Europe's post-industrial landscape is becoming the new frontier for data center growth. According to recent JLL research cited at Data Center World Europe, almost 90% of European data center development over the past 5 years has happened on brownfield sites.

The appeal seems evident: existing power infrastructure, lower land costs, and often more streamlined permitting than greenfield projects. But a panel of industry specialists at Data Center World Europe including Michal Gabrielczyk, Acting COO at British AI operator Era4; Francesc Queralt, Founder of powered land developer BtMData; and Nicola Lombardi, Project Director at architecture firm Scott Brownrigg; made clear that the brownfield opportunity comes with nuance.

That same JLL research notes that the next capacity cycle will bring much more greenfield development, rising to 39% of the 2026 to 2028 pipeline of new capacity, suggesting the limits of brownfield options.

Here are three insights every operator, developer, and designer should understand before committing capital to a brownfield site.

Existing Permits Can Be the Real Prize, Not Just Power

Brownfield sites are usually pitched on fast access to powered land, but some of the most valuable assets that come with industrial sites are the environmental permits already attached to the land. Queralt described this value in his project converting a textile mill in Italy into a data center site.

The facility already held a permit for a 100 MW thermoelectric power plant that was built to serve the factory’s manufacturing operations. "It's a no brainer,” he said, noting that access to power is “quicker in our case because there's already an environmental license, 100-megawatt thermal megawatts, and that would take years in Europe – in Italy at least, years – and that's something that we already have today.”

While access to existing powered land is a benefit given the years-long delays operators can face waiting for new grid connection requests, existing permitting enabling on-site generation can also cut years of regulatory process. Developers should consider environmental licenses and historical permits as a core part of site due diligence, not a secondary consideration behind power access.

Today’s Compute Gear Might Be Too Heavy for Existing Buildings, Especially as Rack Densities Climb

One of the most practical challenges raised on the panel was structural capacity, and it is becoming more urgent as AI workloads drive up rack weights. Lombardi laid out the physical reality facing designers converting industrial buildings: "If we are talking about single-story development, it's relatively feasible, but it becomes much more difficult when we're talking about multi-story facilities." He quantified just how much the load requirements have shifted, noting that racks can be “1-1.5 tonnes, and can turn to over 2 tonnes easily," with floor loads reaching 15 to 25 kilonewtons per square meter in some AI deployments.

Gabrielczyk echoed the same concern from an operator's perspective, pointing to the hardware Era4 is deploying today and what’s coming next. "The rack densities do worry me a little bit. … We're deploying Blackwood Ultra, that's Nvidia B300 at the moment, so those are heavy," he said. "We know what's coming with Vera Rubin, the Nvidia next generation that's starting to be deployed. What happens after that, some of those racks are getting really, really heavy, and so you start worrying about concrete slab thickness. Will that slab be strong enough? You can't take that for granted.”

The lesson is clear: developers need to assess how much weight brownfield sites’ existing buildings can bear, compared with the weight of today’s computing equipment. Structural assessment must happen early and specifically against current and near-future hardware specifications, not against historical industrial loading standards.

Community Buy-In Depends on Framing the Project as Regional Investment, Not Just a Facility

Brownfield sites are often in areas of post-industrial decline, where perhaps a single industry dominated local employment, and panellists agreed that project success hinges on community support.

Queralt described the stakes in the Italian town where his project is located, where a once-dominant textile factory has shrunk from 1,000 employees to 200. "The decline of this factory, which was the economic engine of the local community, also marks the decline of the town," he said. "So everyone is supportive of finding a solution to that because the alternative is closing down and having a ruin in five years."

Gabrielczyk expanded on this point with a broader strategy for winning community support, drawing a comparison to telecom infrastructure rollouts. “We’ve seen this model work in telco, where in rural parts of Africa and India operators come in, deploy a tower, and alongside this a local energy source,” he said. “This has been the anchor for bringing power and connectivity to that community.”

He suggests data centers can play a similar role, serving as an anchor that can draw in regional industry and economic growth. Lombardi, however, added a note of caution on managing expectations about job creation. "Sometimes there is an expectation on industrial land to generate employment to a scale that obviously data centers difficultly can do," he said. Redevelopers should make clear that while data centers can bring investment and create jobs, they probably won’t replace lost manufacturing jobs at an equal rate.

Overall, brownfield redevelopment offers real advantages to developers and operators: existing permits, lower land costs, and often a faster path to deployment. It can also offer benefits to community, finding an economically productive reuse of a declining industrial site.

But as this panel made clear, success depends on utilizing historical environmental permits as strategic assets, rigorously assessing structural capacity against modern rack densities, and framing projects as catalysts for regional investment rather than standalone facilities imposed on a community.