IPMVP Option C Explained: Whole-Building M&V Made Simple

The International Performance Measurement and Verification Protocol (IPMVP) provides a standardized framework for quantifying energy savings. Option C — Whole Facility measurement — is the most commonly used approach for buildings with multiple interacting systems.

What Is IPMVP Option C?

Option C uses whole-building utility meter data to determine savings. Instead of measuring individual equipment, you compare the building's total energy consumption before and after an efficiency project, adjusting for weather and other variables.

Savings = Adjusted Baseline Energy - Post-Retrofit Energy ± Adjustments

When to Use Option C

Option C is ideal when: - Multiple energy conservation measures (ECMs) are implemented simultaneously - Individual system-level measurement is impractical or cost-prohibitive - The expected savings are large enough to be detectable at the whole-building level (typically >10%)

The EdiMono Workflow

1. Define the baseline period — usually 12 months of pre-retrofit data
2. Build the regression model — EdiMono tests multiple model forms automatically
3. Collect post-retrofit data — at least 12 months recommended
4. Calculate adjusted baseline — what the building *would have* consumed under post-retrofit weather
5. Determine savings — the difference between adjusted baseline and actual consumption
6. Assess uncertainty — EdiMono calculates fractional savings uncertainty per ASHRAE 14

Statistical Requirements

ASHRAE Guideline 14 sets minimum thresholds: - R² ≥ 0.70 — the model explains at least 70% of consumption variance - CV(RMSE) ≤ 20% — the model's prediction error is within acceptable bounds - Fractional savings uncertainty ≤ 50% at 68% confidence — savings are statistically detectable

Interactive vs. Non-Interactive Effects

One challenge with Option C is that it captures *all* changes, not just the intended ECMs. You need to account for non-routine adjustments: - Changes in building occupancy or operating hours - New equipment additions (e.g., EV charging stations) - Space use changes (e.g., converting offices to labs)

EdiMono allows you to define non-routine adjustments and see their impact on reported savings.

Key Takeaway

Option C is powerful because it captures interactive effects between systems. EdiMono automates the regression modeling, statistical validation, and savings calculations — turning what used to be weeks of spreadsheet work into a few clicks.