Increased Energy Efficiency Using Passive Measures in a 375 Watt Per Square Foot Data Center

Paul L. Leonard, LEED® AP, KlingStubbins
Steve Spinnazola, RTKL Associates, Inc.

RTKL | KlingStubbins, a joint venture, is working with the U.S. Army Corps of Engineers, Baltimore District, to deliver a master plan, full A/E/I design services, as well as site, civil, and landscape design for a new large-scale, secure government headquarters campus. The 2,400,000-gross-square-foot (GSF) campus will house secure and redundant services for multiple buildings and support facilities, including an office building (housing operations facilities, conference and training functions, auditorium, multiple food service venues, fitness center, and library), data center, central utility plant, visitor control center, and the remote inspection facility, with parking for 5,100 cars in structured parking.

There are many lessons that, we, as a company and as an industry, have learned in the evolution of the design of chemistry and biotechnology laboratories that can be leveraged in the design of optimized data centers. Some of these techniques include airflow management and control measures, airflow modeling to verify process containment, and optimizing service temperatures to efficiently meet the process use.

With the increased focus on energy use intensity in data centers, we will communicate how the cross pollination of laboratory HVAC design techniques have been utilized to achieve a design power utilization efficiency (PUE) of below 1.4 for a 9.2 megawatt (MW) data center. Actual operating PUE's will also be presented as a real time operating metric. The measures employed are passive server cabinet low pressure drop chimneys, computational fluid dynamic airflow modeling in underfloor plenum and return air ceilings, medium grade (52°F) chilled water supply, increasing cooling plant efficiency, waterside economizer, reduced fan power, increased return air temperatures to cooling units, central humidification control, chilled water storage, and rotary UPS to support cooling water distribution.

The base design for the data center was 150 watts/square foot (sq. ft.). The measures above achieved a load density of 375 watts/sq. ft. densifying the original design criteria over selected areas of the data center ,while lowering the PUE and increasing cooling plant efficiency.

Active chilled beams serving 2 million sq. ft. of office areas were also served from the data center cooling systems, raising the energy efficiency of the entire facility.

The facility as a whole is tracking LEED Silver. Aspects of the "Data Center Environmental Performance Criteria" (developing sustainability standard for data centers) will be presented. KlingStubbins is a working member of this committee and will present how the development of this standard is driving data center design to a higher performance standard.


Paul L. Leonard, PE, LEED AP, principal and KlingStubbins' director of engineering, focuses on integrated engineering system design. He is also responsible for all mechanical, electrical, and plumbing (MEP) engineering, directing multiple teams and sustainable solutions for projects. He is also leading efforts in system modeling; optimizing system operation, energy use, and thermal comfort. A 15-year member with the firm, Mr. Leonard most recently held the position of engineering design principal, where he worked with clients establishing global engineering criteria and conceptual engineering direction for major projects. His experience encompasses research laboratories, pharmaceutical production facilities, central utility plants, mission critical facilities, and office spaces. His client portfolio includes Merck & Co., Pfizer, Johnson & Johnson, sanofi-aventis, Amgen, JPMorgan Chase, DuPont, Vanguard and IBM. Mr. Leonard has presented on energy conservation and system solutions at industry associations such as 7x24, ASHRAE, the International Society for Pharmaceutical Engineering (ISPE), and Tradeline. He has further shared this knowledge with publications like Pharmaceutical Engineering, HPAC Engineering, and Pharmaceutical Processing. Mr. Leonard received his Bachelor of Science in mechanical engineering from Drexel University.

Steve Spinazzola, as the firmwide director of RTKL's MEP studio, offers more than 29 years of experience in both mechanical design and project management on a wide range of mission critical, office, educational, health and science, retail, and institutional projects.

Mr. Spinazzola specializes in project management and HVAC design and is registered as a professional engineer in more than 33 states. He is also the co-inventor of an advanced data center cooling technology that has six patents and is currently being deployed in data centers all over the world. His client portfolio includes IBM, Verizon, eBay, Johns Hopkins University, Cleveland Clinic, INTELSAT, and Blue Cross Blue Shield. Mr. Spinazzola is a LEED Accredited Professional, and he received his Bachelor of Architectural Engineering from Pennsylvania State University.