1.1 DCiE

What is it?

The Data Center infrastructure Efficiency (DCiE) KPI is defined as:

DCiE = IT ENERGY consumption / Total ENERGY consumption

 

Why should you care?

In literature the DCiE value is defined as the ratio between the total electrical power going into a data center and the total power going to the active IT components on the data center floor. Electrical power is measured in kiloWatt (kW) and is by definition a point in time value. As such, the resulting DCiE shows strong fluctuations during the day. Since a DCiE value needs to represent an overall efficiency number for data center facilities, we prefer energy measurements above power measurements and redefine the DCiE value as the ratio between the total energy (kWh) used by the data center and the energy used by the IT equipment. The time period over which energy measurements should be collected varies with the effect one tries to observe:

  • Hourly; typically yields information on DCiE reactions to both differing IT load and cooling efficiency during day vs. night ambient temperatures.
  • Daily; typically yields information on workday vs weekend IT load fluctuations.
  • Monthly; Yields the DCiE reaction to seasonal ambient temperature differences and possibly changes in electrical IT load due to changes in the IT environment on the data center floor.
  • Yearly; Since all outside influences have been averaged out, this yields information on the effect of operational changes and is the most preferential for reporting purposes.

 

How does it relate to the other items in the model?

The DCiE value is nonspecific because it totals in all effects that contribute to the efficiency of the data center facilities. Electrical losses due to transformers, UPS' en electrical cabling are added to energy use in lighting, cooling, humidity control, security equipment etc. Since some of these can only be changed by a total replacement of the equipment, the model has additional KPI’s that are highly influenced by human actions and are of great importance to cooling efficiency.

Which KPI’s are directly related to this KPI?

  • KPI’s Bypass and Recirculation measure the quality of the airflows and temperatures. The better they are, the lesser energy is used by the cooling system which in its turn increases the DCiE score.
  • KPI Electrical and Mechanical Management delivers the input to calculate the DCiE on a realtime basis.
  • KPI Change and Configuration Management influences this KPI because any change made to the data center and IT can impact energy consumption.
  • KPI Product Lifecyle Management ensures that less energy is wasted on old hardware and that new hardware fits the energy efficiency strategy/guidelines of the data center.
  • KPI Capacity Management is used to improve the capacity utilization of facility equipment. It results in a higher efficiency of the cooling and electrical systems.
  • KPI Service Level Management supports chargeback and other means to drive energy efficiency.

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