Meanwhile, the hot water in the radiators is piped to some evaporative towers on the Data Centre roof. When the water evaporates, the heat inside it is transferred to the outside air. Canberra’s low humidity makes it an ideal place to employ free cooling. If the humidity does get too high for evaporative cooling to work efficiently, we do have some industrial chillers we can use to cool down the water. Overall, the estimated Power Usage Efficiency for the NCI Data Centre is 1.24, making it 250% more efficient than the average Data Centre in the United States.