CBCP CBCP Energy Management & Sustainability 2 — Questions and Answers
Question 1: What is 'demand-controlled ventilation (DCV)' and why is it significant in energy commissioning?
- Ventilation controlled by occupant manual switches
- Adjusting outdoor air supply based on actual CO2 levels to reduce over-ventilation energy waste (Correct answer)
- Emergency ventilation triggered by smoke detectors
- Controlling ventilation based on outdoor temperature only
Correct answer: Adjusting outdoor air supply based on actual CO2 levels to reduce over-ventilation energy waste
DCV uses CO2 sensors as a proxy for occupancy to modulate outdoor air intake, preventing energy waste from over-ventilating lightly occupied spaces.
Question 2: An energy model predicts a building will use 45 kBtu/sq ft/yr, but post-occupancy metering shows 72 kBtu/sq ft/yr. What is the first step in a commissioning investigation?
- Replace all HVAC equipment immediately
- Review BAS trend data and compare actual operating schedules and setpoints against design assumptions (Correct answer)
- Increase insulation on all exterior walls
- Install more energy meters
Correct answer: Review BAS trend data and compare actual operating schedules and setpoints against design assumptions
Reviewing BAS trend data against design assumptions identifies whether operational deviations (schedules, setpoints, equipment runtime) explain the gap.
Question 3: What is 'measurement and verification (M&V)' in the context of energy commissioning?
- Verifying electrical panel labels match circuit schedules
- A systematic process of measuring and analyzing energy data to confirm that energy conservation measures achieve their predicted savings (Correct answer)
- Calibrating water flow meters only
- Testing fire alarm notification appliances
Correct answer: A systematic process of measuring and analyzing energy data to confirm that energy conservation measures achieve their predicted savings
M&V quantifies actual energy savings from conservation measures by comparing measured baseline and post-implementation energy consumption.
Question 4: Which ASHRAE standard provides guidance on measurement and verification of energy and water savings in buildings?
- ASHRAE 55
- ASHRAE 62.1
- ASHRAE Guideline 14 (Correct answer)
- ASHRAE 90.1
Correct answer: ASHRAE Guideline 14
ASHRAE Guideline 14 provides protocols for measuring and verifying energy and water savings from efficiency projects.
Question 5: What is the purpose of a 'building energy audit' conducted during retro-commissioning?
- Reviewing the building's financial statements
- Systematically identifying energy waste, inefficiencies, and opportunities for improvement in existing building systems (Correct answer)
- Auditing safety compliance records
- Reviewing contractor submittals
Correct answer: Systematically identifying energy waste, inefficiencies, and opportunities for improvement in existing building systems
An energy audit evaluates existing building systems to identify operational deficiencies and capital improvements that reduce energy consumption.
Question 6: In a chilled water system, what commissioning check helps verify that the chiller is operating at or near its design efficiency (kW/ton)?
- Measuring chilled water pipe insulation thickness
- Verifying entering and leaving chilled water temperatures, flow rate, and compressor power draw to calculate actual efficiency (Correct answer)
- Checking condenser water chemical treatment logs
- Testing expansion valve superheat settings
Correct answer: Verifying entering and leaving chilled water temperatures, flow rate, and compressor power draw to calculate actual efficiency
Calculating actual kW/ton requires measuring water temperatures, flow, and electrical power, confirming the chiller matches its rated efficiency.
CBCP CBCP Energy Management & Sustainability 2
What is 'demand-controlled ventilation (DCV)' and why is it significant in energy commissioning?