The PUE is defined as follows:
PUE = Total Facility Power/IT Equipment Power (1)
and its reciprocal, the DCiE is defined as:
DCiE = 1/PUE =
IT Equipment Power/Total Facility Power x 100% (2)

For equations 1 and 2, the Total Facility Power is defined as the power measured at the utility meter — the power dedicated solely to the datacenter (this is important in mixed-use buildings that house datacenters as one of a number of consumers of power). The IT Equipment Power is defined as the equipment that is used to manage, process, store, or route data within the data center. It is important to understand the components for the loads in the metrics, which can be described as follows:
1. IT Equipment Powerower. This includes the load associated with all of the IT equipment, such as compute, storage, and network equipment, along with supplemental equipment such as KVM switches, monitors, and workstations/laptops used to monitor or otherwise control the datacenter.

The PUE and DCiE provides a way to determine:
• Opportunities to improve a datacenter’s operational efficiency.
• How a datacenter compares with competitive datacenters.
• If the datacenter operators are improving the designs and processes over time.
• Opportunities to repurpose energy for additional IT equipment.
While both of these metrics are essentially the same, they can be used to illustrate the energy allocation in the datacenter differently. For example, if a PUE is determined to be 3.0, this indicates that the datacenter demand is three times greater than the energy necessary to power the IT equipment. In addition, the ratio can be used as a multiplier for calculating the real impact of the system’s power demands. For example, if a server demands 500 watts and the PUE for the datacenter is 3.0, then the power from the utility grid needed to deliver 500 watts to the server is 1500 watts. DCiE is quite useful as well. A DCiE value of 33% (equivalent to a PUE of 3.0) suggests that the IT equipment consumes 33% of the power in the datacenter.

The datacenter-only portion of a building utility meter should be measured since power not intended to be consumed in the datacenter would result in faulty PUE and DCiE metrics. For example, if a datacenter resides in an office building, total power drawn from the utility will be the sum of the Total Facility Power for the datacenter, and the total power consumed by the non-datacenter offices. In this case the datacenter administrator would have to measure or estimate the amount of power being consumed by the non-datacenter offices (an estimate will obviously introduce some error into the calculations).

IT Equipment Power would be measured after all power conversion, switching, and conditioning is completed and before the IT equipment itself.

Rackwise has designed the "Green Report" it's a quality dashboard that allows you to quickly communicate the “green” status of your data center using The Green Grid’s metrics of Power Usage Effectiveness (PUE) and Data Center Infrastructure Efficiency (DCiE).

The Rackwise "Green Report" calculates the PUE and DCiE from an organization’s model of the data center. The report further breaks down top resource consumers by type, servers, network, storage equipment, or other.

Learn more by going to - http://www.rackwise.com/index.php/components/green-report