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The building commissioning process often relies upon the controls contractor to retrieve critical operating data, establish operating benchmarks, and verify the sequence of operation. A cynic might make a remark about professor Fox conducting a class in poultry science. BACbone bypasses the controls contractor and lets the commissioner harvest information straight from the controlling devices – machine to machine. On site or via the web, the commissioner has total access to BACnet compliant devices and can generate a complete system database.
Within BACbone, every value can be analyzed with the X-Ray. Mathematical expressions quickly sort through the database to provide the commissioner with insights into the functioning of the controls and mechanical equipment. Relationships can be exploited to reveal non-conformance to project requirements.
At M2M Systems Integrators we’ve employed the BACbone to investigate many project parameters. The following are examples of mathematical expressions that have been useful in discovering HVAC problems.
VAV controller K factors equal to factory default value indicating possible gaps in TAB execution.
Space temperature greater than setpoint plus 1 degree or space temperatures less than setpoint minus 1 degree to reveal problem areas.
The value mixed air temperature less return air temperature divided by the value of outside air temperature less return air temperature expressed as percentage less the control signal to the outside air actuator expressed as a percentage where differences in excess of 20% suggest that a damper linkage may have come loose and the air handler merits investigation. Other possible sources of discrepancy may be sensor error, indeterminate tempeature readings during mild ambient conditions, and controller error.
Mathematical manipulation of real time information holds exciting potential for starting building mechanical systems off on the right foot during commissioning and maintaining them for sustainable performance over the long term.
Download the Blue Lake report (300 kb .pdf). |
