Can we use data centres to heat our homes?

6 Dec 2023

Image: © Dabarti/

Kim Gunnelius of Verne Global discusses the benefits of heat distribution systems, the challenges in implementing them into data centres and the importance of proper public policy.

Data centres have become major users of energy and look set to be an even greater strain on the grid in the future.

These centres already account for nearly 20pc of Ireland’s electricity consumption, but the recent focus on AI systems is also spurring on their development. There are estimates that data centres could use more than 20pc of the world’s electricity by 2030.

Data centres also have to be kept at optimum temperatures to operate effectively, so a lot of their energy consumption is focused on cooling and ventilation systems.

With concerns around the environmental impact of data centres and their strain on energy grids, organisations are looking at various ways to reduce their impact. New forms of cooling systems, a focus on renewable energy and new materials to improve heat dissipation are some examples.

But what if we could take the heat produced by these centres and use them to heat other buildings? A study from earlier this year suggested that up to 97pc of the electrical energy from data centres could be recovered as heat.

Kim Gunnelius, the managing director of Verne Global in Finland, discussed the benefits of utilising heat recovery in data centres.

“By redirecting this surplus heat to warm nearby buildings, provide hot water or support industrial processes, data centres can make a positive impact on energy efficiency and emissions reduction,” Gunnelius said. “However, this opportunity often goes untapped, and waste heat is released into the atmosphere or, at best, inefficiently managed.”

Getting the most from waste heat

Gunnelius said servers, storage devices and networking equipment are the “primary sources” of waste heat generation in data centres, as they have to “continuously” process data. But other parts of data centres – such as cooling systems – also generate heat.

This presents various sources of waste heat that could be utilised, but Gunnelius said that it first would need to be processed and distributed.

“The temperature of the waste heat is often relatively low, but district heating and other industrial uses often require heat at higher temperatures,” he said. “The heat may need to be increased to 70 degrees Celsius or more to make it suitable for district heating.”

Gunnelius said one way to utilise the heat from data centres would be to transfer it to a heat exchange system. By using heat pumps or other heating systems, the waste heat could be brought up to the required temperature.

“The now-processed waste heat is then distributed through a dedicated heat distribution network,” Gunnelius said. “This network can consist of pipes or other infrastructure that carries the heat to the end user.

“In addition to district heating, the distributed waste heat can be utilised for manufacturing processes, warming greenhouses for agriculture and heating municipal swimming pools.”

Verne Global said it has utilised this idea in one of its data centres in Finland called ‘The Air’, which uses heat exchangers to extract excess heat from the air and transfer it to water systems.

“Through the use of heat pumps, the water is elevated from around 30 degrees Celsius to a temperature suitable for the district heating company, typically exceeding 90 degrees Celsius and even reaching 100 degrees Celsius during cold days for the required temperature,” Gunnelius said.

“For every 1MW of IT power allocated to the servers, 1.3MW of heat is generated. The heat pumps consume an additional 300kW of electricity to raise the temperature. Remarkably, the system incurs only minimal energy losses, amounting to just a few percent.”

Heat distribution obstacles

But while this method sounds like a potentially effective way to reduce the energy impact of data centres, Gunnelius noted that there are obstacles in implementing this approach across the board.

Verne Global’s Finnish data centre benefits from an “existing district heating network”, which means a pipeline already exists near the data centre to simplify the connection process. In other locations, data centres may not have the same benefits.

“The Air facility benefitted from specific subsidies available in Finland, where the utilisation of excess heat for secondary purposes also meets one of the criteria for a reduced power tax classification,” Gunnelius said. “But even in countries that mandate heat reuse and provide financial incentives, the lack of existing infrastructure available for integration can be a significant obstacle.”

To make an effective heat reuse system, Gunnelius said there needs to be a “substantial initial investment” for the required infrastructure, heat exchangers and distribution systems. The location of the data centre is also important, as some centres may need to transport the heat across long distances to reach end users, which would require pipelines or heat distribution networks.

“As a result, while heat recovery can be easily implemented in Helsinki, due to a direct connection to the district heating network, it may be more challenging to do so in remote areas and smaller towns in Finland,” Gunnelius said.

Public policy support

Gunnelius said public policy is important to promote sustainable data centre practices and to ensure that heat recovery is included in the “broader trend of green data centre design and operation”.

He added that the subsidies provided by Finland are one example of how governments can incentivise data centre operators to invest in heat recovery technology.

“Likewise, from France to Denmark, governments have implemented tax incentives and in some cases, mandated the recovery of waste heat as a prerequisite for obtaining new building permits,” Gunnelius said.

But it is also important that the infrastructure around data centres is able to effectively reuse the heat that comes from data centres. Gunnelius said there are examples where data centre providers are mandated to bring waste heat to the property line “even when there are no plans for the municipality to reuse that heat”.

“This can work against sustainability goals due to unnecessary equipment purchases and added project-related carbon footprint,” Gunnelius said. “Requiring heat reuse in such situations, where the district infrastructure is not ready – and with no certainty it ever will be – does not make much sense.”

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Leigh Mc Gowran is a journalist with Silicon Republic