“Over time, building performance drifts out of tolerance from the original design intent. When occupancy changes, equipment wears, and temporary setpoint adjustments aren’t restored, a building will perform very differently than it did at move-in. For these reasons, even a fairly new building that was commissioned and aligned with design intent before occupancy may not be meeting its owner’s operational expectations.
Even when the components are complex, the HVAC system control logic should not be. If facility staff, in response to a building occupant complaint or a change in tenancy, cannot quickly find a simple or temporary adjustment to the system, they will be forced to override the controls and deviate from the intended, and presumably optimal, sequence of operations.
Some of the problems that routinely occur include: permanent temperature resets that may result in simultaneous heating and cooling or poor refrigeration performance, system static pressure increases to overcome isolated air distribution issues, automatic start/stop overrides, manual locking of outside air dampers, disabling energy conservation control features, non-functioning sensors, previously unknown control device and valve failure and improper installation of components.”