retro commissioning by John A. Herbert

The principal is sound, if not the name. If you are old enough to remember the adverts for a crypton tune-up, you’ll understand the gist.

Due to mechanical wear and tear the engineering systems in our buildings inevitably need attention, and some twenty years ago, the phrase re-commissioning entered our vocabulary to brand the process of tuning the often forgotten ACMV systems.

But it is not really commissioning, not even close. Commissioning occurs after a new system is installed and those static systems are set into operation for the first time, complete with the countless startup and shutdown checklists.

Here in Hong Kong, T&C (Testing and Commissioning) is commonly used for starting new systems. To fix old buildings, the term “commissioning” is a misnomer in my view, it simply doesn’t apply to an existing system already operating.  Building tuning, my preferred term, is apter. We want to check and adjust, not start from scratch. For example, for the chilled water circuit, the point of re-commisisoning, as it is called, would be to check the flow rates and pressures satisfy the design intent, Because pumps and motors may have changed, the control valves need checking, what’s the value authority, etc. From experience, flow direction labels installed backward are confusing.

John A. Herbert energy expert

Indeed, a key target for undertaking re-commissioning is the same as an energy audit, to find cost saving opportunities and lower operating costs. Particularly for air conditioning systems, warmer weather over the last three years has caused increased energy costs, and the Observatory is predicting that this season will be another record.  Yet, some buildings are still operating today where the set points were checked at Practical Completion.

Yet, some buildings operating today have set points last checked at Practical Completion. Although buildings appear to be static, internally the mechanical and electricity systems need attention.

For advice regarding re-commissioning contact the experts today!