Energy Use Measurement, Documentation, and Customer Reporting
What this domain tests
This domain covers how you measure energy use, document the baseline and result, and report savings honestly. The exam expects true-RMS electrical measurement, weather normalization and clear customer-facing documentation.
Core rules
- Use a true-RMS power meter or data logger; nameplate FLA is not measured current. Single-phase kW = volts × amps × power factor / 1,000. Three-phase kW = volts × amps × power factor × 1.732 / 1,000.
- Measure run time and duty cycle, not just instantaneous kW. Energy = kW × hours; cost = kWh × tariff.
- Normalize comparisons with degree days or matched weather periods. A mild year is not a savings measure.
- Document baseline conditions, instrument type and calibration, date and time, model and serial numbers, AHRI number, measured airflow, static pressure, superheat or subcooling, and ΔT.
- Separate measured savings from estimated or modeled savings, and state uncertainty.
Worked example
A condensing unit draws 3.2 kW and runs 8 hours per day for 120 cooling days. Energy = 3.2 × 8 × 120 = 3,072 kWh. At $0.14/kWh, cost = $430. After correcting a dirty condenser and low airflow, draw falls to 2.8 kW: savings = 0.4 × 8 × 120 = 384 kWh, or $53.76 per season. The report should show the measurement method, the weather period and the assumption that run hours were unchanged.
Traps
- Multiplying nameplate FLA by voltage and calling it kW.
- Ignoring power factor on motor loads.
- Comparing bills from two different weather years without normalization.
- Reporting projected savings as measured results.