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Ann Arbor City Hall
Natural Gas Powered Chiller
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DESCRIPTION:
An obsolete 200 ton, TonRack electric powered chiller in the Ann Arbor
City Hall was replaced in March of 1992 with a new, 150 ton TecoChill brand
gas powered chiller to provide air-conditioning for the 90,000 square foot
building. The cost to install the chiller, after MichCon's incentive rebate
of $35,000 was $156,000 (this cost includes additional work done to replace
cooling coils). The installation of this new chiller reversed the trend
of increasing electric costs, which was averaging a 6% increase per year.
Further electric bill savings for the city hall have also been realized
through additional energy saving measures, including lighting retrofits
and a building energy management system installed in 1996.
GAS CHILLER FEATURES:
- variable speed operation allowing load following capability
- routine maintenance conducted by in-house staff
- bi-annual servicing by a TecoChill technician at a cost of $1,400/year
- nearly problem free operation since its installation
- The manufacturer predicted an engine rebuilt would be required after 15,000
running hours at a cost of $8000.
- The chiller has logged over 17,900 running hours, with an average load
of 46%, with no engine rebuild required to date.
ENERGY SAVINGS:
- Electric costs rose over 6% per fiscal year between 1987 and 1991.
- After the natural gas chiller was installed, the electric costs have decreased
every fiscal year.
- Electric costs were lower for FY95-96 than they were for FY 86-87.
- After the natural gas chiller was installed, the natural gas costs have
increased every fiscal year.
- The electric cost decrease outweighs the natural gas increase, creating
a net annual energy savings. The annual savings has averaged $28,000/year
since 1992 compared to the baseline costs for fiscal year 91-92.
- A portion of the electric cost decrease is due to a decrease in the electric
demand cost. This decrease in cost can be attributed to the gas chiller.
- Future energy savings in the building may reflect energy conservation measures
performed in 1996, including lighting system retrofits and the installation
of an energy management system
Pre- and Post-Chiller Installation Energy Cost
Pre- and Post Chiller Installation Energy Usage
FOR FURTHER INFORMATION CONTACT:
Dave Konkle, Municipal Energy Coordinator
Ann Arbor City Hall
100 N. Fifth Avenue
Ann Arbor, MI 48107-8647
(313) 996-3150
Feel free to contact us if you have any ideas for case studies:
Main Telephone Line: (517) 241-6228
Main Fax line: (517) 241-6229
Energy Office, Department of Consumer and Industry Services
Office of Policy and Leglislative Affairs
P.O Box 30221
Lansing , MI 48909