International Agreement on PUE for Measuring Data Center Efficiency
By T. Lau
April 5, 2010
As more attention is focused on data centers and the amount of energy it takes to power them, more companies are finding the commercial and public relations value in undertaking Green IT projects. The problem, as I've blogged about previously, is that there is very little standardization on how to measure Green IT effectiveness and preventing outlandish or unprovable claims when it comes to how green a data center actually is. The EPA's forthcoming Energy Star for Data Centers program will go a long way towards establishing this common standard, but the program is for U.S.-based data centers only.
Over the weekend, news emerged of an international agreement to establish data center energy efficiency. The agreement is between The Green Grid (U.S.-based industry group), the U.S. Environmental Protection Agency, the European Commission Joint Research Centre, the Japan Ministry of Economy, Trade and Industry, and the Green IT Promotion Council (Japan-based industry group). For now the agreement is limited to these three regions, but could expand to include others such as China and India in the future.
The agreement establishes the Power Usage Effectiveness (PUE) as the "preferred energy efficiency metric." Specifically, the agreement states the following shall be "guiding principles" as interim steps, and that data centers are "recommended" to measure PUE according to the principles:
- PUE is a measurement of the total energy of the data center divided by the IT energy consumption.
- The industry should improve IT measurement capability to enable take the measurement directly at the IT load (servers). At a minimum, IT energy measurements should be measured at the output of the UPS.
- For a dedicated data center, total energy measurement should include all energy sources at the point of utility handoff. For data centers in larger buildings, total energy should include all cooling, lighting, and support infrastructure in addition to IT load.
That's all the agreement contains for now. There is much work left to be done, including defining how PUE is calculated and how total energy should be measured. A task force with representatives from each group is meeting throughout the year to develop these measures.