Data centres keep our digital world running, from streaming shows to supporting cloud applications. Yet all that power comes at a cost — energy use is rising fast, and efficiency is no longer optional.

Inside every data centre, servers convert electricity into computing power — and in doing so, they generate heat. Every kilowatt of energy consumed produces waste heat that builds up within the facility. Traditionally, this heat has been removed through cooling systems and simply exhausted into the atmosphere.

Today, there’s a better option. Instead of letting server heat go to waste, data centres can turn it into a resource — cutting energy use, easing environmental pressure, and even warming nearby homes. Digital Realty’s sustainable energy solutions help organisations get the balance right between performance and environmental responsibility.

Why data centre sustainability matters

Data centres use a lot of power. They account for about 1% of the world’s electricity — and that number keeps climbing as more businesses move to the cloud. Energy efficiency isn’t just about saving on bills; it’s central to meeting environmental targets.

Simple steps to reuse energy and reduce waste make a real difference, both for operational costs and long-term sustainability. For more on how efficiency is measured, see our guide on Power Usage Effectiveness (PUE).

The untapped potential of waste heat

Every data centre generates waste heat as servers and IT equipment do their work. Data centre waste heat recovery is the process of capturing that heat and reusing it to warm nearby buildings or feed district heating networks.

In the past, this energy was simply vented away. Today, captured heat can warm offices, hospitals, or feed into local energy networks. It’s not always simple — differences in temperature, regulations, and grid connections can complicate things — but the potential is significant.

Some of Digital Realty’s projects show what’s possible when that potential is realised:

Vienna: Supplies more than half of the required warmth to Floridsdorf Hospital, expected to save up to 4,000 tons of CO₂ emissions per year when fully operational
Amsterdam (AMS5): In partnership with Dutch energy provider Polderwarmte, our AMS5 data centre will channel excess heat to business parks in Schiphol-Rijk, supporting local heating needs and reducing waste heat emissions.
Stockholm: Since 2015, our facility has contributed to Stockholm Exergi’s district heating network, supplying excess heat to over 800,000 residents through a 3,000-kilometre network.
Zurich: We plan to provide 18 MW of heat from our data centre operations to businesses around Zurich Airport, with estimated CO₂ savings of 15,000 tons annually in phase one.
Frankfurt (FRA14): Through a 15-year contract with SAMSON AG, we will supply waste heat from our FRA14 data centre to the Rolf Sandvoss Innovation Center, eliminating gas heating and cutting more than 80 tons of CO₂ per year.

These projects demonstrate how a byproduct of digital operations can power local infrastructure and reduce carbon emissions — turning a challenge into community value.

Learn more about reducing carbon in cloud operations in How to Calculate and Reduce Cloud Carbon Footprint.

From problem to potential – how recovery systems work

Heat recovery systems have become smarter and more capable. Sensors and Data Centre Infrastructure Management (DCIM) tools track temperatures and redirect heat where it’s needed, keeping performance steady and energy use low.

Heat can be redirected to local heating networks, district energy schemes, or nearby buildings. Integrating with chilled water systems and local grids makes this possible while reducing environmental impact.

Digital Realty’s new-build facilities include chilled water systems designed to connect to local heat networks. In Stockholm, for instance, our facility links directly to the city’s district heating system, supplying excess heat to homes nearby. By designing for recovery from the start, data centres can make waste heat work for their operations and the wider community.

Of course, this approach comes with challenges. Differences in temperature, grid access, and regulation can add complexity, while upfront investment requires careful planning and close collaboration with local energy partners. But the long-term environmental and social benefits far outweigh the initial effort.

Data centre efficiency best practices

Boosting efficiency isn’t all about big projects — small adjustments help too. Modular cooling, and using energy-efficient Uninterruptable Power Supply (UPS) systems can noticeably reduce power use without affecting performance.

Metrics like Power Usage Effectiveness (PUE) and Data Centre Infrastructure Efficiency (DCIE) help track results. At Digital Realty, modernisation projects and strategic equipment refits ensure sites stay efficient, while helping customers save on energy and improve profitability. Discover how these practices fit into our ESG strategy.

Local impact and future direction

As cloud services grow, so does the demand for sustainable infrastructure. Data centres are in a unique position to support local sustainability goals, sharing excess heat and integrating with renewable energy initiatives.

Digital Realty works closely with local councils and energy partners to ensure its facilities contribute to regional decarbonisation efforts — from supplying hospitals and homes with recycled heat to supporting business parks and innovation centres. These sites help communities become more sustainable while keeping IT services running reliably.

Projects such as those in Vienna, Zurich, and Frankfurt demonstrate the environmental impact of waste heat recovery, with potential annual savings of thousands of tons of CO₂ emissions.

Turning waste heat into value

Sustainability in data centres isn’t just about cutting costs — it’s essential for climate goals and long-term digital growth. Waste heat recovery shows how operations can create value while reducing environmental impact.

Digital Realty helps organisations meet their performance targets without compromising sustainability. Our energy-efficient designs and innovative solutions ensure your data centre supports both business success and environmental ambitions.

Get in touch to find out how our data centre solutions can support your ESG strategy.

FAQs

What is data centre waste heat recovery?
It’s the process of capturing heat generated by IT equipment and reusing it to warm nearby buildings or feed district heating networks.

What environmental impact can waste heat recovery have?
Projects such as those in Vienna, Zurich, and Frankfurt demonstrate potential annual savings of thousands of tons of CO₂ emissions.

What are the main challenges in reusing waste heat?
Differences in temperature, grid access, and regulation can add complexity, but planning and partnerships help overcome them.

How to reuse waste heat from data centres?
Heat can be redirected to local heating networks, district energy schemes, or nearby buildings. Integrating with chilled water systems and local grids makes this possible while reducing environmental impact.

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