Commissioning: making your buildings perform, from project to operation

A commercial building handed over with no defects can consume 50% to 100% more than planned three years after delivery. Everyone signed, nobody tested. Commissioning tackles that gap phase by phase: a commissioning process follows the project from design through to operation and checks that the energy performance promised shows up in the operating costs. Otherwise the design team specifies, the contractor delivers, and nobody looks.

Understanding commissioning and its different approaches

What commissioning means

Commissioning, or Cx, is a quality process applied to a building's technical installations. You do not note that a piece of equipment is installed: you run it and record what it actually does, against what the brief asked for.

The commissioning process covers HVAC (heating, ventilation and air conditioning), the BMS and the building's technical packages. Administrative handover, by contrast, checks that there is a signature at the bottom of a certificate. A BMS can be handed over with no defects listed and still be full of them, because nobody tested it.

What a commissioning process sets out to do

Three objectives :

1. Contractual compliance : what was delivered matches what the specification asked for.
2. Real energy performance : making sure the building reaches the consumption level announced at design stage, not only in simulation.
3. Quality of operation: making sure the control sequences do what they should with occupants inside, on a Monday in January, not only on the test bench.

Initial commissioning on a new installation

On a construction project or a major refurbishment, commissioning starts at the briefing stage, not at handover. The agent reviews the control sequences on paper, sets the acceptance criteria, follows the site and tests every new installation at start-up. A fault found on paper costs one meeting; found after delivery, it costs rework, a variation order and often two years of excess consumption.

Retro-commissioning on an existing building

Retro-commissioning addresses buildings in operation where nobody knows any more what the BMS is doing. The survey asks simple questions: which setpoints are actually applied, how many overrides are active, what the history says. Nine BMS installations out of ten are shaky, and it shows as soon as you open the cabinet. The action plan first corrects whatever weighs most on operating costs.

The three approaches compared

Each type of commissioning matches a moment in the building's life; the table above guides the choice. An assignment costs between 1% and 3% of the works budget (source: Akéa Énergies).

On an existing portfolio, retro-commissioning is the first step: no building works, and operating costs fall as soon as setpoints and schedules become coherent again, because energy in commercial buildings is wasted mostly outside occupancy. Continuous control, by contrast, assumes a BMS that has already been made reliable: optimising a system nobody understands is like fine-tuning the heating curve of a boiler whose three-way valve nobody has checked.

The parties involved and the commissioning plan

The commissioning agent: role and independence

The commissioning agent is a third party. Their commissioning assignment comes down to three verbs: check that what is installed matches the specification, test how it actually runs, document every gap in a report that can be held up in a dispute.

Their independence from the design team and from the BMS integrator is what makes the findings credible. You cannot be both the person who programmed the sequences and the person who signs to say they work. Nobody doubts the integrator's honesty. Their position, yes.

Advisory and commissioning: what is the difference?

BMS Advisory helps the client decide: frame the need, write the brief, challenge a quotation. The commissioning assignment checks that the decision was carried out correctly.

The design team designs and directs the works; the agent checks the result. In our experience the two hats often sit on the same head: an advisor who wrote the specification is well placed to check it was followed, provided they sell nothing afterwards.

The client and the information asymmetry

The property decision maker carries the budget and the risk, and usually decides with no in-house BMS expertise, on the advice of the people who will sell the works. When they are quoted €1m for a BMS, the person quoting is also the person who will bank it. Commissioning breaks that information asymmetry : a commissioning agent who sells nothing has only one interest, that the findings are correct.

The measurement and verification plan

The commissioning plan writes down the proof before the works start: indicators, measurement points, calculation method. Without it, the gains announced at the end are declared gains, and a declared gain is not discussed, it is disputed.

The IPMVP protocol provides the methodological framework for performance monitoring; the degree-day weather correction separates what the control system changed from what the winter did on its own. That level of rigour makes energy performance auditable by a third party and defensible.

The list of commissioning operations

Each operation targets a specific checkpoint, a long way from a paper audit. Fine-tuning happens task by task, on the installation itself:

• Functional tests on HVAC: start, stop, changeover of each item of equipment
• Verification of the BMS control sequences in the controller, not in the manual
• Check of temperature and flow setpoints zone by zone
• Test of alarms and thresholds: an alarm that does not get through does not exist
• Review of the documentation delivered: drawings, schematics, points list, backups
• Training of the operating teams on day-to-day procedures

The programme and the parties involved at each stage

The programme of a construction project says which party steps in at which phase. The client approves the objectives, the design team leads the design and the site works, the contractors build, the agent checks at every milestone and the operator takes over at handover.

That last handover is where things break most often. The operator who gets the keys rarely receives the approved sequences and the list of what was tested. They receive a password.

The stages of the process and the measurable benefits of commissioning

Design phase: build commissioning in from the briefing stage

From the design phase onwards, the agent reviews the HVAC and BMS specifications with a single question: how will we prove this works? They approve the control sequences on paper and set measurable acceptance criteria, with a figure, a tolerance and a method. What the specification does not write down will never be obtained at handover. Getting this right costs hours; getting it wrong costs variation orders.

Construction phase: site supervision and installation checks

During site supervision, the agent compares the installation against the construction drawings: hydraulic connections, controller wiring, sensor positions. A room sensor mounted above a convector is invisible once the false ceiling is closed. A gap picked up at this stage costs ten times less than after handover.

