NFrance Data Center Cooling Retrofit With N+1 Design

Live Cooling Upgrade at NFrance’s Data Center: N+1 Redundancy and Water-Free Heat Rejection

Introduction

According to Vertiv’s announcement dated July 20, 2026, the cooling infrastructure at NFrance’s sovereign data center in Toulouse was upgraded.
The data center remained continuously operational throughout the work.
The new DX-based system uses dual refrigerant circuits, independent condensers, and N+1 redundancy.
The reported project data indicates an energy saving of approximately 20% and the elimination of cooling-related water consumption.
The main lesson is not about a single piece of equipment, but about coordinating redundancy, transition sequencing, and rollback capability.

Replacing the thermal infrastructure of an operating data center is a particularly sensitive intervention. While parts of the old system are being isolated, the IT load continues to generate heat, and the remaining cooling capacity may be temporarily constrained. A poorly timed operation can therefore create risk even if the final design of the new system provides adequate redundancy.

The reported results are project-specific. The approximately 20% energy saving is measured against NFrance’s previous infrastructure and is not a general performance claim for DX cooling.

The NFrance project illustrates how live-site implementation can be combined with N+1 standby capacity, separated refrigerant circuits, and reduced resource consumption. However, the reported results apply to a specific facility. For other data centers, the appropriate architecture must be determined through on-site measurements and risk analysis.

Who is this for, and why is it relevant?

An N+1 designation alone does not demonstrate full system resilience. Common failure points across refrigerant circuits, condensers, power supplies, controls, and airflow paths must be assessed separately.

The announcement is primarily relevant to data center operators, facility managers, IT infrastructure leaders, project owners, technical procurement teams, and designers. Its professional focus is on how an aging or less efficient cooling system can be upgraded while maintaining service continuity.

This is not solely a cooling engineering issue. The transition also affects electrical capacity, controls, monitoring systems, white-space airflow, maintainability, and operating procedures. The work should therefore be managed as an integrated infrastructure project.

A phased implementation is fundamental to a safe live-site transition. Every stage requires a predefined load limit, verification point, and rollback plan.

What happened at NFrance’s Toulouse data center?

According to Vertiv, the cooling infrastructure upgrade at NFrance’s sovereign data center in Toulouse was completed while the facility remained continuously operational throughout the installation. The new direct expansion, or DX, solution was designed with dual refrigerant circuits and independent condensers, while the equipment capacity is supported by N+1 redundancy.

Based on the published information, 50% of the cooling capacity remains available if one refrigerant circuit fails. Vertiv also states that the system can restart automatically within 40 seconds. These are important design characteristics, but they can only be interpreted in the context of the complete system architecture, actual heat load, and accepted operating conditions.

The project reduced energy consumption by approximately 20% compared with the previous infrastructure and eliminated cooling-related water consumption. Because these results are site-specific, they cannot be applied automatically to other facilities.

Why are live-site upgrades important now?

In many data centers, cooling equipment life cycles, changing rack loads, and available electrical capacity do not evolve at the same rate. At the same time, a complete shutdown is often commercially or contractually unacceptable. The success of an upgrade therefore increasingly depends on how safely the new infrastructure can be integrated into the existing environment.

A live-site project must address temporary operating states as well as the final redundancy arrangement. During a particular transition phase, less standby capacity may be available, or a system previously considered independent may rely on a shared electrical, control, or airflow component. Risk therefore arises not only during the work itself but also within the temporary configurations between individual phases.

What does this mean operationally?

The reported 50% remaining capacity in the NFrance project indicates that failure of one refrigerant circuit does not immediately result in the complete loss of cooling. From an operational perspective, however, it is also necessary to determine under which load, outdoor temperature, and airflow conditions this partial capacity remains sufficient.

The automatic restart within 40 seconds must likewise be evaluated in relation to thermal inertia. Operators need to examine how server inlet air temperatures change during this period, where localized hot spots may occur, and which alarm or intervention thresholds apply. Nominal system specifications are not a substitute for functional testing under real operating conditions.

The limits of N+1 redundancy

N+1 means that one additional unit is available beyond the capacity required to meet the baseline demand. However, this does not necessarily provide complete path independence. If multiple cooling units rely on the same distribution board, controller, condenser-side component, or airflow path, the system may still contain a common point of failure.

The redundancy assessment must therefore follow the entire functional chain: electrical supply, switchgear, controls, refrigerant circuit, condenser, indoor unit, air delivery, and monitoring. Maintenance conditions must also be modeled, because the availability of a standby unit alone does not guarantee that the system can tolerate a second event.

Common mistake

A common mistake is for the project team to validate only the capacity of the final configuration, without validating the transition phases. When equipment is isolated, pipework or cabling is reconnected, or controls are transferred, the available cooling reserve may be temporarily reduced.

Another risk is accepting automatic restart or N+1 failover solely on the basis of manufacturer documentation. On-site integration, configuration settings, and monitoring logic may differ from the theoretical arrangement. Commissioning with predefined scenarios and documented failure simulation is therefore required.

Energy and water use: interpreting the results correctly

The reported energy reduction of approximately 20% is a significant project metric, but the comparison is against NFrance’s previous system. At another facility, the outcome would be influenced by factors including the condition of the existing equipment, part-load operation, outdoor environment, airflow, and control strategy.

Eliminating cooling-related water consumption can reduce a site’s dependence on water. However, technology selection should not be based on a single metric. Energy use, water demand, maintainability, outdoor noise, space requirements, and available capacity under extreme weather conditions should be assessed together.

Recommended next step

Preparation for a similar upgrade should begin with a load and infrastructure audit. Measurements should cover the actual heat load, power density per rack, airflow issues, electrical reserves, and failure points in the existing system.

This can be followed by a phased transition plan. Each phase should define the available cooling capacity, permitted IT load, environmental limits, decision points, and rollback procedure. The need for temporary cooling should be determined from calculated and measured risk rather than treated as a universal requirement.

Commissioning should verify more than the startup of the new equipment. Tests should cover refrigerant circuit failure, standby-unit activation, automatic restart, the alarm chain, monitoring integration, and maintenance operating states. In Digital Technologies’ engineering approach, auditing, design, implementation, and handover form a single verifiable process, with particular attention to operational continuity and long-term maintainability.

Conclusion

The main message from NFrance’s Toulouse project is that, with appropriate preparation and phased implementation, the cooling infrastructure of an operating data center can be upgraded without downtime. Dual refrigerant circuits, independent condensers, and N+1 capacity improve fault tolerance together, but actual operational resilience depends on assessing the complete system chain and all temporary operating states.

Improved energy and water performance is an important result, but it does not replace a site-specific engineering assessment. Ultimately, a successful upgrade is one that allows the system to remain safe, measurable, sustainable, and maintainable during failures, maintenance activities, and future capacity changes.

Sources

Vertiv, July 20, 2026: https://www.vertiv.com/en-emea/about/news-and-events/news-releases/2026/nfrance-modernizes-sovereign-data-center-cooling-with-vertiv-thermal-management-solutions-and-services/
Data Center Dynamics: https://www.datacenterdynamics.com/en/news/nfrance-cuts-data-center-power-bill-by-20-percent-using-vertiv-dx-cooling-system/