For two decades, IPMVP Option D — calibrated simulation — was the protocol no banker would accept. Too many knobs, too much modeller discretion, no clean counterfactual.
Four years ago, an AI-HVAC pilot's savings claim was a footnote in a CFO's deck. In 2026, the convergence of ASHRAE Guideline 14-2023 , IPMVP Option C with NMEC normalization , automated M&V 2.0 platforms , and California's expanded…
The Measurement & Verification (M&V) discipline is quietly splitting into two worlds. On one side: the legacy Option C spreadsheet — monthly utility bills, manual regressions, a 12-month wait before anyone can confirm savings.
A practitioner's framework for the IPMVP Option C / Option D choice — where calibrated simulation earns its complexity.