Underfloor-air distribution system supports mission of FedEx® Institute of Technology
The University of Memphis’ FedEx Institute of Technology is a joint collaboration between the University of Memphis and FedEx Corporation. The $23 million facility is designed to advance interdisciplinary research and introduce a new generation of highly skilled graduates to the workplace. The technically advanced building features some of the most sophisticated information-technology tools available to provide an environment in which students and researchers help solve real-world problems by incorporating businesses and leading organizations into the learning and research process.
The Institute is the recipient of several prestigious awards, including Buildings Magazine’s 2004 New Construction Award, the AIA Tennessee Award of Merit and the ASHRAE Region VII Award for Institutional Buildings Flexibility key to building design As architects set about creating a design for the facility, flexibility was a key component of their discussions with the building owner – flexibility to keep pace with rapid changes in technology, and flexibility to change interior spaces according to the particular needs of educational projects.
Flexibility key to building design
As architects set about creating a design for the facility, flexibility was a key component of their discussions with the building owner – flexibility to keep pace with rapid changes in technology, and flexibility to change interior spaces according to the particular needs of educational projects.
To accommodate changes in technology and support the flexibility of function, the design team turned to the Johnson Controls FlexSys™ underfloor-airdistribution system. The FlexSys system provides access to voice, data and power systems, while delivering conditioned air throughout the upper floors of the building without being impacted by changes to the floor plan.
“The FlexSys system is an integral part of the project design,” says Rebecca Courtney, of Memphis-based Looney Ricks Kiss, the architectural firm that partnered with The Crump Firm, Inc., also of Memphis, to design the building. “We based our decision to support the installation of an underfloor system on the need for programmatic flexibility, and the ability to handle changes in technology. That’s a mission of the building – to stay in the forefront of technology and be flexible.”
Inside the 95,000-square-foot facility, classrooms, computer labs, research centers, collaborative areas, meeting rooms, and exhibit spaces greet visitors. The four-story building also includes a cyber café and a 200-seat, fully interactive auditorium called “The Zone,” which features videoconferencing capabilities, wireless Internet access and a sophisticated audience-response system.
Designed to teach the newest technologies using the most advanced techniques, the research and educational facility incorporates Wi-Fi capabilities and a Voiceover Internet Protocol network, as well as plasma-screen video-output throughout, and a 2.5 gigabit Internet connection to Oak Ridge National Laboratory. “That’s a lot of technology with connections that need to be out of sight, but easily accessible, so they can be updated as new technologies develop,” says Jim Hellums, University of Memphis assistant vice president for the physical plant. “We decided an underfloor system would enable us to run the electronic cables and wires under the floor, while providing better control over air-conditioning to spaces that would probably be reconfigured on a regular basis.”
According to Jeff Haltom, project manager with the mechanical design firm, Shappley Design Consultants, Inc., one of the most difficult design challenges was the fact that nobody knew exactly how spaces within the building would be used. “We asked how many people would be in each room and how much equipment and lighting they would require. The answer was, ‘nobody knows.’ A room could hold 50 people or 5. It could be filled with computers, or there might be no computers.
“That kind of information almost dictated an underfloor system,” continues Haltom. “We needed a system that was very flexible – one that could handle a small load, a large load, or anything in between, depending on projects that were in progress. That’s the benefit of an underfloor system. It can adapt to changes in load easily and efficiently.”
The FlexSys system offers the flexibility the building requires. “It gives the building owner a lot of versatility in how they use the space available to them, and how they partition it,” says Jeff Smith, owner of Morgan and Turner, mechanical contractor for the project. “It’s really quite simple, like the The underfloor system provides cleaner ceilings that feature exposed structure. “The Johnson Controls FlexSys system made our design work even easier because it does not require a fanpowered variable air volume box overhead to provide perimeter heating and cooling.” Jeff Haltom Project Manager Shappley Design Consultants, Inc. plug-and-play components of a computer. If you want something new or want to configure the space for different uses, you simply take boxes out or put boxes in at your leisure. The system is extremely versatile for a research environment like this one, which is characterized by churn.”
Hellums agrees. “We envision this building acting like an incubator for research, with the ability to be reconfigured as the research demands. An underfloor system enables us to make those kinds of changes easily and gives us better control over the airconditioning going into those changing spaces. All we need to do is add or take away diffusers, and the variable-flow system compensates for increases or decreases in load.”
Simplicity of the FlexSys system delivers savings
Haltom likes the simplicity of the system’s layout. “We probably cut our design time by a factor of four using an underfloor system,” says Haltom. “We didn’t have to worry about getting ductwork, piping, and boxes around architectural constraints and working with other trades, coordinating our work with the location of plumbing, sprinklers and electrical conduits, etc.”
