Scope
- Airflow: diffuser, grille and duct flows; comparison with design values and air balancing recommendations.
- Air handling units and fans: airflow, static pressure difference and electrical power; specific fan power (SFP, W/(m³/s)).
- Indoor conditions: temperature, relative humidity and air velocity; thermal comfort assessment.
- Filters and ducts: filter pressure drops, duct leakage and insulation defects.
- Heat recovery: heat recovery efficiency from supply and exhaust temperatures.
Method and instruments
Air velocity, airflow, temperature and humidity are measured with the testo 440 set; differential pressure with the testo 510i; surface and fluid temperatures with the testo 915i and the Bosch GTC 400 C thermal camera.
Duct airflow is calculated from a multi-point velocity traverse across the section (log-Tchebycheff or equal-area method); at diffusers, airflow is measured with a vane probe.
The electrical power of fan and air handling unit motors is measured with the Kyoritsu KEW 6315, so that the power per unit of airflow (SFP) can be calculated and compared with the classes of TS EN 16798-3.
Regulations and standards
- TS EN 12599Test procedures and measurement methods for handing over ventilation and air conditioning systems
- TS EN 16798-1Indoor environmental input parameters for the energy performance of buildings
- TS EN 16798-3Ventilation for non-residential buildings; specific fan power classes
- TS EN ISO 7730Thermal comfort: PMV and PPD indices
Deliverables
- Measurement report and measurement point plan
- Airflow table: design value, measured value and difference (%) for each diffuser and duct
- Air handling unit and fan performance table: airflow, pressure difference, electrical power, SFP
- Indoor measurements and thermal images; findings and recommendations (air balancing, filters, fan speed control, leaks) with the estimated energy impact
Frequently asked questions
When is air balancing needed?
When some rooms receive too little or too much air, when there is noise or doors are hard to open (pressure difference), and after refurbishments. Measured flows are compared with the design and damper settings are recommended room by room.
Why does our air handling unit use so much energy?
Common causes are dirty filters (high pressure drop), fans running at fixed speed, excessive airflow and heat recovery that is out of operation. Electrical power and airflow are measured together to calculate the SFP, which is compared with the classes of TS EN 16798-3.
Should the system be running during the measurement?
Yes; the system is measured under normal operating conditions. Sharing the mechanical design or the air handling unit nameplate values in advance speeds up the comparison.