Ice Thermal Storage System Saves VA Hospital Money
Contracting for Energy SavingsRobert A. Palazzi, chief, design and development for the VACHS, was selected to act as energy manager for the project. He sought the expertise of several energy service companies (ESCOs), reviewed proposals, and selected EUA Cogenex (Lowell, MA) based on the company’s ability to meet the VA’s needs and provide guidance concerning finances and energy service contracts. Working with Cogenex, Palazzi implemented the first Energy Savings Performance Contract (ESPC) within the VA system.
The project was completed in two phases. Phase One replaced approximately 8,000 incandescent and fluorescent fixtures with modern, energy efficient fixtures. Two inefficient 885-ton centrifugal chillers were replaced with a 1,000 ton, two-stage, new steam absorption chiller and a new 800-ton electric centrifugal chiller, both by York International (York, PA). The aging cooling tower, chilled water, and condenser water pumps were all replaced with new equipment and energy efficient motors. Bell & Gossett (Morton Grove, IL) provided the base-mounted centrifugal pumps.
A ddc control system, the Infinity SCX 920, by Andover Controls (Andover, MA) was installed to control the new chiller plant. Square D (Palatine, Il) provided the electrical distribution control center. By implementing Phase One, VACHS pioneered performance contracting for energy services in the VA system.
Phase Two expanded the plant capacity with a 6,600 ton/hr ice thermal storage system by Baltimore Aircoil Company (Baltimore), the TSU 60MAP, and converted the chilled water pumping system to a primary/secondary loop operation. This expansion provided the necessary cooling capacity for the addition to the clinic, which added 100,000 sq ft to this facility. The ice storage system is driven by screw machines that operate at night, during off-peak electric utility periods, to provide the 20˚F fluid necessary to make the ice. The stored ice is then used during the on peak electric utility period, requiring only the electrical power necessary to move the fluid to the heat exchangers. APV Heat Exchangers Inc. (West Sussex, England) provided the plate-and frame-exchanger.
Both ice thermal storage and conventional cooling systems were evaluated for Phase Two, and ice storage (without consideration for energy rebates) proved to be the lower first cost alternative. According to Stuart Erhardt, Senior Project Manager of Cogenex, “Ice thermal storage and night time chiller operation at lower wet bulb temperatures met capacity requirements with existing equipment. This enabled the VA to avoid the capital investment for additional cooling towers that would have been required with a conventional system. With the added benefit of energy rebates, there was no question that ice was the way to go.
Diversified Technology Consultants (North Haven, CT) acted as the design-build consultant, and Mulvaney Mechanical Inc. (Ridgefield, CT) was the mechanical contractor for the project.
Success on Many LevelsThe project earned rebates from United Illuminating Company totaling $310,966 for lighting and high efficiency motors and $100,000 from Southern Connecticut Gas for the installation of the absorption chiller.
An additional $294,520 rebate was received from the United Illuminating Company for the ice thermal storage system. The actual savings for the project add up from each part of the project: $285,000 from the chiller plant, $185,000 from the lighting, and $130,000 from the ice thermal storage system.
The hospital saved on electrical costs as well. Chiller plant kilowatt usage went from 2,580,134 to 16,680; the new lighting systems’ electrical usage went from 2,470,800 to 8,276; and the ice thermal storage uses a mere 7,222 kW.
According to Mr. Palazzi, “The ESPC that has been initiated at VA Connecticut Healthcare System, West Haven campus has exceeded our original expectations.”
Intangibles factor into the savings as well. The new chiller plant is saving energy and experiencing reduced maintenance and repair costs; the system conserves nonrenewable fuels achieving environmental fuels and energy cost reduction goals identified in the Energy Policy Act of 1992; The ice thermal storage system saved $650,000 in first cost, and is saving $100,424 annually in operating costs.
To date, the VA Connecticut Healthcare System project has earned several awards and acknowledgements, such as the Federal Energy Management Team Award for Energy Savings Performance Contract, the Energy Champion Award by DOE for the “You Have The Power Campaign,” and the Total Rehab Award given by Energy User News (an Engineered Systems sister publication).