Metering and Considerations
Metering is the backbone of M&V. Key considerations include what to measure (energy, power, flow, temperature, runtime, weather), where (measurement boundary), how often (interval: hourly, daily, monthly), and with what accuracy. Meter accuracy, calibration, and installation must match the data quality objectives in the M&V plan.
Key concepts: accuracy vs. precision, meter calibration intervals, data logging and communications, data validation and gap handling, sampling (statistical vs. judgment), and temporary vs. permanent metering. Interval data (hourly or 15-minute) supports regression and load-shape analysis; monthly data limits model sophistication. Weather data sources (on-site vs. airport) and their representativeness matter.
Traps: assuming a meter's accuracy is better than its specification; ignoring calibration drift; using a single spot measurement to represent a season; failing to validate data (outliers, missing intervals); and choosing an interval too coarse for the measure (e.g., monthly data for a measure with strong daily variation). Questions may test whether temporary metering can substitute for permanent metering (yes, if documented and sufficient) and whether sampling requires a statistical basis (often yes for large populations).
Worked example: A pump retrofit. Measure pump power with a power meter (±1% of reading) at 15-minute intervals for two weeks, plus flow and head at representative conditions. Validate data by checking for gaps and outliers; if 5% of intervals are missing, document the gap-filling method. Extrapolate runtime using a logged run-hour signal rather than assuming schedule. Report meter accuracy and calibration date in the M&V report.