Technique using outdoor air or naturally cold water to cool a data centre without mechanical refrigeration.
Free cooling exploits outdoor climatic conditions, cold air or source water, to remove heat from a data centre without using, or using as little as possible, mechanical refrigeration. When ambient temperature is low enough, this approach drastically reduces cooling energy consumption and improves PUE, which explains the location of many sites in cold regions. Its performance, however, depends directly on the local climate, creating seasonal dependence and vulnerability to extreme heat episodes. For the insurer, free cooling ties site operation to physical climate risk: a heatwave exceeding design thresholds can saturate the system and constrain operation, turning a weather hazard into a business interruption. The rising frequency of heatwaves under climate change gradually erodes the safety margin of these installations.
A Nordic data centre designed for free cooling can see its thermal margin reduced by increasingly hot summers, exposing the operator to an interruption risk during heatwaves.
free cooling, refroidissement naturel, refroidissement adiabatique