As AI accelerates demand for high-performance computing, the data center industry faces a critical challenge: how to provide significantly higher power densities without compromising sustainability or operational efficiency.
For European data center operator Data4, the answer lies in rethinking the cooling architecture from the ground up. The company’s latest initiative, its first industrial-scale direct liquid cooling (DLC) deployment in a colocation environment, is a bold step toward that future.
Responding to a new era of customer demands
By the end of 2023, demand from Data4’s most advanced customers had reached a critical threshold. The need to accommodate power-hungry GPU-driven workloads was evident, and traditional air cooling systems were no longer sufficient.
In response, Data4 accelerated the launch of new DLC infrastructure at its Marcoussis, France campus, retrofitting an existing data center, DC01, as a testing ground for what it called “DLC by Design.”
The goal was ambitious: to offer a solution capable of supporting up to 130 kilowatts per rack, while ensuring operational reliability, ease of maintenance and measurable improvements in sustainability.
To achieve this, Data4 assembled a dedicated team of experts, not only in IT and infrastructure, but also in fluid dynamics, skills more commonly associated with aerospace engineering than data center design.
Design of a new cooling paradigm
One of the main technical challenges was the development of a new generation of cooling distribution units (CDU). Working closely with key partners such as Schneider Electric and Danfoss, Data4 optimized the design of the CDUs to minimize thermal pinching and reduce dependence on the primary cooling circuit.
Special attention was paid to filtration and redundancy, essential components to ensure continuous performance in a high-density, high-risk environment.
The cooling circuit was redesigned using prefabricated stainless steel pipes made from 50% recycled material. This choice not only reduced the carbon footprint of the room layout by 70% compared to traditional black steel, but also improved modularity and installation speed.
Compared to traditional black steel, the piping system, developed in collaboration with Victaulic, allowed for faster installation with minimal disruption to existing infrastructure.
Redefining operational boundaries in co-location
In a co-location context, DLC introduces a fundamental change in the interface between the data center operator and its customers. Unlike air cooling, where the infrastructure boundary is typically at the rack level, DLC requires a direct hydraulic connection between the rack and the facility’s chilled water system.
This means that any problem, such as a leak or improper handling by a customer, can spread throughout the cooling circuit, potentially affecting multiple tenants.
This change requires new protocols for risk management, operational accountability, and customer onboarding. Data4 has implemented enhanced monitoring and containment strategies to mitigate these risks, while preparing protocols to share responsibilities and ensure safe operations.
Demonstrating the environmental value of DLC
Beyond the engineering feats, the project serves as a proof of concept for a more sustainable remodeling model. According to a life cycle analysis conducted by APL, the new DLC system reduces the overall environmental impact by 40% compared to conventional air-only cooling. This includes the benefits derived from material optimization, equipment rationalization and energy savings during operation.
To validate its approach, Data4 developed a rigorous commissioning protocol in collaboration with the Uptime Institute. Each phase of the implementation, from testing to performance validation, was reviewed by external experts to ensure alignment with industry best practices. The result is not only a high-performance cooling solution, but also a replicable model that builds trust with both customers and partners.
Accelerating commissioning with hybrid load banks
Commissioning is a critical phase in the readiness-to-service (RFS) schedule of any data center project. It is often time-consuming, especially when validating complex refrigeration systems. To speed up this process, Data4 has developed, in collaboration with Rentaload, hybrid load banks capable of testing up to 140 kW in liquid cooling and an additional 60 kW in air.
These load banks simulate real-world workloads and enable simultaneous validation of both heat dissipation pathways (air and liquid), speeding commissioning and improving confidence in system performance prior to customer deployment.
Innovation through collaboration
The DLC solution was developed jointly with an ecosystem of strategic partners, including Schneider Electric, Danfoss, Victaulic, Belimo, Rentaload, APL and Ceme, the latter responsible for coordinating the implementation on the ground.
This multi-stakeholder approach allowed Data4 to act quickly: the solution was developed in just six months and deployed in three, demonstrating the agility of the team and the maturity of the ecosystem.
Scalability for the future of AI workloads
What makes this project a game-changer is not just the technology itself, but the scale at which Data4 is now prepared to deploy it. With more than 250 megawatts of capacity under design at its European facilities, the company is laying the foundation for wide-scale adoption. Consider DLC not just a technological improvement, but a strategic enabler for a resilient, high-performing infrastructure.
In a sector where sustainability and performance are often seen as opposites, Data4 argues that they can – and should – go hand in hand. By redesigning its data center ecosystem around liquid cooling, the company is not only meeting the demands of AI workloads, but is also advancing its commitment to reduce the carbon footprint of every new megawatt built by 38% by 2030.
A plan for the next generation of data centers
DLC by Design is more than an engineering milestone. It is a declaration of intent from Data4: to lead the transformation towards an efficient, scalable digital infrastructure prepared for the next era of computing.
