward and quite suitable for those cooling systems. With the increasing deployment of large mechanical chilled water plants in data centers over the past five years, there has been a big push to use very complex, robust programmable logic controllers (PLCs) in these central plants. Additionally, we are finding facilities with hybrid control systems comprising both DDC and PLC controls systems within the facility, incorporating an integrated and seamless system front end. DDC systems are typically deployed within administrative and other non-critical areas, PLCs to run the central utility plant, and supervisory control and data acquisition (SCADA) systems, power monitoring systems, and branch circuit monitoring electrical power at the equipment rack. In these facilities, we have to validate that these systems are communicating with each other. Moreover, there is a significant cost differential between DDC and PLC systems; therefore, a first-cost versus equipment lifecycle cost analysis must be done prior to adopting a controls strategy.
Dickens: Agree. To optimize the energy use of a data center, you need to be able to respond to varying loads. In legacy data centers the relationship between what the server is drawing and the amount of heat being rejected from the HVAC system is two to three times removed. The solution is obvious—you need to sync demand and response. And while ASHRAE has moved us in the right direction by encouraging the relocation of the temperature sensors from the CRAC return air inlet to the IT servers inlet, we are still reacting to a symptom (an increase in space temperature), not the source of the problem.
Wesemann: I agree with this because many automation and controls systems are designed for either good mechanical controls, or good electrical monitoring and controls, but not both. They do one or the other very well, then rely on custom interfaces and programming to get the other. It is difficult to find systems, vendors, and installers who do both mechanical and electrical monitoring and controls very well.