Most data centers operate in a temperature range between 68 and 72 degrees, and some are as cold as 55 degrees. Raising the baseline temperature inside the data center – known as a set point – can save money spent on air conditioning. Data center managers can save 4 percent in energy costs for every degree of upward change in the set point, according to Mark Monroe of Sun Microsystems, who discussed data center set points at a conference last year. But nudging the thermostat higher may also leave less time to recover from a cooling failure, and is only appropriate for companies with a strong understanding of the cooling conditions in their facility

Google: Raise Your Data Center Temperature « Data Center Knowledge