Immersion Cooling vs Air Cooling: The Numbers Behind the Revolution

The Technical and Economic Case for Immersion Cooling

Traditional air-cooled data centres are hitting a thermal wall. Modern GPUs generate heat densities that air simply cannot handle. Here's the full technical comparison between air cooling and single-phase immersion cooling.

Thermal Performance

Air Cooling:

Inlet air temperature: 18-20°C
GPU die temperature: 80-85°C
Temperature gradient: 60-65°C
Thermal throttling: Yes (15-25% performance loss under sustained load)
GPU lifespan: 3-4 years

Immersion Cooling:

Dielectric fluid temperature: 35-40°C
GPU die temperature: 40-45°C
Temperature gradient: 5-10°C
Thermal throttling: No
GPU lifespan: 7-10 years

Energy Efficiency

For a 1 MW GPU cluster:

Air Cooling:

PUE: 1.67-2.0
Total facility power: 1.67-2.0 MW
Annual energy: 14,640-17,520 MWh
Annual cost (€0.12/kWh): €1.76-€2.10M

Immersion Cooling:

PUE: 1.03-1.15
Total facility power: 1.03-1.15 MW
Annual energy: 9,030-10,074 MWh
Annual cost (€0.12/kWh): €1.08-€1.21M

Savings: €0.55-€1.02M annually per MW

Space Efficiency

Immersion cooling enables 65% higher GPU density:

Air-cooled rack: 4-6 GPUs per rack (thermal constraints)
Immersion-cooled tank: 12-16 GPUs per tank (direct cooling, no airflow requirements)

For a 100 MW facility:

Air-cooled: 16,000-24,000 GPUs, 4,000-6,000 racks, 40,000 m² floor space
Immersion-cooled: 32,000-48,000 GPUs, 2,000-3,000 tanks, 15,000 m² floor space

Space savings: 62% reduction

Environmental Impact

Air-cooled 1 MW cluster:

Annual CO2 emissions: 4,380 tonnes (at 0.5 kg CO2/kWh EU average)
Water consumption: 2.5 million gallons/year
Carbon per GPU: 0.73 tonnes CO2/year

Immersion-cooled 1 MW cluster:

Annual CO2 emissions: 452 tonnes
Water consumption: 0 gallons
Carbon per GPU: 0.075 tonnes CO2/year

Reduction: 90% lower carbon footprint

The Bottom Line

Immersion cooling is not a future technology—it's the present. For high-density GPU workloads, it's the only viable cooling solution. The economics are clear, the environmental benefits are undeniable, and the performance advantages are measurable.