How to optimise data centre cooling

Improve data centre cooling with these simple steps from the Green Grid.

Improve your data centre cooling strategy with best practices offered by Vic Smith of the Green Grid.

Develop an air-management strategy 
Without an effective management strategy, air will follow the natural dynamics set up by a facility's physical layout and the positioning and characteristics of its IT and cooling equipment. This could lead to the hot air and cold air mixing, and it could produce uncertainty in the matching of equipment deployment and relative rack capacity. The first step should be the hot-aisle/cold-aisle layout for air management in the data centre.

Move cooling systems closer to the load 
Locating cooling closer to IT equipment can reduce data centre cooling costs by more than 30% compared with traditional approaches to cooling.

Select the best data centre cooling method 
IT shops must choose between air conditioning units (ACUs) and liquid-based cooling. ACUs are known to consume a significant portion of energy in most data centre cooling systems. Mounting the cooling modules as close as possible to the source of heat -- placing them directly above, alongside, or within high density -- reduces the distance that the fans must move air. This can provide up to 70% savings on the energy required to move the air.

Water or refrigerant liquid-based cooling
These approaches are more effective than air at transferring heat. This especially benefits higher-density applications. In a liquid-based cooling system, hot air passes through an air-to-water or air-to-refrigerant heat exchanger located near the heat load. The heat is transferred to the liquid, where it can be more efficiently removed from the building. However, as fluid properties vary, it is important to choose the correct heat-transfer fluid for the application.

Assess the availability of free cooling 
The Green Grid's EMEA Free Cooling Map, available online, allows data centre managers in Europe to input their specific variables, such as location, local energy costs, IT load and facility load, to determine the specific potential energy savings for individual facilities. In addition to free data centre cooling from outside air, the tool provides information about savings that could be obtained using water-side economisers.

Know your actual data centre temperature requirements
It is important to realise, though, that most data centres actually run at temperatures much lower than necessary for IT equipment. There are a number of possible reasons for this: misguidance on optimal data centre temperature, causing a fear that a higher IT equipment temperature will affect reliability; a room that is kept cold to achieve a longer ride-through time during a cooling outage; a room temperature based on personnel comfort level. Obviously, personnel comfort will have to be weighed against opportunities for data centre energy savings.

Vic Smith is the Chair of EMEA Technical Work Group for The Green Grid and a Contributor to SearchVirtualDataCentre.co.uk. 

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