This document specifies carbon usage effectiveness (CUE) as a key performance indicator (KPI) for quantifying the CO₂ emissions of a data centre during the use phase of the data centre life cycle.

CUE is a simple method for reporting the CO₂ intensity of the data centre operating. By reporting CO₂ emissions, it is possible to present the data centre's contribution to climate change (enhanced greenhouse effect).

This document:

a) defines the CUE of a data centre;

b) introduces CUE measurement categories;

c) describes the relationship of this KPI to a data centre’s infrastructure, information technology equipment and information technology operations;

d) defines the measurement, the calculation and the reporting of the parameter; and

e) provides information on the correct interpretation of the CUE.