Certified Energy Auditor Certification Energy Audit Data Analysis 3 — Questions and Answers
Question 1: Which data visualization method is most appropriate for identifying energy consumption anomalies over a continuous 12-month period?
- Pie chart showing percentage of energy by end use
- Time-series line graph of daily or monthly consumption (Correct answer)
- Bar chart comparing annual EUI across building types
- Scatter plot of energy use versus outdoor air temperature
Correct answer: Time-series line graph of daily or monthly consumption
A time-series line graph reveals trends, anomalies, and seasonal patterns in energy data across a continuous time period.
Question 2: An auditor calculates a simple payback period of 4.2 years for a lighting retrofit. If the facility's minimum acceptable payback threshold is 3 years, what should the auditor recommend?
- Approve the project since payback under 5 years is industry standard
- Present the project with a note that it does not meet the facility's financial criteria without further optimization (Correct answer)
- Reject the project entirely as it is not cost-effective
- Recalculate using a 10-year analysis period to show cumulative savings
Correct answer: Present the project with a note that it does not meet the facility's financial criteria without further optimization
The auditor should present the measure honestly, noting it misses the threshold, and may suggest modifications (e.g., rebates, phased implementation) to improve the economics.
Question 3: When using interval meter data (15-minute readings) for demand analysis, what is the auditor primarily trying to identify?
- Total monthly energy consumption for billing verification
- Peak demand events and their coincidence with rate penalty periods (Correct answer)
- Equipment cycling frequency and motor efficiency
- Power factor correction opportunities
Correct answer: Peak demand events and their coincidence with rate penalty periods
Interval data allows auditors to pinpoint exactly when peak demand occurs, enabling strategies to shift or curtail loads during utility peak pricing windows.
Question 4: A change-point model identifies a 'balance point temperature' of 58°F for a commercial building. What does this value represent?
- The setpoint temperature of the building's thermostat
- The outdoor temperature below which heating energy consumption begins to increase (Correct answer)
- The minimum outdoor temperature at which the building can maintain comfort without HVAC
- The temperature differential across the building envelope
Correct answer: The outdoor temperature below which heating energy consumption begins to increase
The balance point (change point) is the outdoor temperature at which the building transitions from free-cooling/heating mode to active conditioning, marking the start of weather-dependent energy use.
Question 5: What is the significance of a negative net present value (NPV) for an energy conservation measure?
- The measure will save more energy than projected
- The discounted future savings do not outweigh the initial investment cost (Correct answer)
- The utility rebate was not included in the calculation
- The measure has a payback period longer than the discount rate
Correct answer: The discounted future savings do not outweigh the initial investment cost
A negative NPV means the present value of all future energy savings, discounted at the chosen rate, is less than the upfront cost—the investment destroys value at that discount rate.
Question 6: An auditor reviews power factor data and finds the facility operates at 0.72 PF. Why is this significant for an energy audit?
- Low power factor increases apparent power demand, potentially triggering utility penalty charges (Correct answer)
- Power factor below 0.8 violates NEC electrical code requirements
- A power factor of 0.72 indicates excessive harmonic distortion in the system
- Low power factor directly increases real power (kWh) consumption at all times
Correct answer: Low power factor increases apparent power demand, potentially triggering utility penalty charges
Many utilities impose power factor penalties when PF falls below 0.85 or 0.9, increasing demand charges even though real power consumption is unchanged.
Question 7: In an energy audit report, what does 'avoided cost' represent in the context of energy savings calculations?
- The cost of energy that would have been consumed without the improvement measure (Correct answer)
- The maintenance costs eliminated by replacing old equipment
- Utility rebates and incentives applied to offset installation costs
- The cost difference between standard and high-efficiency equipment
Correct answer: The cost of energy that would have been consumed without the improvement measure
Avoided cost is the value of energy that would have been purchased but is no longer needed due to the efficiency measure, calculated using the applicable utility rate.
Certified Energy Auditor Certification Energy Audit Data Analysis 3
Which data visualization method is most appropriate for identifying energy consumption anomalies over a continuous 12-month period?