Heat density once again is a top concern of data-center managers, a survey sponsored by Emerson Network Power reveals.

When asked to identify their top three facility/network concerns, 42 percent of the more than 100 respondents—all members of the Data Center Users’ Group (DCUG), an association of data-center, information-technology, and facility managers across North America—cited heat density, ranking it third behind energy efficiency (49 percent) and adequate monitoring (51 percent). Heat density was the No. 1 concern the first four years of the biannual survey, starting in 2005. By the spring of 2012, it had dropped to fourth place, with availability joining adequate monitoring and energy efficiency in the top three.

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“Throughout the past few years, much emphasis has been placed on availability, infrastructure monitoring, and efficiency and rightly so,” Bob Miller, vice president, Liebert global solutions, Emerson Network Power in North America, and a member of the DCUG board of directors, said. “As data-center professionals continue to struggle with growing capacity needs and tightened budgets, attention is turning back to one of the most fundamental aspects of the data-center infrastructure: effectively and efficiently managing heat. If not addressed, heat-density issues threaten to negatively impact performance levels of the data center.”

When asked their plans for their data centers over the next 12 months, 65 percent of the respondents said they plan to consolidate or replace servers, 64 percent said they plan to add servers, 27 percent said they plan to consolidate data centers, and 19 percent said they plan to build a new data center.

The survey also found:

• Fifty-six percent of the respondents believe their current data-center capacity will suffice for three years or less.

• Twenty-seven percent of the respondents reported their data centers experienced hot spots during the previous 12 months, while 15 percent reported their data centers experienced an outage.

• Thirty percent of the respondents cited a lack of capital expenditure as the primary factor limiting their organization’s ability to accommodate growth.

• Power density per rack averaged 5.94 kw, up slightly from 5.92 kw in the fall 2012 survey.

The top operational and efficiency-related metrics being measured in data centers are temperature (93 percent), power utilization (88 percent), humidity (79 percent), and cooling utilization (72 percent). Fifty-six percent of the respondents measure power-usage effectiveness.