建筑与环境空调英文文献和中文翻译
1. IntroductionIncreased reliance on the storage, transfer, and processing ofdigital information throughout all aspects of society has causedsignificant growth in data center energy use. These buildings houseinformation technology (IT) equipment, such as computer servers,as well as storage and network devices. In the United States, datacenter energy use doubled between 2000 and 2006 to about 60billion kWh annually and is expected to continue to rapidlyincrease [1e3]. While growth projections made before the currenteconomic downturn may overestimate near-term growth in datacenter activity, a recent evaluation showed that significant growthcontinued at least through 2008 with data centers consuming ∼70 billion kWh during that year [4]. That level of energy use corre-sponds to emissions of ∼1.2 1013gy 1of fossil carbon (42 Mt/y ofCO2), based on the average carbon intensity of 160 gC/kWh for USelectricity production [5].Non-IT components in data centersdheating ventilation andair-conditioning (HVAC) equipment, uninterruptible powersupplies (UPS), and building lightingdaccount for approximatelyhalf of data center electricity demand [6]. Total data center energydemand is often characterized with a simple metric, the powerusage effectiveness (PUE) [7], which is defined as the ratio of thetotal data center building load to the data center IT equipment load.Based on industry consensus regarding data center practices,previous estimates have applied a PUE of 2.0 to represent currentaverage data center energy efficiency, implying that IT and non-ITenergy use are equal [1,2,4]. However, IT equipment operates indata centers of significantly different types and sizes, which couldaffect actual PUE values. Masanet et al. [4] apportioned estimatesof national IT energy use among different data center space types based on International Data Corporation (IDC) data for 2005 USinstalled servers [1,8,9]. In that analysis, five space types were usedto categorize the locations of IT energy use: server closets, serverrooms, localized data centers,mid-tier data centers, and enterprise-class data centers. Table 1 shows that each space type representsa significant portion of total IT energy use in the United States.Along with differences in data center space type, the location ofan operating data center could affect the energy demand of non-ITequipment.