Certified Energy Auditor Certification Certified Energy Auditor Energy Audit Data Analysis Questions and Answers 2 — Questions and Answers
Question 1: When performing a regression analysis on building energy consumption, which variable is most commonly used as the independent variable?
- Heating degree days (Correct answer)
- Building square footage
- Number of occupants
- Electricity rate
Correct answer: Heating degree days
Heating degree days are the standard independent variable in energy regression analysis because they directly correlate with weather-driven energy consumption.
Question 2: What does a Coefficient of Determination (R-squared) value of 0.92 indicate in an energy baseline model?
- 92% of energy variance is explained by the model (Correct answer)
- The model has a 92% chance of being correct
- Energy use will decrease by 92%
- The building operates at 92% efficiency
Correct answer: 92% of energy variance is explained by the model
An R-squared value of 0.92 means the regression model explains 92% of the variability in the energy consumption data.
Question 3: During an energy audit, you discover that a building's Energy Use Intensity (EUI) is 120 kBtu per square foot per year. Compared to the CBECS median for office buildings, this value is:
- Above average, indicating potential for improvement (Correct answer)
- Below average, indicating good performance
- Exactly at the national median
- Too low to be accurate
Correct answer: Above average, indicating potential for improvement
The CBECS median EUI for US office buildings is approximately 80-90 kBtu/sf/yr, so 120 kBtu/sf/yr is above average and suggests energy savings opportunities.
Question 4: Which statistical method is most appropriate for identifying abnormal energy consumption patterns in interval meter data?
- CUSUM analysis (Correct answer)
- Simple averaging
- Peak demand calculation
- Power factor correction
Correct answer: CUSUM analysis
Cumulative Sum (CUSUM) analysis is specifically designed to detect shifts and trends in energy consumption data over time.
Question 5: When normalizing energy data for weather, what is the primary purpose of using a change-point model instead of a simple linear regression?
- To account for different heating and cooling energy relationships (Correct answer)
- To simplify the calculation process
- To eliminate the need for weather data
- To reduce the number of data points required
Correct answer: To account for different heating and cooling energy relationships
Change-point models capture the distinct relationships between energy use and temperature for heating and cooling modes, which a single linear regression cannot accurately represent.
Question 6: An energy auditor collects 12 months of utility bill data and finds the coefficient of variation of the root mean square error (CV-RMSE) is 28%. According to ASHRAE Guideline 14, this baseline model is:
- Not acceptable for monthly data (Correct answer)
- Acceptable for monthly data
- Acceptable for hourly data only
- Not enough information to determine
Correct answer: Not acceptable for monthly data
ASHRAE Guideline 14 requires CV-RMSE to be no greater than 15% for monthly calibrated models, so 28% does not meet the standard.
Certified Energy Auditor Certification Certified Energy Auditor Energy Audit Data Analysis Questions and Answers 2
When performing a regression analysis on building energy consumption, which variable is most commonly used as the independent variable?