Adiabatic cooling

On July 19, 2022, the day the United Kingdom passed 40°C for the first time, Google Cloud and Oracle reported cooling failures at their London data centers. Google powered down part of a zone to protect its machines. Neither said which cooling technique had failed. Adiabatic cooling lowers the temperature of incoming air by evaporating water into it. It draws little electricity, and it is what drove down the energy efficiency metrics of data centers built over the past fifteen years. Its performance depends on the wet-bulb temperature of outside air, not the dry-bulb alone, so it collapses exactly when it is most needed, during an episode that is both hot and humid. The technique trades a dependence on electricity for a dependence on water. Where the resource is contested, water becomes an operating constraint, and a local acceptance issue that the water usage metric measures. For insurance, the climate peril destroys nothing here: it pushes the installation past a design limit, and servers shut down on thermal protection before any physical damage occurs. The loss then takes the form of business interruption without prior damage. Many property wordings do not trigger in that case, and it has to be handled by a dedicated clause.