Setting an 8% utility target and a production-linked monthly M&V baseline

01 · CASE ANALYSIS

Operating challenge

Production-equipment electricity changed relatively little while supporting utility electricity increased. Monthly records were insufficient for precise chiller/pump performance analysis.

Measured chilled-water ΔT was 3.8°C in April, 3.1°C in July and 3.4°C in October against an 8°C design value. Compressor unloading consumed about 11% of compressor electricity. Seasonal utility behavior required a monthly baseline.

02 · CASE ANALYSIS

Target basis and factor model

Cooling performance was estimated at about 0.60–0.64 kWh/RT using prior facility benchmarks, with a reference mean around 0.646. Compressed-air benchmark mean was approximately 0.117. Together with low ΔT and unloading, the report judged approximately 8–10% potential and selected an 8% project target.

For month m, Factor(m) = [baseline total electricity(m) − baseline production electricity(m)] / baseline production electricity(m). Savings(m) = current production electricity(m) × agreed baseline Factor(m) − [current total electricity(m) − current production electricity(m)]. Production electricity is an activity proxy, not a direct production-volume measurement.

03 · CASE ANALYSIS

Operating improvement scope

Review cooling demand, valves, pumping and chiller balance to address low ΔT. Adjust compressor combinations, loading/unloading and pressure to demand, and align AHU/other-utility operation with production and seasons.

The report cites prior low-ΔT field experience of about 5–10% cooling-system savings, but that is background experience, not a measured result at this copper factory.

04 · CASE ANALYSIS

Baseline agreement and M&V

Agree before implementation whether to use the most recent year’s monthly factors or the three-year monthly means. The source considers recent-year behavior practical, while longer means can moderate individual-year abnormalities.

For precise potential analysis, obtain at least a week of seasonal 5–10-minute chiller/pump power, chilled-/cooling-water temperatures and valve-position records. The 8% remains a target until actual reporting-period data are evaluated against the agreed baseline.

05 · CASE ANALYSIS

Engineering lesson

A pragmatic proxy baseline can support M&V when detailed data are scarce, but its boundary and assumptions must be agreed. Do not present benchmark-derived targets as measured equipment savings.