The University of Oldenburg is one of the few universities in Germany to recover waste heat from parts of its Data Centre. The measure is part of the "WärmewendeNordwest" project funded by the Federal Ministry of Education and Research (BMBF), which is headed by Oldenburg energy computer scientist Prof Dr Sebastian Lehnhoff. As part of the project, several innovative cooling and heating systems are being installed at the university and intelligently linked in order to reduce energy costs and_{CO2 emissions}.

The first measure to be implemented is a heat recovery system for the university's new high-performance computing cluster, which will be installed in 2023. "The cluster's servers are cooled with water, as modern processors have an enormous power density," reports Meik Möllers, Head of Building Management. The cooling water has a temperature of around 45 degrees Celsius when it leaves the cluster. This thermal energy is now utilised for heating: Using a high-temperature heat pump, the water is heated to 75 degrees Celsius and then fed into the university's heating network. This heat supplements the output of the combined heat and power plant on the Haarentor campus, which supplies buildings A1 to A15, the library, canteen and sports wing with heat. "As the heat from the Data Centre is available all year round, it can be used to heat the university swimming pool, for example," explains Möllers. The annual heat supply from the heat recovery system is around 500,000 kilowatt hours. This corresponds to the heating requirements of around 30 four-person households or a saving of a good 100 tonnes of_CO2.

The other servers in the Data Centre are air-cooled. A highly efficient compression refrigeration system was recently installed so that they can operate safely in future even at outside temperatures of more than 40 degrees Celsius. Thanks to these two measures, the university already fulfils the legal requirements of the new Energy Efficiency Act ahead of schedule. Coming into force at the end of 2023, it sets standards for the first time for the energy efficiency of Data Centres, which will go into operation from 2026. The university invested 2.5 million euros from its own funds to bring the cooling and power supply for the scientific computers up to date in terms of energy efficiency, with a further 300,000 euros coming from project funds.

With the increasing digitalisation of research, teaching and administration at the University of Oldenburg, the demand for computing power and storage capacity is also growing, and with it the energy consumption of the IT infrastructure. With a share of around 30% of total consumption, the Data Centre is currently the largest electricity user within the university. In particular, the necessary air conditioning of the server rooms is very energy-intensive and costly. The new computer cluster therefore has an efficient cooling system using outside air. New high-performance computers are equipped with direct water-cooled server processors, which enable higher supply and return temperatures of the cooling water. Even at temperatures of up to 35°C, the outside temperature is sufficient to achieve optimum cooling of the Data Centre. Therefore, no compression chiller is required to reduce the cooling water temperature. This saves around 500,000 kWh of energy and around EUR 110,000 in energy costs every year.