Some note for Data Centre Power Better Practice Guide

ICT Efficiency
Reducing the power needed by the ICT equipment (the productive use) is often the most effective way to maximise power efficiency. Reducing the ICT equipment’s power load means smaller overhead power is needed, as for example, less heat is generated so less cooling is needed.

Actions that reduce the power needed by ICT equipment include:

  • Virtualisation – moving workloads from dedicated ICT equipment (including servers, storage and networks) to shared ICT equipment can reduce the amount of power required by 10% to 40%.
  • Decommissioning – disused ICT equipment can be left powered on rather than decommissioned and removed.
  • Modernising – the latest models of ICT hardware are using much less power for equivalent performance. Gartner advises that server power requirements have dropped by two thirds over the past two generations.
  • Consolidation – Physical and logical consolidation projects can rationalise the data centre ICT equipment.

Cooling Efficiency

The cooling systems are usually the major source of overhead power consumption, and so there is usually value in making cooling more efficient. There is a wide range of data centre cooling technology, which provides agencies with great flexibility about investing in an optimum solution.

Common techniques to minimise power use include:

  • Free air cooling brings the cooler air outside the data centre into the data centre through dust and particle filters. In most Australian cities free air cooling can be used over 50 per cent of the time, and in Canberra over 80 per cent of the time.
  • Hot or cold aisle containment is a technique that aligns all the ICT equipment in the racks so that all of the cold air arrives on side of the rack and leaves on the other side of the rack. This means that the chilled air produced by the cooling system is delivered to the ICT equipment without mixing with the warmer exhaust air.
  • Raising the data centre temperature exploits the capability of modern ICT equipment to operate reliably at higher temperatures. Data centres can now operate at between 23 and 28 degrees Celsius, rather than the 18 to 21 degrees Celsius. Operating at higher temperatures means much less power is needed for cooling, and free air cooling becomes even more effective. The American Society of Heating Refrigeration and Air-conditioning Engineers (ASHRAE) publish guidance on maintaining optimum air temperatures in data centres.




Agencies should also evaluate the environmental impact of cooling solutions. The environmental impact of cooling systems is typically excessive water use, however some cooling systems use hazardous chemicals.

The investment case for cooling systems is quite different to ICT equipment. The asset life is usually 7 to 15 years. During the life of the cooling systems, the ICT equipment can be expected to change between two and five times. The amount of cooling required will vary significantly as the ICT equipment changes. This variability means that agencies should seek cooling solutions that can adjust as the demand for cooling rises and falls.