Energy Efficiency Case Studies
ST. MARY-CORWIN MEDICAL CENTER
Mary-Corwin Medical Center began implementing energy efficiency upgrades to its
facility in the mid-1980s. A performance contract with an energy service company
(ESCO) beginning in 1989 became the catalyst for significant upgrades and
savings at this 225-bed hospital located in southern Colorado.
Working with the ESCO, hospital administrators designed a package of
equipment upgrades aimed at leveraging an approved federal grant into more
energy savings. The ESCO agreed to accept 95 percent of the hospital's actual
savings over the seven-year life of the contract as payment.
An initial energy audit of St. Mary's showed that modifications to the
525,000 square foot facility's cooling system would increase patient and staff
comfort and result in significant energy savings. A flat-plate heat exchanger
enables facility management staff to turn off chillers during mild weather. Two
chilled water loops were joined, making it possible for a new, more efficient
700-ton chiller to handle the cooling load for the entire facility, and allowing
two smaller, less efficient chillers to be retired from service.
The ESCO also installed a computerized energy management system, which
enables hospital staff to monitor and control the chilled water system, air
handling systems, and boilers from a central location. In addition, the energy
management system automates many of these processes. Lastly, 20 large
air-handling units were upgraded with new starters and two-speed motors,
allowing the units to operate at lower speed during the night or during moderate
weather when space cooling needs are substantially less.
Total cost for the efficiency upgrades was $765,000. Energy cost savings
total almost $180,000 per year, ten percent greater than estimated, resulting in
a simple payback period of 4.25 years. With the assistance of the ESCO, St.
Mary's is investing these savings into additional efficiency upgrades, including
a lighting retrofit and boiler plant modifications.