Data center energy efficiency from new technology and stricter codes

Energy efficiency insights

• There is a growing trend toward using air-cooled chillers and refrigerant-based cooling systems in data centers to reduce water usage.
• Data centers are increasingly viewed as potential sources of low-grade waste heat, which can be integrated into district geothermal systems to enhance energy efficiency.

Respondents:

• Amanda Carter, PE, Electrical Discipline Lead, Stantec, Chicago
• Brian A. Rener, PE, LEED AP, Mission Critical Leader, Smith Group, Chicago
• William Kosik, PE, CEM, LEED AP, Lead Senior Mechanical Engineer, kW Mission Critical Engineering, Chicago

Courtesy: WTWH Media

How has ASHRAE Standard 90.4: Energy Standard for Data Centers: Energy Standard for Data Centers (or other editions) affected your work?

William Kosik: In the last six months to a year, the municipalities where our projects are located have started using the latest version of the International Energy Conservation Code (IECC). Many municipalities have adopted their own energy efficiency code based on the IECC. The codes require that the permits for data center projects includes calculations for the mechanical load component (MLC) and electrical load component (ELC). Some of these municipalities have established MLC and ELC values that are more stringent than the requirements of the 90.4 standard.

What unusual systems or features are being requested to make data center projects more energy efficient?

Amanda Carter: Reducing overall water usage is becoming a bigger focus of the data center industry, especially in areas with limited or strained water capacity. This is leading to the use of mechanical systems that, until recently, have been less popular in the data center world, including air-cooled chillers and refrigerant-based cooling systems. Such moves have a negative impact on previous data center goals to attain a power usage effectiveness (PUE) rating as close to 1.0 as possible. PUE is the ratio of total power input to power used for IT loads, meaning a facility with a PUE close to 1.0 is delivering most of its power directly to the IT loads. These low water usage mechanical systems often have a higher power requirement than their higher water usage equivalents, pushing the PUE up.

Brian A. Rener: With dedicated warm-water cooling systems for HPC in heating dominated climates, there is an opportunity for integration into district geothermal systems. As these systems are always exporting heat, they can make a smaller geothermal field more effective or allow it to serve a larger community. Pumping to geothermal heat exchangers can be done as a side stream with minimal impact to operations. To the extent heat can be exported that is less energy and water used for systems cooling.

Figure 1: With a generator power capacity of 80MW, the Digital Realty Data Center Campus in Franklin Park, Illinois, provides co-location and peering services. Courtesy: Stantec and Digital Realty.

What types of sustainable features or concerns might you encounter for these buildings that you wouldn’t on other projects?

Amanda Carter: Data center campuses are often built in less populated areas due to the amount of land required. This often leads to designing around dark sky requirements and completing noise studies to ensure we aren’t disturbing adjacent properties.

How has the demand for heat recovery technology influenced the design for these kinds of projects?

Brian A. Rener: Data centers and HPCs always operate in cooling and export heat to the environment. Instead of thinking of these facilities as separate entities, the best application considers them as a resource for low-grade waste heat in a heating dominated climate. Whether this heat is exported indirectly via heat exchangers as low-grade heat to be utilized by other buildings for heating with heat recovery chillers or if the low-grade heat is utilized to temper a geothermal loop and extend its capacity for winter heating. The application lowers energy use and saves water as compared to a standalone building.

How do you prioritize energy-efficient technologies in data center design to reduce environmental impact while maintaining performance?

William Kosik: As engineers in the building design and construction industry, we are responsible for understanding the aspects of data center design that impact electricity and water consumption and other related environmental factors. When we work with our clients, even those who we have already designed data centers, part of our early design work includes feasibility studies and analyses on water and energy consumption. Depending on the client, and type and location of data center, some of the recommendations with be included in the project and will ultimately end up in the design standards.

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