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
A retro-commissioning investigation finds that supply air static pressure setpoint is 1.5 in. w.g. and never resets downward even at low load. The recommended measure is:
Answer: Implement supply air static pressure reset based on VAV box damper positions
Static pressure reset—reducing setpoint when all VAV boxes have adequate flow—is a proven RCx measure that cuts fan energy significantly at partial load.
During RCx, it is discovered that a building's controls sequence calls for chilled water supply temperature reset, but the reset has been disabled. The most likely reason found in O&M interviews is:
Answer: Operators disabled it after occupant complaints about inadequate cooling during one summer
Operators often disable energy-saving sequences after a comfort complaint, and the sequence never gets re-enabled—a common RCx finding that represents recoverable savings.
Which of the following is NOT typically part of the RCx investigation phase?
Answer: Installing permanent submetering equipment throughout the building
Permanent submetering installation is a capital project, not a standard RCx investigation activity; RCx uses existing meters, portable loggers, and BAS trends.
A large office building's chiller plant is found to run two equally sized chillers at 40% load each rather than one chiller at 80% load. This is most likely due to:
Answer: A control sequence that lacks a chiller staging algorithm based on load
Without a proper staging algorithm, chiller plants often run multiple machines at low efficiency rather than consolidating load on fewer chillers operating near their peak efficiency.
In retro-commissioning, the term 'deferred maintenance' refers to:
Answer: Maintenance tasks that have been postponed and are now causing performance degradation
Deferred maintenance consists of overdue upkeep tasks—dirty coils, worn belts, failed actuators—that directly reduce system performance and are commonly uncovered during RCx.
Which type of retro-commissioning finding requires the MOST coordination between the RCx provider and the building owner before implementation?
Answer: Replacing a pneumatic actuator with a DDC actuator
Replacing a pneumatic actuator with DDC involves capital cost, potential downtime, and interface with existing control sequences, requiring owner approval and contractor coordination.
A building's outdoor air damper is found to be stuck at 100% open year-round. During summer in a hot-humid climate, the primary energy penalty is:
Answer: Excessive latent and sensible cooling load added to the mechanical system
In a hot-humid climate, a fully open outdoor air damper forces the cooling system to remove large amounts of heat and moisture from unconditioned outdoor air continuously, greatly increasing cooling energy use.