1. NEBB (National Environmental Balancing Bureau) does not recommend field temperature measurement as a valid method of comparing field performance to rated capacity due to measurement inaccuracies.
2. If coil capacity is critical and manufacturers data is unacceptable then factory testing should be specified where all variables can be controlled. Factory testing can be expensive and has programme impacts so should be specified as the exception rather than the rule.
3. Often coil testing is specified to be performed pre-occupancy which means that it does not take into account the real space heating and cooling loads e.g people, computers, equipment and sometimes lighting. In some cases load banks can be used to simulate space heat load.
4. If post-occupancy coil testing is specified this means that the systems need to be put into full heating/cooling mode during the testing which will impact on the occupant comfort during the test period.
5. HHW coils can be tested by fully opening the HHW control valves and measuring the on and off-coil air and water temperatures and flows. The coil kW can be calculated irrespective of the on-coil conditions.
6. CHW coils are more difficult to test as there needs to be a cooling load to ensure the heat transfer occurs when the CHW coil valves is fully opened. On-coil conditions (wet and dry-bulb temperatures) need to be achieved to verify the total cooling capacity; this is a variable that cannot be controlled and will impact the coil performance.

Even if coil capacities could be successfully tested in the filed and verified to meet the design requirements we often find that the design does not end up meeting the occupant comfort requirements.

It is our recommendation that field coil testing is unnecessary and the following steps are:

1. Coils/control valves are correctly selected to meet the design requirements – This is carried out during the contractor technical submittal and approval process
2. Waterside is properly balanced to CIBSE or NEBB accepted tolerances
3. Airside is properly balanced to CIBSE or NEBB accepted tolerances
4. BMS is commissioned to achieve stable temperature control

The above steps can be verified and accepted by the Engineer prior to handover. Post occupancy monitoring of the system via the BMS will confirm if the space conditions are being met which may result in the Engineer instructing some tuning of the system.

The participants will be supported by Carl D’Rose, Airlab’s NEBB Certified Professional who will be organising study groups for the technicians to ensure they have the confidence and knowledge to pass the final stringent exam.

GOOD LUCK GUYS!!

This confirms Airlab’s commitment to the NEBB program and our objective of ensuring we deliver the highest quality HVAC commissioning services to the industry.

This will significantly enhance Airlab’s ability to manage the commissioning process of large commercial, institutional and healthcare infrastructure projects.

Both Chris and Carl have extensive experience in the HVAC industry in New Zealand and in Carl’s case, the United States of America.

Their work with Airlab will nicely dovetail with the building services coordination work and ICA (Independent Commissioning Authority) work that they presently carry out with Pacific Consultants. Thus Airlab will be in a position to offer clients a complete packaged commissioning and commissioning management service which has become increasingly necessary on major projects.

Its members perform testing, adjusting and balancing of HVAC systems, commission and retro-commission building systems, carry out sound and vibration testing, and test and certify laboratory fume hoods and cleanrooms.

To achieve certification Airlab had to demonstrate it had the required instrumentation (calibrated) and that it employed a qualified NEBB Supervisor for the certified systems.

Airlab has been admitted to the Australian chapter of NEBB.