Water Usage at AI Scale: Insights from a 100 MW Comparative Analysis

Overview

The study compares four designs: a traditional air-cooled site, an AI factory with liquid cooling at 32 C TCS, the same factory at 45 C TCS, and a 45 C version with right-sized equipment. Each is simulated in Dallas and Paris. The scenario basis is 188 kW liquid-cooled server racks, 86.6 MW of liquid plus 13.4 MW of air-cooled load, and networking racks of 20/40 kW cooled by air.

The effect of each step is given separately. Moving from air to liquid (32 C TCS) lowers on-site water about 8% in Dallas, and PUE about 7% (cooling overhead about 63% lower). Raising TCS from 32 C to 45 C cuts WUE 66 to 82% depending on location while improving PUE only about 0.6%. Example values: Dallas 0.42 to 0.22 L/kWh, Paris 0.12 to 0.06 L/kWh. Right-sizing the equipment for 45 C reduces WUE about 50% against the 32 C baseline.

The paper also supplies typical WUE ranges: about 1.7 to 4 L/kWh with cooling towers and about 0.2 to 1.5 L/kWh with adiabatic dry coolers. It shows adiabatic assist is poor value at high TCS temperature: in Paris it improved PUE by only about 0.13% while raising water use from 0 to 0.07 L/kWh. The conclusion is that water use is not a fixed price; cooling architecture and liquid temperature can shift it by 66 to 82%. The limit is that only two climates and four schemes are modelled, so other climates need their own calculation.

Key points

1. Typical WUE is about 1.7 to 4 L/kWh with cooling towers and about 0.2 to 1.5 L/kWh with adiabatic dry coolers.
2. Air to liquid (32 C TCS): on-site water about 8% lower in Dallas; PUE about 7% lower (cooling overhead about 63% lower).
3. TCS 32 to 45 C: WUE down 66 to 82%, PUE down about 0.6% (cooling overhead about 13%).
4. Right-sizing for 45 C: WUE down about 50% and PUE about 0.5% versus the 32 C baseline.
5. Dallas WUE falls from 0.42 to 0.22 L/kWh; Paris from 0.12 to 0.06 L/kWh.
6. In Paris at high TCS, adiabatic assist cut PUE only about 0.13% but raised water from 0 to 0.07 L/kWh.
7. Scenario basis: 188 kW liquid-cooled racks; 86.6 MW liquid plus 13.4 MW air-cooled load.

Using it in design

• Compute and display WUE (L/kWh IT) next to PUE for every cooling design.
• Use default WUE ranges: tower 1.7 to 4, adiabatic dry cooler 0.2 to 1.5, dry cooler without adiabatic 0.
• When TCS is 40 C or higher, recommend switching off adiabatic assist and show the water-versus-energy delta.
• For AI factories default the heat split to about 87% liquid / 13% air; add a water-stressed-site flag that steers toward high-temperature liquid with dry coolers.

Who should read it

Designers planning AI campuses in water-constrained regions, and decision makers who must commit to a WUE target.

Related standards

• ISO/IEC 30134-9 (WUE)
• The Green Grid WUE
• ASHRAE TC9.9 Liquid Cooling Guidelines

Publication details

Authors

Fabian Janischowsky; Amir Ibraheem; Maria A. Torres Arango

Publisher

Schneider Electric

Year

2026

Document number

WP 220

Document language

English

Source type

Manufacturer

Access

Free to read

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation