ACEEE-datacenters

ABSTRACTOver the past few years, the authors benchmarked 22 data center buildings. From thiseffort, we have determined that data centers can be over 40 times as energy intensive asconventional office buildings. Studying the more efficient of these facilities enabled us tocompile a set of “best-practice” technologies for energy efficiency. These best practices include:improved air management, emphasizing control and isolation of hot and cold air streams; rightsizingcentr al plants and ventilation systems to operate efficiently both at inception and as thedata center load increases over time; optimized central chiller plants, designed and controlled tomaximize overall cooling plant efficiency, central air-handling units, in lieu of distributed units;“free cooling” from either air-side or water-side economizers; alternative humidity control,including elimination of control conflicts and the use of direct evaporative cooling; improveduninterruptible power supplies; high-efficiency computer power supplies; on-site generationcombined with special chillers for cooling using the waste heat; direct liquid cooling of racks orcomputers; and lowering the standby losses of standby generation systems.Other benchmarking findings include power densities from 5 to nearly 100 Watts persquare foot; though lower than originally predicted, these densities are growing. A 5:1 variationin cooling effectiveness index (ratio of cooling power to computer power) was found, as well aslarge variations in power distribution efficiency and overall center performance (ratio ofcomputer power to total building power). These observed variations indicate the potential ofenergy savings achievable through the implementation of best practices in the design andoperation of data centers. al plants and ventilation systems to operate efficiently both at inception and as thedata center load increases over time; optimized central chiller plants, designed and controlled tomaximize overall cooling plant efficiency, central air-handling units, in lieu of distributed units;“free cooling” from either air-side or water-side economizers; alternative humidity control,including elimination of control conflicts and the use of direct evaporative cooling; improveduninterruptible power supplies; high-efficiency computer power supplies; on-site generationcombined with special chillers for cooling using the waste heat; direct liquid cooling of racks orcomputers; and lowering the standby losses of standby generation systems.Other benchmarking findings include power densities from 5 to nearly 100 Watts persquare foot; though lower than originally predicted, these densities are growing. A 5:1 variationin cooling effectiveness index (ratio of cooling power to computer power) was found, as well aslarge variations in power distribution efficiency and overall center performance (ratio ofcomputer power to total building power). These observed variations indicate the potential ofenergy savings achievable through the implementation of best practices in the design andoperation of data centers.