What Happens If a Building Is Not Commissioned?

Many buildings are handed over with defects no one spotted. Without commissioning (Cx), those defects become the owner’s problem – inherited by the building operator and absorbed into the cost of running the building. The project team cannot close out until issues are resolved – and on some projects the remedial work needed to fix them has taken years.

Systems fail, energy costs run high, and the problems compound with every passing year. Understanding what building commissioning is gives you the baseline; this article is about what happens when it is skipped.

The Short Answer – What Goes Wrong Without Commissioning

Studies cited by the U.S. Department of Energy DOE and the U.S. Environmental Protection Agency EPA indicate that commissioned buildings typically have operating costs 8% to 20% lower than comparable non‑commissioned buildings. Deficiencies that go undetected include control failures, undersized or misbalanced HVAC (Heating, Ventilation, and Air Conditioning) systems, missing specified equipment, and sensors that do not read correctly – problems that will compound in cost and comfort over the building’s entire operational life.

That 8% to 20% range is consistent with the savings reported in LBNL’s analysis of a large database of commissioning projects. The difference between commissioning and construction – and why Cx sits outside the construction process rather than inside it – is exactly why these faults slip through. For a deeper look at that distinction, see the difference between commissioning and construction.

What Actually Goes Wrong on Site

When commissioning is skipped, buildings do not usually fail in dramatic ways on day one. More often, they are handed over with a layer of hidden defects that show up later as comfort complaints, wasted energy, unstable controls, and systems that never quite perform as designed. Research from Lawrence Berkeley National Laboratory (LBNL) shows that the same fault types recur across large numbers of buildings: controls issues, HVAC equipment faults, sensor errors, and installation mismatches.

Controls are one of the biggest problem areas. Incorrect schedules, out-of-sequence operation, and poor control logic can leave equipment running when it should be off, or responding badly to changing loads, which drives unnecessary energy use and creates operating headaches for the facilities team.

HVAC equipment faults are just as common. Improper setup, installation defects, and configuration problems can stop systems from meeting design intent, so plant and distribution systems compensate by running longer or harder than they should.

Sensors are another frequent source of trouble. If a sensor is out of calibration, poorly located, or mapped incorrectly, the BMS receives bad information and makes bad automatic decisions because it is being fed the wrong inputs.

Commissioning is what helps to catch these issues and close them out while the project team is still in place. Without a detailed and focused commissioning process that includes verification, the defects remain in the building and become an operational problem instead of a construction closeout issue.

The consequences extend into life-safety systems as well, putting occupants at real risk if sequences are wrong or untested.

Life-safety systems – smoke control, emergency power, fire suppression sequencing – are subject to the same verification gap. A fire alarm that triggers the wrong damper sequence, or an emergency generator that starts but fails under load, are life-safety failures that a functional performance test would have caught before occupancy.

When commissioning is skipped, the project typically does not generate the documentation the facilities management team needs. Missing documentation means the FM team has no verified baseline to work from: no confirmed set points, no signed-off sequences of operation, no functional test records to cross-reference when a fault develops.

With no records or knowledge properly exchanged, equipment and systems are more likely to be put into manual override. BMS alarms get turned off or cancelled because the correct response is unknown. Workarounds accumulate. Within the first couple of years of occupancy, the building management system on an un-commissioned building often reflects the FM team’s adaptations to unresolved faults rather than the design intent.

Two documents in particular anchor the commissioning process from start to finish: the Owner’s Project Requirements and the Systems Manual. Without commissioning, these documents often do not exist, or exist only in incomplete form.

The Owner’s Project Requirements (OPR) is the foundational document of any construction or commissioning project that translates the owner’s vision into concrete, measurable criteria. Serving as the project’s “true north,” it defines exactly what the finished facility must achieve to be deemed successful. The OPR acts as the baseline against which design decisions, system tests, and the final handover process are evaluated to ensure the delivered building actually performs as the owner intended.

The Systems Manual is a system-focused document that includes the design and construction documentation, facility guide, operation manual, maintenance information, training information, and Cx records. It is the repository from which the FM team operates throughout the building’s life.

Training is another critical area that often does not get delivered properly. It is essential that O&M personnel have the knowledge and skills required to operate the facility to meet the OPR.

Training requirements are defined in the OPR, developed during the design phase, delivered during construction, and verified by the CxA against signed attendance records before occupancy. Without this, the FM team can end up taking control of a building they were never properly taught to operate.

The Compound Effect on Cost

How much does skipping commissioning cost? The honest answer is that it depends on building size, system complexity, and how long faults are left unresolved. What the published data does show is that the cost penalty is not limited to one defect or one bad season of operation — it shows up in energy, maintenance, callbacks, and building performance over time.

The operating-cost advantage of commissioned buildings – typically 8% to 20% lower than comparable non-commissioned buildings, according to DOE and EPA – is one dimension of that gap. Over a large facility and a long life, that differential compounds into a significant budget line.

In parallel, Lawrence Berkeley National Laboratory’s meta-analysis of 643 buildings found median whole-building energy savings of 13% in new construction and 16% in existing buildings after commissioning, along with significant non-energy benefits such as improved indoor air quality. Over the life of a building, even a low-teens percentage improvement in energy performance can translate into substantial avoided costs.

The cost of skipping commissioning rarely affects just a single item. It is a compounding machine: systems run inefficiently, faults remain hidden until occupancy, maintenance teams inherit unstable controls, and project teams spend more time dealing with corrective work that should have been resolved before handover. DOE guidance also cites evidence that commissioning can reduce change orders and contractor callbacks when issues are identified early.

Commissioning costs money once; not commissioning tends to spread the cost across the entire operating life of the building, where it is harder to diagnose, more disruptive to correct, and usually more expensive to live with.

What Commissioning Prevents

Commissioning exists to catch problems before the owner inherits them. That is its core function, and it is worth being direct about what that list looks like in practice.

The purpose of commissioning is verification: ensuring the building performs to the Owner’s Project Requirements (OPR) as set out in the Basis of Design (BOD). In practice, that means a Commissioning Authority (CxA) and Commissioning Engineer (CxE) are reviewing design documents, inspecting installed work, and running functional tests against the sequence of operations before anyone moves in.

What problems does commissioning prevent? LBNL research across large numbers of buildings shows a consistent pattern: control failures caught before occupancy, HVAC faults identified and corrected, sensors verified against calibrated references, and missing equipment identified against the design specification. These are the items that – without Cx – become operational problems the building team is diagnosing years into the building’s life.

The types of commissioning available on a project – new construction Cx, retro-commissioning, ongoing Cx – exist precisely because buildings accumulate faults over time. Commissioning does not end at handover; it is the mechanism by which building performance is maintained. Without an initial commissioning process, retro-commissioning (RCx) becomes a fault-finding exercise rather than an optimisation one, because there is no trusted baseline to return to.

Where to Go Next

This article sits within the P1 cluster on CommissioningManager.com. The related articles below give context on each area raised here:

• What building commissioning is – the foundational hub article for this cluster.
• The purpose of commissioning – what the process is designed to achieve and why it exists.
• The difference between commissioning and construction – why Cx is a separate scope, not a subset of the build.
• Who is responsible for commissioning – roles, appointments, and accountability on a live project.
• Types of commissioning – new construction, retro-commissioning, ongoing Cx, and how they differ.
• Testing vs commissioning – the difference – a question that comes up on nearly every project.