Choosing a colocation datacenter in Europe

Every useful shortlist starts with a requirements sketch. How much power do you actually need at move-in, and what is the realistic growth path over the contract term? What rack density does your hardware run at today — and what will your next hardware generation need? Who and where are the users this deployment serves, and how latency-sensitive are they?

Two numbers do most of the work: total power (in kW or MW) and power per rack (kW/rack). Modern general-purpose deployments commonly run at 5–15 kW per rack; GPU and AI workloads routinely need 30 kW and beyond, which many older facilities cannot cool. Being honest about these two numbers early prevents the most common selection mistake: falling in love with a site that cannot physically host your growth.

European colocation concentrates in a handful of major metros — Frankfurt, London, Amsterdam, Paris and Dublin are the established tier, each with deep carrier ecosystems and internet exchanges. They offer the widest choice and the best connectivity, and they are also where power constraints bite hardest: Amsterdam and Dublin in particular have restricted new grid connections for years.

Around them, a strong second ring has developed: Madrid for Iberia and subsea routes, Warsaw for central and eastern Europe, Oslo and the Nordics for low-cost renewable power, Vienna as the CEE gateway, and German regional markets like Hamburg, Berlin and the Rhine-Ruhr area. For many workloads a second-ring metro delivers better economics and faster delivery than the congested core — the trade-off is usually interconnection depth.

A common pattern is a pair: one site in a connectivity-dense core metro, one in a power-rich regional market. If your workload is latency-tolerant — batch, training, archive — the regional market can be the primary.

Tier ratings (I–IV) describe redundancy topology: Tier III means concurrently maintainable — the facility can undergo maintenance without downtime — and is the de-facto standard for business-critical colocation. Tier IV adds fault tolerance at a meaningful price premium. Treat tier claims precisely: a certified rating from the Uptime Institute is not the same as “built to Tier III principles”, and for many workloads a well-run Tier III beats a poorly run Tier IV.

Certifications answer a different question: how the operator runs the facility. ISO 27001 (information security) is the baseline European buyers expect; ISO 22301 (continuity), ISO 50001 (energy), SOC 2, PCI DSS and EN 50600 signal maturity for specific requirements. Ask for scope documents — a certificate that covers the operator’s head office but not the facility you are buying into is common enough to check for.

In most European metros the scarce resource is not floor space but grid power. Connection queues in constrained markets run years, and a facility’s marketing capacity can be far ahead of what its grid connection actually delivers today. The questions that separate solid offers from optimistic ones: is the power committed and contracted with the utility, what is secured today versus planned, and what happens to your expansion rights if the operator’s next grid tranche slips?

Energy price exposure belongs in the same conversation. Understand what is passed through and how: fixed, indexed, or spot-linked power pricing changes your cost profile more than most contract terms. Sustainability requirements — renewable sourcing, PUE commitments, heat-reuse obligations in some jurisdictions — are increasingly regulatory rather than optional, especially in Germany under the Energy Efficiency Act.

Air cooling remains the default and handles densities into the low tens of kW per rack when engineered well. Above that, liquid options — rear-door heat exchangers, direct-to-chip, immersion — move from exotic to necessary. If AI or HPC is anywhere in your roadmap, ask facilities not whether they “support liquid cooling” but which method, at what density, delivered by when, and whether the mechanical and electrical headroom exists on your contracted footprint.

Density headroom is a cheaper insurance than a second migration. A facility that can double your per-rack power without relocating you is worth a premium over one that is already at its design limit.

Where a facility stands — and who owns the operator — determines which legal regimes reach your infrastructure. EU-based facilities under EU-owned operators keep matters inside the GDPR framework; UK sites sit under UK GDPR post-Brexit; and US-parented operators can face extraterritorial obligations under the US CLOUD Act regardless of facility location. For regulated sectors and public-sector buyers these distinctions increasingly decide shortlists.

Sovereignty questions deserve the same precision as technical ones: ask about operator ownership, where support and admin access sit, and which contractual commitments back the answers.

Compare facilities on verified facts, not brochure language: committed power and delivery date, density and cooling method, certifications with scope, connectivity options and cross-connect pricing, and the expansion terms that protect your growth. Beware of directories that sell placement — if an operator can pay to rank higher, the ordering tells you about marketing budgets, not fit.

This platform takes the opposite approach: search and comparison are free and anonymous, operators cannot buy ranking, and paid features reward data quality only. When your shortlist is ready, one request reaches the operators you select — they respond with proposals, and your contact details stay with the platform until you choose to engage.