Certified Energy Auditor Certification Energy Audit Data Analysis 4 — Questions and Answers
Question 1: An energy auditor is analyzing a chiller plant and calculates a coefficient of performance (COP) of 2.8. The manufacturer's rated COP is 5.5. What action should the auditor prioritize?
- Flag the chiller for immediate replacement with a higher-efficiency unit
- Investigate operating conditions such as condenser water temperature, fouling, and refrigerant charge (Correct answer)
- Recommend increasing chilled water supply temperature setpoint
- Calculate the energy penalty of the chiller and move on to other systems
Correct answer: Investigate operating conditions such as condenser water temperature, fouling, and refrigerant charge
A COP far below rated performance typically indicates an operational or maintenance issue—fouled tubes, high condenser water temp, low refrigerant—rather than an immediate need for replacement.
Question 2: What is the purpose of conducting a 'blower door test' during an energy audit?
- To measure the airflow capacity of air handling units
- To quantify building envelope air leakage at a standardized pressure differential (Correct answer)
- To test the performance of exhaust fans in meeting code requirements
- To balance supply and return airflows in the HVAC distribution system
Correct answer: To quantify building envelope air leakage at a standardized pressure differential
A blower door test depressurizes or pressurizes the building to a standard 50 Pa and measures air infiltration rate (ACH50), identifying envelope leakage magnitude and locations.
Question 3: When analyzing lighting system data, an auditor calculates lighting power density (LPD) in W/ft². This metric is primarily compared against:
- The installed lamp wattage ratings from manufacturer datasheets
- ASHRAE 90.1 or IECC code allowances for the space type (Correct answer)
- The facility's historical LPD from five years prior
- IES recommended illuminance levels for task areas
Correct answer: ASHRAE 90.1 or IECC code allowances for the space type
LPD is benchmarked against ASHRAE 90.1 or IECC code maximums for the specific space type to determine if the lighting system is code-compliant or over-lit.
Question 4: An auditor identifies that a commercial building's HVAC system runs at full capacity overnight when the building is unoccupied. What data analysis step should be performed first?
- Calculate the annual energy cost of overnight HVAC operation
- Review BAS/BMS schedules and control sequences to identify programming errors or sensor failures (Correct answer)
- Recommend installing occupancy sensors throughout the building
- Measure room-by-room temperatures during unoccupied hours
Correct answer: Review BAS/BMS schedules and control sequences to identify programming errors or sensor failures
Before recommending solutions, the auditor must determine whether the overnight operation is a control issue (wrong schedule, failed sensor) or an intentional setpoint strategy.
Question 5: Which statistical method is best suited for identifying whether two variables—such as production volume and energy consumption—have a meaningful linear relationship?
- Chi-square test of independence
- Pearson correlation coefficient analysis (Correct answer)
- Analysis of variance (ANOVA)
- Confidence interval estimation
Correct answer: Pearson correlation coefficient analysis
The Pearson correlation coefficient (r) measures the strength and direction of a linear relationship between two continuous variables, commonly used in energy-production regression analysis.
Question 6: A facility's annual electricity bill shows demand charges representing 45% of total cost. What type of energy conservation measure should the auditor prioritize recommending?
- Measures that reduce total kWh consumption through equipment efficiency
- Demand response strategies and load shifting to reduce peak kW (Correct answer)
- Renewable energy generation to offset consumption charges
- Power factor correction to reduce reactive power
Correct answer: Demand response strategies and load shifting to reduce peak kW
When demand charges dominate the bill, reducing peak demand through load shifting, demand response, or peak shaving will yield the greatest cost savings.
Question 7: What does a 'metered savings' approach in M&V Option B (IPMVP) require that Option A does not?
- Stipulation of baseline operating conditions using engineering assumptions
- Continuous measurement of all energy parameters affected by the installed measure (Correct answer)
- Calculation of savings using a whole-building regression model
- Verification of equipment installation through on-site inspection only
Correct answer: Continuous measurement of all energy parameters affected by the installed measure
IPMVP Option B requires continuous sub-metering and measurement of all key parameters (power, runtime) for the specific measure, while Option A stipulates some parameters to reduce monitoring cost.
Certified Energy Auditor Certification Energy Audit Data Analysis 4
An energy auditor is analyzing a chiller plant and calculates a coefficient of performance (COP) of 2.8.
The manufacturer's rated COP is 5.5.
What action should the auditor prioritize?