In 2010, data centres world-wide used about 350 TWh of electricity. It is just over 1% of the world’s total electricity use and it is constantly growing. Most of the power consumed by the Information Technology (IT) equipment is converted into waste heat, which must be removed to avoid damage to the equipment. The energy requirement of the cooling system represents up to 40% of the overall data centre energy consumption. A strong focus was put on enhancing the efficiency of the cooling system in data centres in recent years.

In Europe, the total energy consumption of data centres was 56 TWh/year in 2007 and is expected to increase up to 104 TWh/year in 2020. The increase is mainly due to key drivers such as streaming services for movies and television, the emerging Internet Of Things (IOT) technologies and an overall increase in digital products and services. On the other hand, buildings are expected to become increasingly more efficient in reducing the thermal energy demand.

Apart from a small number of extremely large scale data centres with IT loads of 5 MW, there are also hundreds of thousands of midsize enterprise data centres with IT loads between 500 kW and 5 MW, and even more small data centres with IT loads below 500 kW all across Europe. As an example a midsize data centre with 1 MW IT load releases 3,700 MWh thermal energy per year into the atmosphere (equivalent to around 0.46 MWhth of waste energy/MWh of electricity consumed by the data centre). This would result into 48 TWh/year of potential waste heat that could be recovered by data centres in the future.