A PUE (power usage effectiveness) metering scheme in a data center can be very simplistic consisting theoretically of only two meters, at one extreme, or it can be much more comprehensive and consist of dozens of metering points. This paper provides guidance on determining what level of metering is appropriate for a particular data center, given its capacity (kW), power and cooling architecture, business objectives, and the degree to which infrastructure systems (e.g., chillers, generators) are shared.