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22.11.2021 Article

Harnessing waste heat — a new standard improves energy efficiency of data centres

Novel solutions are needed to reduce emissions from telecommunications, and the focus is now on data centres with high energy consumption. The new ERF standard gives data centres the means to measure, in a reliable and comparable manner, how much of the heat that they produce can be recovered and exploited. The international standard, prepared under the guidance of Finnish experts, helps data centres to cut not only their CO2 emissions but also energy costs.

When you use Google or start an online video, a server hums somewhere inside a data centre and consumes electricity. This electrical energy is largely transformed into heat that needs to be removed from the data centre. The heat is lost in the atmosphere unless it is recovered and exploited.

As there is no end in sight for global data consumption, emissions from data centres are likely to only increase. It has been estimated that the world’s data centres already generate as much carbon dioxide as all air traffic combined before the coronavirus pandemic. Standards have an important role in the improving of data centre energy efficiency. Published in August 2021, the ERF standard ISO/IEC 30134-6:2021 Information technology – data centres key performance indicators – Part 6: Energy Reuse Factor (ERF) is part of a larger set of standards that support environmental aspects in the development, operations and management of information technology.

Recycling wasted heat and cutting costs

Heat recovery is key to improving the energy efficiency of data centres. The ERF standard allows data centres to demonstrate, in a reliable and comparable manner, how much of the heat that they produce is currently exploited. When the standard was drafted, there was a lot of discussion about indicators. Finally, the standard was developed around ERF (Energy Reuse Factor). ERF is a simple indicator showing to what extent energy used by data centres is recycled.

“In practice, ERF is the percentage of energy that is being exploited. The ERF standard covers all the energy of a data centre that can be utilised. It does not necessarily have to be in the form of heat, and the standard includes conversion factors for other types of energy, too. In this way, the standard opens the door for future development,” says Mikko Aho, Head of Sales at Rittal Oy and chair of the Finnish Standardization Group SFS/SR 311.

In order to recover heat, the data centre requires a heat pump system. The investment pays off when waste heat is efficiently recycled: energy is saved, emissions decrease and competitiveness improves.

In Finland, it is often possible to connect the data centre to the district heating network, in which case waste heat can be sold for the purposes of heating water and apartments. While not every country has district heating, there are also other possibilities for heat recycling.

“The heat produced by a data centre can be used for other purposes depending on the specific circumstances in each country. In Norway, for example, energy could be diverted to the needs of fish farming,” says Aho.

Apart from energy efficiency, the carbon footprint of data centres is affected by how the power they use is produced. The greatest environmental benefit from the reuse of waste heat is achieved when it is combined with the use of green electricity.

“In this way we can operate data centres that are carbon neutral or even carbon negative. One example is the Seinäjoki Data Center, which is being built in the city of Seinäjoki,” Aho says.

Finland convinced an international standardization group of the benefits of heat recovery

For a cold country like Finland, the benefits are especially notable, and it is not surprising that when the preparation of the ERF standard started in 2014 it was at Finland’s initiative.

“When developing an international standard, the experts of the ‘warmer’ countries had to be convinced as well. This was greatly helped by the 2016 global ISO standardization meeting in Finland, which focused on data centres in particular. Our group visited the Yandex data centre in Mäntsälä, which has implemented a heat recovery system. The practical example impressed the international members of the group,” says Aho.

Finnish experts were closely involved in the preparation of the standard from the beginning to the end. Pekka Järveläinen from JustIn served as the chair of the standardization group when the idea for the standard was born. Other active members of the group included Jari Innanen from Granlund, Jari Niittylahti from Fujitsu and Markus Leinonen from the Regional Council of Kainuu who, as an editor, was largely responsible for writing the standard.

Will the ERF standard be used to support regulations?

Cities are increasingly looking for forms of heat production other than combustion, and data centres are seen as part of future heat production. There is also a change in energy taxation that requires utilising waste heat. This change may well encourage data centres to start using the ERF standard.

“It has also attracted decision-makers’ attention. At the turn of the year, a legislative amendment is expected allowing data centres to access the industry energy tax category II if they exploit heat at an adequate level. Hopefully, the legislators will take into account the ERF standard and apply it in their requirements. Large data centres will then have to follow it if they want tax reliefs for their energy consumption,” Aho says.