What “Free” Data Center Cooling Really Means
Many times, you may come across the term “free” data center cooling However, not many are aware of what “free” cooling really is and the key things it includes. Here is a quick overview:
Free data center cooling is the concept of avoiding electrical refrigeration and instead using the outside cooler air to dissipate heat from a data center. There are primarily two ways to achieve free cooling: air-side and liquid-side. In air-side cooling, air is used as the medium for transferring the heat while in liquid side, water is the medium used for cooling. Water is a much better medium than air because 40,000 cubic feet per minute (cfm) of air are required to cool a 250 kW data center.
When it comes to air-side cooling, one option is using the Kyoto wheel. The statistics around the Kyoto wheel are interesting in terms of energy efficiency. It is reported that this approach uses only 8 to 25% of energy as compared to mechanical refrigeration. The wheel can provide free cooling for 81% of the year in San Jose and 47% in Dallas. The challenge of using air-side cooling is the impact of humidity and pollutants in the outside air which can hamper the energy gains provided by the process.
A water-side free cooling system needs to be designed with careful consideration. The main principle is that the system needs to have controls in place so that the mechanical refrigeration can be bypassed when the outside air temperature is low enough.
No matter which system one opts for, it is clear that energy efficiency, especially in the area of cooling, is one of the top most priorities for all data center managers. GreenGrid has even published a free air energy savings calculator on its website which can give you an estimate on savings based on your choice of datacenter capacity and location.