EMP Data Collection & Analysis 2 — Questions and Answers
Question 1: Which statistical measure is most useful for identifying outliers in energy consumption data?
- Mean absolute deviation
- Interquartile range (IQR) (Correct answer)
- Arithmetic mean
- Geometric mean
Correct answer: Interquartile range (IQR)
The IQR defines the middle 50% of data, and values beyond 1.5×IQR from the quartiles are flagged as outliers.
Question 2: A utility meter records energy use every 15 minutes. What is this interval called?
- Billing cycle
- Interval data (Correct answer)
- Demand response window
- Peak shaving period
Correct answer: Interval data
Sub-hourly meter readings captured at fixed time steps are called interval data and are used for detailed load profiling.
Question 3: An energy manager wants to compare the energy efficiency of buildings of different sizes. Which metric is most appropriate?
- Total annual kWh
- Energy Use Intensity (EUI) (Correct answer)
- Peak demand (kW)
- Power factor
Correct answer: Energy Use Intensity (EUI)
EUI normalizes energy consumption by floor area (kBtu/sq ft/year), enabling fair comparison across buildings of different sizes.
Question 4: What does a low R² value in a regression model for energy consumption indicate?
- The model perfectly predicts energy use
- The independent variables explain little variance in energy use (Correct answer)
- Energy costs are below the industry benchmark
- The data collection interval is too short
Correct answer: The independent variables explain little variance in energy use
A low R² means the chosen independent variables (e.g., weather, occupancy) do not adequately explain the variation in energy consumption.
Question 5: Which data source provides outdoor temperature data most commonly used in energy regression analysis?
- Utility smart meters
- Heating degree days (HDD) and cooling degree days (CDD) (Correct answer)
- Building automation system logs
- Power quality analyzers
Correct answer: Heating degree days (HDD) and cooling degree days (CDD)
HDD and CDD are derived from weather station data and are the standard independent variables for correlating energy use to outdoor temperature.
Question 6: What is the primary purpose of a data historian in an industrial energy management system?
- To generate utility invoices
- To store and retrieve time-series process and energy data (Correct answer)
- To control HVAC setpoints automatically
- To calculate carbon offset credits
Correct answer: To store and retrieve time-series process and energy data
A data historian archives time-series data from sensors and control systems, enabling trend analysis and performance benchmarking.
Question 7: When normalizing energy data for weather, which base temperature is most commonly used for calculating heating degree days in the US?
- 55°F
- 65°F (Correct answer)
- 72°F
- 80°F
Correct answer: 65°F
65°F (18.3°C) is the standard US base temperature for calculating HDD, representing the point below which heating is typically required.
EMP Data Collection & Analysis 2
Which statistical measure is most useful for identifying outliers in energy consumption data?