Commissioning is routinely the first thing to be compressed when a programme slips. It sits at the end of the Gantt chart, it has no visible physical output the way a fit-out does, and it is easy to assume it can simply happen faster if the earlier activities have overrun. In practice, commissioning has its own logic, its own dependencies and its own minimum durations — and treating it as elastic is one of the more reliable ways to hand a client a building that looks finished but does not yet work as intended.
Commissioning has dependencies, not just a duration
Systems cannot be properly commissioned until the building fabric around them is substantially complete — a space that is still being fitted out around live plant is not a stable enough environment for accurate testing. Electrical systems generally need to be energised and proven before mechanical systems that depend on them can be commissioned. Building management system points need to exist and be mapped before control strategies can be validated. Compress the earlier trades and you do not just shorten the programme — you push all of these dependencies later, and commissioning inherits the delay on top of its own irreducible duration.
Seasonal constraints are real, not an excuse
A heating system commissioned properly needs conditions in which heat is actually being called for; the same is true in reverse for cooling. Where a programme lands commissioning in the wrong season, the honest options are: accept a period of seasonal commissioning after handover, build a witnessed simulation into the strategy, or accept that some performance parameters will be validated later rather than at handover. What should not happen is a system being signed off as fully commissioned when it has not actually been tested under the conditions it will operate in.
Witnessing is not paperwork
A witnessed commissioning regime — where the client’s representative, and often a specialist independent of the installing contractor, physically observes tests being carried out — exists because self-certified commissioning has an obvious conflict of interest built into it. The contractor commissioning its own installation is not commissioning fraudulently in most cases; it is simply under programme and commercial pressure to sign things off. Independent witnessing changes that dynamic, and the records it produces are what a client can actually rely on once the defects period has passed and the original team has moved on.
Soft landings, not a hard handover
The building that passes commissioning on the day of practical completion and the building that performs well in its first year of occupation are not automatically the same thing. Occupancy patterns, seasonal cycles and the operational team’s own competence with the controls all affect real performance, and a commissioning strategy that stops at handover misses the period where most of that gets proven or exposed. A structured aftercare period — revisiting commissioning data against actual seasonal performance, and making sure the operational team genuinely understands what they have been handed — closes the gap between “commissioned” and “working as intended.”
Programming it properly
In practice, this means commissioning needs its own line items in the programme, with realistic durations set by what the systems actually require rather than by whatever time happens to be left; a clearly identified point at which the building is stable enough to start; a witnessing regime agreed before it is needed, not negotiated during a dispute; and a handover that includes a defined aftercare period rather than ending the day the keys change hands. None of this is exotic. It simply requires commissioning to be treated as a programme item with its own logic — not as the buffer that absorbs everyone else’s delay.