Letters

Staff -- Consulting-Specifying Engineer, 8/1/2006

Credit earned, credit due

We must take exception to an incorrect statement in the May 2006 issue. In discussing the McCormick Place West Expansion, the article, “Trading Up for Flexibility,” (CSE 5/06, p. 28) states, “the chilled-water-and-air system designed by ESD for the McCormick Center expansion...” The engineers of record for the McCormick Place West Expansion are, in fact, the McCormick Place Design Team Take II, which is a joint venture of A. Epstein and Sons, Globetrotters and several other consultants. The mechanical contractors, who are a part of Mc4West, LLC., were also intimately involved in the design. The owner, MPEA, and several of their other consultants, including ESD, provided continuing input and performed peer reviews of the construction documents.

For the record, the original schematic design and scope documents were prepared by ESD. But as part of our contract, Take II modified and completed the schematic design at the beginning of the project. Since that time, there have also been a substantial number of changes in the project that deviate from the original scope. For example, the chilled glycol distribution system being installed is a variable-primary configuration instead of the primary-secondary arrangement proposed in the original scope. The 45ºF outlet air temperature indicated in this article was in the original scope. However, it should also be noted that this outlet temperature is used only in the exhibition spaces.

Kenneth E. Beilke, P.E., A. Epstein and Sons, Intl., Inc., Chicago

Editor's note: The following is a letter responding to a CSE Pure Power e-newsletter story about Sun Microsystems employing a DC power solution for its new data center. The story can be found in the Pure Power community at www.csemag.com.

Regarding “DC Power Could Reduce Data Center Energy Use by 20% While Improving Reliability,” (Pure Power e-newsletter, 6/27/06) I agree that a DC power supply can be more efficient at the data center equipment level. However, there are other issues that were not addressed in the article, notably the efficiency of converting AC to DC power at the load level required in a data center.

Additionally, an uninterruptible power supply is a major component in a data center environment, which creates the need to install large backup batteries to deliver the high current and redundancy desperately needed in a data center operation. I would like to see a comparison between the energy savings vs. the high cost of maintenance and the floor space required to accommodate UPS batteries.

Sandu Davidovitch, IDT Co.