SAN FRANCISCO, June 30 – As part of its continuing celebration of the 100th anniversary of modern air conditioning by its founder, Dr. Willis H. Carrier, Carrier Corp. today recognized an energy-efficient heating, ventilating, and air conditioning (HVAC) investment in a 14-story, two-tower, Sacramento office building complex, with a Carrier Regional Environmental Leadership Award.
The award was presented to Plaza Towers, Sacramento, during the Building Owners and Managers Association (BOMA) International’s Annual Conference and The Office Building Show (June 28 - July 1, 2003), at the San Francisco Marriott and Moscone Center. Representatives from Downtown Plaza Towers Associates, the owners of the Plaza Towers building, received a plaque recognizing their leadership in green building design.
“Periodically, Carrier Corp. 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,” Don Carlson, Carrier’s Northwest region commercial service area manager, said. “Plaza Towers is a great example of green building design.”
The Two Towers: Maintaining Comfort in a 14-Story Office Building
Originally built in 1969, Plaza Towers, at 555 Capitol Mall, consists of two 14-story office towers and houses a variety of commercial tenants in the heart of downtown Sacramento. The 373,618 sq. ft. building has been proactively maintained by its owner, Downtown Plaza Towers Associates, with its most recently renovation occurring in 1997.
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 a advantage in our competitive commercial real estate market,” Sillix explained. “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 VFD’s maximize the chillers’ efficiency by allowing cooling to be precisely matched to the building load. The VFDs dramatically 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. In many cases, with the 19XRV’s price and performance, building energy analysis results in a two-year payback or less,” Countryman explained. “This is an especially attractive option in climates, like Sacramento, with wide outdoor temperature variations, where part-load conditions occur frequently.”
According to the Plaza Towers building’s chief engineer Tony Troglia, the performance of the 19XRVs has already been outstanding.
“With our old chillers the best we could run was .9 kw/ton. With our new chillers, we’re reaching .38 kw/ton,” Troglia said.
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.
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.” Troglia said. “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.”