HVAC commissioning is the formal process by which a mechanical system is verified to operate in accordance with its design intent. It covers airflow measurement and balancing, control system verification, equipment performance testing, and documentation of all results in a commissioning report submitted with the occupancy permit application. In Saudi Arabia, where the Saudi Building Code mandates formal HVAC commissioning for qualifying buildings, this process is both a regulatory requirement and a professional quality standard.
Yet in the vast majority of HVAC commissioning programmes — in Saudi Arabia and internationally — one critical preceding step is missing: verification that the duct system delivering air to the building’s spaces is actually capable of delivering what the design intended. Without confirmed duct integrity, everything else in the commissioning process is built on an uncertain foundation. This article argues that duct leakage testing should be a mandatory prerequisite to HVAC commissioning — and explains why the current absence of this requirement is costing building owners and operators throughout the Kingdom.
The Logic of Sequence: Why Testing Must Come First
HVAC commissioning establishes the operating baseline for the building’s mechanical system. It sets supply airflows, adjusts balancing dampers, configures control sequences, and measures actual system performance against design targets. All of these activities assume that the duct system through which air flows is substantially intact — that the air measured leaving the air handling unit is approximately the same air that arrives at the supply grilles in the occupied spaces.
If the duct system has significant leakage — which, as discussed, is extremely common in Saudi construction — this assumption is false. A duct system leaking 20% of supply airflow into ceiling voids and plant areas will never be balanced correctly, because the air available at the terminal devices is 20% less than what the balancing engineer is trying to distribute. Airflows measured at grilles will be lower than design. The commissioning engineer will attempt to compensate by opening dampers, increasing fan speeds, and adjusting set points — masking the underlying problem rather than resolving it.
The result is an HVAC system commissioned to operate in an abnormal state — fan pressures higher than design, energy consumption higher than designed, terminal airflows still below target — with a commissioning report that records these abnormal settings as the building’s baseline. Every subsequent assessment, every energy audit, every performance benchmark is then measured against a fundamentally compromised starting point.
What Commissioning Without Duct Testing Misses
The specific impacts of commissioning a leaky duct system without prior leakage testing include several compounding problems that persist for the entire life of the building.
Fan energy is the first and most immediately measurable impact. Supply fans sized to deliver a specified airflow against a calculated static pressure must operate at higher speeds and pressures when the system leaks — consuming significantly more electrical energy than designed. For large commercial systems in Saudi Arabia, fan energy represents a substantial proportion of total HVAC electrical consumption. Running fans at excessive speeds also accelerates bearing wear and motor degradation, increasing maintenance frequency and shortening equipment life.
Comfort and ventilation are the next impacts. Spaces served by duct branches with higher leakage rates will consistently receive less supply air than spaces served by tighter branches, regardless of how carefully the system is balanced. This creates persistent comfort complaints and ventilation deficiencies in affected areas that cannot be resolved by adjusting dampers or increasing supply temperatures — because the problem is in the distribution infrastructure, not the control settings.
Energy code compliance is the third impact. The Saudi Building Code specifies maximum duct leakage thresholds for commercial HVAC systems. A system commissioned without a leakage test may be unknowingly operating in non-compliance with SBC requirements — a liability that only becomes apparent when the building undergoes an energy audit, a certification assessment, or a regulatory inspection.
The Current Gap in Commissioning Practice
Standard commissioning protocols in Saudi Arabia — and in most international markets — do not require duct leakage testing as a prerequisite. ASHRAE Guideline 1.1, which forms the basis for HVAC commissioning practice internationally, includes duct leakage testing as a recommended element of the commissioning process but does not mandate it as a prerequisite to TAB. SMACNA standards specify acceptable leakage limits for duct construction but do not require pre-commissioning verification.
This gap exists partly for historical reasons — duct leakage testing was until relatively recently a specialised service not widely available to commissioning teams — and partly because the costs of non-compliance fall on the building owner rather than the commissioning body. Commissioning engineers who deliver a complete TAB report are fulfilling their contractual obligation regardless of whether the duct system beneath the balancing results is leaky or tight.
Closing this gap requires either regulatory action — adding duct leakage testing to SBC commissioning requirements, which is a direction already signalled in the code’s trajectory — or client-driven specification, with building owners and developers requiring leakage testing as a contractual pre-commissioning milestone.
The Aeroseal Arabia Approach: Test Before You Commission
Aeroseal Arabia works with HVAC contractors, commissioning engineers, and building developers across Saudi Arabia to integrate duct leakage testing into the pre-commissioning programme. The testing is carried out after duct installation is complete and all terminals are sealed, using RetroTec-certified duct blaster equipment following the SMACNA test protocol.
Where the test reveals leakage above the SBC threshold, Aeroseal’s internal duct sealing technology is available to bring the system into compliance before commissioning begins. The sealing process requires no duct disassembly, no access to concealed ductwork, and no interruption to other construction activities — the sealant is introduced through the AHU connection point and distributes itself through the pressurised system to every leakage pathway.
The result is a duct system that enters commissioning in a verified, compliant condition — enabling the commissioning engineer to carry out TAB against a foundation of confirmed duct integrity, producing commissioning results that accurately reflect the system’s design performance rather than compensating for underlying infrastructure deficiencies.
The Business Case for Building Owners
For building owners and developers, the financial case for requiring pre-commissioning duct leakage testing is straightforward. The cost of a duct leakage test on a typical commercial building in Saudi Arabia is a small fraction of the building’s annual HVAC energy cost. If the test reveals a compliant system, the owner has a documented record of compliance and a confirmed starting point for future energy performance assessments. If it reveals non-compliance, the owner has the opportunity to require remediation under the construction contract before handover — rather than discovering the problem after occupancy when remediation costs and contractual leverage are both significantly diminished.
Conclusion
Duct leakage testing should be a mandatory prerequisite to HVAC commissioning on every commercial building project in Saudi Arabia. The logic is unambiguous: commissioning a duct system without knowing its leakage condition is commissioning against an unknown baseline, producing results that may be meaningless as performance benchmarks and that mask a significant ongoing energy and comfort liability. Aeroseal Arabia provides pre-commissioning duct leakage testing and, where required, same-visit remediation to bring systems into SBC compliance before the commissioning clock starts. Contact our team to discuss integrating leakage testing into your project’s commissioning programme.
