A Chiller Plant That’s Never on Vacation

By Consulting Specifying Engineer Staff November 2, 2018

The Hilton @ Sandestin Beach Golf Resort & Spa, located in Destin, Fla.,
along Florida’s northwest Gulf Coast between Pensacola and Panama City, features 600 guest suites, 32,000 sq. ft. of meeting space, four on-site restaurants, four championship golf courses, 13 tennis courts, two outdoor and one indoor swimming pool, and a full-service spa, salon and fitness center. The high heat and humidity of the region make cooling the indoor facilities critical to the success of the entire operation, 24 hours a day, 365 days a year.

“During the peak summer months, we typically have 3,000 guests on-site,” notes Leonard Martin, CEOE, SMA and director of engineering at the Hilton @ Sandestin Resort. “Keeping each of those guests cool and comfortable during their stay here is always our number one priority.”

To fulfill the resort’s obligation to its clientele, Martin recently reviewed the facility’s entire HVAC infrastructure. Hilton @ Sandestin Resort was built more than 20 years ago. Since that time, the demand for cooling has grown from 650 tons over 325,000 of air conditioned space to 1,200 tons over 750,000 sq. ft. As a result, the original chiller plants could no longer provide sufficient cooling. Reliability and efficiency of the aging HVAC equipment was also at issue, as was the control system responsible for plant operation.

To address these problems, Martin elected to conduct a thorough analysis of the existing HVAC system. “We decided that if we were going to spend money on the cooling system,” he explains, “we wanted to make sure we did it right so that we would no longer have problems.”

Martin invited several vendors to submit recommendations for improvement of the resort’s three chiller plants, and ultimately chose a plan that proposed the following chiller plant improvements:

  1. Replace three air-cooled chillers with three larger water-cooled screw chillers.

  2. Retrofit two 20-year old centrifugal chillers with graphic control centers.

  3. Add an electronic variable speed drive (VSD) to the lead chiller.

  4. Tie the entire HVAC system together with an integrated systems network.

Replacing the three air-cooled chillers (one 135-ton and two 200-ton) with three 200-ton water-cooled screw chillers brought the chillers inside where they were no longer exposed to corrosive coastal elements. In addition to the improved reliability and longevity attributed to the move indoors, the chillers provided much-needed additional cooling capacity as well as the improved efficiencies associated with water-cooled units.
Operation of the remaining two 277-ton water-cooled chillers also improved with the addition of the control centers. Designed to update and upgrade older chiller technology, the control center provides chiller operators with a real-time graphical screen that presents information in a format that is easy to understand. Graphical interfaces enable better chiller control for efficient and stable operation, resulting in reduced wear and tear of components and greater long-term reliability. Graphical trending and historical reports enable operators to optimize adjustments, schedule maintenance and pinpoint potential problems before they cause downtime.

According to Martin, “The new… panels allow our staff to quickly review operating status should something out of the ordinary appear. It makes determining whether or not a problem exists pretty simple.”

As for the new variable speed drives, VSDs are exceptionally efficient at off-design conditions, efficiently decreasing the chiller’s power draw in response to off-design loads and water temperatures. In the case of the Hilton @ Sandestin Resort installation, the addition of variable-speed drive has doubled the efficiency of the chiller plant, reducing the amount of energy required to operate the chillers from approximately .85 kW/TR to .4 kW/TR.

Installation of the network further improved chiller plant efficiency at the Hilton @ Sandestin Resort. One of the remote communications options enabled by the control is linking chiller control to broader building control. It is actually a building automation system that monitors and instantly compensates for a multitude of changing conditions, including outdoor climate, indoor environment, occupancy level and utilization patterns, any or all of which can vary hour by hour and impact the efficiency of an HVAC system. Software capability included with the system can be customized around specific building operations and offers remote monitoring and repair features.

Work on the chiller plants at the Hilton @ Sandestin Resort began late in the fall of 2003 and was completed on a tight time schedule shortly after the first of the year, during the resort’s off-season. Downtime was not an option because the hotel is open and busy year‘round.

Six months later, all the improvements were put to the test during the hot, humid Florida summer. Changes to the chiller plants passed with flying colors. First, according to Martin, complaints about the HVAC system, once so prevalent, disappeared, and guests are cool, comfortable and happy. Secondly, the HVAC system is operating more efficiently, with kilowatt usage down approximately nine percent. That spells significant savings in utility costs for the resort — an estimated $375 per day when the project was completed.

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