DC Explorer: system archetype
Brownfield liquid-cooling retrofit
An operating air-cooled hall adds liquid-cooled racks. CDUs connect either to the existing chilled-water system or reject heat to room air, within the limits of the existing electrical, structural and plant capacity.
Draft conceptual topology, not yet engineering-reviewed. It shows which systems connect, not capacities, quantities, redundancy or a design. It is not a single-line diagram or a schematic, and it does not show that any products are compatible. Updated 18 Oct 2026.
When to use it: Use it to plan the questions an operating site must answer before adding high-density racks.
System graph
Lines show what feeds what: electrical heat network controls and services. Select a box to jump to its entry. The 3D explorer shows the same systems.
Systems and connections
Electrical
Utility connection and substation
Brings grid supply on site at transmission or distribution voltage. A connection allocation is not commissioned IT load.
Feeds: Transformers and protection (supply)
On CoolPower Index: Switchgear & Transformers suppliers, Data centre power distribution
Transformers and protection
Steps voltage down and isolates faults. Ratings, impedance and protection settings come from the electrical design.
Fed by: Utility connection and substation (supply)
Feeds: MV and LV switchgear and distribution (stepped-down supply)
On CoolPower Index: Switchgear & Transformers suppliers, Data centre power distribution
MV and LV switchgear and distribution
Distributes power to IT, mechanical and building loads and allows sections to be isolated for maintenance.
Fed by: Transformers and protection (stepped-down supply), Standby generation (backup interface)
Feeds: UPS and batteries (critical feed), CDU (liquid-to-liquid or liquid-to-air) (new circuits)
On CoolPower Index: Switchgear & Transformers suppliers, Data centre power distribution
UPS and batteries
Rides through supply interruptions for selected it and critical mechanical paths. Which loads are UPS-backed is a design choice, not a default.
Fed by: MV and LV switchgear and distribution (critical feed)
Feeds: Racks and rack power (PDUs or power shelves) (UPS-backed IT supply)
On CoolPower Index: UPS & Power Distribution suppliers, Backup power and energy storage, Data centre power distribution, Cooling and power RFI checklist
Standby generation
Supplies backup power after a utility outage once started. Standby duty is not continuous prime power.
Feeds: MV and LV switchgear and distribution (backup interface)
On CoolPower Index: Gensets & On-site Power suppliers, Backup power and energy storage
Thermal
Cold plates on new racks
Capture heat from the new high-density servers.
Fed by: Servers and accelerators (processor heat)
Feeds: CDU (liquid-to-liquid or liquid-to-air) (technical loop)
On CoolPower Index: CDUs & Direct Liquid Cooling suppliers, Direct liquid cooling (direct-to-chip), Cooling technology selection guide
CDU (liquid-to-liquid or liquid-to-air)
Liquid-to-liquid units need a facility water connection. Liquid-to-air units reject heat into the room and add to the CRAH load.
Fed by: Cold plates on new racks (technical loop), MV and LV switchgear and distribution (new circuits), Commissioning and service access (tie-in and flushing during operation), Fire safety, leak detection and water treatment (leak detection near live IT)
Feeds: Existing chilled-water system (liquid-to-liquid option), Existing CRAHs (liquid-to-air option, heat to room)
On CoolPower Index: CDUs & Direct Liquid Cooling suppliers, Coolant distribution units (CDUs), Direct liquid cooling (direct-to-chip), CDU comparison guide, Cooling and power RFI checklist, Brownfield liquid cooling upgrades
Existing chilled-water system
Spare capacity, temperatures and tie-in points decide whether CDUs can connect without new plant.
Fed by: CDU (liquid-to-liquid or liquid-to-air) (liquid-to-liquid option), Existing CRAHs (heat to water)
Feeds: Existing chillers (return water)
On CoolPower Index: Warm-water cooling loops
Existing CRAHs
Keep cooling the existing air-cooled racks and any heat rejected to the room.
Fed by: CDU (liquid-to-liquid or liquid-to-air) (liquid-to-air option, heat to room), Servers and accelerators (residual air heat)
Feeds: Existing chilled-water system (heat to water)
On CoolPower Index: Chillers & Precision Cooling suppliers, Cooling technology selection guide
Existing chillers
May need capacity checks or upgrades when liquid load is added.
Fed by: Existing chilled-water system (return water)
Feeds: Existing outdoor heat rejection (condenser heat)
On CoolPower Index: Chillers & Precision Cooling suppliers, Heat rejection, Cooling technology selection guide
Existing outdoor heat rejection
Must handle the added heat plus compressor input.
Fed by: Existing chillers (condenser heat)
On CoolPower Index: Heat Rejection suppliers, Heat rejection
IT and network
Racks and rack power (PDUs or power shelves)
Hold IT equipment and distribute power inside the rack. Rack density and weight drive floor, power and cooling requirements.
Fed by: UPS and batteries (UPS-backed IT supply)
Feeds: Servers and accelerators (rack power)
On CoolPower Index: Direct liquid cooling (direct-to-chip), 800 VDC rack power
Servers and accelerators
Turn nearly all of their electrical input into heat at the IT boundary. Power and cooling needs depend on the exact model and configuration.
Fed by: Racks and rack power (PDUs or power shelves) (rack power)
Feeds: Network switches and optics (data), Cold plates on new racks (processor heat), Existing CRAHs (residual air heat)
On CoolPower Index: Direct liquid cooling (direct-to-chip)
Network switches and optics
Connect servers, storage and the outside world. Network power and cabling are often missed in early estimates.
Fed by: Servers and accelerators (data), Storage (data)
On CoolPower Index: No verified portal record linked yet.
Storage
Holds data for the workload. Configuration, usable capacity and power vary widely.
Feeds: Network switches and optics (data)
On CoolPower Index: No verified portal record linked yet.
No 3D model for this system yet.
Context
Controls and monitoring (BMS, EPMS, DCIM)
Coordinates plant, alarms and metering. Interfaces and sequences must be specified and commissioned.
On CoolPower Index: No verified portal record linked yet.
No 3D model for this system yet.
Fire safety, leak detection and water treatment
Detection, suppression, leak sensing and fluid quality management. Requirements depend on local codes and the fluids used.
Feeds: CDU (liquid-to-liquid or liquid-to-air) (leak detection near live IT)
On CoolPower Index: No verified portal record linked yet.
No 3D model for this system yet.
Commissioning and service access
Testing against the design intent, plus space and procedures to maintain equipment without unplanned outages.
Feeds: CDU (liquid-to-liquid or liquid-to-air) (tie-in and flushing during operation)
On CoolPower Index: No verified portal record linked yet.
No 3D model for this system yet.
Size it
The archetype has no built-in numbers. Use the engineering pack to work out load, heat, rack, CDU and flow figures from your own assumptions. Both are saved in the same brief.
Sources
These references explain system functions. They do not validate this topology. NVIDIA's reference design is one specific design, not a universal pattern to scale.
- U.S. DOE FEMP, Best Practices Guide for Energy-Efficient Data Center Design (26 July 2024) (opens in a new tab) checked 18 Oct 2026
- U.S. DOE FEMP, Cooling Water Efficiency Opportunities for Federal Data Centers (opens in a new tab) checked 18 Oct 2026
- NVIDIA, DSX Facilities Infrastructure Reference Design Overview (design guide v2.0, 19 August 2026) (opens in a new tab) checked 18 Oct 2026
Other archetypes: Conventional air-cooled colocation, Mixed air and direct liquid cooling, Dense AI liquid-cooled cluster.