A closer look at free cooling
The data center cooling challenge
Colocation continues to be adopted as part of a diversified infrastructure strategy. But the fact that these facilities are well-connected and provide space for high density configurations brings with it a challenge. Increasingly you can expect to see racks of less than 3 m², containing up to 20 servers, with a consumption of up to 6KW – and sometimes even much more. Now imagine a 30m² room with 60 of these ‘ovens’ running day and night. The need for very careful management of power and cooling is critical. And it requires a constant evolution in best practices and technologies to do it efficiently, and in an environmentally friendly manner.
Key Principles of Free Cooling
Free cooling is optimal when the outdoor temperature is lower than that anticipated within the IT rooms. In some locations, this temperature difference is highly predictable, but in others, managing the inversion of these temperatures is necessary to ensure cooling reliability. On very hot days, additional measures must be taken to cool the outdoor air before it is delivered to the IT rooms, resulting in increased energy consumption within the facility and potentially diminishing the relative value of a free cooling strategy.
To optimize free cooling (and reduce electricity consumption), the outdoor temperature should be lower than that of the IT rooms for most of the year. This may challenge certain companies’ choices regarding where to install their infrastructure. To address this issue, another possibility is to operate the IT rooms at a higher temperature. Again, this may seem counterintuitive. However, the industry as a whole now utilizes higher temperatures within its facilities, supporting broader adoption of free cooling.
This passive cooling method that leverages the building’s thermal inertia to regulate internal temperature using outdoor air often works in conjunction with mechanical ventilation systems that control air intake and exhaust to maintain optimal conditions. Night ventilation is a key component of this approach, utilizing cooler nighttime temperatures to pre-cool the data center without resorting to traditional air conditioning systems.
However, implementing free cooling can be complex due to several factors. Firstly, climate variations require flexible design to adapt to changing conditions, while air filtration is necessary to remove outdoor contaminants. Additionally, humidity management is crucial to prevent equipment damage. Despite these challenges, free cooling can offer significant long-term energy savings, albeit requiring initial investment in additional systems and security.
Mechanical Free Cooling
Mechanical free cooling is a sophisticated cooling method used in data centers and other facilities where precise temperature control is essential. Unlike traditional free cooling, which primarily relies on natural ventilation to take advantage of outdoor temperature variations, mechanical free cooling uses mechanical equipment to enhance and control the cooling process.
In mechanical free cooling, equipment such as heat exchangers, fans, and control systems are used to transfer heat from IT equipment to a cooling fluid, typically water. This fluid is then cooled using outdoor air when conditions are favorable, often at night or during cooler periods.
Mechanical free cooling systems can be configured in various ways, including using cooling towers, air-to-water heat exchangers, evaporative cooling systems, or vapor compression cooling systems. The goal is always to minimize the use of traditional air conditioning systems, reducing energy consumption and associated costs.
While mechanical free cooling may require larger initial investments than natural free cooling, it generally offers more precise temperature control and may be more suitable for environments where climatic conditions are less favorable or more variable.
Free Cooling: Your Environmental Footprint
Cooling data centers is perhaps the biggest challenge faced by data center managers when seeking to reduce their environmental impact. The efficiency of cooling processes and solutions presents significant obstacles to reducing a data center’s power usage effectiveness (PUE) indicator. Historically, most installations had a PUE below 1.8, but it is becoming increasingly common to see it reach 1.2 when cooling has been optimized.
Free cooling is one of the most commonly used techniques to facilitate this evolution and allow you to reduce your environmental footprint. DATA4 has continuously evaluated its own environmental footprint and sought to reduce its PUE in its facilities. Thanks in part to the implementation of free cooling technologies, Data4 has managed to reduce its PUE by over 20%, and our new installations now target a PUE of less than or equal to 1.25.
