Data Collection & Analysis
What this domain tests
Data collection and analysis covers the measurement plan, instrument selection, sampling, and data quality. The exam wants evidence that your numbers can survive scrutiny.
Core rules
- Choose continuous logging for variable loads and spot measurements for steady ones.
- Match interval to the load: 1–15 minutes for electric demand, hourly for temperature.
- Use the right tool: power logger for kW, ultrasonic or clamp-on flow for water, infrared for envelope and electrical hot spots, balometer for airflow, combustion analyzer for boilers.
- Record calibration status, accuracy, and measurement location.
- Reconcile measured data with utility bills; a 10% gap needs explanation, a 30% gap needs investigation.
Worked example
A chiller sub-meter logs 250 kW for 2,000 hours, giving 500,000 kWh. The utility bill allocates 480,000 kWh to cooling. Difference = 20,000 ÷ 500,000 = 4%, within instrument and allocation error, so the measurement is accepted. If the gap were 30%, you would check CT ratio, logger clock, and whether other loads share the circuit.
Traps
Extrapolating a single spot reading to a full year; ignoring part-load behavior; forgetting occupancy and schedule changes; and failing to document assumptions so the analysis cannot be reproduced.