ASHRAE’s 2011 Expanded Thermal Guidelines has caused a lot of controversy and confused many in the data center industry. Although ASHRAE released the information a year ago in May 2011, it is still highly debated and sometimes misinterpreted.
ASHRAE’s Technical Committee 9.9 (TC 9.9) was formed specifically to focus on data centers. Its conclusions have been authoritative in the very conservative mission-critical world since the first edition of the Thermal Guidelines came out in 2004 (the recommended range was 68°F to 77° and 40 to 55 percent relative humidity [RH]). The second edition released in 2008 expanded the recommend range slightly to 64.4° to 80.6°. Nonetheless, even today many data center managers still keep it at a “safe” temperature and humidity; very tightly controlled with 68° and 50 percent RH targets, just as was originally recommended in the 2004 edition.