Start-up: functional tests and fine-tuning

Start-up is where the paper meets the building. The agent runs the functional tests : AHU in summer then winter mode, control loops, setpoints by zone, behaviour on fault. Fine-tuning adjusts the parameters until the system runs as specified. It is the last safeguard, and the one the delivery schedule breaks most often.

Operation: monitoring over the building's life

Commissioning does not stop at the handover certificate, even if most assignments sold do stop there. In operation, performance monitoring compares consumption against the baseline every month. Without it, the conditions that hold performance in place disappear at the first complaint or override, and operating costs climb with no alert. Tracking baselines across the building's life cycle lets you correct before the gap becomes the new normal.

The full commissioning life cycle

The commissioning process runs through five phases across the building's life cycle : briefing, design, site works, start-up, operation. What the timeline shows above all is that the risk sits at the handovers. Between acceptance and operation, the approved settings are overwritten by overrides nobody records. The question to ask before signing: of those five phases, how many does the quotation actually cover?

Cutting operating costs through measurable energy savings

Commissioning done properly produces energy savings from the first year, and operating costs fall accordingly. They still have to be measured: the IPMVP protocol requires a weather-corrected baseline, without which the gains stay declarative. ADEME in fact ties its funding for local authorities to 40% energy savings (source: ADEME commissioning factsheet). We do not promise that figure to a building we have not seen.

Meeting the regulations: Décret tertiaire and BACS decree

The Décret tertiaire , the French decree on energy reduction in commercial buildings, requires a progressive cut in consumption for buildings over 1,000 m²; commissioning provides the evidence of those cuts in operation. The BACS decree (building automation and control system, decree no. 2020-887) requires automation and control functions: sites above 290 kW have had to comply since 1 January 2025, and the deadline for the 70-290 kW band was pushed back to 1 January 2030 by decree no. 2025-1343 (source: Légifrance). A BMS that complies with the decree and has never been tested is still a BMS that over-consumes.

Obtaining and keeping certifications: HQE and environmental labels

HQE certification calls for evidence on the energy and comfort targets; commissioning supplies it: measurements in real conditions, approved sequences, post-handover monitoring. But a label is a photograph, not a performance. We have seen certified buildings tick every box at delivery and over-consume three years later.

Preventing energy drift after handover

The performance gap between planned and real consumption can reach 50% to 100% in a commercial building in operation (source: professional literature, COSTIC commissioning handbook). The causes are mundane: overrides put in place to calm a complaint and never removed, design documentation lost at the first change of operator, a setpoint pushed to 24 °C for the director on the top floor (seen many times). Putting structured monitoring in place, with baselines compared and alerts on the gaps, stops that energy drift.

Budget and return on investment

An assignment costs between 1% and 3% of the works budget (source: Akéa Énergies). The return on investment is calculated against the operating costs avoided over five to ten years. On a large commercial site, commissioning pays for itself in one to three years. On a small building, the payback can stretch considerably: the absolute gains stay modest and the payback period becomes hard to defend. Every company has to run that calculation on its own portfolio, with its own history, not with a range.

ADEME funding for local authorities

ADEME co-funds commissioning assignments for local authorities, covering the study and monitoring costs. The scheme assumes a costed action plan and a documented savings target.

The 10 questions to ask before signing an assignment

Before signing a commissioning assignment, the client needs concrete criteria, because commercial proposals rarely spell out what matters: real scope, deliverables, measurement protocol. In practice the most useful assignments are those whose commissioning plan also covers operation and the handover to the teams in place. The others stop at the handover certificate, exactly when the problems start.

The checklist above covers four themes: technical scope, deliverables, success indicators and continuity after the defects liability period. Each question comes with its warning sign. An assignment whose overall delivery is not framed at this stage ends up as a PDF report nobody reads again.

Foobot: from commissioning to continuous energy control

BMS Advisory: make the BMS reliable before optimising it

A BMS that has never been audited cannot be optimised. Our BMS Advisory starts with a survey that pulls no punches: active overrides , meter reliability where readings are inconsistent, sequences put back in order, maintenance contract reviewed. It is the field equivalent of retro-commissioning, with our own tools for testing the points. That reliability work stands on its own: there is not necessarily an AI layer behind it. AI control only comes in if the building lends itself to it.

AI Control: extending the gains from commissioning with a digital twin

Once the BMS is reliable, AI Control extends the gains from commissioning over time. A digital twin is trained on the BMS history, the weather and occupancy; predictive control rewrites the HVAC setpoints every 15 minutes through the existing BMS, with no building works.

Measured result at Valeo: −28.6% HVAC consumption, verified under the IPMVP protocol with degree-day weather correction. Performance monitoring stays continuous and auditable by a third party, the only honest way to announce an energy performance figure.

Optimal Start: optimising start-up zone by zone

Optimal Start recalculates the heating start time every day, zone by zone, from thermal inertia, the weather and real occupancy. Predictive optimal start replaces the conventional optimiser, whose logic has not moved in 25 years: a single start time for the whole building.

It runs on the existing BMS. With start-up by zone, occupants arrive in spaces that are up to temperature, without having heated empty floors.

FAQ - Commissioning