Plan commissioning before the first pipe is tested
Commissioning goes smoothly when it is planned early. A commissioning plan agreed with the consultant sets out the sequence, the method statements and inspection test plans (ITPs) for each system, the test sheets to be used, who witnesses each test and what readings must be recorded. Without it, tests are repeated because the consultant was not called, or the wrong instrument was used, or the record does not show calibration.
Sequence matters because systems depend on each other. Chillers cannot be commissioned before permanent power is available and the chilled-water system is flushed and treated. Smoke control cannot be proven until the fire alarm and BMS interfaces exist. Building the T&C programme backwards from the authority inspection date is the most reliable way to expose these dependencies.
Static tests: pressure, insulation resistance and continuity
Static tests are done before systems are concealed or energised. Water supply, chilled-water, condenser-water and firefighting pipework is hydrostatically tested to the pressure and hold time stated in the specification, usually in sections as the work progresses, and each test is signed off before ceilings close. Drainage is tested by water or air test and later by flow test. Refrigerant pipework for VRF is pressure-tested with dry nitrogen and vacuum-tested before charging.
On the electrical side, cables are insulation-resistance tested with a calibrated tester, and earth continuity, polarity, earth electrode resistance and RCD trip times are recorded. Switchboards are inspected for torque marks, labelling and IP rating. These records form part of the utility inspection pack before DEWA, SEWA, ADDC or Etihad WE will energise the building.
- Hydrostatic tests of water, chilled-water and fire mains by section, with gauge calibration certificates
- Drainage water or air tests before concealment, then flow and CCTV checks where specified
- Duct leakage tests where the specification requires them
- Insulation resistance, continuity, polarity and earth resistance for every circuit
- Nitrogen pressure and vacuum tests on refrigerant lines
Flushing, water treatment and start-up
Closed chilled-water and condenser-water circuits are flushed to remove welding debris, mill scale and construction dirt, with strainers cleaned repeatedly and coils bypassed until water runs clean. Chemical cleaning and dosing follow, and water samples are taken to confirm treatment. Skipping this step is a common cause of blocked control valves and fouled plate heat exchangers within the first year.
Start-up of major equipment, chillers, pumps, AHUs, generators and fire pumps, is normally done with the manufacturer's representative present. They check rotation, alarms, safeties and operating parameters and issue a start-up report. In UAE summer conditions it is important to verify air-cooled chiller and condensing unit performance near peak ambient, because a unit that runs well in winter may trip on high head pressure in August.
Testing, adjusting and balancing (TAB)
TAB sets the air and water flows the design requires. Air balancing adjusts dampers so each diffuser, grille and fresh-air point delivers its design flow, and confirms fan duty and static pressure. Water balancing sets flow through each coil using balancing valves or confirms pressure-independent valves are working, so that chilled-water delta-T is close to design. A low delta-T across the plant is often a balancing problem rather than a chiller problem.
TAB should be performed by an independent or specialist team with calibrated instruments, and the report must list design value, measured value and percentage deviation for every terminal. Fresh-air flow deserves particular attention in the UAE, because humid outdoor air that is under-supplied or not dehumidified leads to condensation, mould and occupant complaints.
Integrated systems and cause-and-effect testing
The cause-and-effect matrix defines what each fire alarm input must trigger: AHU shutdown, smoke damper operation, stair and lift-shaft pressurisation start, smoke extract fans, lift homing, access-control release, public address messages and sprinkler flow switch alarms. Integrated testing walks through every line of the matrix, zone by zone, with all trades present, because a single failure usually sits at the interface between two contractors.
Stair pressurisation is checked for pressure differential with doors closed and air velocity through an open door, and door opening force is confirmed. Fire pump tests cover automatic start on pressure drop, jockey pump settings and running on emergency power. These results form the core of the civil defence inspection, and the building cannot obtain its completion certificate until they pass.
- Fire alarm devices tested and addressed against the approved zone chart
- AHU and FCU shutdown on alarm in the affected zone
- Smoke and fire damper operation with BMS indication
- Pressurisation fans, smoke extract fans and make-up air
- Lift homing and fire fighting lift functions
- Generator auto-start and transfer to life-safety loads
Authority witness and the inspection pack
Civil defence inspections in each emirate, Dubai Civil Defence, Sharjah Civil Defence, ADCDA and others, focus on life-safety systems and require the approved drawings, material approvals, test certificates and a working demonstration. Utility authorities inspect the electrical installation and metering before permanent connection, and water authorities may inspect tanks and connections. Pre-inspections by the consultant before the authority visit catch most failures.
Common reasons for failed inspections include missing firestopping, devices obstructed by later fit-out works, mismatched device addresses, pressurisation readings outside the required range and incomplete documentation. A clean, indexed inspection file is almost as important as the installation.
Handover documents, training and how Manolia closes out
Handover is a document exercise as much as a site one. The client's facility team needs O&M manuals with equipment data, spare parts lists and maintenance schedules, as-built drawings that match the site, all test and commissioning records, warranties from manufacturers and the contractor, authority certificates, and a record of training sessions with attendance sheets. Training should be practical, at the equipment, covering normal operation, alarms and emergency procedures.
Testing, commissioning and handover is the eighth and final stage of Manolia's delivery process, preceded by a dedicated quality inspection stage so that systems arrive at commissioning already checked. That structure, applied across more than 100 completed projects since 2001, is designed to make handover a confirmation rather than a scramble.
- O&M manuals, indexed by system, with equipment data sheets
- As-built drawings in agreed formats
- Signed test certificates, TAB report and cause-and-effect results
- Warranty certificates and spare parts and tools handover
- Authority completion and connection certificates
- Training records and asset register for the FM team
Frequently asked questions
What is the difference between testing and commissioning?
Testing verifies that an installation is sound, for example that a pipe holds pressure or a cable has adequate insulation resistance. Commissioning brings systems into operation, sets them up and proves they perform as designed, alone and together. Testing comes first and is mostly static; commissioning is dynamic and ends with integrated system tests.
Who witnesses MEP tests on UAE projects?
The consultant or its resident engineer witnesses most tests and signs the test sheets, with the main contractor's QA/QC present. Manufacturers attend start-up of major equipment. Civil defence witnesses life-safety system demonstrations, and utility authorities inspect electrical and water connections before energising or supplying the building.
Why do chilled-water systems often show low delta-T after handover?
Typical causes are incomplete water balancing, control valves sized or set incorrectly, coils bypassing water at low load, dirty coils or strainers, and three-way valves where two-way valves were intended. Proper TAB and BMS trend reviews during commissioning catch most of these before handover.
What should O&M manuals contain?
They should include a system description, equipment data and certificates, operating procedures, maintenance schedules and procedures, spare parts lists, supplier contacts, test records and the relevant as-built drawings. Manuals organised by system and linked to an asset register are far more useful to the facility team than a pile of catalogues.
Can a building be occupied before commissioning is complete?
Occupation normally requires the authority completion certificate, which depends on life-safety systems passing inspection. Some non-safety commissioning, such as fine-tuning of BMS trends, may continue after handover under an agreed snag list, but fire, smoke control and electrical safety must be complete and accepted first.