Existing-Building Retro-Cx Flashcards
7 cards from real CCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Existing-Building Retro-Cx flashcards as text
During trend log analysis, you notice that the AHU supply air temperature oscillates ±6°F around setpoint every 8 minutes. This pattern most likely indicates:
Answer: Hunting caused by aggressive PID control gains
Rapid, regular oscillation around setpoint is the classic signature of a PID loop that is over-tuned (too high gain or too low integral time).
Retro-commissioning of lighting systems most commonly reveals savings opportunities through:
Answer: Correcting daylighting control setpoints and occupancy sensor coverage gaps
Miscalibrated daylighting sensors and poorly positioned occupancy sensors are operational faults that prevent lighting controls from delivering their designed energy savings.
Which metric is most commonly used to prioritize retro-commissioning measures for implementation?
Answer: Simple payback period
Simple payback (cost divided by annual savings) is the standard metric in RCx because it communicates project value to building owners without requiring complex financial modeling.
A steam heating system shows persistent condensate backup in multiple traps. The most likely cause identified in RCx is:
Answer: Failed-closed steam traps blocking condensate drainage
Failed-closed steam traps block condensate from draining, causing backup that floods heat exchanger coils and reduces heat transfer efficiency.
The retro-commissioning scoping phase is primarily used to:
Answer: Determine the extent of the investigation and develop the project plan
Scoping defines the systems to be investigated, the data to be collected, and the project schedule and budget before detailed field work begins.
When verifying economizer operation during RCx, which condition should trigger economizer lockout?
Answer: Outdoor air enthalpy above the building's high-limit cutoff setpoint
Economizers should lock out when outdoor air enthalpy (or dry-bulb temperature, depending on the control strategy) exceeds the high-limit setpoint to prevent introducing warm, humid air.
A retro-commissioning team finds that a building's BAS has hundreds of unacknowledged alarms spanning six months. This primarily indicates:
Answer: Alarm fatigue and inadequate O&M procedures for alarm management
A backlog of unacknowledged alarms indicates that O&M staff are overwhelmed or untrained on alarm management, allowing real equipment faults to go unaddressed.