The ability to meet a fast-track construction schedule and a 30% savings in electricity costs were critical factors in the selection of a Daikin Modular Central Plant for a new community library and recreation center in Queen Creek, Arizona. Those impressive energy savings were in turn a contributing factor in the building's anticipated LEED (Leadership in Energy and Environmental Design) Silver certification by the U.S. Green Building Council. (At the time of this article, the Queen Creek Library was registered as LEED NC 2.2 with the USGBC.)

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The Queen Creek Branch Library and Recreation Annex was designed and built through a partnership between the Town of Queen Creek and the Maricopa County Library District. The 47,000 square foot, one-story building houses a library, three meeting rooms and a large recreation center with six classrooms and two multi-purpose rooms in a strikingly modern masonry and steel building. The Daikin Modular Central Plant and cooling tower are situated in an enclosed service yard next to the building.

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The Daikin Modular Central Plant (MCP) is a pre-engineered, pre-assembled module that combines a chiller, boiler, cooling tower, pumps and interconnecting condenser water piping. This integral module is a low-cost alternative to site-built central plant that reduces installation time and site assembly time.

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Lee Councilor, facilities manager with the Town of Queen Creek, was sold on the Daikin Modular Central Plant featuring Daikin's frictionless chiller with a magnetic bearing centrifugal compressor after visiting an MCP installation nearby.

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"When we saw that we could achieve a 30 percent energy savings over traditional plants, choosing a Daikin MCP was a no-brainer. We watched the Daikin plants operating at a Scottsdale high school and saw how they performed fully loaded. After that, we opted for the Daikin central plant with the frictionless chillers rather than a traditional central plant, which would have had an immense energy draw," Councilor says.

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When the mechanical contractor, Tri City Mechanical of Chandler, Arizona, joined the project, they saw an immediate opportunity to recommend the Daikin Modular Central Plant. "We were familiar with the Daikin technology on other projects and knew the energy-savings potential for the Queen Creek facility," says Pete Menconi, chief engineer with Tri City Mechanical.

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Electrical Costs Savings of 30% a Month

Councilor says the energy savings of the Daikin Modular Central Plant in kilowatt hours over traditional central plants has been impressive. "Since the regular operation of the plant, our average electrical bill is approximately $3,700 per month, representing at least a 30 percent savings over a similar facility with a traditional central plant." He is particularly impressed with the low start-up energy required for the frictionless centrifugal chillers. "We're seeing a large cost reduction over traditional central plants in our community. A traditional chiller has a large startup current, using between 300 and 500 amps. With this unit, it's only 15 to 19 amps."

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The HVAC system at Queen Creek uses a four-pipe system. The Daikin Modular Central Plant features a configuration of one Daikin Model WMC frictionless chiller, containing two 75-ton compressors. Councilor says: "With the two compressors, if one happens to go down, we can run the other one and still keep some cooling going. In older systems, you have to take the whole chiller down."

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Councilor's facility staff appreciates that the Daikin WMC Chiller's magnetic bearing centrifugal compressor eliminates the need for oil handling equipment, offering savings on maintenance and repair costs compared to traditional centrifugal compressor chillers.

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Without the loss of friction suffered in traditional centrifugal compressors chillers, the frictionless chiller is ultra efficient. In addition, the frictionless magnetic-bearing compressors eliminate the metal-to-metal contact noise of conventional bearings, making the Daikin WMC frictionless chiller the quietest centrifugal chiller in the industry with sound power levels as low as 77 dBA per ARI Standard 575.

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