Digital Realty breaks ground on a 15MW Zurich bet

Data Center Dynamics reported this week that Digital Realty has broken ground on ZUR4, a 15MW data center in Glattbrugg, Switzerland, first announced in 2023 and not expected to switch on until 2028. The gap between those two dates matters more than the megawatts: five years from announcement to electrons, in a market where capital has never been the constraint.

ZUR4 will add about 6,300 square meters of floor space to a campus that already runs ZUR1, ZUR2, and ZUR3, and Digital says the building is engineered for high-density deployments and AI workloads, with cooling systems the company describes only as state-of-the-art. The density figure speaks for itself: 15MW across 6,300 square meters works out to roughly 2.4kW per square meter, more than three times the density of ZUR1, which has operated since 2000 at 5MW across 7,400 square meters. It is the AI-era spec in a single number: a mechanical plant built to move heat the way the old campus never had to.

The existing three buildings total around 25,000 square meters and 45MW of capacity, with ZUR2 breaking ground in 2019 and launching around 2020. ZUR3, announced under the Interxion banner in 2020, was meant to open its first phase in mid-2022 with 2,900 square meters; it is now live, and the full build-out will run to 11,000 square meters and 24MW. Digital Realty's practice here is to add capacity in chunks, let the existing tenant base absorb it, then add the next chunk. Add ZUR4's 15MW to the 45MW now live, and the campus is positioned to roughly double once ZUR3 completes and ZUR4 comes online.

The five-year runway deserves attention, and it has nothing to do with steel: by the time a groundbreaking happens, the zoning and building permits are in hand; what takes years in a place like Zurich is the grid connection and the approvals around it. Digital Realty is not buying into generation or signing behind-the-meter power deals here, as some developers do elsewhere. The bottleneck in the AI buildout has shifted from land and chips to electrons, and ZUR4 is a pure grid-tenant play: the company controls the building, but the schedule for delivered megawatts belongs to the Swiss grid.

The company is not hiding that ZUR4 is a merchant bet: there is no hyperscaler anchor on the building; the pitch, from managing director Yves Zischek, is about the ecosystem of more than 200 customers already on the campus and more than 6,000 worldwide, the language of multi-tenant colocation rather than build-to-suit. Under the capital hierarchy this publication has described, hyperscaler-anchored assets clear at infrastructure pricing and everything else is merchant risk, which is what ZUR4 is. It may be exactly the right way to build in a market where single-tenant hyperscaler demand is scarce, and the phased approach keeps the exposure incremental. But the economics of this building rest on two things the builder does not control: the grid delivering 15MW in 2028, and the campus's existing customers absorbing the space. The 200 on-site customers are a moat of sorts — they give the campus a base load a greenfield site would not have, and a natural leasing pipeline for the new building.

The local politics are, at least, friendly: Barbara Franzen, a member of the Cantonal Council, called the expansion a demonstration that digital infrastructure has become the backbone of Zurich's economy and praised the investment for securing jobs and "digital self-determination." Not every jurisdiction greets a data center with that language, and the contrast with the consent battles this publication has covered elsewhere is stark. But political support does not change the physics of the grid.

Digital Realty has had a busy month beyond Zurich, per this publication's records: 50MW allocated in Singapore's second capacity call, and a federal courthouse colocation contract in Washington that the judiciary's RFI has put back in play with no automatic renewal. The company takes capacity where it can get it and defends the contracts it already holds. Zurich is the long game — a campus assembled on the same plot for more than two decades, upgraded and extended generation after generation, now being positioned for AI-era density. That patience is the counterweight to the merchant risk.

ZUR4 is the right kind of merchant bet: incremental, anchored to a campus with hundreds of live customers, and timed to a plausible delivery year. But in a market where the binding constraint is electrons, the 2028 date is a promise the grid, not the builder, will keep. The building is the easy part.