Facility Fix: Chilling Out
By Jillian Ruffino
Published in the March 2008 issue of Today's Facility Manager
When this manager was tasked with finding more efficient chillers for the Regina General Hospital in Saskatchewan, Canada, efficiency and low life cycle costs were his primary requirements.
What is your position? How many years have you been in the facility management profession?
I am the manager of the energy centers and building automation for the Regina Qu’Appelle Health Region (RQHR). I have been involved with facility management for 21 years and have been with the RQHR for eight years.
Please give a brief description of the facilities involved in this project.
Regina General Hospital is one of Regina’s two tertiary care hospitals and is part of the RQHR. It is an acute care facility and major referral center serving southern Saskatchewan. We have a variety of specialties, including cardio sciences, neuro sciences, and trauma care.
The hospital was established more than 100 years ago. Regina General’s most recent renovation was completed in 1998, when we added several new facilities.
Why was the decision made to pursue this project for the facility?
We had an aging chiller plant that cost too much to maintain and operate. Hospital officials specified that new equipment must serve the facility cost-effectively and meet the facility’s requirements for the next 25 to 50 years.
Please describe the decision making and research process for this project.
We had been using natural gas absorption chillers that were installed in 1997. They had become too expensive to operate and time consuming to maintain. The price of natural gas alone had gone up approximately 200% over the last eight years, which made the switch to electricity that much more attractive.
Now, we use centrifugal chillers from April through October. During the winter season they are offline. We kept the absorption chillers and use them as backup only. Through the life cycle analysis it was determined that significant capital would be saved, about CA $200,000 Canadian dollars annually.
What was the vendor selection process like? Did you feel limited?
Low life cycle costs were our primary requirement. We conducted a capital and operational cost analysis of bids submitted from several manufacturers. We made the final decision based on a total net present value calculation using 2006 dollars. This took into account the capital cost of the equipment and 25 year operating costs (assuming maintenance costs are equal).
What led you to choose the specific solution that you did?
The cost analysis of several different systems provided the answer, which was two McQuay 1350 ton dual compressor centrifugal chillers arranged in series counterflow. After calculating payback amounts over 25 years, it was apparent that the series counterflow arrangement of the chillers provided the lowest life cycle costs. It’s nice when it’s that obvious.
What benefits have you reaped as a result of this project?
Series counterflow chiller plants may be the most energy efficient and environmentally responsible chiller installations available. They are more energy efficient than chillers arranged in parallel series, because they allow for more efficient operation of each chiller.
Multiple chillers are commonly used, because they afford redundancy over single chiller plant designs. There are times when low supply water temperature and differential temperatures make sense. Large chilled water plants at healthcare and institutional facilities are excellent candidates for this type of solution.
In addition to the series counterflow arrangement, McQuay dual compressor centrifugal chillers are designed to provide part load efficiency. The chiller can unload smoothly to match the exact building load—down to 5% of the full load capacity without an inefficient hot gas bypass system.
While single compressor chillers are most efficient at or near 100% capacity and often require hot gas bypass to unload, a dual compressor centrifugal chiller is most efficient at 50% to 60% capacity and can easily unload much further. The dual compressor centrifugal chillers use two compressors on a common refrigeration circuit, which is the reason for the part load efficiency gain.
What energy saving benefits have you reaped as a result of this project?
When we switched from absorption cooling to centrifugal, our natural gas consumption was reduced by approximately 12%; however, our electrical has risen about 6%.
In large institutions, it is difficult to quantify the energy savings on any particular project exactly. However, we believe we experienced a net savings around 35,000 gigajoules (9.73 million kilowatt hours) of energy.
Did you encounter any unexpected highlights or challenges while implementing this project?
It was not only a relief to get away from the high maintenance of the old chillers, it was also satisfying to realize that we are keeping our energy usage as efficient as possible and putting money back into health care. We’re getting much more out of our HVAC system these days.
How did this project require you to change your operations and maintenance practices?
Overall, our operation and maintenance practices didn’t really change significantly. The additional time required to operate and maintain absorption chillers was re-allocated.
What has been the reaction to the project from upper management and elsewhere in your organization?
The Saskatchewan Ministry of Health is the governing body of all health facilities in the province, and it had an additional requirement: under a new policy, all chillers in the health system must use a refrigerant that is not scheduled for phaseout under the terms of the Montreal Protocol. McQuay chillers use HFC-134a refrigerant, which has no ozone depletion potential or phaseout schedule.
How have the community and customers responded to this project?
While most people never think about facility operations and maintenance, we were able to save the day for many occupants just last summer. We installed a certain amount of reserve capacity, which proved beneficial when Regina’s Humidex rating exceeded 40°C (104°F) for seven consecutive days.
What was the most professionally rewarding aspect of this project?
There were a number of individuals involved with this project. Both the former manager of building maintenance services, Doug Wilson, and the now retired chief engineer, Rick Pearce, did an absolutely fabulous job in planning and organizing the installation of this new chiller plant. The successful completion of any complex project, which requires the efforts of multiple disciplines, is always the most rewarding.
Send questions to H.V.A.C. Sales Ltd. president Brent Smith.
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