Open Data Center: Next-Generation ML Infrastructure Design Principles, Revision 0.7.0 (Design Specification, effective Aug 27, 2026)

Overview

The document gathers unified facility design principles for hot-aisle-contained (HAC) ML halls. Its version history runs from 0.3.0 (December 2025, initial Google release) through 0.5.0 (February 2026, adding minimum row length, row quantity guidance, row power density, humidity and liquid-to-air ratio) to 0.7.0 (June 2026). Revision 0.7.0 removed Google-specific near-term tables, TPU pod scaling, campus layouts and environmental limits (for example 10%-38% RH), moved row layouts from rigid lengths to modular kW/ft density, and standardised rack height at 100 inches and weight at 8,000 lb. It is a pre-1.0 draft and the numbers may change.

On structure, the design target for the heaviest single rack is 8,000 lb (3,629 kg) over a 28 x 48 in (711 x 1,219 mm) footprint, and the weight of the special handling equipment must be added to the total moving load. Peak IT weight is the AC/DC sidecar plus the ML rack: 7,000 lb (3,175 kg) plus 8,000 lb, giving 15,000 lb (6,804 kg) over 56 x 48 in. Two-busway configurations need at least 18 ft (5.5 m) clear height to the underside of the beam; four-busway layouts with extra tray tiers may need more. A 12 ft (3.7 m) transport aisle and a 24 ft (7.3 m) aisle pitch are recommended, with racks front-justified in the cold aisle.

The row minimums table gives hot aisle 54 in (1,372 mm), cold aisle face to face 82 in (2,083 mm), rack height 100 in (2,540 mm), rack depth 71 in (1,803 mm) and transport aisle 12 ft (3,658 mm). The blended capacity target is 25 kW/ft (82 kW/m), requiring 15 kW/ft (49 kW/m) of air cooling and 25 kW/ft (82 kW/m) of liquid cooling. Peak IT density is 350 kW/ft (1,148 kW/m), with 2027 peak racks expected at 125 kW/ft (410 kW/m). Cluster size is 12 MW minimum and 24 MW preferred, and every data hall must provide at least 4 power blocks.

On cooling, clusters are to be designed for 25 kW/ft liquid and 15 kW/ft air by 2028, with wall manifolds sized to feed the full length of the machine row. Table 3, at 3 m/s, gives at 1 lpm per kW: 91 kW for a 1 in pipe, 365 kW for 2 in, 820 kW for 3 in and 1,459 kW for 4 in; at 1.5 lpm per kW the limits are 61, 243, 547 and 972 kW. Available quick connects currently reach only 2 in. For high-density ML racks the liquid cooling cap is expected at about 335 kW/ft (1,100 kW/m) plus 15 kW/ft (49 kW/m) of air. The appendix shows HAC layouts, filler panels and cross sections with fan-wall or in-row cooling.

Key points

1. Design target for the heaviest single rack is 8,000 lb (3,629 kg) over 28 x 48 in; with a 7,000 lb AC/DC sidecar the peak is 15,000 lb (6,804 kg) over 56 x 48 in.
2. Two-busway configurations need at least 18 ft (5.5 m) clear height to the underside of the beam; a 12 ft (3.7 m) transport aisle and 24 ft (7.3 m) aisle pitch are recommended.
3. Minimum row dimensions: hot aisle 54 in (1,372 mm), cold aisle 82 in (2,083 mm), rack height 100 in (2,540 mm), rack depth 71 in (1,803 mm).
4. Blended density target is 25 kW/ft (82 kW/m): 15 kW/ft (49 kW/m) air cooling and 25 kW/ft (82 kW/m) liquid cooling capability.
5. Peak IT density target is 350 kW/ft (1,148 kW/m); 2027 peak racks are expected at 125 kW/ft (410 kW/m).
6. Cluster size baseline is 12 MW minimum and 24 MW preferred; each data hall must provide at least 4 power blocks.
7. Manifold sizing at 3 m/s: a 2 in pipe carries about 365 kW and a 4 in pipe about 1,459 kW at 1 lpm/kW (243 and 972 kW at 1.5 lpm/kW).
8. Available quick connects currently top out at 2 in.
9. For 350 kW/ft ML zones, liquid cooling is capped at about 335 kW/ft (1,100 kW/m) plus 15 kW/ft (49 kW/m) of air cooling.
10. Rigid row lengths were replaced by a modular kW/ft density approach; the document is a Rev 0.7.0 pre-1.0 draft.

Using it in design

• Base floor and transport-route load checks on the 8,000 lb rack and the 15,000 lb rack-plus-sidecar combination, and include the weight of the moving equipment.
• Take at least 5.5 m clear height to the underside of the beam for a two-busway layout, and allow extra height for four-busway layouts and added tray tiers.
• Lay out the hall with minimum 54 in hot aisle, 82 in cold aisle, 12 ft transport aisle and 24 ft aisle pitch, and seal hot-aisle containment gaps behind shallower racks with filler panels.
• Size wall manifolds to feed the full row length for 25 kW/ft liquid and 15 kW/ft air, and for high-density zones to about 335 kW/ft of liquid capacity.
• When picking pipe diameter from the table, note the difference between 1 lpm/kW and 1.5 lpm/kW flow assumptions (365 versus 243 kW at 2 in) and the 2 in quick-connect limit.
• Reflect at least 4 power blocks per hall and the 12-24 MW cluster target in the electrical architecture; because this is a pre-1.0 draft, confirm numbers against the current revision before design freeze.

Who should read it

Engineers designing the architecture, electrical and mechanical systems of AI/ML data halls, and colocation developers.

Document contents

1. Version History
2. License
3. Compliance with OCP Tenets
4. Specifications
5. Facility and Infrastructure Specifications
6. Structural and Weight requirements
7. Row Layout and Clearance
8. Power and Density Requirements
9. Cluster and Power Density Targets
10. Power Architecture and Interfaces
11. Thermal Management and Cooling
12. Data Center Requirements
13. Connectivity and Infrastructure
14. Rack Cooling Density Caps
15. Appendix (typical HAC layouts and cross sections)

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Publication details

Authors

AMD; Google; Meta; NVIDIA

Publisher

Open Compute Project Foundation

Year

2026

Document language

English

Source type

Industry body

Access

Open licence — downloadable

Licence

OWFa 0.9 — Open Compute open specification licence; redistribution permitted

Licence evidence

www.opencompute.org

Citation