Beyond Cooling: How Data Centres Can Become Heat Hubs for Net Zero Infrastructure

Every year, data centres in London release enough waste heat to warm up to half a million homes, according to AECOM and the Greater London Authority. Most of it is vented straight into the atmosphere. But buried beneath headlines about megawatt-hungry facilities is an overlooked reality: data centres don’t just consume energy - they also produce it.

Every watt of power that runs a server eventually becomes heat, and with the right approach, that heat doesn’t have to be wasted. It can be captured, upgraded, and repurposed to warm nearby homes, schools, hospitals and businesses.

Heat reuse projects are already underway in London and Tallaght, backed by public funding and growing regulatory support. For developers, that opens up a new strategic consideration: where and when could heat reuse add value to the community, the planning case, or the bottom line?

The Missed Opportunity in Energy Planning

Despite the scale of energy flowing through data centres, heat reuse is rarely considered at the design stage. Planning conversations typically focus on electrical load and cooling efficiency, while the thermal energy being ejected from the site is overlooked.

That’s a missed opportunity - data centres produce a steady stream of low-grade heat 24/7 - and with rising gas prices and growing pressure to electrify heat, that waste is becoming harder to justify. Treating it as a usable resource, rather than an unfortunate by-product, could reduce costs, improve resilience and create tangible benefits, both for operators and the communities they operate in.

The technology is already available. Systems like heat exchangers, ground source heat pump (GSHP) boreholes and district heating networks are proven and in use - including in data centre settings. These are the tools that can capture, store, upgrade and distribute heat locally. GSHPs are especially well-suited here: they’re highly efficient, can be scaled for large developments, and enable inter-seasonal heat storage in the ground.

What’s missing is integration - developers, utilities and local authorities often work in silos, with limited coordination around thermal infrastructure. This means that viable reuse opportunities often go unnoticed.

It’s also a question of mindset. Data centres are still often treated as standalone assets - consuming energy, creating jobs, but disconnected from the communities around them. That model isn’t sustainable, in any sense of the word. As demand for low-carbon heat grows, integrated design - where digital and thermal infrastructure are planned together - is a better solution for both operators and the communities they operate in.

Inside the Heat Reuse Model

So how does heat reuse from data centres actually work?

The principle is straightforward, even if delivery requires careful coordination. Low-grade heat generated during data centre cooling is captured before it’s vented. That thermal energy is then transferred via heat exchangers and fed into a ground array - typically a set of vertical boreholes drilled into the earth beneath or near the site.

The ground acts as a thermal battery, storing and balancing heat throughout the year. Ground source heat pumps (GSHPs) then extract that stored heat, upgrade it to a usable temperature and feed it into a district heating network - supplying homes, schools, hospitals and commercial buildings.

These systems are already operating across Europe, including a live project in Tallaght, Dublin, where data centre heat is captured, upgraded and piped into a local district network. In the UK, a large-scale scheme is now underway in West London that will recover data centre heat for use in a new district heating system serving homes and commercial buildings. Integration is proven and practical, especially where local demand is high and the network is within reach. The key is early-stage planning. Retrofitting is possible, but co-designing thermal and digital infrastructure from the outset is cheaper, more efficient and far more scalable.

This model also provides flexibility, as stored heat can be drawn on when it’s needed, rather than just when the data centre is producing excess. That means the system can smooth demand, reduce grid stress and operate more like a real energy asset than a passive donor.

Why Now?

Until recently, the idea of reusing waste heat from data centres sat on the fringes of energy strategy - a niche opportunity, often dismissed as too complex or too site-specific to scale - but that’s starting to change. Several factors are converging to bring heat reuse into the mainstream. 

First, governments are beginning to actively support it. In the UK, funding from the Green Heat Network Fund is enabling large-scale projects, including the West London scheme. In Ireland, the Tallaght system has become a case study for how data centre heat can reliably serve public buildings.The UK government is also preparing legislation on Heat Network Zoning, which would mandate certain buildings - including new developments - to connect to local heat networks where available.

Second, planning requirements are evolving. In some regions, local authorities are starting to ask for clearer answers on how new developments will contribute to net zero goals, including what happens to waste heat. For data centre operators, being able to demonstrate a heat reuse strategy can support planning approvals and build goodwill with local stakeholders.

Finally, energy economics are shifting. The drive to decarbonise heating - one of the most difficult parts of the net zero equation - is creating new urgency around viable alternatives to gas. Data centre heat may not be a universal solution, but where the conditions are right, it offers a scalable, low-carbon supply.

The Business Case

While often framed as a sustainability initiative, heat reuse has real commercial implications for operators.

A credible heat reuse plan can support smoother planning processes, especially in urban or sensitive locations where data centre developments often face public or political resistance. It also contributes directly to ESG goals, offering a tangible local impact that’s increasingly important to investors, customers and regulators.

Beyond reputational benefits, a well-planned heat reuse strategy can strengthen the overall case for development. It may help reduce infrastructure duplication, demonstrate alignment with local energy priorities, or open up future collaboration with public bodies and utilities. For example, ground arrays typically last around 100 years, making them ideal for futureproofing local heat infrastructure. Even where implementation is complex, the ability to show forward thinking on heat can be a meaningful differentiator.

Of course, not every site will be suitable for heat reuse, and not every opportunity will stack up commercially. With the right local conditions, partners and design strategy, it becomes a credible addition to the planning and sustainability case for new developments.

Putting Heat on the Agenda

As energy systems become more local, decarbonised and interconnected, the boundaries between digital and thermal infrastructure are blurring - drawing data centres into wider conversations about how we plan and manage heat.

That shift brings complexity, but also opportunity. Operators who think ahead and engage early with local heat strategy will be better placed to navigate planning challenges, demonstrate public value and align with long-term energy goals. In a sector facing growing scrutiny, the ability to deliver low-carbon heat alongside digital services could be what sets the next generation of data centres apart.