OR-10-013 -- Data Centers' Energy Auditing and Benchmarking-Progress Update PDF

This paper presents a summary of the energy audit and optimization studies conducted on more than 40 data centers. Comparison of data center energy efficiency metrics is presented. Those metrics include energy utilization metrics such as the Power Usage Effectiveness (PUE), Data Center infrastructure Efficiency (DCiE), mechanical PUE, electrical PUE and thermal or air management metrics such as bypass and recirculation air flow ratios. Additionally, percentages of cooling system, fans, UPS losses, and lighting to total data center power were analyzed and presented. The impact of climate zone as well as the operational load density compared to design load density were considered as well. These metrics incorporate and integrate together the major factors that decrease the effectiveness of computer room air cooling and the entire data center infrastructure. The energy utilization metrics determine the extent of the efficiencies of the data center supporting mechanical and electrical infrastructures. Interestingly, the database indicated that small data centers [Raised Floor Area (RFA) <10,000 ft²] or corporate data centers have higher average PUE than the larger ones. Small data centers were observed to have partially populated IT equipment racks and floors, oversized and aging cooling systems, higher levels of air mixing (recirculation and bypass air) in the raised floor areas, no implementation of free cooling, low UPS load factor, and no direct cooperation between the IT and the facilities departments. However, enterprise data centers were observed to implement more energy saving techniques such as “free cooling” as well as higher level of cooperation between IT and facilities. Many of those large data centers were also observed to participate in various professional IT and facilities organizations’ seminars to stay informed about new advances in their field as well as industry best practices.

Units: I-P