Cincinnati's best-kept construction secret promises to keep hundreds of downtown office workers cool this spring and summer.
Work on the initial phase of the downtown cooling district, the first project of a joint venture between Cinergy Corp. and Trigen Energy Corp., is nearing completion in the basement of the Fourth & Walnut Centre.
''We expect to turn on the system April 1,'' said Donna L. Robichaud, general manager of Trigen Cinergy Solutions of Cincinnati, which is building the cooling district.
Four electric chiller units in the building's basement will be used to cool water to 38 degrees Fahrenheit for air conditioning in office buildings connected to the system via a network of 24-inch underground pipes.
Each of the chillers is capable of 1,875 tons of cooling, a measure of their cooling output. By comparison, a central home air conditioning system is capable of 2ï to 3 tons of cooling.
Initial system
The 7,500-ton system, which is expandable to 15,000 tons, will initially cool two or three buildings on Fourth Street between Walnut and Vine streets. But two dozen office buildings in the central business district have expressed interest in tying into the system during the next several years, Ms. Robichaud said.
The initial phase of the project, which has been under construction since last fall, cost about $12 million. When the entire system is completed, the cost is projected at $31 million, she said.
The next phase of the construction will extend the twin-pipe system up Vine Street to Fountain Place. Further extension of the system will hinge on which buildings join, she said.
Because the chillers are being installed in the basement of the Cinergy-owned building and the street trenches for the chilled water pipes were dug at night, many businesses downtown aren't aware of the project, she said.
Possible cost savings
''We're one of the best-kept secrets in Cincinnati,'' she said.
But by tapping into Cinergy's chilled water system, building owners can avoid the cost of replacing and repairing the chillers and cooling towers in their buildings, she said.
It also allows the building owners to avoid the cost and hassle of finding replacements for chlorofluorocarbons, the banned chemical refrigerant now used in building cooling systems.
Cinergy's cooling system will use the environmentally friendly replacement refrigerant R-134A.
The potential benefits for each building vary depending on an engineering analysis, said Dan Toon, sales manager for the project. But Cinergy has been able to show savings for each of the dozen buildings it has studied so far, he said.
For building occupants, the 38-degree water, several degrees cooler than that used in most building systems, means less humidity and greater comfort, Ms. Robichaud said.
Some downtown building owners don't need convincing.
George Cornwell, president of S.N. Phelps Realty, which owns the 28-story Fourth & Vine Tower, formerly the PNC Tower, said he expects to be one of the district's first customers.
''I have two other buildings in Chicago, a total of about 1.5 million square feet, which are part of a cooling district operated by the parent of Consolidated Edison, and I've been very satisfied.''
Mr. Cornwell said his economic analysis of joining a cooling district vs. maintaining his own chiller system was pretty much even, but other considerations such as the reliability of being on a larger system and the cooler temperature tipped his evaluation in favor of district cooling.
Cinergy hopes to use the cooling district as a way to offer building owners and operators other services as the utility market is deregulated, Ms. Robichaud said.
One possible future project is developing a central heating system for the downtown buildings.
