HVAC commissioning requires a structured set of measurements covering airflow, temperature, humidity, pressure and electrical parameters to confirm that a system meets its design specification before handover. In Singapore, HVAC commissioning is governed by the Building and Construction Authority (BCA) Green Mark standards, the Singapore Standard SS 553 Code of Practice for Air Conditioning and Mechanical Ventilation, and the requirements of mechanical and electrical (M&E) consultants on each project. Getting the measurements right at commissioning protects the building owner, validates the contractor's work and ensures occupant comfort and energy performance from day one.
Unitest Instruments supplies and calibrates a wide range of instruments used in HVAC commissioning across Singapore's commercial, industrial and institutional building sectors. This guide covers the key instrument categories, what each measures, and how to select the right tool for each task.
Airflow Measurement
Airflow is the most fundamental HVAC commissioning measurement. Design air change rates, fresh air percentages and room pressurisation all depend on accurate airflow data. Three main instrument types are used:
Vane Anemometers
Rotating vane anemometers measure air velocity by counting the rotation of a small propeller in the airstream. They are simple, affordable and suitable for measuring at diffusers and grilles at relatively low velocities. Modern digital vane anemometers display velocity (m/s), volumetric flow (l/s or m³/h), and can log readings for statistical analysis. They are the workhorse of diffuser balancing. However, they require a capture hood or careful placement at the outlet face to avoid underestimating flow by missing edge velocities.
Hot-Wire Anemometers (Thermal Anemometers)
A hot-wire or thermal anemometer measures air velocity by sensing the cooling effect of airflow on a heated wire or thermistor. They offer much higher sensitivity than vane types and can measure very low velocities accurately — useful in cleanrooms, laboratories and areas where tight airflow control is required. Many models combine velocity measurement with temperature sensing.
Capture Hoods (Air Balancing Hoods)
A capture hood is a fabric cone that fits over a diffuser or grille and channels all the discharge air through a flow-measurement sensor in the hood's neck. This gives a direct volumetric flow reading at the terminal device without requiring velocity traverses or area calculations. Capture hoods are the fastest way to balance air systems during commissioning and are widely used by M&E contractors in Singapore.
Temperature and Humidity Measurement
Verifying supply air temperature, return air temperature, outside air temperature and room conditions against design is a core commissioning task. The following instruments are used:
Digital Thermometers and RTD Probes
For spot-checking air temperatures at supply and return grilles, digital thermometers with type K thermocouple or platinum RTD probes are standard. Insertion probes sized for ductwork penetration allow duct air temperature measurement. Temperature accuracy of ±0.1–0.5 °C is typically required for commissioning data.
Combined Temperature and Humidity Meters
Room conditions must be measured and documented at commissioning, particularly for office buildings targeting Green Mark certification. Combined temperature and humidity meters — also called psychrometers or hygrometers — measure dry-bulb temperature and relative humidity simultaneously. Rotronic instruments, available through Unitest Instruments, are widely used for this purpose in Singapore's demanding tropical environment. Look for instruments calibrated across the full humidity range relevant to Singapore (typically 60–90% RH for ambient conditions).
All temperature and humidity instruments used for commissioning should carry current calibration certificates traceable to national standards. Unitest Instruments' SAC-SINGLAS accredited laboratory provides calibration for thermometers, RTD sensors and humidity meters.
Static Pressure Measurement
Static pressure measurements are used to balance air handling systems, check fan performance against the design pressure curve, and verify room pressurisation (positive or negative relative to adjacent spaces). The primary instrument is the digital manometer, also called a differential pressure gauge or magnehelic gauge.
Digital Manometers and Micromanometers
A digital manometer measures the pressure difference between two points in the duct system (or between a room and a reference space). For HVAC commissioning, micromanometers — capable of resolving very small pressure differences (down to 0.1 Pa) — are needed for low-pressure systems such as cleanrooms and biological containment areas where precise pressure control is critical. CS Instruments, one of Unitest Instruments' supplier brands, manufactures portable differential pressure instruments suitable for HVAC commissioning work.
Pitot tube traverses — a method of measuring duct airflow by measuring the total and static pressure at multiple traverse points across the duct cross-section — require a micromanometer connected to the pitot tube. This method is used for measuring airflow in large ducts where capture hoods cannot be used.
Electrical Measurements for HVAC Equipment
HVAC systems consume significant electrical energy. Commissioning includes verifying that motors, variable speed drives (VSDs) and compressors operate within their electrical ratings and that energy consumption matches design predictions. Several instruments are needed:
Clamp Meters
A clamp meter measures current without breaking the circuit by clamping around a conductor. For HVAC commissioning, clamp meters are used to measure the operating current of AHU fan motors, chiller compressors, pump motors and cooling tower fans, and to verify that these match nameplate data and design calculations. Fluke clamp meters, available from Unitest Instruments, are widely used in Singapore's M&E industry for this purpose.
Power Quality Analysers
For larger plant items — chillers, large AHU fans, primary and secondary chilled water pumps — a power quality analyser provides comprehensive data on voltage, current, power factor, harmonic distortion and energy consumption (kWh). This data is required for BCA Green Mark energy performance calculations and for baseline energy monitoring programmes. Read our detailed guide on power quality analysis for more information.
Insulation Resistance Testers
Motor insulation resistance testing (megger testing) is carried out before energising motors for the first time and as a commissioning check. A minimum insulation resistance is specified by the motor manufacturer and by the Singapore Code of Practice for Electrical Installations (SS 638). Fluke insulation resistance testers are suitable for this purpose.
Balancing and Commissioning Data Recording
Singapore's BCA requirement for M&E commissioning documentation — particularly for Green Mark projects — means that commissioning data must be recorded systematically and retained. Digital instruments with data logging capability and direct output to spreadsheets or commissioning software save time and reduce transcription errors. Key data to record includes:
- Room-by-room airflow at each supply and return terminal
- Supply air temperature and humidity at each AHU
- Fan static pressure across AHUs
- Chiller entering and leaving water temperatures
- Condenser water temperatures (for water-cooled systems)
- Motor running currents and calculated power
- Room conditions (temperature and humidity) at each sampled space
Calibration of HVAC Commissioning Instruments
All instruments used for HVAC commissioning should be calibrated before use on the project. In Singapore, calibration of temperature, pressure and humidity instruments by a SAC-SINGLAS accredited laboratory ensures that commissioning data is defensible to building owners, government authorities and auditors.
Unitest Instruments offers accredited calibration for thermometers, humidity sensors, pressure gauges, manometers and electrical measurement instruments under our SAC-SINGLAS accreditation LA-2023-0845-C. Standard in-lab turnaround is 3–5 working days. For contractors needing instruments at short notice, our instrument rental service provides calibrated instruments ready to use. Contact us to discuss your commissioning instrument needs.
Selecting the Right Instruments for Your Project
The instrument selection depends on the project scope. A small office fit-out requires a vane anemometer, a thermometer and a digital manometer. A large district cooling or hospital project may require capture hoods, micromanometers, power analysers, extensive data logging and pitot traverse equipment. Cleanroom projects add requirements for particle counters, very precise temperature and humidity measurement and pressure differential monitoring.
Our team at Unitest Instruments can help you assemble a calibrated instrument kit for any commissioning project. We supply Fluke, CS Instruments, Comark, Rotronic and other brands through our product range, and our calibration laboratory ensures every instrument leaves with a current, traceable certificate.