01An empty shell is not a data centre
Developers hand over a shell and core (“Cat A”): the structure, roof, external envelope, floor slab, and a power and water supply to the building. It is weatherproof and serviced, but it cannot run a single server.
Everything that makes it a data centre (the power distribution, the cooling, the white space, the cabling, the controls) is the fit-out (“Cat B”). Closing that gap, on time and proven to work, is a project in its own right.
What the shell gives you
Structure, roof and walls, a floor slab, and incoming power, water and fibre to the building boundary. The canvas, nothing more.
What the fit-out adds
Switchgear and UPS, busway and PDUs, cooling, raised floor or slab, racks, containment, structured cabling, fire and security, BMS: everything above the slab.
Why it is a discipline
A dozen trades and systems have to converge in the right order, coordinated so they do not clash on site, and proven to work together before a live load ever touches them.
Why sequencing matters
Get the order or the coordination wrong and the costs compound: rework, delay, a hall that cannot be maintained. Get it right and it is fast, clean and right first time.
02From shell to live, phase by phase
A fit-out runs as a sequence of overlapping phases, each building on the last.
Step through them below and watch the hall build up from the slab. Each phase links into the deep-dive guide where there is one.
Interactive / Fit-out phase explorer
Build the hall from the shell up
Choose a phase, or drag the slider, to walk the fit-out from an empty shell to a live hall.
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Shell and core
The empty building handed over by the developer: structure, roof, external envelope, floor slab, and power, water and fibre to the boundary. Weatherproof and serviced, but it cannot run anything.
OutputA clean, surveyed shell: the canvas to design into.
Deep divePhases overlap in practice: design continues as early works begin, and cabling follows containment row by row. But the dependencies are real. You cannot commission what is not installed, and you cannot install well what was not coordinated. Good fit-out runs phases in parallel without breaking the order that matters.
03What separates a smooth fit-out from a painful one
The phases are the same on every project. What decides whether it is fast and right first time, or a running battle of rework and delay, is the discipline around them.
Coordinated design first
Model the whole hall (power, cooling, containment, cabling) and clash-detect it before anything is installed. The cheapest place to fix a problem is the model, not the site.
One source of truth
A single design model drives the drawings, the quantities and the build, so everyone works to the same numbers and nothing drifts out of sync.
Sequencing and logistics
The right trades in the right order, materials on site when needed, access and lay-down planned. Most delay is logistics, not labour.
Our own engineers
Directly employed teams across the disciplines mean accountability and fewer gaps at the seams between trades, which is where projects usually go wrong.
Quality and certification
Test and certify as you go (cabling links, power, containment) with the records kept, rather than a scramble at the end.
Commissioning built in
Plan the testing from day one, so commissioning validates a design that was always meant to be tested, not a last-minute hurdle.
04Commissioning: proving it before it is live
Commissioning is the most underrated phase: the structured testing that proves the hall works, ideally finding every fault on test, under simulated load, rather than in production with a customer's equipment installed.
It runs in five recognised levels, each building on the last.
| Level | Stage | What it proves |
|---|---|---|
| L1 | Factory acceptance (FAT) | Each major item works to specification before it ships, tested at the manufacturer |
| L2 | Site acceptance (SAT) | Equipment arrives undamaged and correct, on delivery and once positioned |
| L3 | Pre-functional / component | Every component is installed correctly, connected and ready, with static checks in place |
| L4 | Functional performance | Each system works on its own under control: UPS, cooling, generators, BMS |
| L5 | Integrated systems testing (IST) | Everything works together under simulated load: fail the utility supply and prove the whole hall rides through |
Under simulated full load, the test deliberately fails the utility supply and proves that generators, UPS and cooling carry the hall without interruption: the scenario you never want to discover for the first time in production. A hall that has passed IST is one you can hand over with confidence.
05Readiness: what sets a fit-out up to succeed
Most fit-out pain is decided before the first cable is pulled: in how well the project is scoped, coordinated and sequenced.
What moves the outcome, weighted by how much it matters:
Notice what sits at the top: it is all up front. Design coordination, a single source of truth and a commissioning plan. Get those right and the build runs smoothly; leave them to chance and no amount of effort on site fully recovers it.
06How Optronix helps
Fit-out is what we do: turning a shell, or a drawing, into a live, proven data hall.
We design, supply, install, certify, commission and hand over across the full lifecycle, with our own engineers, for hyperscale, colocation and enterprise clients across the UK, EMEA and worldwide.
Model-derived design, fast
We turn a client drawing into a costed, coordinated design (layout, power, cooling, containment and cabling counts) in under 48 hours, built in our own Whitespace Builder, so the model drives the drawings, the quantities and the build.
One accountable team, end to end
Directly employed engineers across the disciplines, with no subcontract handoffs at the seams, so the design that is signed off is the one that is installed, tested, certified and handed over.
- 01
Design and coordinate
The whole hall modelled and clash-checked (power, cooling, white space, containment, cabling) and costed from your drawing.
- 02
Install and certify
Power distribution, containment, white space and the structured cabling plant, installed cleanly and tested and certified as we go.
- 03
Commission and prove
Structured commissioning through to integrated systems testing: the hall proven under load before it goes live.
- 04
Hand over and operate
As-built drawings, test records and O&M documentation, then ongoing operational support, smart hands and changes.
A shell or a drawing
Tell us what you are starting with and where it needs to get to.
We will come back with a costed, coordinated fit-out plan: designed, delivered, commissioned and handed over.
Sources and notes
- Shell and core (Cat A) and fit-out (Cat B): standard commercial property and data centre delivery terminology.
- Commissioning levels L1 to L5 (FAT, SAT, pre-functional, functional, integrated systems testing): common data centre commissioning practice.
- Design coordination, clash detection and sequencing per common BIM and construction delivery practice; cabling per TIA-942 and ISO 11801 (see our structured cabling guide).
General guidance, not a delivery specification. Fit-out scope, sequencing and commissioning regimes vary by project, building and client; phases overlap and terminology differs between markets. Confirm scope and standards against your own project and an engineered programme.