CCP Existing-Building Retro-Cx 2 — Questions and Answers
Question 1: During a retro-commissioning investigation, you discover that a chiller is operating at 20% below its rated efficiency. What is the MOST likely first step?
- Replace the chiller immediately
- Review maintenance logs and conduct a refrigerant charge check (Correct answer)
- Install a new BAS to monitor the chiller
- Increase the chilled water setpoint by 5°F
Correct answer: Review maintenance logs and conduct a refrigerant charge check
Reviewing maintenance logs and checking refrigerant charge are low-cost diagnostic steps that often reveal the root cause of chiller efficiency degradation.
Question 2: Which document is the primary deliverable at the END of a retro-commissioning project?
- Commissioning Plan
- Findings and Recommendations Report (Correct answer)
- Owner's Project Requirements
- Systems Manual
Correct answer: Findings and Recommendations Report
The Findings and Recommendations Report summarizes all identified deficiencies, proposed measures, and projected savings for the owner's decision-making.
Question 3: A VAV box consistently delivers less airflow than its minimum setpoint. After calibrating the flow sensor, the problem persists. What should be investigated next?
- Controller firmware version
- Duct leakage upstream of the VAV box (Correct answer)
- Thermostat calibration in the zone
- Chilled water valve stroke
Correct answer: Duct leakage upstream of the VAV box
Duct leakage upstream of a VAV box reduces available static pressure, causing actual airflow to fall short of the setpoint even with a properly calibrated sensor.
Question 4: In retro-commissioning, a 'no-cost/low-cost' measure is best described as an improvement that:
- Requires less than $5,000 in capital and is implemented during the RCx project (Correct answer)
- Is funded through the utility rebate program only
- Defers maintenance costs to future budget cycles
- Involves replacing outdated HVAC equipment with high-efficiency models
Correct answer: Requires less than $5,000 in capital and is implemented during the RCx project
No-cost/low-cost measures are operational or minor adjustments made during the RCx engagement itself, typically with simple paybacks under two years.
Question 5: What is the primary purpose of the 'master list of findings' in a retro-commissioning project?
- To document all deficiencies identified so they can be prioritized and tracked to resolution (Correct answer)
- To serve as the formal contract between the RCx provider and the building owner
- To replace the existing Operations and Maintenance manuals
- To list all equipment scheduled for replacement in the next fiscal year
Correct answer: To document all deficiencies identified so they can be prioritized and tracked to resolution
The master list of findings is a living document that tracks every identified issue, its proposed correction, cost, and status through project closeout.
Question 6: A building energy model is used during RCx to:
- Replace the need for trending data from the BAS
- Baseline current energy use and quantify savings from proposed measures (Correct answer)
- Satisfy ASHRAE 90.1 compliance requirements automatically
- Generate as-built drawings for the facility manager
Correct answer: Baseline current energy use and quantify savings from proposed measures
Energy modeling during RCx establishes a calibrated baseline and allows the team to estimate the energy and cost savings of each recommended measure.
Question 7: Which condition would most strongly indicate that an existing building is a good candidate for retro-commissioning?
- The building was constructed within the last two years
- Energy use intensity is significantly higher than CBECS benchmarks for the building type (Correct answer)
- All HVAC equipment was replaced five years ago
- The building has never had occupant comfort complaints
Correct answer: Energy use intensity is significantly higher than CBECS benchmarks for the building type
An EUI significantly above the Commercial Buildings Energy Consumption Survey (CBECS) median for its building type signals operational inefficiencies that RCx can address.
CCP Existing-Building Retro-Cx 2
During a retro-commissioning investigation, you discover that a chiller is operating at 20% below its rated efficiency.
What is the MOST likely first step?