Last month, this column presented monitoring-based commissioning (MBCx) as a subset of ongoing commissioning of buildings that have previously been commissioned or retro-commissioned. The MBCx elements of ongoing commissioning involve remote monitoring of data collected by devices installed in the systems. Categories and examples of such devices include:
- Utility energy meters;
- Energy submeters; and
- BAS or third-party software diagnostic system points, such as:
- Relative humidities;
- Air quality;
- Air and water flow measuring stations;
- Amperage; and
- Valve or damper position feedback.
Installing these devices as part of a major construction project is just the first step toward implementing an MBCx plan. The next step is to have the design/construction commissioning professional verify the MBCx devices and reporting systems function as specified by the design engineers. This includes confirmation of point-to-point checkout, verification of device calibration and range, and review of data reports/trends and user interface functionality.
This initial commissioning is non-trivial and has historically been far more difficult than it really should be. For example, flow meters and energy meters almost never work correctly the first time they are tested. Multiple parties are involved in making meters useful, and having everyone do the correct thing and coordinate amongst themselves is a challenge.
This starts with the design engineer selecting the right meter for each specific application and designing the system components (pipe, ductwork, etc.) such that each meter can be installed per the manufacturer’s recommendations. Then, the contractor installs the device according to the manufacturer’s instructions and wires it to the correct control panel and termination point configured to accept the meter’s signal. Next, the controls contractor converts the meter’s signal into a meaningful value for the MBCx data analysis, and, in some cases, this involves software calculations. Finally, the controls contractor creates reports that present the data in a format conducive to human evaluation. The process is even more complex if the MBCx plan includes customized software to perform the data analysis.
After initial commissioning is successful, the MBCx equipment and reporting system is passed on to the owner’s facilities professionals for MBCx plan implementation. In order for the MBCx process to be meaningful and valuable, the facilities staff not only needs to monitor and act on the data on a regular basis, it also needs to maintain all of the associated MBCx hardware and software throughout the life of the system.
Garbage in, garbage out (GIGO) applies directly to an MBCx program, and it is critically important to ensure all devices (meters and sensors) are maintained, calibrated, and provide reasonable input values to the system. Maintenance and calibration takes real time and financial resources, and any owner committing to an MBCx plan needs to recognize and plan for it.
The best way to accomplish this is to treat the MBCx components similar to other equipment in the owner’s preventive maintenance (PM) program. Each component should have a regularly scheduled PM procedure, which, depending on the component, could include cleaning, adjusting, replacing parts, calibration checks, etc. These procedures should be based on the manufacturer’s recommended maintenance protocols and performed by in-house staff or outsourced service contractors.
The frequency of the PM procedures should initially be programmed based on the manufacturer’s recommendations but can be adjusted based on the owner’s experience and findings during the first few cycles. In general, I think an owner should assume at least annual PM procedures for each of the MBCx input devices (refer to bulleted list near the beginning of this article).
As MBCx has become a more common topic of discussion during design, owners have become aware of the potential additional capital costs associated with implementing an MBCx plan. Owners are making decisions based on the perceived benefits of those additional first costs. I recommend the ongoing time and financial resource commitments associated with sustaining an MBCx program after construction also be included in that cost/benefit analysis.
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