Power Usage Effectiveness analysis and optimization in the INFN CNAF Tier-1 data center infrastructure

The accurate calculation of the power usage effectiveness (PUE) is the most important factor when trying to analyse the overall efficiency of the power consumption in a big data center. In the INFN CNAF Tier-1 a new monitoring infrastructure, also known as Building Management System (BMS), has been recently implemented using the Schneider StruxureWare™ Building Operation (SBO) software. During the design phase of this new BMS, a great attention was given to the possibility of collecting several detailed information about the electric absorption of specific devices and parts of the facility. Considering the annual trends and the demands for reducing the operating costs it became clear that some improvements were certainly needed in the very short time. For this reason, a hardware upgrade of the cooling chillers and related chilled water pumps distribution system was seriously considered using innovative cooling technology. We focused on chillers using the Danfoss Turbocor centrifugal compressors technology that uses magnetic levitation and an oil-free approach for obtaining the best efficiency. Subsequently, we studied a solution that could easily compensate the initial investment during the first years of usage (considering the Total Cost of Ownership of the project) and that will improve the overall PUE of our data center.