“The Johnson Controls FlexSys system made our design work even easier,” says Haltom, “because it does not require a fan-powered variable air volume box overhead to provide perimeter heating and cooling.” Instead, the system offers a fan-powered, electric-heat, perimeter system that eliminates the need for an overhead perimeter system, something required by some underfloor systems. “Johnson Controls kept everything underfloor, eliminating an overhead system entirely and all the constraints that go along with it, adds Haltom.”
Ductwork, too, was all but eliminated. The air-handling unit for each floor is located against one edge of the building, raising concern as to whether equal static pressure could be maintained throughout the floor plenum. Shappley decided to run three ducts per floor to ensure that air is delivered to the opposite edge of the building undisturbed by cables or anything else that would interfere with it. “Ductwork is almost non-existent when you compare an underfloor system to an overhead system. We have three un-insulated duct runs of about 45 feet each. That might compare to 20 times as much duct for an overhead system,” states Haltom.
“Less ductwork brings advantages like reduced mechanical costs of a job,” explains Smith. “I would estimate the underfloor system resulted in designtime savings of 15 to 18 percent. It also gives architects and designers more room to work, because it doesn’t take up any ceiling space. And, because the floor serves as the conduit for conditioned air, it is easier for an underfloor system to maintain a uniform temperature throughout the space.”
“One of the things that underfloor air allows you to do is to change the actual floor-to-ceiling height in the building,” says Hellums. “We were able to shrink the building height as much as three feet by putting the air-conditioning underneath the floor, and reducing the requirement for interstitial space above the ceiling. That was a big plus that really helped sell the project. When combined with less ductwork, the underfloor system offered appreciable cost savings.”
Courtney estimated those savings to be approximately $200,000, adding, “From a purely aesthetic standpoint, the underfloor system gave us cleaner ceilings that feature exposed structure. It also helped with the acoustical performance of the space, because underfloor systems are so much quieter than traditional overhead systems. Air blowing through the flooring system cannot be heard as easily as air blowing through traditional overhead ductwork.”
Variable-air-volume control ensures occupant comfort
“One of the things that we liked about Johnson Controls was the fact that the FlexSys system offered automatic variable-air-volume control in the floor diffusers,” says Hellums. “Many competing systems use manually operated swirl diffusers that have the potential to under-cool or over-cool a building, when it is not occupied. We wanted a system that would allow us to control temperature with a thermostat.”
“We also appreciated the fact that the FlexSys system works with other manufacturers’ controls. In this case, we were able to work with Johnson Controls and marry their wireless thermostats with the FlexSys system, eliminating the need for lowvoltage control wiring that can limit the flexibility of the system. Now, individuals in the building can adjust the temperature in their work areas by clicking the appropriate icon on their computer and sliding the bar up or down. It’s that simple and that efficient.”
Comfort is also maintained because the underfloor return-air system removes most of the heat generated by the many computer systems throughout the building. “Ceiling returns efficiently remove this heat as the warm air rises away from building occupants. As a result, rooms don’t become overheated, and that has been a big plus here in this technologyfilled environment, adds Hellums.”
The FlexSys system at the FedEx Institute is paired with a YORK MAXE™ 800-ton centrifugal chiller with an OptiSpeed™ variable-speed drive. “When you combine the efficiency advantages of both the underfloor-airdistribution system and the variablespeed drive centrifugal chiller, the operating cost of the total system is lowered. With the FlexSys system we’re able to deliver 65 degrees Fahrenheit air compared to a conventional overhead system’s 55°F air, potentially saving 15 percent on refrigeration energy, and, thanks to lower supply-air static pressure requirements we could see fan energy savings of 30 percent,” says Mike Slattery, Johnson Controls sales engineer.
Sealing plenum critical to system efficiency
The system was not without its challenges. “The biggest issue was making sure the underfloor plenum was sealed,” says Hellums. “The other was keeping it clean of construction dust, as work progressed above the floor.”
“We were constantly concerned with the leakage rate: the amount of air that leaks through cracks in the floor and around any electrical boxes or the air terminals themselves, adds Smith. “It was critical to make sure the building envelope was sealed, and that all the junction boxes had gasketing and were sealed properly. We had a Johnson Controls project manager on site who helped us with that.”
Project management is an important part of the Johnson Controls offering. “Underfloor-air is a new type of system to most contractors,” explains Slattery. “Although it’s not rocket science, the system requires a contractor to be aware of certain things, if the system is to perform to expectations, things like coordination issues and the sealing of penetrations into the plenum, including pipes, wires and structural elements. By including project management in our offer, we think we are ensuring a better installation and a system that operates more efficiently for our customer.”