Tech Explained: Here’s a simplified explanation of the latest technology update around Tech Explained: Cooling high-density AI racks: Where RDHx technology delivers measurable ROI in Simple Termsand what it means for users..
As data center operators contend with rising rack densities driven by power-intensive, AI-driven workloads, the associated increase in thermal output and energy demand has shifted cooling decisions from an operational consideration to a business-critical priority. The challenge is no longer simply removing heat, but doing so efficiently, predictably, and without constraining compute growth in today’s high-performance environments.
Rear door heat exchanger (RDHx) technology represents a significant shift in how modern data centers approach thermal management. By addressing heat directly at the rack level rather than conditioning entire rooms, RDHx systems fundamentally reshape both the economics and performance of cooling infrastructure.
Rethinking cooling at the source
Traditional air-based cooling approaches have become increasingly inefficient as rack power density rises. Air is a relatively poor heat-transfer medium, and maintaining consistent temperatures across rows results in overcooling, hotspots, and increased energy consumption. While conventional racks once operated at 10-20kW, today’s AI-focused facilities are deploying racks exceeding 60kW, and, in some cases, surpassing 150kW. This trend is driving the adoption of more efficient, scalable, and sustainable next-generation cooling technologies.
RDHx systems take a different approach. Mounted directly to the rear of server racks, they capture heat from exhaust air as it leaves the servers, then cool it using an efficient heat exchanger. This direct heat removal significantly reduces the workload on room-level air conditioning systems and eliminates many airflow challenges associated with high-density deployments.
The result is not only improved cooling effectiveness, but also more stable and predictive thermal behavior – a critical advantage for performance-sensitive environments. Furthermore, RDHx can be retrofitted or deployed in new facilities, enabling scalable adoption without disruptive upgrades or infrastructure overhauls.
Energy efficiency as a strategic lever
Energy efficiency remains one of the primary drivers of localised cooling technologies. By removing heat at the point of generation, RDHx systems minimise the need for excessive air movement, reducing dependence on energy-intensive computer room air conditioning (CRAC) and computer room air handling (CRAH) units, which often face scalability limitations and adaptability to fluctuating thermal loads typical of AI workloads.
Lower fan energy, reduced compressor usage, and improved heat transfer efficiency all collectively contribute to meaningful reductions in power consumption. In an environment defined by unpredictable energy pricing and tightening environmental regulations, these savings have both financial and compliance significance.
Importantly, these efficiency gains accumulate over time. What may seem like a modest improvement at the component level can yield significant long-term benefits over years of continuous operation.
Reliability through thermal stability
Temperature variability remains a persistent threat to data center reliability. Hotspots, recirculation, and uneven cooling frequently drive hardware stress, premature component failures, and operational disruptions.
By enabling consistent rack-level heat removal, RDHx systems promote uniform thermal conditions and greatly decrease the chance of localised overheating. Improved thermal control also helps mitigate risks associated with humidity fluctuations and condensation, protecting IT equipment while preserving overall system performance and operational resilience.
Stable operating temperatures directly correlate with longer hardware lifecycles, reduced maintenance requirements, fewer unplanned outages, and increased performance – factors which are increasingly important in high-density AI environments.
Additionally, because RDHx solutions integrate directly at the rack level, they free up valuable floor space – a significant benefit in space-constrained environments.
Unlocking latent computing capacity
Cooling limitations frequently restrict compute expansion long before physical space or power availability. Operators may find themselves unable to increase rack density without costly mechanical upgrades.
RDHx alleviates this constraint by expanding the effective cooling capacity of existing white space. Servers can operate at higher performance levels without impacting stability, enabling greater workload consolidation and deferring expensive facility expansions.
The financial implications are considerable: improved asset utilisation, delayed capital expenditure, and enhanced return on existing infrastructure investments.
Operational and maintenance advantages
Beyond energy and performance factors, RDHx deployments can simplify ongoing operations. Reducing reliance on complex airflow management reduces the tuning and balancing associated with traditional systems.
Fewer thermal incidents and lowered hardware stress also result in fewer service interventions and lower indirect operational strains on IT teams.
Capex efficiency and scalability
Expanding conventional cooling systems often requires substantial capital investments, including ductwork modifications, additional CRAC units, or plant upgrades. These projects are disruptive, time-consuming, and costly.
In contrast, RDHx solutions scale incrementally. Cooling capacity can be expanded at the rack level, aligning investment directly with IT growth. This modular approach improves financial planning, reduces the risk of overprovisioning, and supports more agile infrastructure strategies.
A holistic view of ROI
When evaluated comprehensively, the return on investment associated with RDHx technology extends beyond simple energy savings. The value equation typically includes:
- Reduced operational expenditure through improved efficiency
- Extended hardware lifespan and lower failure rates
- Increased compute density and utilization
- Deferred facility upgrades and expansions
- Simplified maintenance and operational stability
Collectively, these factors frequently outweigh modest differences in upfront cost.
Integrating cooling into a wider infrastructure strategy
Cooling decisions cannot be considered in isolation. Power architecture, monitoring capabilities, and physical infrastructure must operate cohesively to deliver sustained efficiency and resilience.
Legrand is increasingly focused on delivering integrated solutions that combine thermal management, power distribution, and intelligent monitoring. RDHx technology, as demonstrated by ColdLogik RDHx from USystems (a brand of Legrand), shows how targeted, rack-level cooling strategies can serve not merely as efficiency enhancements but also as strategic enablers of scalability, sustainability, and long-term operational stability.
In modern data centers cooling is a primary determinant of cost, scalability, and competitive advantage. Technologies that improve thermal efficiency at the source will increasingly define how facilities evolve to support the demands of next-generation workloads.
For more information on Legrand’s ColdLogik RDHx, visit the Legrand website