The Energy that Feeds Data Centers

Data centers form 30 to 40 percent of a building’s operating costs, and reducing them is a complicated matter for owners, tenants and clients who know little about them. A facilities/operations manager’s job is to ensure that proper infrastructure is in place, along with varying degrees of backup and reliability to support data center equipment. Reliability and the elimination of downtime are the bases for judging any data center’s success or failure. Other important considerations are the data center’s energy demand and amount of redundancy necessary to build into cut sheets, matrix and equipment lists and striking a balance between reliability and maintaining energy performance.What needs to be established first is the location of the data center. The space, if possible, should be internal to the floor plate, with vapor barriers to prevent moisture migration owing to air leakage, wind and differential vapor pressure. Second but often overlooked is the selection of the most energy-efficient data equipment possible. Intel Corp. has reported that the Alliance for Telecommunications Industry Solutions is conducting a major project to evaluate energy efficiency in telecommunications equipment. The organization is developing energy-utilization metrics to guide equipment purchases and network planning. Other available metrics are power usage effectiveness and data center infrastructure efficiency. Both compare the overall data center’s power consumption with the power consumed by IT or Information and Communication Technology equipment. These should be examined before a purchase is made.Other than the IT equipment, HVAC systems are the biggest consumers of energy in data centers and will need to be carefully sized. Using American Society of Heating, Refrigerating and Air-Conditioning Engineers Inc. Standard 90.1 as a guide gives the designer a baseline from which to work. ASHRAE’s standard interior design conditions for a Class 1 environment, as well as Thermal Guidelines for Data Processing Environments, should be referenced, though remember that they are guidelines, not codes. Economizer cycles and proper sizing of the equipment to reduce inefficient partial loading all need to be considered and modeled. Remember that energy codes for commercial buildings are drafted for human occupancy and energy-efficiency ratings based on maintaining human comfort. Thus the conditions for IT equipment are far different than for general office space. The proper functioning and life expectancy of data center IT equipment requires temperature and humidity conditions that are, unfortunately for those who spend much time in these centers, not very compatible with human comfort.Once a data center is installed and operating, separate metering of equipment is a very important means of trending actual versus nameplate consumption. Data centers can gradually fill up over time, so energy usage must be trended and examined at both full and partial loads to ensure that efficiency and operating standards are being met.One can optimize energy consumption and mitigate costs by following the above guidelines and utilizing the trending, metering, and benchmarking tools available.