Layer 1 · head to head
Two-phase immersion vs Single-phase immersion
Marginal thermal gain against a live PFAS regulatory question.
| Two-phase immersion | Single-phase immersion | |
|---|---|---|
| Capital cost | Highest | High, and it changes the whole facility design |
| Density supported | Highest available | 100+ kW per rack equivalent |
| PUE | Approaching 1.02 | 1.02-1.10 |
| Maturity | emerging | proven |
Two-phase immersion
The catch: The fluids are expensive and several are under regulatory pressure as PFAS rules tighten. That is a supply and compliance risk sitting on top of an already niche choice.
Decides: Thermally excellent, commercially awkward. Watch the fluid regulation before committing a fleet to it.
Single-phase immersion
The catch: Direct-to-chip is the 2026 production method; immersion is not. Serviceability, hardware warranties and the fact that you cannot mix it into a normal hall are the reasons, not thermal performance — where it wins.
Decides: Best PUE available. Chosen by people building a purpose-built fleet, not by people upgrading a datacentre.
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