Building Data Centres at AI Speed: Why Prefabrication Matters
The AI boom has ignited a new kind of pressure in the UK data centre market. Hyperscalers, cloud providers and “neo-AI” operators are racing to build faster than ever before, driving unprecedented demand for cabling, power and cooling. The result is an industry sprinting at full speed, with aggressive timelines and unrelenting pressure to create capacity.
According to recent data, Europe’s built data‑centre capacity currently sits around 10.37 GW, with forecasts indicating it will more than double to over 17GW by 2030. Yet lead times remain stubbornly tight. As AI workloads surge, operators are searching for every advantage that helps them deliver more, faster, and with absolute reliability.
Prefabrication is emerging as a key solution. Often associated with large modular builds, its principles – such as pre-terminated cabling, rack systems, and containment solutions – can also transform network infrastructure deployment. By leveraging prefabricated assembly’s organisations can achieve faster installation, improved quality assurance, and reduced on-site risk. This approach enhances delivery certainty, supports scalability, and accelerates time-to-service across both new and existing data centre environments. However full prefabrication can only be achieved through complete BIM collaboration between all disciplines and a frozen, agreed design before commencement. Any late design changes can make pre-built assemblies obsolete.
Rethinking data centre construction
While the benefits of prefabrication are increasingly recognised, its greatest impact lies in how it transforms the construction process itself. Instead of unpacking and assembling thousands of individual components on a crowded, dusty site, critical elements are prepared off-site in controlled conditions, much like a data centre’s own production line. Tasks such as opening boxes of cables, fibre cassettes, and enclosures are replaced by efficient work within dedicated prefabrication facilities, where racks are assembled, preloaded, labelled, and delivered to site ready for immediate installation. This approach places greater emphasis on logistical planning, including delivery sequencing, lifting plans, site access, and careful packaging and labelling.
Equally important are dimensional accuracy and tolerance management; for example, prefabricated fibre assemblies must be ordered to precise lengths, as any deviation can cause significant constraints to containment systems—too long creates excess, but too short can be far more problematic.
By shifting complexity upstream, prefabrication not only accelerates deployment but also brings predictability and repeatable quality across multiple builds. It allows teams to focus on integration and commissioning rather than assembly. In projects where network infrastructure sits on the critical path to go-live, every day saved can make the difference between meeting delivery milestones or falling behind—making prefabrication not just a technical choice, but a strategic advantage.
The cost of late engagement
Despite its clear advantages, prefabrication is often considered too late in the data centre build process. Connectivity partners are frequently engaged only after designs are finalised, limiting opportunities to prefabrication solutions. Engaging these partners earlier enables constructability studies that identify integration challenges, optimize designs for delivery, and ensure that prefabrication and connectivity requirements are aligned from the outset.
When this happens, the impact is felt across the build:
- Teams spend valuable time unpacking and sorting equipment rather than installing it.
- Space on site becomes congested, reducing efficiency and flow.
- Dust and debris increase the risk of damaging or contaminating products.
- Manual coordination between teams becomes more complex, raising the potential for errors.
- Delays at the cabling and fit-out stage, typically the final phase of data centre construction, can significantly push back the date the site is brought online.
Prefabrication can remove many of these challenges, but only if it’s embedded into design decisions and timelines from the outset. Treating connectivity as a design input, rather than a downstream activity, allows teams to plan for modularity, off-site assembly, and smoother handovers.
Prefabrication from day one
To unlock its full value, the considerations for prefabrication must begin at the concept and schematic design stage. When architects, engineers, and connectivity specialists collaborate early, they can develop a shared design approach that supports repeatability and efficient installation. Network construction is treated as a design input and not an afterthought.
Early integration enables work to progress in parallel. While the main structure is being built, specialist prefabrication teams can assemble and test network modules off-site. By the time the site is ready, the network components are too, fully built, labelled, and quality checked. Time savings on the network scope can typically be around 20%, while improving working conditions and reducing on-site congestion.
Beyond schedule improvements, prefabrication supports a more flexible and sustainable model for data centre design. Standardised, modular cabling can be upgraded or expanded as workloads evolve, extending the lifespan of facilities and reducing waste over time.
Onnec’s prefabrication expertise
For more than 30 years, Onnec has been designing and delivering the network foundations behind some of the world’s most demanding digital environments. Our prefabrication capability builds on that experience, bringing control and efficiency to complex data centre delivery.
These benefits are tangible:
- Less waste
- Fewer supervision hours required
- Lower on-site labour requirements
- Management of logistics, site access and labelling
- Quicker network deployments
All of these benefits are supported by Onnec’s rigorous quality assurance and project management frameworks.
From design and procurement to installation and long-term support, Onnec provides a fully integrated service. Strong relationships with leading manufacturers allow us to tailor every solution to the client’s requirements, ensuring consistency, scalability, and value across large or multi-site programmes.
As AI-driven data centre projects accelerate worldwide, the demand for speed, predictability, and quality has never been greater. Prefabrication has emerged as a key enabler in meeting that demand, a proven method to streamline delivery, enhance consistency, and reduce risk on even the most complex builds. Early engagement and standardised designs are essential to de-risk the critical final stages of any data centre project.
Partnering with Onnec early in the design process allows effective prefabrication to be integrated into the programme from the outset. The result is greater control, smoother delivery, and fewer last-minute challenges when it matters most. In an environment where every day counts, prefabrication provides a practical, tested route to delivering AI infrastructure faster, with higher quality and reliability.
Ultimately, prefabrication is a powerful tool for modern construction, but its success is not automatic. It requires a cultural shift: moving away from siloed ways of working toward true collaboration and shared goals. When all disciplines align early and the design is locked in, the benefits are clear. Without that foundation of coordination and commitment, the risks can quickly outweigh the rewards.
