R-454B Delivers 38% Higher EER Than R-410A in Data-Center Rack Cooling Tests

Applied Thermal Engineering published a 2025 paper that commercial HVAC and data center contractors should pull up the next time they're quoting against an R-410A legacy install. Across 24 realistic in-rack cooling tests, R-454B hit roughly 5.8 EER at 9 kW loads. That's 38% above R-410A under matched conditions, with comparable PUE and substantially lower TEWI.

R-454B has a GWP of 466. R-410A sits at 2088. The environmental math was already on R-454B's side.

Now the efficiency math is too.

The study used a normalized EER approach plus steady-state detection to make sure both refrigerants were compared at the same operating point. That methodology matters because in-rack cooling tests can be gamed by cherry-picking load bins, and the authors were explicit about avoiding that. The advantage is load-dependent: at matched supply-air conditions (16-20°C), the two refrigerants ran close to even, and R-454B's lead widened as rack load climbed toward the 9 kW test point.

For California contractors facing the refrigerant transition and rapid data center build-out, the takeaway is that R-454B isn't a compromise choice. In this test, it outperformed the incumbent on the metric customers care about most: kWh per kWh of heat removed.

What changes for servicing A2L systems

R-454B is A2L, which means mildly flammable. The service practices need updating. Electronic leak detection rated for A2L refrigerants is mandatory. Brazing and soldering procedures need to account for the presence of a mildly flammable gas if there's any residual charge. Recovery equipment rated for A2L. Refrigerant storage that accounts for the flammability class.

EPA 608 remains the baseline certification. Manufacturer-specific A2L training is now expected for warranty work on new equipment. Daikin, Carrier, Trane, and several others have free or low-cost courses available online.

The brazing torch isn't going away. The process around it is just more careful.

Why this matters for data centers specifically

California data center power demand is climbing sharply. The state's AI and cloud workloads are growing fast, and cooling energy is a significant slice of total site consumption. A 38% EER improvement on in-rack cooling, where load density is highest, compounds across thousands of rack positions at hyperscale sites.

For colocation operators selling against PUE targets, R-454B's comparable PUE number means the efficiency gain translates into customer pricing without giving up other metrics. That's the kind of result that moves procurement decisions.

For residential and light commercial, the same efficiency story plays out at smaller scale. Manufacturers shipping R-454B equipment in 2026 and 2027 are building on research like this to justify the transition cost.

For more on the refrigerant story, see our EPA refrigerant transition update and R-410A ban rollback coverage.

Source

"Experimental performance characterization of R-454B and R-410A in data center server rack mount cooling unit: Energy efficiency and environmental impact assessment." Applied Thermal Engineering (2025). https://www.sciencedirect.com/science/article/abs/pii/S0140700725004682