Analyzing data centers: sustainable buildings/energy efficiency

Data is the lifeblood of any business or organization—which makes a data center a facility’s beating heart. Here, engineers with experience on data center projects show how to succeed on such facilities, and how to keep your finger on the pulse of data center trends in regards to sustainable buildings/energy efficiency.

By Consulting-Specifying Engineer April 27, 2017


  • Robert C. Eichelman, PE, LEED AP, ATD, DCEP, Technical Director, EYP Architecture and Engineering, Albany, N.Y.
  • Karl Fenstermaker, PE, Principal Engineer, Southland Engineering, Portland, Ore.
  • Bill Kosik, PE, CEM, LEED AP, BEMP, Senior Mechanical Engineer, exp , Chicago
  • Kenneth Kutsmeda, PE, LEED AP, Engineering Manager—Mission Critical, Jacobs, Philadelphia
  • Keith Lane, PE, RCDD, NTS, LC, LEED AP BD&C, President, Lane Coburn & Associates LLC, Bothell, Wash.
  • Brian Rener, PE, LEED AP, Senior Electrical Engineer, SmithGroupJJR, Chicago
  • Mark Suski, SET, CFPS, Associate Director, JENSEN HUGHES, Lincolnshire, Ill.
  • Saahil Tumber, PE, HBDP, LEED AP, Senior Associate, Environmental Systems Design, Chicago
  • John Yoon, PE, LEED AP, Lead Electrical Engineer, McGuire Engineers Inc., Chicago

CSE: Energy efficiency and sustainability are frequent requests from building owners. What net zero energy and/or high-performance systems have you recently specified on data center buildings (either an existing building or new construction)?

Eichelman: The strategy to reach net zero energy first requires that the IT equipment and the supporting infrastructure use as little energy as possible. High-efficiency UPS and distribution topologies that result in high load factors, such as distributed and block-redundant systems, will drive down energy use. Economizers, high-temperature chilled water, containment systems, and containerized data center solutions will also help to increase efficiency. Efficiency gains in the IT system, such as through virtualization, offer the biggest opportunity to reach net zero, as these will not only reduce the power requirements of the IT equipment but the supporting infrastructure as well. To reach net zero, the remaining power requirement must be offset by renewable energy sources. These can consist of solar PV, wind, or fuel cell systems, although they can be cost-prohibitive. On a recent project, a data center and an adjacent office building were designed concurrently. To help achieve net zero energy for the office building, the waste heat from the data center IT equipment was reclaimed through the use of a heat pump to heat the office building and lower its total energy consumption.

CSE: What suggestions or design tips do you have for designing data closets in existing buildings to help achieve the energy efficiency goals of the building owner?

Rener: The buildings’ primary HVAC systems are often tuned to take advantage of changing occupancy, yearly cycles, and outside-air economization. However, data closets or small computer rooms in buildings have 24/7 constant loads. The cooling systems for these closets may require a dedicated system or cooling loop.

Fenstermaker: Try to recover the heat from the data closet for use in heating the building when needed. If the building does not use a water-source heat pump system, a VRF system with heat-recovery abilities may be a good application for a retrofit project.

CSE: What types of renewable or alternative energy systems have you recently specified to provide power for such projects? This may include photovoltaics, wind turbines, etc. Describe the challenges and solutions.

Kutsmeda: Data centers are large consumers of energy. Because the energy provided per footprint is low with PVs and wind turbines, they tend to be used more for the data center general house loads (lighting, office/maintenance spaces, and supplemental cooling) instead of for critical load. Fuel cells are another alternative option Jacobs has used for providing power to the data center. Fuel cells are an efficient, clean energy source that can be grid-independent. Because fuel cells are direct current (DC) voltage-based, they tie into and work well with DC voltage plants and DC voltage distribution systems. Jacobs is also designing more microturbine systems for data centers, especially in areas with high electrical rates. Not only can microturbines be used to power data centers, they can also be used to cool through the use of an absorption chiller.

Kosik: I was on a team that applied for a patent for a control system that combines renewable energy (wind and photovoltaic) with a hydrogen fuel cell. The idea is the renewable power electrolyzers make hydrogen, and when possible, the fuel cell uses the hydrogen to power parts of the data center. There are lots of creative ideas that are in development that will continue to drive the need for more efficient renewable energy sources and storage of energy.

Tumber: I have used fuel cells as the primary means of power in a data center project. The solid oxide fuel cells use natural gas and convert it to electricity using an electrochemical process. We did a TCO (total cost of ownership) analysis, and the fuel cell was the better option as compared with other technologies. Another advantage was clean power and lower carbon dioxide emissions. The biggest challenge was to receive AHJ approval. The AHJ initially considered fuel cells as combustion devices similar to gas-fired boilers and generators and wanted us to comply with the associated codes and standards. We had to explain the technology and design to them, and it took some time to get them on board.

CSE: What are some of the challenges or issues when designing for energy efficiency for data centers?

Rener: There is always a balance in designing for energy efficiency and maintaining continuous uptime. We have worked with certain research-based clients who are more willing to push the envelope on energy efficiency and be on the “bleeding edge,” Tier I reliability design, while others are more comfortable using established best practices that still yield significant energy savings. The benefit that SmithGroupJJR has had in working with the bleeding-edge clients is that we are able to understand the challenges in aggressive energy-efficient design, work through them in an operating environment, and then apply those lessons to our clients who are less risk adverse based on actual performance.

Tumber: Owner flexibility and buy-in are critical to meet energy efficiency goals that are aggressive. It can occasionally be challenging to design a data center that has industry-leading metrics across the board for criteria, such as availability, resiliency, PUE, time to market, cost per megawatt, and more. If energy efficiency is paramount, then other criteria typically require some degree of relaxation. For example, to deploy high-performance equipment to meet energy efficiency goals, the project cost per megawatt could increase. Reaching a sensible compromise that is acceptable to all stakeholders can sometimes be challenging. On a related note, always consider the total cost of ownership as energy efficiency and usage alone might not tell the complete story.

CSE: How does designing for energy efficiency impact operational effectiveness?

Rener: On the electrical side, using 415/240 V systems instead of 208/120 V improves efficiency but can introduce increased arc fault energy levels and may result in needing special operational procedures for changing out electrical equipment. Design and specification alternatives are available to minimize this safety concern for operational effectiveness.

Kosik: It shouldn’t. Energy efficiency and operational effectiveness are not mutually exclusive. It just requires a superior design, commissioning, and operations training. The design engineer needs to know where reliability and energy use intersect and make sure things like part-load operation and sequencing of mechanical and electrical systems are done.