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Advice for reducing datacentre power consumption

With the current economic climate, cutting costs and saving money remains a top priority. Within the IT industry many datacentre managers continue to look for ways to improve the efficiency of their infrastructure and get the most for their budget.

The bottom line is that the cost of operating a datacentre is directly related to the cost of power. New equipment can offer improvements in performance and space, but these assets require greater operational and cooling power to function. This need and the growing cost of power combined with the effects on global climate are challenging organisations to operate with higher efficiency and conserve more.

Before a company begins the process of getting "greener," it is essential that current power consumption rates are measured to provide  an accurate benchmark for efficiency. The biggest error a company can make is not using a consistent baseline for data. However, simply taking the manufacturer's power consumption figures for servers and other equipment is a mistake. These are only estimates which have a significant protection margin added that will significantly skew any end-user measurement. Accurate measurement software solutions will have de-rated values for specific equipment, which provides a more true-to-life measurement of power consumption.

Power usage effectiveness (PUE) is a metric that is often used to measure the efficiency of the datacentre's power usage before and after green initiatives have been implemented. PUE can be calculated by taking the total power consumed by a datacentre facility and dividing it by the power consumed by the IT equipment. The resulting ratio provides the effective power overhead for a unit of IT load. For example, a PUE value of 2.0 means that for every watt used to power IT equipment, an additional watt is required to deliver the power and keep the equipment cool.

The data needed to calculate the total facility power usage can be obtained by reading the power meters serving the facility or through its building management system (BMS). Many device manufacturers provide software applications that can monitor the power consumption and others support standard protocols (SNMP) and various data collection methods for passing metrics to third-party applications.

The other required variable needed to complete the PUE calculation is the total power used by the IT infrastructure. The IT Infrastructure devices included in this calculation include:
  • Servers

  • Telco Equipment

  • Storage Systems


Obtaining the power consumption values for these devices can be easily done with datacentre management tools. Consumption values published by the manufacturers are not accurate enough for this type of measurement. If an organisation has limited measurement tools, the IT department can work together with the facilities management team to attribute how much power is consumed by the datacentre. If this figure isn't available from one central tool, it may need to be aggregated from the values in a number of points throughout the power infrastructure.

However, using a tool designed specifically for this function makes the measurement process easier and provides a repeatable process for measuring future values and tracking improvements. By modeling the effects to key metrics before spending money and manpower to implement these changes, datacentre managers have a powerful way to justify their efforts to reduce power consumption. Without modeling, it can only be a guess as to whether expensive changes will actually reduce the PUE value for a datacentre. Using PUE to measure the effectiveness of datacentre power usage in terms of the computing power it contains allows you to see how optimising space, power, and cooling can save money while reducing your carbon footprint. Using datacentre management software further extends these savings by modeling these changes virtually to measure their effect on PUE.



  • Pelco
  • Schneider Electric Partner
  • APC Partner