This document describes the treatment of data centre metrics in circumstances where electrical energy is stored and exported from within the data centre boundaries of other standards in the ISO/ IEC 30134 series. This document specifies the Excess Electrical Energy Factor (XEEF) as a Key Performance Indicator (KPI) to quantify the electrical energy provided back from data centre to the utility. This document has the structure common to the standards of the ISO/IEC 30134 series