Retro-commissioning

Recovering performance without replacing equipment

Most existing buildings do not underperform because their equipment is inadequate. They underperform because nobody has verified what that equipment actually does. Retro-commissioning acts on settings, control logic and operating schedules — which is why it produces results within a budget cycle rather than a capital programme.

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Terminology

Three words that are not interchangeable.

French certification schemes distinguish three cases, and the distinction is worth keeping because it determines what the assignment can rely on. Commissioning applies to new installations. Recommissioning applies to a building in operation that already went through the process at design and construction stage — there is a reference to return to. Retro-commissioning applies to a building that never had it, which is the overwhelming majority of the existing stock.

The practical difference is the starting point. Recommissioning compares against a documented original state. Retro-commissioning has to establish that state first, because nobody wrote down what the building was supposed to do. That reconstruction is the first phase of the assignment and it is what distinguishes it from an energy audit.

Distinction

Not an energy audit, and not a substitute for one.

An energy audit identifies savings opportunities and prices works: it looks at what should be installed. Retro-commissioning verifies what the existing installations actually do against what was expected of them, and corrects it through settings and control logic.

The two are complementary and they do not answer the same question, nor commit the same budget. One produces a works programme; the other produces actions that require no capital. On a portfolio under pressure, the sequence usually matters: establishing what the current installations are capable of, once properly operated, changes the case for the works that follow — sometimes substantially.

Where a French audit is required by regulation, the DDADUE energy audit obligation and the ISO 50001 route set the frame. Retro-commissioning sits alongside them rather than in place of them.

What we find

The same five findings, on most buildings.

The recurrence is striking, and it is good news: these are correctable without capital expenditure.

  • Commissioning overrides left in place. Forced valves, forced fans, manual modes set during start-up years earlier and never released. Nobody remembers why they are there, and the building has been running in a configuration nobody chose.
  • Schedules that no longer match occupancy. Heating and ventilating spaces that are empty, night setback disabled after a complaint, holiday regimes never programmed. This is the single largest recoverable item on most non-residential buildings.
  • Unbalanced hydronic circuits. Which forces the whole system to overheat in order to satisfy the least favoured space.
  • Ventilation flow rates never verified. Frequently far from the design values, in both directions, with consequences for both energy and indoor air quality.
  • Control logic diverging from its documentation. The functional description says one thing, the parameters loaded into the controller say another, and no one has compared the two since start-up.

On a portfolio

Where to start, using data you already hold.

Nobody retro-commissions an entire estate. The real question is which building comes first, and it can be settled on signals that already exist in your systems, without additional instrumentation.

  • Recently renovated buildings whose bills did not fall as predicted. The investment has been made; the gap is in operation. The energy model gives the reference, the invoice gives the reality, and the difference identifies the building.
  • Plant rooms rebuilt two to five years ago. Recent enough for the control system to be capable, old enough for start-up overrides to have settled in and for everyone to have forgotten them.
  • Buildings with high complaint rates. They carry a hidden management cost, and they offer the most legible demonstration: a comfort problem investigated and resolved is immediately visible to occupants.
  • Buildings with an under-used building management system. Many portfolios already hold the measurement and never read it. That is where ongoing commissioning starts at no capital cost, and where French building automation regulation now applies above a power threshold.

For non-residential assets, all of this feeds the declared trajectory required by the French tertiary decree and its annual filing.

FAQ

Questions from asset and estate managers.

Yes, and that is the normal case. The work acts on settings, control logic and schedules rather than on equipment replacement, which makes it compatible with a building in service. The two practical conditions are access to the building management data and an intervention window coordinated with the incumbent operator — both easier to secure in the lease or the operating contract than at the moment they are needed.
An audit identifies savings opportunities and prices works: it looks at what should be installed. Retro-commissioning verifies what the existing installations actually do against what was expected of them, and corrects that through settings. One produces a works programme, the other produces actions requiring no capital. Establishing what current installations are capable of once properly operated often changes the case for the works that follow.
The same five items on most buildings: start-up overrides left in place years earlier, schedules that no longer match occupancy, unbalanced hydronic circuits, ventilation flow rates never verified since start-up, and control logic that has diverged from its own documentation. None of these is a defect in the legal sense, none appears on a snagging list, and all are correctable without capital expenditure.
Recently renovated buildings whose bills did not fall as the model predicted: the investment is already made, the gap sits in operation, and the payback is fastest. Then plant rooms rebuilt two to five years ago, where start-up overrides are usually still in place, and buildings with high complaint rates, which offer the most legible demonstration. None of these three signals requires additional instrumentation.

Go further

The rest of the commissioning material.

A portfolio whose consumption does not add up?

We start from what you already hold — energy models, invoices, complaints, building management data — to identify where operation explains the gap, and scope an assignment against it.

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