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“Periodically, Carrier Corporation presents Regional Environmental Leadership Awards to companies that have invested in energy-efficient projects, which provide innovative, environmentally-sound design solutions for their commercial buildings,” said Don Carlson, Carrier’s Northwest region commercial service area manager. “Plaza Towers is a great example of green building design.”
In 2002, Downtown Plaza Towers Associates reviewed the Plaza Towers’ HVAC system, which consisted of two 30-year-old chillers and integrated boilers. While the old chillers still ran reliably, according to Patricia Sillix, RPA, Downtown Plaza Towers Associate’s vice president of asset management and past-president of BOMA’s Sacramento chapter, they realized that newer technology would undoubtedly provide more energy efficiency.
“We knew that if we could keep our HVAC system’s operating costs down, we’d have an advantage in our competitive commercial real estate market,” explained Sillix. “To be able to offer our tenants office space with high-quality, modern building features, at a reasonable price, is very important.”
In the end, Downtown Plaza Towers Associates decided to replace the building’s two aging chillers with two new 740-ton 19XRV Evergreen centrifugal chillers with factory-installed, unit-mounted variable-frequency drives (VFDs). According to Carrier Service sales representative Chris Countryman, the 19XRV’s VFDs maximize the chillers’ efficiency by allowing cooling to be precisely matched to the building load. The VFDs reduce power consumption by slowing the speed of the compressor motor when less cooling is needed and when lower inlet condenser water temperature is available.
“Carrier’s 19XRV Evergreen chiller meets the key requirements of today’s customers who demand high efficiency equipment to contain their operating costs, and deliver quick investment payback,” said Countryman. “In many cases, with the 19XRV’s price and performance, building energy analysis results in a two-year payback or less. This is an especially attractive option in climates like Sacramento, with wide outdoor temperature variations, where part-load conditions occur frequently.”
“With our old chillers, the best we could run was 0.9 kW/ton. With our new chillers, we’re reaching 0.38 kW/ton,” said Troglia.
An added benefit of Carrier’s 19XRV chiller, Countryman says, is its usage of chlorine-free, non-ozone depleting HFC-134a refrigerant. Also, by using HFC-134a, instead of water, to cool the VFDs, safety issues inherent with circulating water through VFD cabinets with 460-volt electrical power are also alleviated, he explained.
One requirement for the project, according to Troglia, was that the new chillers integrate with two new boilers that were being installed.
“The Carrier Service team provided engineering, design, and fabrication support; installed the new chillers, boilers, and seismic platforms; and handled all the associated piping and controls,” said Troglia. “Thanks to our new Carrier Comfort Network (CCN), I can now also monitor and control our completely integrated HVAC functions from one location with a personal computer.”
The Plaza Towers received Carrier’s award during the Building Owners and Managers Association (BOMA) International’s annual conference and The Office Building Show, held at the San Francisco Marriott and Moscone Center.
Publication date: 08/11/2003