In a data centre project, the split between workshop and site is more than a logistics question. It decides how much of the system has been checked before it reaches site, and therefore how much uncertainty is left when commissioning starts.

In the industry it is common for around 20 per cent of the work to be done in the workshop and 80 per cent on site. Our ambition is the opposite.

From 20/80 to 80/20

Traditionally, piping systems are mostly built where they will stand. Parts arrive on site and are cut, fitted, welded and installed there. Prefabrication is used, but mostly as a supplement for some sections, bends and supports.

In data centres that split does not hold. Build times are short, power density is high and there is little room for defects that are only found during commissioning. Most of the work should therefore move into the workshop, leaving the site with only what genuinely has to be done there.

Why wait with the checks?

Anything that can be tested, cleaned, inspected and documented in a fixed workshop is done better there than in a building under construction. The workshop has fixed equipment, good lighting, set routines and people who know the process. Inspections can be carried out systematically and documented while the work is under way.

On site several trades work at the same time, there is dust and traffic, and inspections often have to fit into time slots set by others. Work that is pushed to site is therefore done both later and under worse conditions.

Preparation happens while the building goes up

Prefabrication moves work out of the part of the project where time is scarcest. When skids and pipe sections are built while the building goes up, you make use of time that would otherwise be lost.

On site the job then becomes installing finished units rather than producing them. The period where many trades compete for the same space gets shorter, and fewer decisions have to be made under time pressure.

Prefabrication is about more than fit

Prefabrication is often judged on whether the parts fit. Fit matters, but it is only the first question. These three matter just as much.

• Is it clean? A piping system can have perfect geometry and still carry particles, scale or early corrosion on the inside.
• Is it protected? A system that is clean in the workshop is not necessarily clean on site if it has stood open during transport and storage.
• Is it documented? If the documentation does not hold together, the next trade has to check again what has already been checked.

A prefabricated element that fits perfectly but is dirty inside has saved nobody anything. The problem has only been moved to a point where it costs more to find.

What it means for commissioning

When systems arrive on site tested, cleaned, protected and documented, commissioning confirms something you already know. When they arrive unchecked, commissioning turns into troubleshooting, and troubleshooting takes as long as it takes whatever the programme says. That is the difference between a system that is installed and one that is ready.

More control before site

80/20 is not a goal in itself. The numbers describe a priority where as much work as possible is moved to where conditions are controlled. Where the line should be drawn has to be assessed in each project. Read what decides whether prefabrication pays off.

Done right, prefabrication is about more than saving hours. It is about building the system once and handing it over ready for operation.