In or around November 2006, I co-authored a white paper with Vali Sorell (vice president, Syska Hennessy Group) that calculated and compared the energy efficiency of cooling strategies employed in most data centers. (This paper titled, “Will Liquid Cooling Solutions Save Energy?” is available on Syska Hennessy Group’s website at http://www.syska.com/thought/whitepapers/wpabstract.asp?idWhitePaper=5.) In the paper we evaluated the following scenarios:
When the paper was first published, several of the major HVAC manufacturers challenged our calculations; we made minor adjustments based on their input, using equipment efficiencies that they agreed to. Interestingly, this had no significant effect on either the comparison results or conclusions that were generated from the study. The most efficient cooling strategy was, by far, the use of liquid cooled electronics (servers, main frames, etc.). Our final conclusion was that “Liquid cooled equipment without a chiller plant (also not yet commercially available but technically very feasible) can offer significant energy savings compared to all other options. In addition, because of the system’s simplicity, it would be expected that this type of system would be easier to maintain and significantly more reliable than the other scenarios.”