Page 208 -

10: Green IT Case Studies for Universities and a Large Company 173

In 2008, The Green Grid modified the PUE metric to make it simpler to
understand. The new metric is called Data Center Infrastructure
Effectiveness (DCiE). The following graphic (see Figure 10.3) describes
both metrics.
DCiE— Data Center (Infrastructure) Efficiency

PUE— Power Usage Effectiveness

IT Equipment Power 1
DCiE = =
Total Raised Floor Power PUE

Raised Floor Load
Demand from Grid

Power IT Load
(UPS, Switchgear, (Demand from
Transformers, Lights, Servers,
Battery Back-up, Etc.) Storage, TELCO
Equipment,
Cooling Etc…) ptg
(CRAC Units, AHUs,
Chillers, Pumps,
Cooling Towers,
Humidifies,
Ventilation, Etc.)

Source: IBM Green Data Center
Figure 10.3 Data center metrics DCiE and PUE
The PUE of 1.8 translated to a DCiE of 0.56, meaning 56 percent of the
power coming into the data center was going to IT equipment.

Step 2. Build

The subject data center resided in a leased facility. As the landlord did not
want to make significant improvements, the options were limited. The deci-
sion was made to limit the amount of build activity of new data center space
because the parking lot was not considered a viable option.
Fortunately, the “Build” step includes upgrading some of the constrained
components other than space. In this case, additional power could be added.
The additional power enabled the replacement of servers with servers of the
same size but more compute capacity; therefore, the amount of space