• • • AI • • • Those figures also reinforce an important point:


cooling strategy is rarely driven by thermal performance alone. Existing infrastructure, available budget, operational processes and hardware refresh cycles all influence how quickly organisations can adopt new cooling technologies. For many operators, the objective is to increase rack density without introducing unnecessary disruption across the wider facility. As a result, the industry is increasingly moving


toward cooling strategies that combine multiple technologies rather than relying on a single approach. This shift also reflects a broader change in


how cooling strategies are being evaluated. Rather than asking which technology will replace another, operators are increasingly considering where each solution delivers the greatest value. High-density AI clusters may justify Direct-to-Chip cooling, while enterprise applications, cloud platforms and mixed-use environments can often benefit from rack-level liquid cooling. Matching the cooling architecture to the workload allows organisations to increase capacity where it is needed most while maintaining flexibility across the wider data centre.


Understanding the role of RDHx in modern liquid


cooling environments Rear Door Heat Exchangers remove heat directly at the rack exhaust using a liquid-cooled heat exchanger integrated into the rear door of the cabinet. Ambient air enters the rack through the IT


equipment. As the servers operate, hot exhaust air passes across the rear-door heat exchanger, where heat transfers into the liquid loop before the cooled air is discharged back into the room. This approach allows operators to significantly


increase rack density while reducing dependence on room-level cooling systems. Because the liquid remains external to the


server itself, RDHx can be introduced without fundamentally changing the way IT equipment is deployed or serviced. That makes them particularly attractive to organisations seeking to gain the benefits of liquid cooling while maintaining familiar operational practices and minimising disruption to day-to-day maintenance.


Importantly, RDHx can support: • High-density air-cooled environments • Hybrid air/liquid deployments • Brownfield and retrofit facilities • AI clusters with mixed cooling architectures • Gradual transitions toward D2C infrastructure


Although both RDHx and D2C use liquid to


remove heat, they address different challenges. D2C cooling is designed around the thermal demands of the server platform, while RDHx focus on increasing cooling capacity at the rack level. Increasingly, operators are finding value in combining the two approaches, deploying each where it delivers the greatest operational and thermal benefit.


Why hybrid cooling strategies are becoming


increasingly important The future of data centre cooling is unlikely to be defined by a single technology. Instead, many operators are expected to combine multiple cooling methods depending on workload density, infrastructure constraints and operational strategy.


1. Not every workload requires full D2C deployment


Some AI and HPC platforms require direct liquid cooling due to extreme thermal densities. However, many enterprise, cloud and mixed-use environments continue to operate workloads that can still be efficiently supported using advanced air-cooling approaches combined with RDHx technology. Hybrid environments allow operators to apply


D2C selectively where required while maintaining flexibility elsewhere.


2. Existing facilities often require phased transitions


Many data centres were not originally designed for large-scale liquid cooling deployment. In retrofit and brownfield environments, introducing D2C infrastructure can involve:


• Facility water distribution upgrades • CDU deployment • Water treatment considerations • Operational procedure changes • New service and maintenance processes


Infrastructure readiness is often underestimated


during liquid cooling planning. RDHx can help operators increase density and introduce liquid cooling incrementally without immediately redesigning the entire white space.


3. Operational risk often influences cooling decisions


While D2C cooling delivers excellent thermal performance, many operators must also consider operational readiness, maintenance procedures and risk management. Introducing liquid directly to IT equipment often


requires new processes for leak detection, servicing, maintenance and staff training. RDHx can help organisations introduce liquid cooling into the white space while keeping coolant isolated from server hardware, enabling teams to build operational familiarity and confidence before expanding liquid cooling deployments.


4. D2C and RDHx are often complementary Even in D2C environments, not all server components are liquid cooled. Memory, storage, power supplies, networking


components and residual airflow loads may still require air cooling support. RDHx can help manage this remaining heat while improving overall cooling efficiency at the rack level. As a result, RDHx and D2C are increasingly


viewed as complementary technologies rather than mutually exclusive alternatives.


5. Cooling flexibility matters as infrastructure evolves


AI infrastructure is evolving rapidly. Cooling strategies that preserve flexibility can help operators adapt to future changes in server architecture, rack density and facility requirements. One of the key advantages of RDHx is


architectural optionality. Organisations can increase rack densities today while retaining the flexibility to expand D2C deployments as future workload requirements evolve.


RDHx allow operators to: • Increase density today • Reduce room cooling dependency • Support mixed environments • Preserve adaptability for future cooling transitions


This flexibility can be particularly valuable in


facilities where long infrastructure life cycles must coexist with rapidly changing computer technologies.


6. Cooling deployment does not always align with server refresh cycles


Because D2C cooling is integrated into specific server platforms, deployment often aligns with hardware refresh cycles and procurement decisions. RDHx decouple the cooling strategy from


server purchasing timelines, allowing facilities teams to increase cooling capacity independently of IT refresh schedules. This can provide greater flexibility when planning phased AI infrastructure deployments.


Supporting the transition toward


higher-density AI infrastructure D2C liquid cooling will play a major role in future AI and HPC deployments, particularly at the highest rack densities. At the same time, many operators will continue to require practical and scalable transition strategies that align with existing facilities, operational maturity and investment cycles.


RDHx provide an important part of that transition by enabling: • Incremental liquid cooling adoption • Higher rack densities • Reduced dependence on room cooling • Hybrid cooling architectures • Greater operational continuity • Reduced operational disruption • Greater infrastructure flexibility • Lower transition risk


Ultimately, the most effective cooling strategies


will likely combine multiple technologies to balance performance, efficiency, resiliency and long-term flexibility as AI infrastructure continues to evolve. Not every facility is designed for


supercomputing-scale AI environments, or the infrastructure demands associated with full DTC liquid cooling. For many operators, hybrid cooling strategies will provide a more practical path forward by balancing density, resiliency, operational familiarity and infrastructure flexibility.


www.legrand.com electricalengineeringmagazine.co.uk ELECTRICAL ENGINEERING • JULY/AUGUST 2026 21


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48