How is a data center cooled?
You have probably heard about the energy consumption of data centers. Data centers house hundreds, sometimes thousands, of servers. Their energy requirements are therefore enormous, but what really drives up the meters are mainly the cooling systems, in addition to other IT equipment. Here's why cooling is essential and how it all works.
Why do data centers need to be cooled?
IT equipment, such as servers, naturally generates heat. If this heat is not dissipated, the temperature rises very quickly in the buildings housing this equipment. And this inexorable rise in temperature leads to several risks:
● A safety risk for the equipment. Above a certain temperature (ideally around 81°F or less), servers may stop running or even burn out.
● A risk to service continuity. If servers shut down due to overheating, service is interrupted for the end customer, which must not happen.
Maintaining an adequate temperature within data centers is therefore essential to ensure that servers continue to operate without interruption. Cooling data centers is one of the most electricity-intensive aspects of the entire infrastructure. That is why focusing on energy efficiency and sustainable energy has become a top priority.
What are the cooling techniques used in data centers?
There are two major trends in data center cooling: traditional systems and innovations that are gaining ground. Traditionally, data centers are cooled using cold air that is blown under a raised floor to reach the servers and cool them. The hot air emanating from the servers is then recovered through the false ceiling and directed to the cooling units. Two units are used for this purpose:
● The CRAC (Computer Room Air Conditioner) : this system works like a conventional air conditioner, using a compressor and a refrigerant to cool the air.
● The CRAH (Computer Room Air Handling Unit) : this system uses a chilled water plant. Cold water passes through a coil to cool the air blown by the fans.
Other more modern techniques can also be deployed in data centers, such as:
● Free cooling: this method uses outside air to cool rooms. Cold outside air is filtered and injected directly inside. Warm air is then evacuated.
● Adiabatic cooling: this technique uses water evaporation. Water is vaporized into the incoming air. As it evaporates, the water absorbs heat from the air, cooling it without using much electricity.
● Liquid cooling: water or another liquid is used to absorb ambient heat. Cold plates can be installed next to a server or rack on components (CPU, GPU, RAM), or components can be directly immersed in a non-conductive liquid (immersion)..
● Hybrid systems: these generally combine the use of fans with water.
Comparison of methods
Each method has its advantages and limitations. Which one to use depends largely on the infrastructure, its size, and its location. Here is a summary of the specific features of each:
● CRAC: traditional air and compressor system, simple but energy-intensive.
● CRAH: uses chilled water to cool the air.
● Free cooling: uses outside air to cool the room, very effective as long as the outside temperature is low. This is the most suitable method in naturally cold regions.
● Adiabatic cooling: cools the air by evaporating water (trickle), offering high cooling capacity with low power consumption.
● Liquid cooling: using plates or immersion, liquid is much more efficient than air at absorbing heat.
● Hybrid systems: a combination of techniques to optimize efficiency, cost, and space requirements.
Data center energy needs and air conditioning challenges
The development of digital technology, particularly artificial intelligence and the cloud, is leading to a significant increase in data center energy consumption. These infrastructures must continuously power thousands of servers, while ensuring their cooling and security. This is a major challenge that must now be addressed in order to limit the environmental impact of data centers.
Rising consumption by French data centers
According to a report by the French electricity transmission network (RTE), in 2022, data centers in France consumed around 10 TWh, or approximately 2% of the country's total electricity consumption. By 2035, the electricity needs of data centers could triple to reach an average of between 23 and 28 TWh (or 4% of France's estimated consumption for this period). However, more than 90% of French electricity production is carbon-free, which is good news for the carbon footprint of the digital sector*.
Current challenges in air conditioning
Choosing an efficient and sustainable cooling solution is a real challenge for the environment. Various factors must be taken into account.
● The PUE indicator: PUE (Power Usage Effectiveness) is used to measure energy efficiency. This indicator compares the total energy consumed by the data center to the energy used solely by IT equipment. The closer the PUE is to 1, the more efficient the data center is.
● Water stress: Solutions that use a lot of water, such as adiabatic cooling, can be a problem in certain regions. Although water generally circulates in loops within the circuits (once it has been drawn in initially, it is no longer necessary to draw it continuously), it is nevertheless important to consider its use in order to avoid water stress.
● Climate regulations: Certain refrigerants such as R134A (used in CRACs, for example) are no longer permitted due to their harmful effects on the climate. Numerous national and international regulations also govern energy consumption, prompting companies, particularly in the industrial and data center sectors, to consider more sustainable solutions.
UltraEdge: sustainability at the core of our data centers
To meet these challenges, data centers are increasingly committed to finding solutions. High-performance, energy-efficient cooling systems, use of renewable energies, hot aisle and cold aisle containment... There are many ways to reduce the environmental impact of data centers. At UltraEdge, we take these issues very seriously. We are investing heavily in our infrastructure to reduce our PUE and optimize our operational strength. We are also ISO 50001 certified and are committed to implementing measures to reduce our energy consumption.
We have also chosen to install our servers in France (more than 250 servers in France). This allows us to prioritize the use of French carbon-free energy. The proximity of our servers to French companies and customers also allows us to reduce the distance over which data is transmitted. This also means less electricity consumption for network and telecommunications equipment.