Retrocommissioning Keeps BAS Working At Peak Efficiency

6. Retrocommission the BAS. Even with good operating and maintenance practices, wear and tear take their toll on system components, from temperature sensors to valves and dampers. And while the HVAC equipment will most likely keep operating, it will not be operating at peak efficiency. To maximize the potential of the BAS, facility managers must confirm that the information being gathered by the system is correct and accurate, and that all functions are carried out as intended.

The only way to confirm that things are as they should be is with retrocommissioning. Retrocommissioning verifies readings of all sensors and operation of all control devices in the system.

Start by interviewing operators. What problems are they aware of, and what has been attempted to correct them? The reading of every sensor in the system will have to be verified. All devices connected to the system must be cycled and witnessed to confirm they are being operated properly. Failing to do this will allow error creep to slowly rob the system of performance and reliability. How often retrocommissioning should be repeated depends on the complexity of the system; the general recommendation is at least once every two years.

Retrocommissioning can also help to identify changes that have taken place within the facility but have not yet been addressed by the system. Facilities are always in a state of flux. As a result, existing HVAC systems are modified or replaced. While connections from those systems to the BAS should be updated at the time of the occupancy change, not all are. Retrocommissioning is one way to ensure that all systems and their interface with the BAS are current. ■

James Piper, PhD, PE, is a writer and consultant who has more than 35 years of experience in facilities management. He is a contributing editor for Building Operating Management.

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