Data Center Cooling and Refrigerant Trends: Why AI Is Changing HVAC Design

Data center cooling is no longer just a facilities matter of “lowering the server room temperature.” As AI servers and GPU-based high-density racks proliferate, data center cooling has become an infrastructure strategy that ties together power, thermal management, water use, refrigerant regulation, equipment compatibility, and maintenance risk.

ASHRAE explains that AI data centers demand unprecedented levels of power and cooling, and that the shift from CPU-centric to GPU-centric computing is driving new power densities, thermal loads, and design/commissioning approaches.[S1] This shift has a direct impact on refrigerant as well. Refrigerant is no longer simply the working fluid inside a chiller or CRAC unit — it now determines how efficiently a cooling system moves heat, which compressors it is compatible with, which safety standards it must meet, and whether it carries long-term regulatory risk.

In other words, understanding data center cooling trends today requires looking beyond “air cooling vs. liquid cooling” to the refrigerant and compression cycle operating behind the scenes. Understanding data center cooling in this way requires viewing the refrigerant compressor — the refrigerant and the compressor — as a single system.

• Refrigerant is a core variable in data center cooling strategy — it should not be viewed merely as the fluid inside equipment.
• Regulation (the shift to low-GWP) and refrigerant selection translate directly into equipment, service, and supply risk.
• Liquid cooling does not eliminate refrigerant — it shifts the refrigerant load into a water loop.
• Refrigerant selection cannot be separated from compressor selection — they must be evaluated together.

Data centers are a prime example of energy-intensive facilities. The DOE explains that data centers can use far more energy per unit area than typical commercial offices, and that cooling systems such as HVAC and CRAC units — not just IT equipment — account for a significant share of that consumption.[S2]

Refrigerant matters because the core principle of this cooling system is heat transfer via the refrigerant. In a vapor-compression refrigeration system, refrigerant absorbs heat in the evaporator, is compressed by the compressor, and then releases heat in the condenser. This cycle repeats to move heat out of the data center. Refrigerant therefore plays three roles simultaneously:

●     A medium for cooling performance — the thermodynamic properties of the refrigerant affect the efficiency and operating conditions of chillers, CRACs, heat pumps, and DX systems.

●     A subject of regulatory and environmental risk — HFC refrigerants face phase-down and transition pressure due to their high GWP.[S5]

●     A variable in safety and maintenance — some low-GWP refrigerants require more careful review of flammability, pressure conditions, installation standards, and service procedures. ASHRAE Standard 34 covers refrigerant numbering and safety classification.[S6]

Trend 1. The Shift from HFCs to Low-GWP Refrigerants

The biggest refrigerant trend in data center cooling is the shift from an HFC-centric structure to low-GWP refrigerants. Under the AIM Act, the U.S. EPA has the authority to phase down HFC production and consumption, restrict HFC use in specific sectors, and encourage the transition to next-generation technologies.[S5]

This shift is not simply an environmental issue. Refrigerant transitions affect equipment selection, long-term service costs, parts availability, refrigerant charge volume, leak management, and the training level of maintenance staff. If you plan to operate existing refrigerant-based chillers over the long term, you should check the following:

●     Is the long-term supply risk for this refrigerant low?

●     Can you transition to a low-GWP refrigerant while maintaining the same cooling capacity?

●     Is it compatible with existing compressors, heat exchangers, oil, and control systems?

●     Are installation standards and maintenance procedures in place to reflect the change in safety classification?

●     Is a compressor retrofit or retrofit kit available, or is full equipment replacement required?

Because data centers demand continuous operation, treating a refrigerant transition as simply “swapping in an eco-friendly refrigerant” is risky. Refrigerant should be viewed as part of the equipment lifecycle and operational risk.

Key takeaway — Refrigerant transition is not an environmental issue — it is operational risk management.

Trend 3. Liquid Cooling Is Changing How Refrigerant Is Used

Liquid cooling is a major trend in AI data centers. LBNL explains that liquids have far greater heat capacity than air, making them valuable for reducing the energy consumption of cooling systems.[S3] However, liquid cooling is not a technology that eliminates refrigerant altogether. It captures heat more effectively close to the chip or rack, while the facility-side cooling system still determines where that heat ultimately goes and how it is rejected.

Even in liquid-cooling architectures, heat-rejection paths such as coolant circulation through the CDU, the facility water loop, dry coolers, cooling towers, chillers, heat pumps, economizers, and heat recovery systems may still be needed. In other words, liquid cooling is not a “refrigerant-free structure” — it is closer to a structure in which some of the cooling load that refrigerant used to handle directly is shifted to a water or other liquid loop. As a result, refrigerant use, compressor runtime, and chiller-plant load may decrease, but refrigerant-based equipment can still be required depending on facility conditions. The role of the chiller compressor, therefore, does not disappear entirely even in liquid-cooled environments.

In practice, this facility-side heat-rejection path breaks down into specific configurations such as direct-to-chip (delivering coolant directly to cold plates on the CPU/GPU), immersion cooling (submerging entire servers in a non-conductive liquid), and rear-door heat exchangers (mounting a heat exchanger on the back of the rack to cool exhaust air). Whichever method is used, the heat downstream of the CDU still has to be handed off to a water loop or refrigerant-based equipment, so refrigerant and compressor selection remain relevant questions regardless of the method chosen.

Key takeaway — Liquid cooling does not eliminate refrigerant — it redistributes its role.

Trend 5. Refrigerant Also Connects to PUE and WUE

What Are PUE and WUE?

Source: DOE/FEMP Best Practices Guide for Energy-Efficient Data Center Design, Uptime Institute Global Data Center Survey 2025 [S7][S9]

The core of data center cooling is reliably moving heat out of the facility. As AI servers and high-density racks proliferate, this thermal-management chain becomes more complex. Refrigerant is the key medium in that chain, and the compressor compresses the refrigerant to create the conditions that allow heat to move. Going forward, data center refrigerant trends are likely to move in three directions: a shift from high-GWP HFCs to low-GWP refrigerants; refrigerant selection being evaluated together with compressors, chillers, liquid cooling, heat recovery, and safety codes; and refrigerant becoming part of operational stability, maintenance, energy efficiency, and equipment-lifecycle strategy — not just a target of environmental regulation.

As the 2026 HVAC refrigerant transition accelerates — driven by AIM Act phase-down schedules, the shift to A2L refrigerants, and tightening energy efficiency requirements for AI data centers — the window to proactively evaluate refrigerant-compressor compatibility is narrowing. Data center operators and HVAC designers who address refrigerant strategy now will be better positioned to avoid costly rework and operational disruption later.

Data center operators and HVAC designers should therefore stop viewing refrigerant merely as “the fluid inside the equipment.” Refrigerant is a core variable that connects a data center’s thermal-management strategy, regulatory response, and long-term operational risk.

If you’d like to review a refrigerant transition or compressor selection, we recommend consulting LG Compressor & Motor’s data center and commercial cooling solutions along with the Cross Reference materials to check low-GWP refrigerant compatibility and part-load efficiency together.